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| Electronics Semiconductor Division RC4190 Micropower Switching Regulator Features * * * * * High efficiency - 85% typical Low quiescent current - 215 A Adjustable output - 1.3V to 30V High switch current - 200 mA Bandgap reference - 1.31V * * * * * Accurate oscillator frequency - 10% Remote shutdown capability Low battery detection circuitry Low component count 8-lead packages including small outline (SO-8) Description The RC4190 monolithic IC is a low power switch mode regulator intended for miniature power supply applications. This DC-to-DC converter IC provides all of the active components needed to create supplies for micropower circuits (load power up to 400 mW, or up to 10W with an external power transistor). Contained internally are an oscillator, switch, reference, comparator, and logic, plus a discharged battery detection circuit. Application areas include on-card circuits where a non-standard voltage supply is needed, or in battery operated instruments where an RC4190 can be used to extend battery lifetime. These regulators can achieve up to 85% efficiency in most applications while operating over a wide supply voltage range, 2.2V to 30V, at a very low quiescent current drain of 215 A. The standard application circuit requires just seven external components for step-up operation: an inductor, a steering diode, three resistors, a low value timing capacitor, and an electrolytic filter capacitor. The combination of simple application circuit, low supply current, and small package make the RC4190 adaptable to a wide range of miniature power supply applications. The RC4190 is most suited for single ended step-up (VOUT > VIN) circuits because the NPN internal switch transistor is referenced to ground. It is complemented by another Raytheon micropower switching regulator, the RC4391, which is dedicated to step-down (VOUT < VIN) and inverting VOUT = -VIN) applications. Between the two devices the ability to create all three basic switching regulator configurations is assured. Refer to the RC4391 data sheet for stepdown and inverting applications. With some optional external components the application circuit can be designed to signal a display when the battery has decayed below a predetermined level, or designed to signal a display at one level and then shut itself off after the battery decays to a second level. See the applications section for these and other unique circuits. The RC4190 micropower switching regulator series consists of three devices, each with slightly different specifications. The RM4190 has a 1.5% maximum output voltage tolerance, 0.2% maximum line regulation, and operation to 30V. The RC4190 has a 5.0% maximum output voltage tolerance, 0.5% maximum line regulation, and operation to 24V. Other specifications are identical. Each type is available in plastic and ceramic DIPs, or SO-8 packages. Block Diagram 4190 LBR LBD C2 Q2 CX OSC C1 +1.31V 1.31V REF VFB Gnd Q1 +1.2V LX BIAS IC +VS 65-3464-01 Rev. 1.0.0 PRODUCT SPECIFICATION RC4190 Pin Assignments LBR CX GND LX 1 2 3 4 8 7 6 5 65-3464-02 Pin Definitions LBD VFB IC +VS Pin Name LBR CX Gnd LX +VS IC VFB LBD Pin Number 1 2 3 4 5 6 7 8 Pin Function Description Low Battery (Set) Resistor Timing Capacitor Ground External Inductor Positive Supply Voltage Reference Set Current Feedback Voltage Low Battery Detector Output Absolute Maximum Ratings (beyond which the device may be damaged)1 Parameter Supply Voltage (Without External Transistor) PDTA < 50C RM4190 RC4190 SOIC PDIP CerDIP Operating Temperature Storage Temperature Junction Temperature Switch Current For TA > 50C Derate at SOIC, PDIP CerDIP Peak SOIC PDIP CerDIP Note: 1. Functional operation under any of these conditions is NOT implied. Min Typ Max 30 24 300 468 833 Units V V mW mW mW C C C C C RM4190 RC4190 -55 0 -65 125 175 125 70 150 375 4.17 6.25 8.33 mA mW/C mW/C mW/C Operating Conditions Parameter JC JA Thermal resistance Thermal resistance CerDIP SOIC PDIP CerDIP Min Typ 45 200 160 120 Max Units C/W C/W C/W C/W 2 RC4190 PRODUCT SPECIFICATION Electrical Characteristics (+VS = +6.0V, IC = 5.0 A over the full operating temperature range unless otherwise noted.) RM4190 Symbol Parameters +VS VREF ISY Supply Voltage Reference Voltage (Internal) Supply Current Line Regulation LI IC ICO ISO ILBD Load Regulation Reference Set Current Switch Leakage Current Supply Current (Disabled) Low Battery Output Current Oscillator Frequency Temperature Drift V4 = 24V (RC4190) 30V (RM4190) VC 200 mV V8 = 0.4V, V1 = 1.1V 500 1200 200 Measure at Pin 5 I4 = 0 0.5 VOUT < VS < VOUT VS = 0.5 VOUT PL = 150 mW 1.0 Conditions Min 2.6 1.25 1.31 235 0.2 0.5 5.0 Typ Max 30 1.37 350 0.5 1.0 50 30 30 500 1200 200 1.0 Min 2.6 1.20 1.31 235 0.5 0.5 5.0 RC4190 Typ Max 24 1.42 350 1.0 1.0 50 30 30 Units V V A % VO % VO A A A A ppm/C 3 PRODUCT SPECIFICATION RC4190 Electrical Characteristics (+VS = +6.0V, IC = 5.0 A, and TA = +25C unless otherwise noted.) RM4190 Symbol +VS VREF ISW ISY ef Parameters Supply Voltage Reference Voltage (Internal) Switch Current Supply Current Efficiency Line Regulation LI FO IC ICO Load Regulation Operating Frequency Range Reference Set Current Switch Leakage Current Supply Current (Disabled) Low Battery Bias Current Capacitor Charging Current Oscillator Frequency Tolerance +VTHX -VTHX IFB ILBD Capacitor Threshold Voltage + Capacitor Threshold Voltage - Feedback Input Current Low Battery Output Current V7 = 1.3V V8 = 0.4V, V1 = 1.1V 500 V4 = 24V (RC4190) 30V (RM4190, RC4190A) VC 200 mV V1 = 1.2V 0.5 VOUT < VS < VOUT VS = +0.5 VOUT PL = 150 mW 0.1 1.0 V4 = 400 mV Measure at Pin 5 I4 = 0 Conditions Min 2.2 1.29 100 1.31 200 215 85 0.04 0.2 25 5.0 0.01 0.2 0.5 75 50 5.0 0.1 1.0 300 Typ Max 30 1.33 Min 2.2 1.24 100 1.31 200 215 85 0.04 0.2 25 5.0 0.01 0.5 0.5 75 50 5.0 300 RC4190 Typ Max 24 1.38 Units V V mA A % % VO % VO kHz A A ISO I1 ICX 0.1 0.7 8.6 10 1.4 0.5 0.1 1500 5.0 0.1 0.7 8.6 10 1.4 0.5 0.1 500 1500 5.0 A A A % V V A A 4 RC4190 PRODUCT SPECIFICATION Typical Performance Characteristics 4.0 300 250 3.0 200 VS (V) 2.4V 2.0 2.0V 1.8V IQ (A) 150 100 1.0 65-2670 230 215 195 VS = +6V -50 -25 0 +25 +50 TA (C) 0 -75 -50 -25 0 +25 +50 TA (C) +75 +100 +125 0 -75 +75 +100 +125 Figure 1. Minimum Supply Voltage vs. Temperature Figure 2. Quiescent Current vs. Temperature 1.33 FO (Normalized) (%) 1.32 VREF (V) 1.31 1.30 1.29 1.28 -75 +2.0 +1.5 +1.0 +0.5 0 -0.5 -1.0 -1.5 -2.0 -75 -50 -25 0 +25 +50 TA (C) Figure 