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PDF L4937 Data sheet ( Hoja de datos )
| Número de pieza | L4937 | |
| Descripción | DUAL MULTIFUNCTION VOLTAGE REGULATOR | |
| Fabricantes | STMicroelectronics | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de L4937 (archivo pdf) en la parte inferior de esta página. Total 9 Páginas | ||
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® L4937N
DUAL MULTIFUNCTION VOLTAGE REGULATOR
. STANDBYOUTPUT VOLTAGEPRECISION 5V
± 2%
. OUTPUT 2 TRACKED TOTHE STANDBY OUT-
PUT
. OUTPUT 2 DISABLE FUNCTION FOR
STANDBY MODE
. VERY LOW QUIESCENT CURRENT, LESS
THAN 250µA, IN STANDBY MODE
. OUTPUT CURRENTS : I01 = 50mA, I02 = 500mA
. VERY LOW DROPOUT (max 0.4V/0.6V)
. OPERATING TRANSIENT SUPPLY VOLTAGE
UP TO 40V
. POWER-ON RESET CIRCUIT SENSING THE
STANDBY OUTPUT VOLTAGE
. POWER-ON RESET DELAY PULSE DEFINED
BY THE EXTERNAL CAPACITOR
. THERMALSHUTDOWN AND SHORTCIRCUIT
Heptawatt
ORDERING NUMBER : L4937N
D ES CRIPT IO N
The L4937N is a monolithic integrated dual voltage
regulatorswith two very low dropout outputsand ad-
ditional functions such as power-on reset and input
voltage sense. It is designed for supplying micro-
computer controlled systems specially in automo-
PROTECTIONS
tive applications.
PIN CONNECTION (top view)
June 2000
1/9
1 page  
L4937N
ELECTRICAL CHARACTERISTICS (continued)
RESET
Symbol
Parameter
Test Conditions
Min.
VRt
VRth
tRD
tRR
VRL
ILRES
VCTth
VCTth, hyst
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
VS = 14V
CT = 100nF; tR > 100µs
CT = 100nF
RRES = 10KΩ to V01 VS ≥ 1.5V
VRES = 5V
Vo1 -0.4
50
55
1
Note : 1 : VO2 connected to ADJ.VO2 can be set to higher values by inserting an external resistor divider.
2 : Foldback characteristic
Typ.
4.7
100
100
10
2.0
100
Max.
Vo1 -0.1
200
180
50
0.4
1
Unit
V
mV
ms
µs
V
µA
V
mV
FUNCTIONAL DESCRIPTION
The L4937N is based on the SGS-THOMSON Mi-
croelectronics modular voltage regulatorapproach.
Several out-standing features and auxiliary func-
tions are provided to meet the requirements of sup-
plying the microprocessor systems used in automo-
tive applications.
Furthermore the device is suitable also in other ap-
plications 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 fea-
ture 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 250µA when output 2 is dis-
abled (standby mode). The dropout voltage is con-
trolled 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 struc-
tureas 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.
5/9
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| Páginas | Total 9 Páginas | |
| PDF Descargar | [ Datasheet L4937.PDF ] | |
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