LP38869

www.ti.com

SNVS877B – AUGUST 2012 – REVISED APRIL 2013

BOARD TYPE

THERMAL VIAS

JEDEC 2-Layer

None

141°C/W

JESD 51-3

0

131°C/W

1

78°C/W

2

65°C/W

JEDEC 4-Layer

3

59°C/W

JESD 51-7

4

56°C/W

6

53°C/W

9

50°C/W

Noise, PSRR, and Transient Response

The LP38869 is designed to achieve low dropout voltage and low quiescent current in battery-powered systems

while still maintaining good noise, transient response, and AC rejection (see PSRR vs. Frequency in the Typical

Operating Characteristics). When operating from very noisy sources, supply noise rejection and transient

response can be improved by increasing the input and output capacitor values and employing passive post

Reverse Input-Output Voltage

A reverse voltage condition will exist when the voltage at the output pin is higher than the voltage at the input pin.

the input to output voltage becomes reversed. Alternately, this could also happen if a secondary supply is

connected to the LP38869 output.

loop circuitry will attempt to regulate the output voltage. Since the input voltage is less than the output voltage the

control circuit will drive the gate of the pass element to the full ON condition when the output voltage begins to

The internal PFET pass element in the LP38869 has an inherent parasitic (body) diode. During normal operation,

the input voltage is higher than the output voltage and the body diode is reverse biased. However, if the output is

above the input voltage the body diode becomes forward biased and current flows from the output pin to the

input pin through the body diode.

The reverse current in the body diode should be limited to less than 1A continuous and less than 5A peak.

Copyright © 2012–2013, Texas Instruments Incorporated

Submit Documentation Feedback

17

Product Folder Links: LP38869