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PDF L4938N Data sheet ( Hoja de datos )

Número de pieza L4938N
Descripción DUAL MULTIFUNCTION VOLTAGE REGULATOR
Fabricantes STMicroelectronics 
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No Preview Available ! L4938N Hoja de datos, Descripción, Manual

L4938N/ND
® L4938NPD
DUAL MULTIFUNCTION VOLTAGE REGULATOR
. STANDBYOUTPUT VOLTAGEPRECISION 5V
± 2%
. OUTPUT 2 TRACKED TOTHESTANDBY OUT-
PUT
. OUTPUT 2 DISABLE FUNCTION FOR
STANDBY MODE
. VERY LOW QUIESCENT CURRENT, LESS
THAN 250µA, IN STANDBY MODE
. OUTPUT 2 VOLTAGE SETTABLE FROM 5 TO
20V
. 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
. EARLY WARNING OUTPUT FOR SUPPLY UN-
DERVOLTAGE
. THERMAL SHUTDOWN AND SHORTCIRCUIT
PROTECTIONS
PowerDIP
(12+2+2)
SO20
(12+4+4)
PowerSO20
ORDERING NUMBERS: L4938N (PDIP)
L4938ND (SO)
L4938NPD (PSO20)
DESCRIPTION
The L4938N is a monolithic integrated dual voltage
regulatorswith two very low dropout outputsand ad-
ditional functions such as power-on reset and input
voltage sense. They are designedfor supplying mi-
crocomputer controlled systems specially in auto-
motive applications.
PIN CONNECTION (top view)
POWERDIP
SO20
PowerSO20
N.C.
CT
EN
GND
GND
RES
SO
VO1
1 16
2 15
3 14
4 13
5 12
6 11
7 10
89
D95AT156
SI
VS1
VS2
GND
GND
VO2
VO2
ADJ
N.C.
C7
EN
GND
GND
GND
GND
RES
SO
VO1
1 20
2 19
3 18
4 17
5 16
6 15
7 14
8 13
9 12
10 11
D93AT004
SI
VS1
VS2
GND
GND
GND
GND
VO2
VO2
ADJ
GND
N.C.
VS2
VS1
SI
N.C.
CT
EN
N.C.
GND
1 20
2 19
3 18
4 17
5 16
6 15
7 14
8 13
9 12
10 11
D95AT169A
GND
N.C.
VO2
ADJ
VO1
SO
RESET
N.C.
N.C.
GND
April 1999
1/12
This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.

1 page




L4938N pdf
L4938N - L4938ND - L4938NPD
ELECTRICAL CHARACTERISTICS (continued)
RESET
Symbol
VRt
VRth
tRD
tRR
VRL
Parameter
Reset Low Threshold Voltage
Reset Threshold Hysteresis
Reset Pulse Delay
Reset Reaction Time
Reset Output LOW Voltage
ILRES
VCTh
VCTh, hyst
Reset Output HIGH Leakage
Delay Comparator Threshold
Delay Comparator Threshold
Hysteresis
SENSE
Test Conditions
CT = 100nF; tR > 100µs
CT = 100nF
RRES = 10Kto 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
Unit
V
mV
mV
µs
V
1 µA
2.0 V
100 mV
VSlth
VSlth, hyst
VSOL
Sense Threshold Voltage
Sense Threshold Hysteresis
Sense Output LOW Voltage
ILSO Sense Output Leakage
VSI = 1,16V; VS 3V
RSO = 10Kto V01
VSO = 5V; VSI 1.5V
1.16
40
Note : 1 : VO2 connected to ADJ.VO2 can be set to higher values by inserting an external resistor divider.
2 : Foldback characteristic
1.23
100
1.35
200
0.4
1
V
mV
V
µA
FUNCTIONAL DESCRIPTION
The L4938N is based on the STMicroelectronics
modular voltage regulator approach. Several out-
standing features and auxiliary functions are pro-
vided to meet the requirements of supplying the mi-
croprocessor systems used in automotive applica-
tions.
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 transientinput supplyvoltageof 40V.This fea-
ture avoids functional interruptions which could be
generated by overvoltage pulses.
The typical curve of the standby output voltage as a
functionof theinput supply voltage is shown in 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.
The quiescentcurrent 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-
ture as the standbyregulator, but rated for anoutput
current of 500mA.
The output 2 regulatorworks in tracking mode with
the standby output voltage as a reference voltage
when the output 2 programming pin ADJ is con-
nected to VO2. By connecting a resistor divider R1,
R2 to the pin ADJ as shown in fig. 3, the output volt-
age 2 can be programmed to the value :
VO2 = VO1 (1 + R1/R2)
The output 2 regulator can be switched off via the
Enable input.
If a fixed 5 regulation is required ADJ Pin has to be
connected to V02 Pin.
5/12

5 Page





L4938N arduino
DIM.
MIN.
mm
TYP. MAX. MIN.
inch
TYP. MAX.
A 2.35
2.65 0.093
0.104
A1 0.1
0.3 0.004
0.012
B 0.33
0.51 0.013
0.020
C 0.23
0.32 0.009
0.013
D 12.6
13 0.496
0.512
E 7.4
7.6 0.291
0.299
e 1.27
0.050
H 10
10.65 0.394
0.419
h 0.25
0.75 0.010
0.030
L 0.4
1.27 0.016
0.050
K 0° (min.)8° (max.)
L4938N - L4938ND - L4938NPD
OUTLINE AND
MECHANICAL DATA
SO20
B
20
1
e
D
L
A
K
h x 45°
A1
H
C
11
10
E
SO20MEC
11/12

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