4. Oscillator Frequency vs. Temperature 65-2672 -50 -25 0 +25 +50 TA (C) +75 +100 +125 65-1488 +75 +100 +125 Figure 3. Reference Voltage vs. Temperature +2 FO (Normalized) (%) +1 0 -1 -2 0 5 10 15 +VS (V) Figure 5. Minimum Supply Voltage vs. Temperature 20 25 65-2667 30 65-2671 50 5 PRODUCT SPECIFICATION RC4190 Principles of Operation Simple Step-Up Converter The most common application, the step-up regulator, is derived from a simple step-up (VOUT > VBAT) DC-to-EC Converter (Figure 6). L D (+) If the switch is opened and closed repeatedly, at a rate much greater than the time constant of the output RC, then a constant dc voltage will be produced at the output. An output voltage higher than the input voltage is possible because of the high voltage produced by a rapid change of current in the inductor. When the switch is opened, the inductor voltage will instantly rise high enough to forward bias the diode, to VOUT + VD. In the complete RC4190 regulator, a feedback control system adjusts the on time of the switch, controlling the level of inductor current, so that the average inductor discharge current equals the load current, thus regulating the output voltage. VBAT S C RL VOUT (-) 65-1646 Figure 6. Simple Set-Up When switch S is closed, the battery voltage is applied across the inductor L. Charging current flows through the inductor, building up a magnetic field, increasing as the switch is held closed. While the switch is closed, the diode D is reverse biased (open circuit) and current is supplied to the load by the capacitor C. Until the switch is opened, the inductor current will increase linearly to a maximum value determined by the battery voltage, inductor value, and the amount of time the switch is held closed (IMAX = VBAT/ L x TON). When the switch is opened, the magnetic field collapses, and the energy stored in the magnetic field is converted into a discharge current which flows through the inductor in the same direction as the charging current. Because there is no path for current to flow through the switch, the current must flow through the switch, the current must flow through the diode to supply the load and charge the output capacitor. Complete Step-Up Regulator A complete schematic of the minimum step-up application is shown in Figure 7. The ideal switch in the DC-to-DC Converter diagram is replaced by an open collector NPN transistor Q1. CF functions as the output filter capacitor, and D1 and LX replace D and L. When power is first applied, the current in R1 supplies bias current to pin 6 (IC). This current is stabilized by a unity gain current source amplifier and then used as bias current for the 1.31V bandgap reference. A very stable bias current generated by the bandgap is mirrored and used to bias the remainder of the chip. At the same time the RC4190 is starting up, current will flow through the inductor and the diode to charge the output capacitor to VBAT - VD. G E ILX LX R1 6 5 VBAT IC +VS Q1 B OSC GND 3 A CX 2 CX F ID (+) 4 LX D + - RL REF LBR 1 NC LBD 8 NC R3 D1 RC4190 VFB +1.31V 7 R2 + - CF C ILOAD VOUT = VREF ( R2 + 1) R3 (-) 65-2673A Figure 7. Complete Step-Up Regulator 6 RC4190 PRODUCT SPECIFICATION 1.4V A 0.5V (Internal) IL (Max) C 0mA 0.72V (Internal) 0V VBAT LX E VOUT - VBAT LX IMAX 0 mA IMAX F ID 0 mA VLX VOUT + VD VMAX 0.3V (Q1 SAT) 65-2674 CX OSC ILOAD B D VBEQ1 ILX G Figure 8. Step-Up Regulator Waveforms +VS R1 1M CT * 1 F 7 VFB 6 IC 5 +VS R4 R5 Motorola MBR140P V OUT Q1 TIP73 R2 CF 4190 CX 2 LX Q2 2N3904 GND 3 R3 CX * May not be required R5 = 50 VS IMAX R4 = 10 R5 65-2675 Figure 9. High Power Step-Up Regulator (With the addition of a power transistor (TIP73) and a few components, the 4190 can accomodate load power up to 10W.) At this point, the feedback (pin 7) senses that the output voltage is too low, by comparing a division of the output voltage (set by the ratio of R2 to R3) to the +1.31V reference. If the output voltage is too low then the comparator output changes to a logical zero. The NOR gate then effectively ANDs the oscillator square wave with the comparator signal; if the comparator output is zero AND the oscillator output is low, then the NOR gate output is high and the switch transistor will be forced on. When the oscillator goes high again, the NOR gate output goes low and the switch transistor will turn off. This turning on and off of the switch transistor performs the same function that opening and closing the switch in the simple DC-to-DC Converter does; i.e., it stores energy in the inductor during the on time and releases it into the capacitor during the off time. The comparator will continue to allow the oscillator to turn the switch on and off until enough charge has been delivered to the capacitor to raise the feedback voltage above 1.31V. Thereafter, this feedback system will vary the duration of the on time in response to changes in load current or battery 7 PRODUCT SPECIFICATION RC4190 voltage (see Figure 8). If the load current increases (waveform C), then the transistor will remain on (waveform D) for a longer portion of the oscillator cycle (waveform B), thus allowing the inductor current (waveform E) to build up to a higher peak value. The duty cycle of the switch transistor varies in response to changes in load and time. The inductor value and oscillator frequency must be carefully tailored to the battery voltage, output current, and ripple requirements of the application (refer to the Design Equations Section). If the inductor value is too high or the oscillator frequency is too high, then the inductor current will never reach a value high enough to meet the load current drain and the output voltage will collapse. If the inductor value is too low or the oscillator frequency too low, then the inductor current will build up too high, causing excessive output voltage ripple, or over stressing of the switch transistor, or possibly saturating the inductor. voltage applied across the inductor will discharge into the load. As in the step-up case, the average inductor current equals the load current. The maximum inductor current IMAX will equal (VBAT - VOUT)/L times the maximum on time of the switch transistor (TON). Current flows to the load during both half cycles of the oscillator. Complete Step-Down Regulator Most step-down applications are better served by the RC4391 step-down and inverting switching regulator (refer to the RC4391 data sheet). However, there is a range of load power for which the RC4190 has