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L4937N
DUAL MULTIFUNCTION VOLTAGE REGULATOR
.STANDBYOUTPUTVOLTAGEPRECI .OUTPUT2TRACKEDTOTHESTANDBYOUT.OUTPUT .VERY .OUTPUTCURRENTS:I .VERYLOWDROPOUT( .OPERATI .POWER.POWER.THERMALSHUTDOWNANDSHORTCI
2% PUT PIN CONNECTION (top view)
SION 5V
2 DISABLE FUNCTION FOR STANDBY MODE LOW QUIESCENT CURRENT, LESS THAN 250A, IN STANDBY MODE 01 = 50mA, I02 = 500mA max 0.4V/0.6V) NG TRANSIENT SUPPLY VOLTAGE UP TO 40V ON RESET CIRCUIT SENSING THE STANDBY OUTPUT VOLTAGE ON RESET DELAY PULSE DEFINED BY THE EXTERNAL CAPACITOR RCUIT PROTECTIONS
Heptawatt ORDERING NUMBER : L4937N
DESCRIPTION The L4937N is a monolithic integrated dual voltage regulatorswith two very low dropout outputsand additional functions such as power-on reset and input voltage sense. It is designed for supplying microcomputer controlled systems specially in automotive applications.
June 2000
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BLOCK DIAGRAM
THERMAL DATA
Symbol Rthj-case Parameter Thermal Resistance Junction-Case Max. Value 3 Unit C/W
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ABSOLUTE MAXIMUM RATINGS
Symbol VS Tj, Tstg IEN VEN VRES IRES PD DC Supply Voltage Transient Supply Voltage (T < 1s) Junction and Storage Temperature Range Enable Input Current (V EN 0.3V) Enable Input Voltage Reset Output Voltage Reset Output Current Power Dissipation (TA = 80C, R th heatsink = 9C/W) Parameter Value 28 40 -55 to 150 1 VS 20 5 5 V mA W Unit V V C mA
Note : The circuit is ESD protected according to MIL-STD-883C.
APPLICATION CIRCUIT
CS 1F ; C01 6F ; C02 10F, ESR < 10 at 10KHz
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ELECTRICAL CHARACTERISTICS (VS = 14V; -40C Tj 125C unless otherwise specified)
Symbol VS VO1 VO2 - VO1 Parameter Operating Supply Voltage Standby Output Voltage Output Voltage 2 Tracking Error (note 1) Dropout Voltage 1 Input to Output Voltage Difference in Undervoltage Condition Dropout Voltage 2 Input to Output Voltage Difference in Undervoltage Condition Line Regulation Load Regulation 1 Load Regulation 2 Current Limit 1 Current Limit 2 Quiescent Current Standby Mode (output 2 disabled) 6V VS 25V 1mA IO1 50mA 6V VS 25V 5mA IO2 500mA Enable = LOW IO1 = 10mA IO1 = 50mA VS = 4V, IO1 = 35mA 4.90 -25 5.00 Test Conditions Min. Typ. Max. 25 5.10 +25 Unit V V mV
VDP1 VIO1
0.1 0.2
0.25 0.4 0.4
V V V
VDP2 VIO2
IO2 = 100mA IO2 = 500mA VS = 4.6V, IO2 = 350mA
0.2 0.3
0.3 0.6 0.6
V V V
VOL 1.2 VOLO1 VOLO2 ILIM1 ILIM2 IQSB
6V VS 25V IO1 = 1mA; IO2 = 5mA 1mA IO1 50mA 5mA IO2 500mA VO1 = 4.5V VO1 = 0V (note 2) VO2 = 0V IO1 = 0.3mA; TJ < 100C VEN 2.4V VS = 14V VS = 3.5V IO1 = 50mA IO1 = 500mA 55 25 550 100 50 1000
20 25 50 200 100 1700
mV mV mV mA mA mA
210 340
290 850 30
A A mA
IQ
Quiescent Current
ENABLE
VENL VENH VENhyst IEN Enable Input LOW Voltage (output 2 active) Enable Input HIGH Voltage Enable Hysteresis Enable Input Current 0V < VEN < 1.2V 2.5V < VEN < 7V -0.3 2.4 30 -10 -1 75 -1.5 0 1.5 7 200 -0.5 +1 V V mV A A
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ELECTRICAL CHARACTERISTICS (continued) RESET
Symbol VRt VRth tRD tRR VRL ILRES VCTth VCTth, hyst
Note :
Parameter Reset Low Threshold Voltage Reset Threshold Hysteresis Reset Pulse Delay Reset Reaction Time Reset Output LOW Voltage Reset Output HIGH Leakage Delay Comparator Threshold Delay Comparator Threshold Hysteresis
Test Conditions VS = 14V CT = 100nF; tR > 100s CT = 100nF RRES = 10K to V01 VS 1.5V VRES = 5V
Min. Vo1 -0.4 50 55 1
Typ. 4.7 100 100 10
Max. Vo1 -0.1 200 180 50 0.4 1
Unit V mV ms s V A V mV
2.0 100
1 : VO2 connected to ADJ.VO2 can be set to higher values by inserting an external resistor divider. 2 : Foldback characteristic
FUNCTIONAL DESCRIPTION The L4937N is based on the SGS-THOMSON Microelectronics modular voltage regulatorapproach. Several out-standing features and auxiliary functions are provided to meet the requirements of supplying the microprocessor systems used in automotive applications. Furthermore the device is suitable also in other applications requiring two stabilized voltages. The modular approach allows other features and functions to be realized easily when required. STANDBY REGULATOR The standby regulator uses an Isolated Collector Vertical PNP transistor as the regulating element. This structure allows a very low dropout voltage at currents up to 50mA. The dropout operation of the standby regulator is maintained down to 2V input supply voltage. The output voltage is regulated up to the transient input supplyvoltageof40V. This feature avoids functional interruptions which could be generated by overvoltage pulses.
