 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| www..com AS2810 1A Low Dropout Voltage Regulator Adjustable & Fixed Output, Fast Response FEATURES * Adjustable Output Down To 1.2V * Fixed Output Voltages 1.5V, 2.5V, 3.0V, 3.3V, 5.0V * Output Current Of 1A * Low Dropout Voltage 1.2V Typ. * Extremely Tight Load And Line Regulation * Current & Thermal Limiting * Standard 3-Terminal Low Cost TO-220, TO-263, TO-252 & SOT-223 APPLICATIONS * SCSI-II Active Terminator * Portable Palmtap/Notebook Computer * SMPS Post-Regulator * Disk Drives * Portable Consumer Equipment * Portable Instrumentation * Battery charger PRODUCT DESCRIPTION The AS2810 is a low power positive voltage regulator designed to meet 1A output current and comply with SCSI-II specifications with fix output voltage of 2.85V. This device is an excellent choice for use in battery-powered applications and portable computers. The AS2810 features very low quiescent current and very low dropout voltage of 1.2V at a full load and lower as output current decreases. This product is available as adjustable or fixed 1.5V, 2.5V, 3.0V, 3.3V, and 5V output voltages. The AS2810 is offered in a 3-pin surface mount packages SOT-223, TO-220, TO-252 & DD package. The output capacitor of 10F or larger is needed for the output stability of AS2810 as required by most other regulator circuits ORDERING INFORMATION TO-220 3-PIN AS2810YU-X DD PLASTIC 3-PIN AS2810YT-X SOT-223 3-PIN AS2810YM3-X TO-252 3-PIN AS2810YR-X OPEPERATING JUNCTION TEMP. RANGE -45 to +125C X= Output Voltage (1.5V, 2.5V, 3.0V, 3.3V, 5.0V and Blank for Adj.) Y= Output Tolerance, A for 1% Blank for 2% Consult with factory for other fixed voltages. PIN CONNECTIONS SOT-223 (M3) TO-263-3 (T) TO-220-3 (U) TO-252 (R) AS2810 1 2 3 AS2810 1 2 3 AS2810 1 2 3 AS2810 1 2 3 ADJ/ GND VOUT VIN Top View ADJ/GND VOUT VIN ADJ/GND VOUT VIN Front View ADJ/GND VOUT VIN Top View Front View Rev. 10/2/00 www..com AS2810 ABSOLUTE MAXIMUM RATINGS Lead Temp. (Soldering, 10 Seconds) .............................. 300C Storage Temperature Range ............................ -65 to +150C Operating Junction Temperature Range ...................... AS2810 Control Section ............................ -45C +125C AS2810 Power Transistor...........................-45C +150C Input Voltage........................................................ 10V Input to Output Voltage Differential .................... 10V ELECTRICAL CHARACTERISTICS (NOTE 1) at IOUT = 10mA, TA=25C, unless otherwise specified. PARAMETER 1.5V Version Output Voltage (Note 2) 2.5V Version Output Voltage (Note 2) 2.85V Version Output Voltage (Note 2) 3.0V Version Output Voltage (Note 2) 3.3V Version Output Voltage (Note 2) 5.0V Version Output Voltage (Note 2) All Voltage Options Reference Voltage (VREF) Min. Load Current (Note 3) Line Regulation (VREF(Vin)) Load Regulation(VREF(IOUT)) VIN 7V, P Pmax 1.5V (VIN -VOUT)5.75V, 10mAIOUT1A 1.5V (VIN -VOUT)5.75V 2.75VVIN 7V, IOUT=10mA, TJ=25C (Note 3) VIN7V, IOUT=0mA, TJ=25C (Note 2) 10mAIOUT 1A, (VIN-VOUT)=3V, TJ=25C (Note 3) 0IOUT 1A, VIN=7V, TJ=25C (Note 2) VREF=1% IOUT = 1A (Note 3) IOUT 1A (Note 2) VIN=7V 1.4V (VIN- VOUT) (Note3) 1.250 5 0.005 0.005 0.05 0.05 1.1 2 1.2 1.225 1.263 1.270 1.225 10 0.2 0.2 0.3 0.3 1.2 1.2 1.225 1.212 1.270 1.288 10 0.2 0.2 0.3 0.3 1.2 A % V mA % AS2810-5.0V, 0 IOUT 1A, 6.5VVIN12V 5 4.950 4.900 5.050 5.100 4.9 4.65 5.1 5.15 V AS2810-3.3V, 0 IOUT 1A, 4.8VVIN10V 3.3 3.267 3.234 3.333 3.366 3.234 3.069 3.366 3.399 V AS2810-3.0V, 0 IOUT 1A, 4.5VVIN10V 3 2.970 2.940 3.030 3.060 2.94 2.79 3.06 3.09 V AS2810-2.85V, 0 IOUT 1A, 4.5VVIN10V 2.85 2.822 2.793 2.879 2.907 2.793 2.650 2.907 2.936 V CONDITIONS Typ AS2810A Min AS2810-1.5V, 0 < IOUT < 1A, 3.3V Dropout Voltage Current Limit IOUT(MAX) Rev. 10/2/00 www..com AS2810 ELECTRICAL CHARACTERISTICS (Cont.) Long Term Stability Thermal Regulation (VOUT(Pwr)) Temperature Stability (VOUT(T)) Output Noise, RMS Thermal Resistance TA=125C, 1000 Hrs. TA=25C, 20 ms pulse 10Hz to 10kHz TO-220 DD Package SOT-223 Package TA=25C Junction to Tab Junction to Ambient Junction to Tab Junction to Ambient Junction to Tab Junction to Ambient 0.3 (Note 2) 0.01 0.25 0.003 3.0 60 3.0 60 15 156 3.0 60 3.0 60 15 156 C/W 1 0.020 1 0.020 % %/W % % Vo The Bold specifications apply to the full operating temperature range. Note 1: Changes in output voltage due to heating effects are covered under the specification for thermal regulation. Note 2: Fixed Version Only Note 3: Adjustable Version Only Rev. 10/2/00 www..com AS2810 APPLICATION HINTS The AS2810 incorporates protection against over-current faults, reversed load insertion, over temperature operation, and positive and negative transient voltage. However, the use of an output capacitor is required in order to improve the stability and the performances. Stability The output capacitor is part of the regulator's frequency compensation system. Either a 22F aluminum electrolytic capacitor or a 10F