an advantage over the RC4391 in step-down applications. From approximately 500 mW to 2W of load power, the RC4190 step-down circuit of Figure 6 offers a lower component count and simpler circuit than the comparable RC4391 circuit, particularly when stepping down a voltage greater than 30V. Since the switch transistor in the RC4190 is in parallel with the load, a method must be used to convert it to a series connection for step-down applications. The circuit of Figure 11 accomplishes this. The 2N2907 replaces S of Figure 10, and R6 and R7 are added to provide the base drive to the 2N2907 in the correct polarity to operate the circuit properly. Simple Step-Down Converter Figure 10 shows a step-down DC-to-DC Converter (VOUT VBAT) with no feedback control. S L (+) Greater Than 30V Step-Down Regulator VBAT D C RL VOUT (-) 65-1644 Figure 10. Simple Step-Down Converter Adding a zener diode in series with the base of the 2N2907 allows the battery voltage to increase by the value of the zener, with only a slight decrease in efficiency. As an example, if a 24V zener is used, the maximum battery voltage can go to 48V2 when using a RC4190. Refer to Figure 12. Notes: 1. The addition of the zener diode will not alter the maximum change of supply. With a 24V zener, the circuit will stop operating when the battery voltage drops below 24V + 2.2V = 26.2V. 2. Maximum battery voltage is 54V when using RM4190 (30V + 24V). When S is closed, the battery voltage minus the output voltage is applied across the inductor. All of the inductor current will flow into the load until the inductor current exceeds the load current. The excess current will then charge the capacitor and the output voltage will rise. When S is opened, the 2N2907 R6 Lx V OUT D1 1N914 R7 5 R1 V BAT R4 6 1 +VS IC LBR GND 3 CX 2 Cx R4 = VS - 1.31V 5 A 260K ~ 50 R6 ~ IL 4190 4 LX VFB 7 R3 R2 CF R5 65-2676 R5 = 10 VS ~ R7 ~ IL Figure 11. Complete Step-Down Regulator 8 RC4190 PRODUCT SPECIFICATION 2N2907 R6 Lx V OUT D1 1N914 Z1 R2 R7 CF 5 R1 V BAT R4 6 1 IC +VS 4190 LBR GND 3 CX 2 4 LX VFB 7 R3 Cx R4 = VS - 1.31V 5 A 260K 50 ~ R6 ~ IL 65-2677 R5 R5 = 10 VS R7 ~ ~ IL Figure 12. Step-Down Regulator Greater Than 30V Design Equations The inductor value and timing capacitor (CX) value must be carefully tailored to the input voltage, input voltage range, output voltage, and load current requirements of the application. The key to the problem is to select the correct inductor value for a given oscillator frequency, such that the inductor current rises to a high enough peak value (IMAX) to meet the average load current drain. The selection of this inductor value must take into account the variation of oscillator frequency from unit to unit and the drift of frequency over temperature. Use 20% as a maximum change from the nominal oscillator frequency. The worst-case conditions for calculating ability to supply load current are found at the minimum supply voltage; use +VS (min) to calculate the inductor value. Worst-case conditions for ripple are at +VS (max). The value of the timing capacitor is set according to the following equation: 2.4 x 10 f O ( Hz ) = --------------------C X ( pF ) 6 Find a value for the start-up resistor R1: V S - 1.2V R1 = -----------------------5A Find a value for the feedback resistors R2 and R3: V OUT - 1.31V R2 = ----------------------------------IA 1.31V R3 = -------------IA Where IA is the feedback divider current (recommended value is between 50 A and 100 A). Step-Up Design Procedure 1. 2. Select an operating frequency and timing capacitor as shown above (10 kHz to 40kHz is typical). Find the maximum on time (add 5 S for the turn-off base recombination delay of Q1): 1 T ON = --------- + 5s 2F O The squarewave output of the oscillator is internal and cannot be directly measured, but is equal in frequency to the triangle waveform measurable at pin 4. The switch transistor is normally on when the triangle waveform is ramping up and off when ramping down. Capacitor selection depends on the application; higher operating frequencies will reduce the output voltage ripple and will allow the use of an inductor with a physically smaller inductor core, but excessively high frequencies will reduce load driving capability and efficiency. 3. Calculate the peak inductor current IMAX (if this value is greater than 375 mA, then an external power transistor must be used in place of Q1): V OUT + V D - V S I MAX = ---------------------------------------------------- 2I L ( F O )T ON [ V S - V SW ] where: VS = supply voltage VD = diode forward voltage IL = dc load current VSW = saturation voltage of Q1 (typ 0.5V) 9 PRODUCT SPECIFICATION RC4190 4. Find an inductance value for LX: 2. V S - V SW L X ( Henries ) = ------------------------ T ON I MAX Build the circuit and apply the worst case conditions to it, i.e., the lowest battery voltage and the highest load current at the desired output voltage. Adjust the inductor value down until the desired output voltage is achieved, then go a little lower (approximately 20%) to cover manufacturing tolerances. Check the output voltage with an oscilloscope for ripply, at high supply voltages, at voltages as high as are expected. Also check for efficiency by monitoring supply and output voltages and currents [eff = (VOUT) (IOUT)/(+VS)(ISY) x 100%$]. If the efficiency is poor, go back to (1) and start over. If the ripple is excessive, then increase the output filter capacitor value or start over. 5. The inductor chosen must exhibit approximately this value at a current level equal to IMAX. Calculate a value for the output filter capacitor: 3. 6. 4. V S I MAX T ON -------------------- + IL V OUT C F ( F ) = ------------------------------------------------VR where VR = ripple voltage (peak) 5. Step-Down Design Procedure 1. 2. 3. Select an operating frequency. Compensation Determine the maximum on time (TON) as in the stepup design procedure. Calculate IMAX: When large values (>50 k) are used for the voltage setting resistors, R2 and R3 of Figure 7, stray capacitance at the VFB input can add a lag to the feedback response, destabilizing the regulator, increasing low frequency ripple, and lowering efficiency. This can often be avoided by minimizing the stray capacitance at the VFB node. It can also be remedied by adding a lead compensation capacitor of 100 pF to 10 nF in parallel with R2 in Figure 7. 