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| Order this document by TL494/D TL494 SWITCHMODETM Pulse Width Modulation Control Circuit The TL494 is a fixed frequency, pulse width modulation control circuit designed primarily for SWITCHMODE power supply control. * * * * * * * * SWITCHMODE PULSE WIDTH MODULATION CONTROL CIRCUIT SEMICONDUCTOR TECHNICAL DATA Complete Pulse Width Modulation Control Circuitry On-Chip Oscillator with Master or Slave Operation On-Chip Error Amplifiers On-Chip 5.0 V Reference Adjustable Deadtime Control Uncommitted Output Transistors Rated to 500 mA Source or Sink Output Control for Push-Pull or Single-Ended Operation Undervoltage Lockout D SUFFIX PLASTIC PACKAGE CASE 751B (SO-16) N SUFFIX PLASTIC PACKAGE CASE 648 PIN CONNECTIONS Noninv Input 1 Inv Input 2 Noninv 16 Input Inv 15 Input 14 Vref Output 13 Control 12 VCC Oscillator MAXIMUM RATINGS (Full operating ambient temperature range applies, unless otherwise noted.) Rating Power Supply Voltage Collector Output Voltage Collector Output Current (Each transistor) (Note 1) Amplifier Input Voltage Range Power Dissipation @ TA 45C Thermal Resistance, Junction-to-Ambient Operating Junction Temperature Storage Temperature Range Operating Ambient Temperature Range TL494C TL494I Derating Ambient Temperature NOTE: + Error 1 Amp - + 2 Error Amp - VCC 5.0 V REF Symbol VCC VC1, VC2 IC1, IC2 VIR PD RJA TJ Tstg TA TL494C 42 42 500 TL494I Unit V V mA V mW C/W C C C Compen/PWN Comp Input 3 Deadtime Control 4 CT 5 RT 6 0.1 V 11 C2 Q2 Ground 7 10 E2 Q1 -0.3 to +42 1000 80 125 -55 to +125 0 to +70 - 25 to +85 C1 8 9 E1 (Top View) ORDERING INFORMATION Device Operating Temperature Range TA = 0 to +70C TA = - 25 to +85C Package SO-16 Plastic Plastic Rev 1 TA 45 C TL494CD TL494CN TL494IN 1. Maximum thermal limits must be observed. (c) Motorola, Inc. 1996 MOTOROLA ANALOG IC DEVICE DATA 1 TL494 RECOMMENDED OPERATING CONDITIONS Characteristics Power Supply Voltage Collector Output Voltage Collector Output Current (Each transistor) Amplified Input Voltage Current Into Feedback Terminal Reference Output Current Timing Resistor Timing Capacitor Oscillator Frequency Symbol VCC VC1, VC2 IC1, IC2 Vin lfb lref RT CT fosc Min 7.0 - - -0.3 - - 1.8 0.0047 1.0 Typ 15 30 - - - - 30 0.001 40 Max 40 40 200 VCC - 2.0 0.3 10 500 10 200 Unit V V mA V mA mA k F kHz ELECTRICAL CHARACTERISTICS (VCC = 15 V, CT = 0.01 F, RT = 12 k, unless otherwise noted.) For typical values TA = 25C, for min/max values TA is the operating ambient temperature range that applies, unless otherwise noted. Characteristics REFERENCE SECTION Reference Voltage (IO = 1.0 mA) Line Regulation (VCC = 7.0 V to 40 V) Load Regulation (IO = 1.0 mA to 10 mA) Short Circuit Output Current (Vref = 0 V) OUTPUT SECTION Collector Off-State Current (VCC = 40 V, VCE = 40 V) Emitter Off-State Current VCC = 40 V, VC = 40 V, VE = 0 V) Collector-Emitter Saturation Voltage (Note 2) Common-Emitter (VE = 0 V, IC = 200 mA) Emitter-Follower (VC = 15 V, IE = -200 mA) Output Control Pin Current Low State (VOC 0.4 V) High State (VOC = Vref) Output Voltage Rise Time Common-Emitter (See Figure 12) Emitter-Follower (See Figure 13) Output Voltage Fall Time Common-Emitter (See Figure 12) Emitter-Follower (See Figure 13) IC(off) IE(off) - - 2.0 - 100 -100 A A V Vsat(C) Vsat(E) IOCL IOCH tr - - tf - - 25 40 100 100 100 100 200 200 ns - - - - 1.1 1.5 10 0.2 1.3 2.5 - 3.5 A mA ns Vref Regline Regload ISC 4.75 - - 15 5.0 2.0 3.0 35 5.25 25 15 75 V mV mV mA Symbol Min Typ Max Unit NOTE: 2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient temperature as possible. 