A1

A3

C3

VIN

SW

FB

EN

DC/DC

GND

VOUT

LM3673TL-

1.8

C1

B2

C2

10 PF

C1

4.7 PF

2.2 PH

LP3991TL-

1.5

EN

LDO

GND

VIN

C4

4.7 PF

B2

A1

A2

B1

Li-Ion

2.7 ± 4.3V

1.5V

Ferrite

Bead

1.8V

17

LP3991

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SNVS296J – DECEMBER 2006 – REVISED JUNE 2016

Product Folder Links: LP3991

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10.3 DSBGA Mounting

The DSBGA package requires specific mounting techniques which are detailed in AN-1112 DSBGA Wafer Level

Chip Scale Package. Referring to the section Surface Mount Technology (SMT) Assenbly Considerations, the

pad style that must be used with the 4-pin package is a NSMD (non-solder mask defined) type.

For best results during assembly, alignment ordinals on the PCB may be used to facilitate placement of the

DSBGA device.

10.4 DSBGA Light Sensitivity

Exposing the DSBGA device to direct sunlight may cause mis-operation of the device. Light sources such as

halogen lamps can affect the electrical performance if brought near to the device.

The wavelengths that have the most detrimental effect are reds and infra-reds, which means that the fluorescent

lighting used inside most buildings has little effect on performance.

Figure 19. LP3991 Used as a Post DC-DC Regulator