2I L I MAX = ----------------------------------------------------------------------V S - V OUT ( F O ) ( T ON ) ---------------------------- + 1 V OUT - V D 4. LX Calculate LX: V S - V OUT = --------------------------- ( T ON ) I MAX Inductors Efficiency and load regulation will improve if a quality high Q inductor is used. A ferrite pot core is recommended; the wind-yourself type with an air gap adjustable by washers or spacers is very useful for breadboarding prototypes. Care must be taken to choose a permeable enough core to handle the magnetic flux produced at IMAX; if the core saturates, then efficiency and output current capability are severely degraded and excessive current will flow though the switch transistor. A pot core inductor design section is provided later in this datasheet. An isolated AC current probe for an oscilloscope (example: Tektronix P6042) is an excellent tool for saturation problems; with it the inductor current can be monitored for nonlinearity at the peaks (a sign of saturation). 5. Calculate a value for the output filter capacitor: ( V S - V OUT )I MAX T ON ---------------------------------------------- + IL V OUT C F ( F ) = --------------------------------------------------------------------------VR Alternate Design Procedure The design equations above will not work for the certain input/output voltage ratios, and for these circuits another method of defining component values must be used. If the slope of the current discharge waveform is much less than the slope of the current charging waveform, then the inductor current will become continuous (never discharging completely), and the equations will become extremely complex. So, if the voltage applied across the inductor during the charge time is greater than during the discharge time, used the design procedure below. For example, a step-down circuit with 20V input and 5V output will have approximately 15V across the inductor when charging, and approximately 5V when discharging. So in this example, the inductor current will be continuous and the alternate procedure will be necessary. 1. Select an operating frequency (a value between 10 kHz and 40 kHz is typical). Low Battery Detector An open collector signal transistor Q2 with comparator C2 provides the designer with a method of signaling a display or computer whenever the battery voltage falls below a programmed level (see Figure 8). This level is determined by the +1.3V reference level and by the selection of two external resistors according to the equation: R4 V TH = V REF ------ + 1 R5 Where VTH = Threshold Voltage for Detection 10 RC4190 PRODUCT SPECIFICATION +Vs R4 1 LBR C2 R5 V REF 1.31V 65-1651 LBD 8 Q2 I LBD Another method of automatic shutdown without temperature limitations is the use of a zener diode in series with the IC pin and set resistor. When the battery voltage falls below VZ + 1.2V the circuit will start to shut down. With this connection and the low battery detector, the application can be designed to signal a display when the battery voltage has dropped to the first programmed level, then shut itself off as the battery reaches the zener threshold. The set current can also be turned off by forcing the IC pin to 0.2V or less using an external transistor or mechanical switch. An example of this is shown in Figure 15. In this circuit an external control voltage is used to determine the operating state of the RC4190. If the control voltage VC is a logic 1 at the input of the 4025 (CMOS Triple NOR Gate), the voltage at the IC pin will be less than 0.5V forcing the 4190 off (<0.1 A ICC). Both the 2N3904 and 2N2907 will be off insuring long shelf for the battery since less than 1.0 A is drawn by the circuit. When VC goes to a logic 0, 2.0 A is forced into the IC pin through the 2.2 M resistor and the NOR gate, and at the same time the 2N3904 and 2N2907 turn on, connecting the battery to the load. As long as VC remains low the circuit will regulate the output to 5.0V. This type of circuit is used to back up the main supply voltage when line interruptions occur, a particularly useful feature when using volatile memory systems. Figure 13. Low Battery Detector When the battery voltage drops below this threshold Q2 will turn on and sink over 1500 A typically. The low battery detector circuitry may also be used for other, less conventional applications (see Figures 19 and 20). Automatic Shutdown The bias control current for the reference is externally set by a resistor from the IC pin to the battery. This current can vary from 1.0 A to 50 A without affecting the operation of the IC. Interrupting this current will disable the entire circuit, causing the output voltage to go to 0V for step-down applications, and reducing the supply current to less than 1.0 A. Automatic shutdown of the RC4190 can be achieved using the circuit of Figure 14. 5 +V S VBAT R1 6 IC GND 3 65-2678 9.0V Battery Life Extender 4190 R9 Figure 16 shows a common application: a circuit to extend the lifetime of a 9.0V battery. The regulator remains in its quiescent state (drawing only 215 A) until the battery voltage decays below 7.5V, at which time it will start to switch and regulate the output at 7.0V until the battery falls below 2.2V. If this circuit operates at its typical efficiency of 80%, with an output current of 10 mA, at 5.0V battery voltage, then the average input current will be IIN = (VOUT x IL) / (VBAT x ef) or (7.0V x 10 mA) / (5.0V x 0.8 mA) = 17.5 mA. Figure 14. Automatic Shutdown A resistor is placed from the IC pin to ground, creating a voltage divider. When the voltage at the IC pin is less than 1.2V, the RC4190 will begin to turn off. This scheme should only be used in limited temperature range applications since the "turn off" voltage at the IC pin has a temperature coefficient of -4.0 mV/C. At 25C, typically 250 nA is the minimum current required by the IC pin to sustain operation. A 5.0 A voltage divider works well taking into account the sustaining current of 250 nA and a threshold voltage of 0.4V at turn off. As an example, if 3.0V is to be the turn off voltage, then R9 = 1.1/4.75 A and R1 = (3.0 - 1.1) 5.0 A or about 240 k and 390 k respectively. The tempco at the top of the divider will be -4.0 mV (R1 + R9)/R9 or -10.5 mV/C, an acceptable number for many applications. Bootstrapped Operation (Step-Up) In step-up applications, power to the RC4190 can be derived from the output voltage by connecting the +VS pin and the top of R1 to the output voltage (Figure 17). One requirement for this circuit is that the battery voltage must be greater than 3.0V when it is energized or else there will not be enough voltage at pin 5 to start up the IC. The big advantage of this circuit is the ability to operate down to a discharged battery voltage of 1.0V. 11 PRODUCT SPECIFICATION RC4190 Lx 1.0 mH VBAT 4 5 +V S 2.2M 6 Lx D1 2N2907 VOUT = 5V CF 37K 2.4K 4190 V FB Cx 2 Cx 7 13K IC GND 3 1/3 4025 Vc 15K 2N3904 65-2679 Figure 15. Battery Back-Up Circuit 9V to 2.2V VBAT R1 1M Lx 1.0 mH 6 1 R4* 910K 5 +Vs 4190 Cx 2 Cx 50 pF 4 Lx 1N914 VOUT = 9V To 7V R2 110K IC CF 50F LBR GND 3 R5* 260K VFB 7 R3 25K * Optional 65-2680 Figure 16. 