2 MOTOROLA ANALOG IC DEVICE DATA TL494 ELECTRICAL CHARACTERISTICS (VCC = 15 V, CT = 0.01 F, RT = 12 k, unless otherwise noted.) For typical values TA = 25C, for min/max values TA is the operating ambient temperature range that applies, unless otherwise noted. Characteristics ERROR AMPLIFIER SECTION Input Offset Voltage (VO (Pin 3) = 2.5 V) Input Offset Current (VO (Pin 3) = 2.5 V) Input Bias Current (VO (Pin 3) = 2.5 V) Input Common Mode Voltage Range (VCC = 40 V, TA = 25C) Open Loop Voltage Gain (VO = 3.0 V, VO = 0.5 V to 3.5 V, RL = 2.0 k) Unity-Gain Crossover Frequency (VO = 0.5 V to 3.5 V, RL = 2.0 k) Phase Margin at Unity-Gain (VO = 0.5 V to 3.5 V, RL = 2.0 k) Common Mode Rejection Ratio (VCC = 40 V) Power Supply Rejection Ratio (VCC = 33 V, VO = 2.5 V, RL = 2.0 k) Output Sink Current (VO (Pin 3) = 0.7 V) Output Source Current (VO (Pin 3) = 3.5 V) PWM COMPARATOR SECTION (Test Circuit Figure 11) Input Threshold Voltage (Zero Duty Cycle) Input Sink Current (V(Pin 3) = 0.7 V) DEADTIME CONTROL SECTION (Test Circuit Figure 11) Input Bias Current (Pin 4) (VPin 4 = 0 V to 5.25 V) Maximum Duty Cycle, Each Output, Push-Pull Mode (VPin 4 = 0 V, CT = 0.01 F, RT = 12 k) (VPin 4 = 0 V, CT = 0.001 F, RT = 30 k) Input Threshold Voltage (Pin 4) (Zero Duty Cycle) (Maximum Duty Cycle) OSCILLATOR SECTION Frequency (CT = 0.001 F, RT = 30 k) Standard Deviation of Frequency* (CT = 0.001 F, RT = 30 k) Frequency Change with Voltage (VCC = 7.0 V to 40 V, TA = 25C) Frequency Change with Temperature (TA = Tlow to Thigh) (CT = 0.01 F, RT = 12 k) UNDERVOLTAGE LOCKOUT SECTION Turn-On Threshold (VCC increasing, Iref = 1.0 mA) TOTAL DEVICE Standby Supply Current (Pin 6 at Vref, All other inputs and outputs open) (VCC = 15 V) (VCC = 40 V) Average Supply Current (CT = 0.01 F, RT = 12 k, V(Pin 4) = 2.0 V) (VCC = 15 V) (See Figure 12) ICC - - - 5.5 7.0 7.0 10 15 mA - mA Vth 5.5 6.43 7.0 V fosc fosc fosc (V) fosc (T) - - - - 40 3.0 0.1 - - - - 12 kHz % % % IIB (DT) DCmax 45 - Vth - 0 2.8 - 3.3 - 48 45 50 50 V - -2.0 -10 A % VTH II- - 0.3 2.5 0.7 4.5 - V mA VIO IIO IIB VICR AVOL fC- m CMRR PSRR IO- IO+ 70 - - 65 - 0.3 2.0 - - - 2.0 5.0 -0.1 -0.3 to VCC-2.0 95 350 65 90 100 0.7 -4.0 - - - - - - - 10 250 -1.0 mV nA A V dB kHz deg. dB dB mA mA Symbol Min Typ Max Unit * Standard deviation is a measure of the statistical distribution about the mean as derived from the formula, N (Xn - X)2 n=1 N-1 MOTOROLA ANALOG IC DEVICE DATA 3 TL494 Figure 1. Representative Block Diagram Output Control 13 6 Oscillator RT CT 5 - + 4 Deadtime Control 0.7V - + 0.7mA + 1 - 1 2 3 Feedback PWM Comparator Input 2 PWM Comparator + - 15 16 UV Lockout - + - + 3.5V 14 Ref. Output 7 Gnd 4.9V Reference Regulator 12 VCC Deadtime Comparator Ck D Flip- Flop Q Q2 11 10 Q Q1 8 9 VCC 0.12V Error Amp 1 Error Amp 2 This device contains 46 active transistors. Figure 2. Timing Diagram Capacitor CT Feedback/PWM Comp. Deadtime Control Flip-Flop Clock Input Flip-Flop Q Flip-Flop Q Output Q1 Emitter Output Q2 Emitter Output Control 4 MOTOROLA ANALOG IC DEVICE DATA TL494 APPLICATIONS INFORMATION Description The TL494 is a fixed-frequency pulse width modulation control circuit, incorporating the primary building blocks required for the control of a switching power supply. (See Figure 1.) An internal-linear sawtooth