LM2787

www.ti.com

SNVS080F – JULY 2001 – REVISED MAY 2013

(2)

typically 10

further reduce the output resistance. The output resistance of the entire circuit (in dropout) is:

(3)

overall output resistance is equal to the linear regulator load regulation (5mV/mA). The dropout voltage is

should be 1.0µF minimum with less than 0.3

Ω ESR. Larger values may be used for any or all capacitors. All

capacitors should be either ceramic, surface-mount chip tantalum, or polymer electrolytic.

Output Noise and Ripple

Low output noise and output voltage ripple are two of the attractive features of the LM2787. Because they are

small, the noise and ripple can be hard to measure accurately. Ground loop error between the circuit and the

oscilloscope caused by the switching of the charge-pump produces ground currents in the probe wires. This

causes sharp voltage spikes on the oscilloscope waveform. To reduce this error, measure the output directly at

Take the tip cover off of the probe and touch the grounding ring of the probe directly to the output ground. This

should give the most accurate reading of the actual output waveform.

DSBGA Mounting

The DSBGA package requires specific mounting techniques which are detailed in Application Note AN1112.

Referring to the section Surface Mount Technology (SMT) Assembly Considerations, it should be noted that

the pad style which must be used with the 8-pin package is the NSMD (non-solder mask defined) type.

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

DSBGA device.

DSBGA Light Sensitivity

Exposing the DSBGA device to direct sunlight may cause misoperation of the device. Light sources such as

Halogen lamps can also affect electrical performance if brought near the device.

The wavelengths which have the most detrimental effect are reds and infra-reds. The fluorescent lighting used

inside of most buildings has very little effect on performance.

Copyright © 2001–2013, Texas Instruments Incorporated

Submit Documentation Feedback

7

Product Folder Links: LM2787