9.0V Battery Life Extender 3V to 9V VBAT R1 1M Lx 1.0 mH 6 5 +Vs 4190 LBR GND 3 Cx 2 Cx 50 pF 4 Lx VFB 1N914 VOUT = 9V R2 77K 7 R3 13K IC 1 R4* 910 CF 50 F R5* 260K * Optional 65-2682 Figure 17. Bootstrapped Operation (Step-Up) 12 RC4190 PRODUCT SPECIFICATION Buck-Boost Circuit (Step-Up/Down) A disadvantage of the standard step-up and step-down circuits is the limitation of the input voltage range; for a stepup circuit, the battery voltage must always be less than the programmed output voltage, and for a step-down circuit, the battery voltage must always be greater than the output voltage. The following circuit eliminates this disadvantage, allowing a battery voltage above the programmed output voltage to decay to well below the output voltage (see Figure 18). The circuit operation is similar to the step-up circuit operation, except that both terminal of the inductor are connected to switch transistors. This switching method allows the inductor to be disconnected from the battery during the time the inductor is being discharged. A new discharge path is provided by D1, allowing the inductor to be referenced to ground and independent of the battery voltage. The efficiency of this circuit will be reduced to 55-60% by losses in the extra switch transistor and diode. Efficiency can be improved by choosing transistors with low saturation voltages and by using power Schottky diodes such as Motorola's MBR030. Step-Up Voltage Dependent Oscillator The RC4190's ability to supply load current at low battery voltages depends on the inductor value and the oscillator frequency. Low values of inductance or a low oscillator frequency will cause a higher peak inductor current and therefore increase the load current capability. A large inductor current is not necessarily best, however, because the large amount of energy delivered with each cycle will cause a large voltage ripple at the output, especially at high input voltages. This trade-off between load current capability and output ripple can be improved with the circuit connection shown in Figure 19. This circuit uses the low battery detector to sense for a low battery voltage condition and will decrease the oscillator frequency after a pre-programmed threshold is reached. +VBAT D1 1N914 1.0 mH Lx D2 1N914 +VOUT 2N2906 or Equivalent R1 1M 6 IC 4190 CX 2 Cx R4 2.2K 5 +VS LX 4 CF 100 F R2 VFB 7 GND 3 R3 65-2681 Figure 18. Buck Boost Circuit (Step-Up/Down) +VBAT R1 1M 6 IC 1 LBR LBD 8 C2 CX 2 Lx 1N914 +VOUT CF R4 5 +VS 4190 4 LX VFB Gnd 3 7 R2 R5 R3 Cx 65-2683 Figure 19. Step-Up Voltage Dependent Oscillator 13 PRODUCT SPECIFICATION RC4190 The threshold is programmed exactly as the noram low battery detector connection: R4 V TH = V REF ------ + 1 R5 shows a schematic of a step-down regulator with this connection. R2 and R3 set the output voltage, as in the circuit of Figure 2. Choose resistor values so R5 = R3 and R4 = R2, and make R8 25 to 35 times higher than R3. When the output is shorted, the open collector transistor at pin 8 will force pin 2 low and shut off the oscillator and therefore shut off the external switch transistor. The regulator will then remain in a low current off condition until power is removed and reapplied. C2 provides momentary current to ensure proper startup. This scheme will not work with the simple step-up regulator, but will work with the boost-buck converter, providing short circuit protection in both step-up and step-down modes. When the battery voltage reaches this threshold, the comparator will turn on the open collector transistor at pin 8, effectively putting C2 in parallel with CX. This added capacitance will reduce the oscillator frequency according to the following equation: 2.4 x 10 F O = -----------------------C X + C2 -6 Where C is in pF and FO is in Hz. Component values for a typical application might be R2 = 330 k, R5 = 150 k, CX = 100 pF, and C2 = 100 pF. These values would set the threshold voltage at 4.1V and change the operating frequency from 48 kHz to 24 kHz. Note that this technique may be used for step-up, step-down, or inverting applications. RC4190/RC4391 Power Supply A positive and negative dual tracking power supply using a step-up RC4190 and an inverting RC4391 is shown in Figure 21. The inductor and capacitor values were chosen to achieve the highest practical output currents from a +12V battery, as it decays, while keeping the output voltage ripple under 100 mVp-p at 15V output. The circuit may be adapted to other voltages and currents, but note that the RC4190 is step-up, so VOUT must be greater than VBAT. The output voltages may both be trimmed by adjusting a single resistor value (R3 or R4), because the reference for the negative output is derived from +VOUT. This connection also allows the output voltages to track each other with changes in temperature and line voltage. Step-Down Regulator With Protection One disadvantage of the simple application circuits is their lack of short circuit protection, especially for the step-up circuit, which has a very low resistance path for current flow from the input to the output. A current limiting circuit which senses the output voltage and shuts down the 4190 if the output voltage drops too low can be built using the low battery detector circuitry. The low battery detector is connected to sense the output voltage and will shut off the oscillator by forcing pin 2 low if the output voltage drops. Figure 20 VBAT R6 1.0K 6 IC C2 10 F R8 LBD 8 R8 = 35(R3) 4190 2N3635 1N914 +VOUT R1 1M Lx R2 5 +VS VFB LBR CX 2 Cx VOUT = 1.31 ( R2 + 1) R3 Gnd 7 1 3 R3 R5 R4 CF 65-2684 Figure 21. Step-Down Regulator with Protection 14 RC4190 PRODUCT SPECIFICATION The timing capacitors are set up exactly as in the voltage dependent oscillator application of Figure 19. The values of R2, R5, C6, and C4 that are given were chosen to optimize for the +12V battery conditions, setting the threshold for oscillator