L4938E STMicroelectronics, L4938E Datasheet - Page 5

• Manufacturer Part Number: L4938E
• Description: IC REG LDO DUAL 5V/ADV 16DIP
• Manufacturer: STMicroelectronics

Specifications of L4938E

• Regulator Topology: Positive Fixed and Adjustable
• Voltage - Output: 5V, 4.9 ~ 5.1 V
• Voltage - Input: Up to 28V
• Voltage - Dropout (typical): 0.2V @ 100mA, 0.3V @ 400mA
• Number Of Regulators: 2
• Current - Output: 100mA, 400mA
• Current - Limit (min): 100mA, 450mA
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Through Hole
• Package / Case: 20-SOIC (7.5mm Width)
• Polarity: Positive
• Number Of Outputs: 2
• Output Type: Fixed
• Output Voltage: 5.1 V
• Output Current: 5 mA
• Line Regulation: 20 mV
• Load Regulation: 50 mV
• Dropout Voltage (max): 0.2 V
• Input Voltage Max: 20 V
• Maximum Operating Temperature: + 150 C
• Minimum Operating Temperature: - 40 C
• Maximum Power Dissipation: 875 mW
• Mounting Style: Through Hole
• Reference Voltage: 1.23 V
• Voltage Regulation Accuracy: 2 %
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-3355-5; 497-3914-5; 497-3914-5

Figure 1. Application Diagram.
FUNCTIONAL DESCRIPTION
The L4938E/ED/EPD is a monolithic integrated
dual voltage regulator, based on the STM modu-
lator voltage regulator approach. Several out-
standing features and auxiliary functions are im-
plemented to meet the requirements of supplying
microprocessor systems in automotive applica-
tions. Nevertheless, it is suitable also in other ap-
plications where two stabilized voltages are re-
quired. The modular approach of this device
allows to get easly also other features and func-
tions when required.
Standby Regulator
The standby regulator uses an Isolated collector
Vertical PNP transistor as a regulating element.
With this structure very low dropout volotage at
currents up to 100mA is obtained. The dropout
operation of the standby regulator is maintained
down to 3V input supply voltage. The output volt-
age is regulated up to the transient input supply
voltage of 40V. With this feature no functional in-
terruption due to overvoltage pulses is generated.
In the standby mode when the output 2 is dis-
abled, the current consumption of the device (qui-
escent current) is less than 90 A (14V supply
voltage).
for example
BZX97C15
(Note 8)
100K
15V
C
VS1
VS2
S
EN
PR
SI
1.23V
RESET
SENSE
REG1
REG2
1.23V
To reduce the quiescent current peak in the un-
dervoltage region and to improve the transient re-
sponse in this region, the dropout voltage is con-
trolled. A second regulation path will keep the
output voltage without load below 5.5V even at
high temperatures.
Output 2 Voltage
The output 2 regulator uses the same output
structure as the standby regulator but rated for
the output current of 400mA. The output voltage
is internally fixed to 5V if ADJ is connected to
V
The output 2 regulator can be switches OFF via
the enable input.
Figure 2.
OUT2
.
1.23V
1.23V
1.4V
1.23V
+
-
L4938E - L4938ED - L4938EPD
REFERENCE
R
R
1i
2i
total 100K
D94AT079A
typical
R
ADJ
OUT1
OUT2
GND
RES
ADJ
SO
CT
OUT2
ADJ
D94AT080
CT (Note 7)
V
OUT1
R
R
R
SO
C
C
1E
2E
5/12
O1
O2