solid tantalum capacitor between the output terminal and ground guarantees stable operation for all operating conditions. However, in order to minimize overshoot and undershoot, and therefore optimize the design, please refer to the section `Ripple Rejection'. Ripple Rejection Ripple rejection can be improved by adding a capacitor between the ADJ pin and ground as shown in figure 6. When ADJ pin bypassing is used, the value of the output capacitor required increases to its maximum (22F for an aluminum electrolytic capacitor, or 10F for a solid tantalum capacitor). If the ADJ pin is not bypass, the value of the output capacitor can be lowered to 10F for an electrolytic aluminum capacitor or 4.7F for a solid tantalum capacitor. However the value of the ADJ-bypass capacitor should be chosen with respect to the following equation: C = 1 / ( 6.28 * FR * R1 ) Where C = value of the capacitor in Farads (select an equal or larger standard value), FR = ripple frequency in Hz, R1 = value of resistor R1 in Ohms. If an ADJ-bypass capacitor is use, the amplitude of the output ripple will be independent of the output voltage. If an ADJbypass capacitor is not used, the output ripple will be proportional to the ratio of the output voltage to the reference voltage: M = VOUT / VREF Where M = multiplier for the ripple seen when the ADJ pin is optimally bypassed. VREF = Reference Voltage Reducing parasitic resistance and inductance One solution to minimize parasitic resistance and inductance is to connect in parallel capacitors. This arrangement will improve the transient response of the power supply if your system requires rapidly changing current load condition. Thermal Consideration Although the AS2810 offers some limiting circuitry for overload conditions, it is necessary not to exceed the maximum junction temperature, and therefore to be careful about thermal resistance. The heat flow will follow the lowest resistance path, which is the Junction-to-case thermal resistance. In order to insure the best thermal flow of the component, a proper mounting is required. Note that the case of the device is electrically connected to the output. In case the case has to be electrically isolated, a thermally conductive spacer can be used. However do not forget to consider its contribution to thermal resistance. Assuming: VIN = 10V, VOUT = 5V, IOUT = 1.5A, TA = 50C/W, Heatsink Case= 6C/W, Heatsink Case = 0.5C/W, JC = 3C/W Power dissipation under this condition PD = (VIN - VOUT) * IOUT = 7.5W Junction Temperature TJ = TA + PD * ( Case - HS+ HS + JC) For the Control Sections TJ = 50 + 7.5*(0.5+6=3) = 121.25C 121.25C < TJ (max) for the Control & Power Sections. In both case reliable operation is insured by adequate junction temperature. Rev. 10/2/00 www..com AS2810 Basic Adjustable Regulator VIN AS2810 VREF IADJ 50A R2 VOUT = VREF * ( 1 + R /R1) + IADJ * R2 2 R1 VOUT VIN 5V C1 10uF VOUT 3.3V C2 10uF AS2810 Basic Fixed Regulator Fig.2 Basic Adjustable Regulator Output Voltage Consider Figure 2. The resistance R1 generates a constant current flow, normally the specified load current of 10mA. This current will go through the resistance R2 to set the overall output voltage. The current IADJ is very small and constant. Therefore its contribution to the overall output voltage is very small and can generally be ignored. Load Regulation Parasitic line resistance can degrade load regulation. In order not to affect the behavior of the regulator, it is best to connect directly the R1 resistance from the resistor divider to the case, and not to the load. For the same reason, it is best to connect the resistor R2 to the Negative side of the load. R P Parasitic Line Resistance Output Voltage The fixed voltage LDO voltage regulator are simple to use regulators since the VOUT is preset to the specifications. It is important however, to provide the proper output capacitance for stability and improvement. For most operating conditions a capacitance of 22uF tantalum or 100uF electrolytic will ensure stability and prevent oscillation. VIN AS2810 Connect R 1 to Case of Regulator R1 RL R2 Connect R 2 to Load Fig.3 Basic Adjustable Regulator Rev. 10/2/00 www..com AS2810 TYPICAL APPLICATIONS VIN C1 IN AS2810 ADJ OUT R1 VIN C1 IN AS2810 ADJ OUT C2 R1 VOUT LOAD VOUT = VREF (1 + R2 ) + IADJ R2 R1 R2 Fig. 4 1A Current output Regulator Fig. 5 Typical Adjustable Regulator (Note A) VIN IN 5V + 10F AS2810 ADJ OUT VOUT R1 121 1% 150F VIN (Note A) + IN AS2810 ADJ OUT 5V 121 1% + 100F 10F 1k 2N3904 1k 365 1% *C 1 improves ripple rejection. Xc should be ~ R 1 at ripple frequency. R2 365 1% TTL Input + C1 10F* Note A: V IN(MIN) = (Intended V OUT) + (VDROPOUT (MAX)) Note A: VIN(MIN)= (Intended V ) + (VDROPOUT (MAX)) OUT Fig. 6 Improving Ripple Rejection Fig.7 5V Regulator with Shutdown Rev. 10/2/00 www..com AS2810 TYPICAL CHARACTERISTICS Rev. 10/2/00 |
Price & Availability of AS2810
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |