EN

GND(CP)

CP

IN(CP)

OUT(FB)

SET

FB

GND

UVLO

Charge Pump

3.5 MHz

Current

Limit

Thermal

Shutdown

1.200V

2 PA

5V

LP38798SD-ADJ

OUT

OUT

IN

IN

Active Ripple

Rejection

200 mV

PMOS

52 PA

99.5%

98%

tau= 2s

1.24V

LP38798

www.ti.com

SNOSCT6A – MARCH 2013 – REVISED MAY 2013

APPLICATIONS INFORMATION

Functional Block Diagram

Package Information

The LP38798-ADJ is available in the 12-Lead WSON surface mount package that allows for increased power

dissipation compared to the standard PSOP-8 and WQFN-8 packages.

External Capacitors

Like any low-dropout regulator, the LP38798-ADJ requires external capacitors for regulator stability. These

capacitors must be correctly selected for optimum performance.

INPUT CAPACITOR: The minimum recommended input capacitance is 1 µF, ceramic or tantalum. However, if

the LP38798 is operating in conditions where input ripple, fast changes in the input voltage, or large changes in

the load current demand are expected, a minimum input capacitance of 10 µF is strongly recommended.

Ceramic capacitor tolerance and variations due temperature and applied voltage must be considered when

selecting a capacitor to assure the minimum input capacitance requirement is met over the intended operating

range.

The input capacitor must be located as close as physically possible to the input pin and returned to a clean

analog ground. Any good quality tantalum capacitor may be used, while a ceramic capacitor should be X5R or

X7R rated with appropriate adjustments due to the loss of capacitance value from the applied DC voltage.

Larger input capacitance values are encouraged if fast output current steps are expected, as this will minimize

voltage drops at the input pin. However, if there is any PCB trace inductance between the bulk supply and the

input pin it is recommended that a tantalum capacitor be placed in parallel with the ceramic input capacitor. This

will help to damp out undesired ringing that may occur during input transient conditions.

Copyright © 2013, Texas Instruments Incorporated

13

Product Folder Links: LP38798