frequency change at VBAT = +8.5V. As given, this power supply is capable of delivering +45 mA and -15 mA with regulation, until the battery decays below 5.0V. For information on adjusting the RC4391 to meet a specific application refer to the Raytheon RC4391 data sheet. Negative Step-Up Regulator In the circuit of Figure 22, a bootstrap arrangement of supply and ground pins helps generate an output voltage more negative than the input voltage. On power-up, the output filter capacitor (CF) will charge through D2 and LX. When the voltage goes below -2.4V, the RC4190 begins switching and charging CF. The output will regulate at a value equal to the reference voltage (1.31V) plus the zener voltage of D1. RZ sets the value of zener current, stabilized at 1.31V/R2. -I OUT = -15 mA D1 1N914 V REF +1.25V L1 50 H 8 R7 100K 7 6 R1 21M 4 +V BAT (2.4 to 5V) L2 100 H -V OUT C1 150 F D2 1N914 +I OUT = 45 mA +VOUT R7 100K 5 Lx VFB Cx 3 5 6 I +Vs C 4 Lx 4190 VFB LBR 1 7 VREF +Vs 4391 LBD 2 GND LBR 1 R4 100K C3 200 pF R2 68K CF2 330 F 3 GND Cx 2 LBD 8 R3 27K C6 40 pF To +VOUT C7 20 pF R5 18K C5 20 pF C4 40 pF +VOUT = VREF ( -VOUT = +VOUT R2 +1) R3 R6 ( ) R7 65-2685 Figure 21. RC4190/RC4391 Power Supply (15V) D1 R1 1M 7 VFB R2 10K CX 2 CX R3 R4 D2 -V OUT + CF LX -V IN 65-4131 6 IC 4190 Gnd 3 5 +VS LX 4 Q1 Figure 22. Negative Step-Up Regulator 15 16 +VS (5) LX (4) VFB (7) CX (2) Q50 Q13 Q10 Q28 Q27 Q17 Q18 Q30 Q36 Q38 Q48 Q49 C2 29.4pF R8 2K Q31 R7 23K Q8 Q24 Q15 Q14 Q23 R2 70K Q11 Q12 Q22 Q16 R4 131K Q21 Q25 Q26 Q19 Q20 Q34 Q37 R10 80K Q33 Q35 Q39 Q40 Q45 Q46 Q47 Q32 Q9 Q29 Q44 Q41 Q42 Q43 R9 24K 65-2665 PRODUCT SPECIFICATION Q3 Q4 Simplified Schematic Diagram Q5 Q6 C1 14.2pF IC (6) Q7 Q2 R5 3.5K Q1 R3 81.5K R6 34.4K R1 147K (8) LBD (1) LBR (3) Gnd RC4190 PRODUCT SPECIFICATION RC4190 Troubleshooting Chart Symptom Draws excessive supply current on start-up Possible Problem Battery not "stiff" -- inadequate supply bypass capacitor. Inductance value too low. Operating frequency (FO) too low. Output voltage is low. Inductor "sings" with audible hum. LX in appears noisy -- scope will not synchronize. Inductor current shows nonlinear waveform. -IMAX ILX Time 65-3464-04 Inductance value too high for FO or core saturating. Not potted well or bolted loosely. Normal operating condition. Inductor is saturating: 1. Core too small. 2. Core too hot. 3. Operating frequency too low. Inductor current shows nonlinear waveform. -IMAX ILX Time 65-3464-05 Waveform has resistive component: 1. Wire size too small. 2. Power transistor lacks base drive. 3. Components not rated high enough. 4. Battery has high series resistance. Inductor current is linear until high current is reached. -IMAX ILX Time 65-3464-06 External transistor lacks base drive or beta is too low. Poor efficiency. Core saturating. Diode or transistor: 1. Not fast enough. 2. Not rated for current level (high VCE SAT). High series resistance. Operating frequency too high. Motorboating (erratic current pulses). Loop stability problem -- needs feedback capacitor from VOUT to VFB (pin 7), 100 to 1000 pF. 17 PRODUCT SPECIFICATION RC4190 Background Information During the past several years there have been various switching regulator ICs introduced by many manufacturers, all of which attended to the same market, namely controllers for use in power supplies delivering greater than 10W of DC power. Raytheon felt there was another area which could use a switching regulator to even more advance the area of battery powered equipment. Battery powered systems have problems peculiar unto themselves: changes in supply voltage, space considerations, battery life and usually cost. The RC4190 was designed with each of these in mind. The RC4190 was partitioned to work in an eight pin package, making it smaller than other controllers which go into 14 and 16 pin packages. Battery powered applications require the load as seen by the battery to be as small as possible to extend battery life. To this end, the quiescent current of the RC4190 is 15 to 100 times less than controllers designed for nonbattery applications. At the same time, the switch transistor can sink 200 mA at 0.4V, comparable to or better than higher powered controllers. As an example, the 4190 configured in the step-up mode can supply 5.0V at 40 mA output with an input of 3.0V. Cost is usually a primary consideration in battery powered systems. The RC4190, guaranteed to work down to 2.2V, can save the designer and end user money as well because battery costs decrease as the number of cells needed goes down. Soft Start +VS 1M 6 CT IC RC4190 65-2076 The delay introduced by the RC time constant at start-up allows the output filter capacitor to charge up, reducing the instantaneous supply current. A typical value for C is in the 0.1F range. Bootstrapped Low Voltage Start-Up Figure 24 shows the bootstrapped application can be "kicked on" using an extra capacitor and triple pole double throw switch (3PDT). This connection allows the circuit to start up using a single Ni-Cad cell of 1.2V to 1.6V. When power is first applied the 1.2V battery does not provide enough voltage to meet the minimum 2.2V supply voltage requirement. The 22F capacitor, when switched, temporarily doubles the battery voltage to bias up the RC4190. 1N914 D1 LX 100 H 4 22 F TPDT VBAT 1.2V R1 1M 5 +VS LX 4190 IC VBAT CX 100 pF 2 GND 3 65-2078 D2 Motorola MBR140P R2 33K VFB 7 R3 13K VOUT = +5V, 10 mA CF 22 pF 6 Figure 24. Bootstrapped Low Voltage Start-Up 18 RC4190 PRODUCT SPECIFICATION When the switch is the down position, the capacitor charges up to the battery voltage. The, when the switch is changed to the up position, the capacitor is put in series connection with the battery, and the doubled voltage is applied directly to the positive power supply lead of the RC4190. This voltage is enough to bias the junctions internal to the RC4190 and gets it started. Then, when the stepped up output voltage reaches a high enough value, diode D1 is forward biased and the output voltage takes over supplying power to the RC4190. The circuit is shown with component values for +5V output, but the circuit can be set up for other voltages. Question: What happens if too small a core is used? First, one must understand how the inductor's magnetic field works. The magnetic circuit in the inductor is very similar to a simple resistive electrical circuit (see Figure 20). There is a magnetizing force (H, in oersteds), a flow of magnetism, or flux density (B, in