SM8131B Datasheet, PDF(13/21 Page) Nippon Precision Circuits Inc – The SM8131B is a charge pump DC/DC converter that switches between 1 and 1.5 automatically.

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SM8131B Datasheet, PDF (13/21 Pages) Nippon Precision Circuits Inc – The SM8131B is a charge pump DC/DC converter that switches between 1 and 1.5 automatically.

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SM8131B

For example, if the VIN voltage is low and the VOUT output voltage in Ã1.0 mode does not provide sufï¬cient

drive current, then the mode reset will cause a LED undercurrent condition. The LED undercurrent detector

circuit will output an LED undercurrent signal immediately after the switch to Ã1.0 mode, but the output will

stay in Ã1.0 mode and not return to Ã1.5 mode for the duration of the mode hold time. Consequently, the VOUT

output is not boosted during the 85Âµs (min) to 200Âµs (max) mode hold time and the voltage drops and the LED

brightness is reduced. However, the LEDs are OFF for a maximum of 200Âµs only, and this is not discernible to

the naked eye and thus is not a problem.

VIN input voltage

Mode reset

(1.4sec/cycle)

Mode hold

(H: hold)

VOUT mode

(H: 1.5, L: 1.0)

VOUT

output voltage

Low ILED detector

(H: low ILED)

1.4sec

max

200ÂµS

1.0 1.5 threshold

4.2V

VOUT drop due to the mode reset single

NIPPON PRECISION CIRCUITS INC.â13

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