L4938ND013TR ,DUAL MULTIFUNCTION VOLTAGE REGULATORABSOLUTE MAXIMUM RATINGSSymbol Parameter Value UnitV DC Supply Voltage 28 VSTransient Supply Volta ..
L4938ND013TR ,DUAL MULTIFUNCTION VOLTAGE REGULATORELECTRICAL CHARACTERISTICS (VS = 14V; –40°C ≤ TJ ≤ 125°C unless otherwise specified)Symbol Paramete ..
L4938ND013TR ,DUAL MULTIFUNCTION VOLTAGE REGULATORELECTRICAL CHARACTERISTICSRESETSymbol Parameter Test Conditions Min. Typ. Max. UnitV Reset Low Thre ..
L4938NPD ,DUAL MULTIFUNCTION VOLTAGE REGULATORELECTRICAL CHARACTERISTICS (VS = 14V; –40°C ≤ TJ ≤ 125°C unless otherwise specified)Symbol Paramete ..
L4938NPD013TR ,DUAL MULTIFUNCTION VOLTAGE REGULATORL4938N/NDL4938NPD®DUAL MULTIFUNCTION VOLTAGE REGULATOR. STANDBY OUTPUT VOLTAGE PRECISION 5V± 2%. OU ..
L4940D2T10 ,VERY LOW DROP 1.5 A REGULATORSELECTRICAL CHARACTERISTICS OF L4940V5 (Refer to test circuit, V =7V, C =0.1μF, C =22μF,I I OT = 25° ..
LBA673 , Lead (Pb) Free Product - RoHS Compliant
LBA676 , Lead (Pb) Free Product - RoHS Compliant
LBA676 , Lead (Pb) Free Product - RoHS Compliant
LBAS16HT1G , Switching Diode
LBAS16LT1 , Switching Diode
LBAS16LT1G , Switching Diode
L4938ND013TR-L4938NPD013TR
DUAL MULTIFUNCTION VOLTAGE REGULATOR
L4938N/ND 938NP DApril 1999
DUAL MULTIFUNCTION VOLTAGE REGULATOR STANDBY OUTPUT VOLTAGE PRECISION 5V
± 2%. OUTPUT 2 TRACKED TO THE STANDBY 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 SHORT CIRCUIT
PROTECTIONS
DESCRIPTIONThe L4938N is a monolithic integrated dual voltage
regulators with two very low dropout outputs and ad-
ditional functions such as power-on reset and input
voltage sense. They are designed for supplying mi-
crocomputer controlled systems specially in auto-
motive applications.
PIN CONNECTION (top view)1/12
BLOCK DIAGRAM
THERMAL DATA
L4938N - L4938ND - L4938NPD2/12
ABSOLUTE MAXIMUM RATINGS
APPLICATION CIRCUIT
Note : The circuit is ESD protected according to MIL–STD–883C.
L4938N - L4938ND - L4938NPD3/12
ELECTRICAL CHARACTERISTICS (VS = 14V; –40°C ≤ TJ ≤ 125°C unless otherwise specified)ENABLE
L4938N - L4938ND - L4938NPD4/12
FUNCTIONAL DESCRIPTIONThe 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 transient input supply voltage of 40V. This fea-
ture avoids functional interruptions which could be
generated by overvoltage pulses.
The typical curve of the standby output voltage as a
function of the input 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 quiescent current is shown 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 standby regulator, but rated for an output
current of 500mA.
The output 2 regulator works 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.
Note : 1 : VO2 connected to ADJ.VO2 can be set to higher values by inserting an external resistor divider.
2 : Foldback characteristic
ELECTRICAL CHARACTERISTICS (continued)RESET
SENSE
L4938N - L4938ND - L4938NPD5/12
Figure 2 : Quiescent Current vs. Supply Voltage.
Figure 3 : Programmable Output 2 Voltage with External Resistors.
Figure 1 : Output Voltage vs. Input Voltage.
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