Gauss), and resistance to the flux, called permeability (U, in Gauss per oersted). H is equivalent to voltage in the electrical model, flux density is like current flow, and permeability is like resistance (except for two important differences discussed on the following page). First Difference: Permeability, instead of being analogous to resistance, is actually more like conductance (1/R). As permeability increases, flux increases. Second Difference: Resistance is a linear function. As voltage increases, current increases proportionally, and the resistance value stays the same. In a magnetic circuit the value of permeability varies as the applied magnetic force varies. This nonlinear characteristic is usually shown in graph form in ferrite core manufacturer's data sheets. See Figure 26. Electricity Versus Magnetism Electrically the inductor must meet just one requirement, but that requirement can be hard to satisfy. The inductor must exhibit the correct value of inductance (L, in Henrys) as the inductor current rises to its highest operating value (IMAX). This requirement can be met most simply by choosing a very large core and winding it until it reaches the correct inductance value, but that brute force technique wastes size, weight and money. A more efficient design technique must be used. Electrical Circuit I E=I*R E R North Magentic Circuit H =B * South 1 U Flux 65-3464-07 Figure 25. Electricity Versus Magnetism 6000 5000 B Gauss 4000 3000 2000 1000 65-2170 +25C +85C +125C Stackpole Ceramag 24B Hysteresis Loop vs. Temperature 0 -0.5 0 0.5 1 2 2.5 3 H Oersteds 5 7 9 Figure 26. Typical Manufacturer's Curve Showing Saturation Effect 19 PRODUCT SPECIFICATION RC4190 As the applied magnetizing force increases, at some point the permeability will start decreasing, and therefore the amount of magnetic flux will not increase any further, even as the magnetizing force increases. The physical reality is that, at the point where the permeability decreases, the magnetic field has realigned all of the magnetic domains in the core material. Once all of the domains have been aligned the core will then carry no more flux than just air; it becomes as if there were no core at all. This phenomenon is called saturation. Because the inductance value, L, is dependent on the amount of flux, core saturation will cause the value of L to decrease dramatically, in turn causing excessive and possibly destructive inductor current. Core Size Question: Is core size selected according to load power? Not quite. Core size is dependent on the amount of energy stored, not on load power. Raising the operating frequency allows smaller cores and windings. Reduction of the size of the magnetics is the main reason switching regulator design tends toward higher operating frequency. Designs with the RC4190 should use 75kHz as a maximum running frequency, because the turn off delay of the power transistor and stray capacitive coupling begin to interfere. Most applications are in the 10 to 50kHz range, for efficiency and EMI reasons. The peak inductor current (IMAX) must reach a high enough value to meet the load current drain. If the operating frequency is increased, and simultaneously the inductor value is decreased, then the core can be made smaller. For a given core size and winding, an increase in air gap spacing (an air gap is a break in the material in the magnetic path, like a section broken off a doughnut) will cause the inductance to decrease and IMAX (the usable peak current before saturation) to increase. The curves shown in Figure 26 are typical of the ferrite manufacturer's power HF material, such as Siemens N27 or Stackpole 24B, which are usually offered in standard millimeter sizes including the sizes shown. Pot Cores for RC4190 Pot core inductors are best suited for the RC4190 micropower switching regulator for several reasons: 1. They are available in a wide range of sizes. RC4190 applications are usually low power with relatively low peak currents (less than 500mA). A small inexpensive pot core can be chosen to meet the circuit requirements. Pot cores are easily mounted. They can be bolted directly to the PC card adjacent to the regulator IC. Pot cores can be easily air-gapped. The length of the gap is simply adjusted using different washer thicknesses. Cores are also available with predetermined air gaps. Electromagnetic interference (EMI) is kept to a minimum. The completely enclosed design of pot core reduces stray electromagnetic radiation--an important consideration of the regulator circuit is built on a PC card with other circuitry. 22X 13 mm 24 Gauge 70 Turns DC = 0.5 2. 3. Use of the Design Aid Graph (Figure 27) 1. 2. From the application requirement, determine the inductor value (L) and the required peak current (IMAX). Observe the curves of the design aid graph and determine the smallest core that meets both the L and I requirements. 4. Air Gap = 0.02" 3A Air Gap = 0.012" #1 #2 18X 11 mm 26 Gauge 70 Turns DC = 0.7 IMAX (Amperes*) 2A #1 1A #2 #3 0 #4 1 mH 2 mH Air Gap = 0.006" #3 #4 11X 7 mm 30 Gauge 50 Turns DC = 1 3 mH Inductor Value (Henries) *Includes safety margin (25%) to ensure nonsaturation Figure 27. Inductor Design Aid 20 65-2171 14X 8 mm 28 Gauge 60 Turns DC = 0.6 No Air Gap RC4190 PRODUCT SPECIFICATION 3. Note the approximate air gap at IMAX for the selected core, and order the core with the gap. (If the gapping is done by the user, remember that a washer spacer results in an air gap of twice the washer thickness, because two gaps will be created, one at the center post and one at the rim, like taking two bites from a doughnut.) If the required inductance is equal to the indicated value on the graph, then wind the core with the number of turns shown in table of sizes. The turns given are the maximum number for that gauge of wire that can be easily wound in the cores winding area. If the required inductance is less than the value indicated on the graph, a simple calculation must be done to find the adjusted number of turns. Find AL (inductance index) for a specific air gap. L ( indicated ) -------------------------------- = AL 2 Turns Compare the waveform you see to those pictured in Figure 28. Check for saturation at the highest expected ambient temperature. 7. After the operation in circuit has been checked, reassemble and pot the core using a potting compound recommended by the manufacturer. If the core material differs greatly in magnetic characteristics from the standard power material shown in Figure 22, then the following general equation can be used to help in winding and gapping. This equation can be used for any core geometry, such as an E-E core. ( 1.26 ) ( N ) ( Ae ) ( 10 ) L X = ----------------------------------------------------g = ( le ) ( ue ) 2 8 4. 5. in Henrys/turn2 Then divide the required inductance value by AL to give the actual turns squared, and take the square root to find the actual turns needed. L ( required ) ActualTurns = -----------------------------AL Where: N = number of turns Ae = core area from data sheet (in cm2) le = magnetic path length from data sheet (in cm) ue = permeability of core from manufacturer's graph g = center post air gap (in cm) Manufacturers Below is a list of several pot core manufacturers: Ferroxcube Company 5083 Kings Highway Saugerties, NY 12477 Indiana General Electronics Keasley, NJ 08832 Siemens Company 186 Wood Avenue South Iselin, NJ 08830 Stackpole Company 201 Stackpole Street St. Mary, PA 15857 TDK Electronics 13-1-Chome Nihonbaski, Chuo-ku, Tokyo If the actual number of turns is significantly less than the number from the table then the wire size can be increased to use up the left-over winding area and reduce resistive losses. 6. Wind and gap the core as per calculations, and measure the value with an inductance meter. Some adjustment of the number of turns may be necessary. The saturation characteristics may be checked with the inductor wired into the switching regulator application circuit. To do so, build and power up the circuit. Then (recommend Tektronix P6042 or equivalent) around the inductor lead and monitor the current in the inductor. Draw the maximum load current from the application circuit so that the regulator is running at close to full duty cycle. Proper Operation (Waveform is Fairly Linear) Improper Operation (Waveform is Nonlinear, Inductor Is Saturating) IMAX IMAX 0 0 65-3464-08 Figure 28. Inductor Current Waveforms 21 PRODUCT SPECIFICATION RC4190 Mechanical DImensions 8-Lead Ceramic DIP Package Inches Min. A b1 b2 c1 D E e eA L Q s1 Max. Millimeters Min. Max. 8 2, 8 8 4 4 5, 9 7 3 6 Notes: Notes 1. Index area: a notch or a pin one identification mark shall be located adjacent to pin one. The manufacturer's identification shall not be used as pin one identification mark. 2. The minimum limit for dimension "b2" may be .023 (.58mm) for leads number 1, 4, 5 and 8 only. 3. Dimension "Q" shall be measured from the seating plane to the base plane. 4. This dimension allows for off-center lid, meniscus and glass overrun. 5. The basic pin spacing is .100 (2.54mm) between centerlines. Each pin centerline shall be located within .010 (.25mm) of its exact longitudinal position relative to pins 1 and 8. 6. Applies to all four corners (leads number 1, 4, 5, and 8). 7. "eA" shall be measured at the center of the lead bends or at the centerline of the leads when "" is 90. 8. All leads - Increase maximum limit by .003 (.08mm) measured at the center of the flat, when lead finish applied. 9. Six spaces. D 4 1 Note 1 E Symbol -- .200 .014 .023 .045 .065 .008 .015 -- .405 .220 .310 .100 BSC .300 BSC .125 .200 .015 .060 .005 -- 90 105 -- 5.08 .36 .58 1.14 1.65 .20 .38 -- 10.29 5.59 7.87 2.54 BSC 7.62 BSC 3.18 5.08 .38 1.52 .13 -- 90 105 5 s1 8 e eA A Q L b2 b1 c1 22 RC4190 PRODUCT SPECIFICATION Mechanical DImensions (continued) 8-Lead Plastic DIP Package Inches Min. A A1 A2 B B1 C D D1 E E1 e eB L N -- .015 .115 .014 .045 .008 .348 .005 .300 .240 Max. .210 -- .195 .022 .070 .015 .430 -- .325 .280 Millimeters Min. -- .38 2.93 .36 1.14 .20 8.84 .13 7.62 6.10 Max. 5.33 -- 4.95 .56 1.78 .38 10.92 -- 8.26 7.11 Notes: Notes 1. Dimensioning and tolerancing per ANSI Y14.5M-1982. 2. "D" and "E1" do not include mold flashing. Mold flash or protrusions shall not exceed .010 inch (0.25mm). 3. Terminal numbers are for reference only. 4. "C" dimension does not include solder finish thickness. 5. Symbol "N" is the maximum number of terminals. 4 2 Symbol 2 .100 BSC -- .430 .115 .160 8 2.54 BSC -- 10.92 2.92 4.06 8 5 D 4 1 E1 D1 5 8 E e A A1 L B1 B eB A2 C 23 PRODUCT SPECIFICATION RC4190 Mechanical DImensions (continued) 8-Lead SOIC Package Inches Min. A A1 B C D E e H h L N ccc Max. Millimeters Min. Max. Notes: Notes 1. Dimensioning and tolerancing per ANSI Y14.5M-1982. 2. "D" and "E" do not include mold flash. Mold flash or protrusions shall not exceed .010 inch (0.25mm). 3. "L" is the length of terminal for soldering to a substrate. 4. Terminal numbers are shown for reference only. 5 2 2 5. "C" dimension does not include solder finish thickness. 6. Symbol "N" is the maximum number of terminals. Symbol .053 .069 .004 .010 .013 .020 .008 .010 .189 .197 .150 .158 .050 BSC .228 .010 .016 8 0 -- 8 .004 .244 .020 .050 1.35 1.75 0.10 0.25 0.33 0.51 0.20 0.25 4.80 5.00 3.81 4.01 1.27 BSC 5.79 0.25 0.40 8 0 -- 8 0.10 6.20 0.50 1.27 3 6 8 5 E H 1 4 D A1 A SEATING PLANE B -C- LEAD COPLANARITY ccc C e h x 45 C L 24 PRODUCT SPECIFICATION RC4190 Ordering Information Product Number RC4190M RC4190N RM4190D RM4190D/883B RV4190N Temperature Range 0 to 70C 0 to 70C -55C to +125C -55C to +125C -25C to +85C Military Industrial Screening Commercial Commercial Package 8 Pin Narrow SOIC 8 Pin Plastic DIP 8 Pin Ceramic DIP 8 Pin Ceramic DIP 8 Pin Plastic DIP Note: 1. /883B suffix denotes MIL-STD-883, Level B processing. The information contained in this data sheet has been carefully compiled; however, it shall not by implication or otherwise become part of the terms and conditions of any subsequent sale. Raytheon's liability shall be determined solely by its standard terms and conditions of sale. No representation as to application or use or that the circuits are either licensed or free from patent infringement is intended or implied. Raytheon reserves the right to change the circuitry and any other data at any time without notice and assumes no liability for errors. LIFE SUPPORT POLICY: Raytheon's products are not designed for use in life support applications, wherein a failure or malfunction of the component can reasonably be expected to result in personal injury. The user of Raytheon components in life support applications assumes all risk of such use and indemnifies Raytheon Company against all damages. Raytheon Electronics Semiconductor Division 350 Ellis Street Mountain View CA 94043 650.968.9211 FAX 650.966.7742 12/95 0.0m Stock#DS20004190 (c) Raytheon Company |
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