oscillator is frequency- programmable by two external components, RT and CT. The approximate oscillator frequency is determined by: fosc 1.1 RT * CT may be used to sense power-supply output voltage and current. The error-amplifier outputs are active high and are ORed together at the noninverting input of the pulse-width modulator comparator. With this configuration, the amplifier that demands minimum output on time, dominates control of the loop. When capacitor CT is discharged, a positive pulse is generated on the output of the deadtime comparator, which clocks the pulse-steering flip-flop and inhibits the output transistors, Q1 and Q2. With the output-control connected to the reference line, the pulse-steering flip-flop directs the modulated pulses to each of the two output transistors alternately for push-pull operation. The output frequency is equal to half that of the oscillator. Output drive can also be taken from Q1 or Q2, when single-ended operation with a maximum on-time of less than 50% is required. This is desirable when the output transformer has a ringback winding with a catch diode used for snubbing. When higher output-drive currents are required for single-ended operation, Q1 and Q2 may be connected in parallel, and the output-mode pin must be tied to ground to disable the flip-flop. The output frequency will now be equal to that of the oscillator. The TL494 has an internal 5.0 V reference capable of sourcing up to 10 mA of load current for external bias circuits. The reference has an internal accuracy of 5.0% with a typical thermal drift of less than 50 mV over an operating temperature range of 0 to 70C. For more information refer to Figure 3. Output pulse width modulation is accomplished by comparison of the positive sawtooth waveform across capacitor CT to either of two control signals. The NOR gates, which drive output transistors Q1 and Q2, are enabled only when the flip-flop clock-input line is in its low state. This happens only during that portion of time when the sawtooth voltage is greater than the control signals. Therefore, an increase in control-signal amplitude causes a corresponding linear decrease of output pulse width. (Refer to the Timing Diagram shown in Figure 2.) The control signals are external inputs that can be fed into the deadtime control, the error amplifier inputs, or the feedback input. The deadtime control comparator has an effective 120 mV input offset which limits the minimum output deadtime to approximately the first 4% of the sawtooth-cycle time. This would result in a maximum duty cycle on a given output of 96% with the output control grounded, and 48% with it connected to the reference line. Additional deadtime may be imposed on the output by setting the deadtime-control input to a fixed voltage, ranging between 0 V to 3.3 V. Functional Table Input/Output Controls Grounded @ Vref Output Function Single-ended PWM @ Q1 and Q2 Push-pull Operation Figure 3. Oscillator Frequency versus Timing Resistance fosc , OSCILLATOR FREQUENCY (Hz) 500 k CT = 0.001 F VCC = 15 V fout fosc = 1.0 0.5 100 k 10 k 0.01 F The pulse width modulator comparator provides a means for the error amplifiers to adjust the output pulse width from the maximum percent on-time, established by the deadtime control input, down to zero, as the voltage at the feedback pin varies from 0.5 V to 3.5 V. Both error amplifiers have a common mode input range from -0.3 V to (VCC - 