The typical curve of the standby output voltage as a functionof the input supply voltageis shownin fig. 1. The current consumption of the device (quiescent current) is less than 250A when output 2 is disabled (standby mode). The dropout voltage is controlled to reduce the quiescent current peak in the undervoltage region and to improve the transient response in this region. Thequiescent current isshown in fig.2 as a function of the supply input voltage 2. OUTPUT 2 VOLTAGE The output 2 regulator uses the same output structureas the standbyregulator, but ratedfor an output current of 500mA. The output 2 regulatorworks in tracking mode with the standby output voltage as a reference voltage. The output 2 regulator can be switched off via the Enable input.
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Figure 1 : Output Voltage vs. Input Voltage.
Figure 2 : Quiescent Current vs. Supply Voltage.
400
200
RESET CIRCUIT Theblock circuit diagramof the resetcircuit is shown in fig.3. Thereset circuit supervisesthe standbyoutput voltage. The reset threshold of 4.7V is defined by the internal reference voltage and the standby output divider. The reset pulse delay time tRD, is defined by the charge time of an external capacitor CT : CT x 2V tRD = 2A
The reaction time of the reset circuit dependson the discharge time limitation of the reset capacitor CT and is proportional to the value of CT. The reaction time of the reset circuit increases the noise immunity. In fact, if the standbyoutput voltage drops below the reset threshold for a time shorter than the reaction time t RR, no reset output variation occurs. The nominal reset delay is generated for standby output voltage drops longer than the time necessary for the complete discharging of the capacitor CT. This time is typically equal to 50s if CT = 100nF. The typical reset output waveforms are shown in fig.
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Figure 3 : Block Diagram of the Reset Circuit.
Figure 4 : Typical Reset Output Waveforms.
VOUT1 VINPUT
VRT +0.2V VRT
VOUT1
1.5V
tR RESET
tRD tRR
tRD
D95AT216
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DIM. A C D D1 E E1 F F1 G G1 G2 H2 H3 L L1 L2 L3 L4 L5 L6 L7 L9 M M1 V4 Dia mm TYP. inch TYP.
MIN.
2.4 1.2 0.35 0.7 0.6 2.34 4.88 7.42 10.05 16.7 21.24 22.27 2.6 15.1 6 2.55 4.83 3.65 2.54 5.08 7.62
16.9 14.92 21.54 22.52 2.8 15.5 6.35 0.2 2.8 5.08
MAX. 4.8 1.37 2.8 1.35 0.55 0.97 0.8 0.9 2.74 5.28 7.82 10.4 10.4 17.1 21.84 22.77 1.29 3 15.8 6.6
MIN.
0.094 0.047 0.014 0.028 0.024 0.095 0.193 0.295 0.396 0.657 0.386 0.877 0.102 0.594 0.236 0.100 0.200 0.300
0.668 0.587 0.848 0.891 0.110 0.610 0.250 0.008 0.110 0.200
MAX. 0.189 0.054 0.110 0.053 0.022 0.038 0.031 0.035 0.105 0.205 0.307 0.409 0.409 0.673 0.860 0.896 0.051 0.118 0.622 0.260 0.120 0.210 0.152
OUTLINE AND MECHANICAL DATA
3.05 0.100 5.33 0.190 40 (typ.) 3.85 0.144
Heptawatt V
L E L1 M1 A C D1 L5 L2 L3
E E1 F
V
V
D
M H2
V4
L9
H3
H1
Dia.
G
G1 G2
F L7 L6 L4 H2 F1
HEPTAMEC
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Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics (c) 2000 STMicroelectronics - Printed in Italy - All Rights Reserved HEPTAWATTTM is a Trademark of STMicroelectronics STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com
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