A2

B2

VIN

VOUT

Power Ground

VEN

CIN

COUT

LP3991TL

B1

A1

16

LP3991

SNVS296J – DECEMBER 2006 – REVISED JUNE 2016

www.ti.com

Product Folder Links: LP3991

Submit Documentation Feedback

Copyright © 2006–2016, Texas Instruments Incorporated

9 Power Supply Recommendations

The LP3991 is designed to operate from an input voltage supply range from 1.65 V to 4 V.

10 Layout

10.1 Layout Guidelines

The dynamic performance of the LP3991 is dependant on the layout of the PCB. PCB layout practices that are

adequate for typical LDOs may degrade the PSRR or transient performance of the LP3991.

Best performance is achieved by placing all of the components on the same side of the PCB as the LP3991, as

close as is practical to the LP3991 package. All component ground connections must be back to the LP3991

analog ground connection using as wide and as short of a copper trace as is practical.

Connections using long trace lengths, narrow trace widths, and connections through vias must be avoided.

These add parasitic inductances and resistance that results in inferior performance especially during transient

conditions.

A ground plane, either on the opposite side of a two-layer PCB, or embedded in a multi-layer PCB, is strongly

recommended. This ground plane serves two purposes:

1. Provides a circuit reference plane to assure accuracy, and

2. Provides a thermal plane to remove heat from the LP3991 through thermal vias under the package DAP.

10.2 Layout Example

Figure 18. LP3991 Example Layout