CS8271

CS8271 CHERRY | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 6

Technical content

Features

+ - Current Limit Sense Current Source (Circuit Bias) Adj ENABLE Input n Low Quiescent Current n Adjustable Output: 5V to 12V n for Sleep Mode Control n 100mA Output Current Capability n Fault Protection +60V Load Dump -15V Reverse Voltage Short Circuit Thermal Shutdown n Low Reverse Current (Output to Input) ENABLE Package Options CS8271 CS8271

Description

The CS8271 is an adjustable microp- ower voltage regulator with very low quiescent current (60µA typical at 100µA load). The output supplies 100mA of load current with a maxi- mum dropout voltage of only 600mV. Control logic includes . The combination of low quiescent current, outstanding reg- ulator performance and control logic makes the CS8271 ideal for any battery operated equipment. The logic level compatible pin allows the user to put the regu- lator into a shutdown mode where it draws only 50µA of quiescent cur- rent. The regulator is protected against reverse battery, short circuit, over voltage, and over temperature con- ditions. The device can withstand 60V load dump transients making it suitable for use in automotive envi- ronments. The CS8271 is pin compatible with the National Semiconductor LM2931. ENABLE ENABLE Block Diagram 1VOUT Gnd NC Adj VIN NC NC ENABLE Other Packages: Consult factory for 16L SO Batwing, 5L TO-220 and D2PAK. 8L SOIC & PDIP Adjustable Micropower Low Dropout Linear Regulator withENABLE A Company ¨ Rev. 3/26/97 Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: (401)885-3600 Fax: (401)885-5786 Email: info@cherry-semi.com Web Site: www.cherry-semi.com

Lead Temperature Soldering PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Absolute Maximum Ratings Electrical Characteristics: VOUT + 1V ² VIN ² 30V, 5V ² VOUT ² 12V, IOUT = 10mA, -40¡ ² TA ² 125¡, -40¡ ² TJ ² 150¡, VENABLE = 0V; unless otherwise specified. CS8271 n Output Voltage Dropout Voltage I OUT = 100µA, VDROP = (VIN Ð VOUT) 100 150 mV IOUT = 100mA, VDROP = (VIN Ð VOUT) 400 600 mV Load Regulation Measure V OUT when 0.1 1.0 %V OUT IOUT = 100µA, 100mA. LDREG = ABS (ÆVOUT) Line Regulation I OUT = 1mA. Measure VOUT 0.1 0.5 %V OUT when VIN = VOUT + 1V, 30V. LNREG = ABS (ÆVOUT) Quiescent Current, (IQ)V IN = 6V, IOUT = 100µA, 55 120 µA Active Mode V OUT setup for 5V. IQ = IVIN - IOUT VIN = 13V, IOUT = 100µA, 130 200 µA VOUT setup for 12V. IQ = IVIN - 100µA VIN = 30V, IOUT = 100µA, 150 450 µA VOUT setup for 5V, IQ = IVIN - 100µA VIN = 30V, IOUT = 100µA, 200 500 µA VOUT setup for 12V, IQ = IVIN - 100µA IOUT = 50mA, IQ = IVIN - 50mA 4 7 mA IOUT = 100mA, IQ = IVIN - 100mA 12 21 mA Quiescent Current, (IQ)V IN = 6V, ENABLE = 2.5V, 20 50 µA Sleep Mode I QSLEEP = IVIN VIN = 30V, ENABLE = 2.5V, 75 350 µA IQSLEEP = IVIN Ripple Rejection f=120Hz, (Note 1) 60 75 dB Current Limit V OUT = VOUT - 500mV, ILIM = IVOUT 105 200 300 mA Short Circuit Output Current V OUT=0V, ISHRT = IVOUT 15 100 215 mA Thermal Limit (Note 1) 150 180 210 ¡C Overvoltage Shutdown Adjust V IN from 28V to 40V 30 34 38 V until VOUT ²1 V Reverse Current V IN=0V, IREV = IVOUT, VOUT = 13.2V 100 200 µA

PACKAGE PIN # PIN SYMBOL FUNCTION PARAMETER TEST CONDITIONS MIN TYP MAX UNIT Electrical Characteristics: VOUT + 1V ² VIN ² 30V, 5V ² VOUT ² 12V, IOUT = 10mA, -40¡ ² TA ² 125¡, -40¡ ² TJ ² 150¡, VENABLE = 0V; unless otherwise specified. The output voltage of the CS8271 is adjustable to any value between the reference voltage on the Adj pin, (1.272V Typ.) and the maximum input voltage minus the dropout voltage. To adjust the output voltage, a pair of external resistors R1 and R2 are connected as shown in Figure 1. The equation for the output voltage is V OUT = VREF x+ I Adj x R1 where Vref is the typical reference voltage and IAdj is the adjust pin bias current. This is usually 500nA maximum. Figure 1: Output Voltage Adjustment. Adj CS8271 VOUT VOUT VREF R1 + R2 R2( Output Voltage Adjustment Circuit Description 8L SOIC & PDIP 1V OUT 100mA output; adjustable from 5V to 12V. 2 Gnd Ground. 3, 6, 7 NC No Connection. 4 Adj Resistor divider from V OUT to Adj, sets output voltage. 5 Logic level switch, when HIGH, regulator is in sleep mode. IN Input voltage. ENABLE n Enable Threshold 1.15 2.0 2.6 V Enable Input Current V ENABLE = 2.6V 10 20 µA VENABLE = 5V 35 50 µA n Adjustment Pin R1: Feedback resistor between V OUT and Adjust, R2: Adjust resistor to ground. Reference Voltage 100µA ² I OU T² 100mA 1.246 1.272 1.297 V Adjustment Pin Current IAdj = - 20 500 nA Note 1: Guaranteed by design, not 100% tested in production. (VOUT - VREF) VREF ENABLE