2V), and 1.0 k 500 1.0 k 2.0 k 5.0 k 0.1 F 10 k 20 k 50 k 100 k 200 k RT, TIMING RESISTANCE () 500 k 1.0 M MOTOROLA ANALOG IC DEVICE DATA 5 TL494 Figure 4. Open Loop Voltage Gain and Phase versus Frequency 120 110 100 90 80 70 60 50 40 30 20 10 0 1.0 % DT, PERCENT DEADTIME (EACH OUTPUT) A VOL , OPEN LOOP VOLTAGE GAIN (dB) 20 18 16 14 12 10 8.0 6.0 4.0 2.0 0 500 k 1.0 k 10 k 100 k fosc, OSCILLATOR FREQUENCY (Hz) 500 k 0.001 F CT = 0.001 F Figure 5. Percent Deadtime versus Oscillator Frequency AVOL 10 100 1.0 k 10 k f, FREQUENCY (Hz) 0 20 40 60 80 100 120 140 160 180 100 k 1.0 M , EXCESS PHASE (DEGREES) VCC = 15 V VO = 3.0 V RL = 2.0 k Figure 6. Percent Duty Cycle versus Deadtime Control Voltage % DC, PERCENT DUTY CYCLE (EACH OUTPUT) 50 V CE(sat) , SATURATION VOLTAGE (V) 40 2 30 20 10 0 0 1.0 2.0 3.0 3.5 VDT, DEADTIME CONTROL VOLTAGE (IV) 1 VCC = 15 V VOC = Vref 1. CT = 0.01 F 2. RT = 10 k 2. CT = 0.001 F 2. RT = 30 k 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 0 Figure 7. Emitter-Follower Configuration Output Saturation Voltage versus Emitter Current 100 200 300 IE, EMITTER CURRENT (mA) 400 Figure 8. Common-Emitter Configuration Output Saturation Voltage versus Collector Current 2.0 VCE(sat), SATURATION VOLTAGE (V) I CC , SUPPLY CURRENT (mA) 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0 100 200 300 IC, COLLECTOR CURRENT (mA) 400 10 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0 0 5.0 Figure 9. Standby Supply Current versus Supply Voltage 10 15 20 25 30 35 40 VCC, SUPPLY VOLTAGE (V) 6 MOTOROLA ANALOG IC DEVICE DATA TL494 Figure 10. Error-Amplifier Characteristics Figure 11. Deadtime and Feedback Control Circuit VCC = 15V Error Amplifier Under Test + Vin - Feedback Terminal (Pin 3) + Vref - Other Error Amplifier 50k Test Inputs VCC Deadtime Feedback RT CT (+) (-) Error (+) (-) Output Control Gnd 150 2W C1 E1 C2 E2 150 2W Output 1 Output 2 Ref Out Figure 12. Common-Emitter Configuration Test Circuit and Waveform 15V RL 68 C Each Output Transistor Q E CL 15pF VC Figure 13. Emitter-Follower Configuration Test Circuit and Waveform 15V C Each Output Transistor Q E RL 68 CL 15pF VEE 90% VCC 10% tr tf 90% 10% 90% 90% VEE 10% 10% Gnd tr tf MOTOROLA ANALOG IC DEVICE DATA 7 TL494 Figure 14. Error-Amplifier Sensing Techniques VO To Output Voltage of System R1 1 + Error Amp - Vref 1 R2 + Error Amp - 3 2 Negative Output Voltage VO = Vref R1 R2 R1 VO To Output Voltage of System Vref R2 2 Positive Output Voltage VO = Vref 1+ R1 R2 Figure 15. Deadtime Control Circuit Output Control Output Q RT 6 CT 5 Vref DT R1 4 Output Q R2 Figure 16. Soft-Start Circuit Vref DT 4 RS CS 30k 0.001 Max. % on Time, each output 45 - 80 1+ R1 R2 Figure 17. Output Connections for Single-Ended and Push-Pull Configurations C1 QC Q1 Output Control Single-Ended C2 0 VOC 0.4 V Q2 E2 Q2 QE E1 1.0 mA to 500 mA Output Control Push-Pull 2.4 V VOC Vref Q1 C1 E1 1.0 mA to 250 mA C2 E2 1.0 mA to 250 mA 8 MOTOROLA ANALOG IC DEVICE DATA TL494 Figure 18. Slaving Two or More Control Circuits Vref RS 6 5 RT CT Vref 6 RT 5 CT Slave (Additional Circuits) RT Master CT Vin > 40V 1N975A VZ = 39V 270 5.0V Ref Gnd 7 VCC 12 Figure 19. Operation with Vin > 40 V Using External Zener Figure 20. Pulse Width Modulated Push-Pull Converter +Vin = 8.0V to 20V 12 1 2 1M 33k 0.01 0.01 3 15 16 + - Comp - + OC VREF DT CT RT Gnd E1 E2 13 14 4 5 6 7 9 10 + 10 10k 15k 0.001 TL494 C2 11 Tip 32 47 VCC C1 8 47 Tip 32 + 50 25V 1N4934 240 T1 1N4934 22 