L4938ED STMicroelectronics, L4938ED Datasheet - Page 11

• Manufacturer Part Number: L4938ED
• Description: IC VREG ADVANCED DUAL SO-20
• Manufacturer: STMicroelectronics

Specifications of L4938ED

• 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: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)
• Polarity: Positive
• Number Of Outputs: 2
• Output Type: Fixed
• Output Voltage: 5 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: SMD/SMT
• Reference Voltage: 1.23 V
• Voltage Regulation Accuracy: 2 %
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L4938ED, L4938EPD
3
Figure 3.
3.1
3.2
(See note 2)
Application information
Application diagram
1. The leakage of C
2. For transients exceeding 20 V or -20 V external protection is required at the pins SI and EN as shown at
Functional description
The L4938ED and L4938EPD are monolithic integrated dual voltage regulators, based on
the STM modulator voltage regulator approach. Several outstanding features and auxiliary
functions are implemented to meet the requirements of supplying microprocessor systems
in automotive applications. Nevertheless, it is suitable also in other applications where two
stabilized voltages are required. The modular approach of this device allows to get easy
also other features and functions when required.
Standby regulator
The standby regulator uses an isolated collector vertical PNP transistor as a regulating
element. With this structure very low dropout voltage at currents up to 100 mA is obtained.
The dropout operation of the standby regulator is maintained down to 3 V input supply
voltage. The output voltage is regulated up to the transient input supply voltage of 40 V. With
this feature no functional interruption due to overvoltage pulses is generated.
the leakage current may be increased. The external resistor should have more than 30 KΩ.
For stability: Cs ≥ 1 µF, C01 ≥ 10 µF, C02 ≥ 10 µF, ESR ≤ 5Ω (designed target).
pin EN. The protection proposed provides proper function for transients in the range of ±200 V. If the zener
diode is omitted the external resistor should be raised to 200 KΩ to limit the current to 1 mA. Without the
zener diode, the function 20 V or -20 V can not be guaranteed.
T
must be less than 0.5 mA (2 V). If an external resistor between C
Doc ID 17243 Rev 1
Application information
T
and V
OUT1
(See note 1)
is applied,
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