C2** 10mF VOUTVIN Gnd C1* 0.1mF Vref ENABLE C1* Required if regulator is away from power supply filter. C2** Required for output stability. VOUT = Vref x+ I Adj x R1) R1 + R2 R2( Step 6: Test the load transient response by switching in various loads at several frequencies to simulate its real work environment. Vary the ESR to reduce ringing. Step 7: Remove the unit from the environmental chamber and heat the IC with a heat gun. Vary the load current as instructed in step 5 to test for any oscillations. Once the minimum capacitor value with the maximum ESR is found, a safety factor should be added to allow for the tolerance of the capacitor and any variations in regula- tor performance. Most good quality aluminum electrolytic capacitors have a tolerance of ±20% so the minimum value found should be increased by at least 50% to allow for this tolerance plus the variation which will occur at low tem- peratures. The ESR of the capacitor should be less than 50% of the maximum allowable ESR found in step 3 above. Capacitance on the Adjust pin combined with the feed- back resistors R1 and R2 can affect loop stability and should also be considered. The CS8271 internal circuitry produces about 5pF to Ground on the Adjust pin. This capacitance, plus any additional external capacitance on the Adjust pin will create a pole when combined with the resistive feedback network. The effect can be significant when using large values for the feedback resistors to mini- mize quiescent current. A capacitor connected from the Adjust pin to Ground pro- vides additional means to compensate the regulator by creating a pole. Alternately, a capacitor can be connected from the Adjust pin to V OUT to create a zero. The maximum power dissipation for a single output regu- lator (Figure 4) is PD(max)={VIN(max)ÐVOUT(min)}IOUT(max)+VIN(max)IQ (1) where VIN(max) is the maximum input voltage, VOUT(min) is the minimum output voltage, IOUT(max) is the maximum output current, for the applica- tion IQ is the quiescent current the regulator consumes at IOUT(max). Figure 4: Single output regulator with key performance parameters labeled. Once the value of PD(max) is known, the maximum permis- sible value of RQJA can be calculated: RQJA = (2) The value of RQJA can then be compared with those in the package section of the data sheet. Those packages with R QJA's less than the calculated value in equation 2 will keep the die temperature below 150¡C. In some cases, none of the packages will be sufficient to dissipate the heat generated by the IC, and an external heatsink will be required. 150¡C - T A PD VIN Smart Regulator VOUT IOUT IIN IQ Control Calculating Power Dissipation in a Single Output Linear Regulator Application Notes: continued

RQJC typ 45 52 ûC/W RQJA typ 165 100 ûC/W D Lead Count Metric English Max Min Max Min 8L SOIC 5.00 4.80 .197 .189 8L PDIP 10.16 9.02 .400 .355 CS8271 Rev. 3/26/97 Part Number Description CS8271YD8 8L SOIC CS8271YDR8 8L SOIC (tape & reel) CS8271YN8 8L PDIP Package Specification

Ordering Information

PACKAGE DIMENSIONS IN mm (INCHES) PACKAGE THERMAL DATA © 1999 Cherry Semiconductor Corporation Cherry Semiconductor Corporation reserves the right to make changes to the specifications without notice. Please contact Cherry Semiconductor Corporation for the latest available information. Surface Mount Narrow Body (D); 150 mil wide Plastic DIP (N); 300 mil wide 0.39 (.015) MIN. 1.14 (.045) D Some 8 and 16 lead packages may have 1/2 lead at the end of the package. All specs are the same. .203 (.008) .356 (.014) REF: JEDEC MS-001 3.68 (.145) 2.92 (.115) 8.26 (.325) 7.62 (.300) 7.11 (.280) 6.10 (.240) .356 (.014) .558 (.022) 0.33 (.013) 6.20 (.244) 5.80 (.228) 4.00 (.157) 3.80 (.150) 1.57 (.062) 1.37 (.054) D 0.25 (0.10) 0.10 (.004) 1.75 (.069) MAX 1.27 (.050) 0.40 (.016) REF: JEDEC MS-012 0.25 (.010) 0.19 (.008)