k + 50 35V 4.7k 1.0 +VO = 28 V IO = 0.2 A L1 + 50 35V 4.7k 4.7k All capacitors in F Test Line Regulation Load Regulation Output Ripple Short Circuit Current Efficiency Conditions Vin = 10 V to 40 V Vin = 28 V, IO = 1.0 mA to 1.0 A Vin = 28 V, IO = 1.0 A Vin = 28 V, RL = 0.1 Vin = 28 V, IO = 1.0 A Results 14 mV 0.28% 3.0 mV 0.06% 65 mV pp P.A.R.D. 1.6 A 71% L1 - 3.5 mH @ 0.3 A T1 - Primary: 20T C.T. #28 AWG T1 - Secondary: 12OT C.T. #36 AWG T1 - Core: Ferroxcube 1408P-L00-3CB MOTOROLA ANALOG IC DEVICE DATA 9 TL494 Figure 21. Pulse Width Modulated Step-Down Converter 1.0mH @ 2A +Vin = 10V to 40V Tip 32A +VO = 5.0 V IO = 1.0 A 47 150 47k 0.1 C2 Comp - 50 50V + + 3 2 1 14 MR850 5.1k 500 10V + 5.1k 5.1k 1.0M 12 VCC 8 C1 11 TL494 Vref CT 5 - 15 16 + RT 6 D.T. O.C. Gnd E1 4 13 7 9 E2 10 + 150 50 10V 0.001 47k 0.1 Test Line Regulation Load Regulation Output Ripple Short Circuit Current Efficiency Conditions Vin = 8.0 V to 40 V Vin = 12.6 V, IO = 0.2 mA to 200 mA Vin = 12.6 V, IO = 200 mA Vin = 12.6 V, RL = 0.1 Vin = 12.6 V, IO = 200 mA Results 3.0 mV 5.0 mV 40 mV pp 0.01% 0.02% P.A.R.D. 250 mA 72% 10 MOTOROLA ANALOG IC DEVICE DATA TL494 OUTLINE DIMENSIONS N SUFFIX PLASTIC PACKAGE CASE 648-08 ISSUE R 9 -A- 16 B 1 8 NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. DIMENSION L TO CENTER OF LEADS WHEN FORMED PARALLEL. 4. DIMENSION B DOES NOT INCLUDE MOLD FLASH. 5. ROUNDED CORNERS OPTIONAL. DIM A B C D F G H J K L M S INCHES MIN MAX 0.740 0.770 0.250 0.270 0.145 0.175 0.015 0.021 0.040 0.70 0.100 BSC 0.050 BSC 0.008 0.015 0.110 0.130 0.295 0.305 0_ 10 _ 0.020 0.040 MILLIMETERS MIN MAX 18.80 19.55 6.35 6.85 3.69 4.44 0.39 0.53 1.02 1.77 2.54 BSC 1.27 BSC 0.21 0.38 2.80 3.30 7.50 7.74 0_ 10 _ 0.51 1.01 F S C L -T- H G D 16 PL SEATING PLANE K J TA M M 0.25 (0.010) M -A- D SUFFIX PLASTIC PACKAGE CASE 751B-05 (SO-16) ISSUE J 9 16 -B- 1 8 P 8 PL 0.25 (0.010) M B S G F NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSIONS A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. MILLIMETERS MIN MAX 9.80 10.00 3.80 4.00 1.35 1.75 0.35 0.49 0.40 1.25 1.27 BSC 0.19 0.25 0.10 0.25 0_ 7_ 5.80 6.20 0.25 0.50 INCHES MIN MAX 0.386 0.393 0.150 0.157 0.054 0.068 0.014 0.019 0.016 0.049 0.050 BSC 0.008 0.009 0.004 0.009 0_ 7_ 0.229 0.244 0.010 0.019 K C -T- SEATING PLANE R X 45 _ M D 16 PL M J 0.25 (0.010) TB S A S DIM A B C D F G J K M P R MOTOROLA ANALOG IC DEVICE DATA 11 TL494 Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. "Typical" parameters which may be provided in Motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. Motorola does not convey any license under its patent rights nor the rights of others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part. Motorola and are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal Opportunity/Affirmative Action Employer. How to reach us: USA / EUROPE / Locations Not Listed: Motorola Literature Distribution; P.O. Box 20912; Phoenix, Arizona 85036. 1-800-441-2447 or 602-303-5454 MFAX: RMFAX0@email.sps.mot.com - TOUCHTONE 602-244-6609 INTERNET: http://Design-NET.com JAPAN: Nippon Motorola Ltd.; Tatsumi-SPD-JLDC, 6F Seibu-Butsuryu-Center, 3-14-2 Tatsumi Koto-Ku, Tokyo 135, Japan. 03-81-3521-8315 ASIA/PACIFIC: Motorola Semiconductors H.K. Ltd.; 8B Tai Ping Industrial Park, 51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852-26629298 12 MOTOROLA ANALOG IC DEVICE DATA TL494/D *TL494/D* |
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