SM8131B Datasheet, PDF(8/21 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 (8/21 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

EN input signal and LED drive current setting (disable interval)

The LED drive current setting due to EN input is set by the 4-bit counter (16 steps). On the 17th pulse, the

counter DATA = 1 and the current is reset to the maximum current value. When the counter DATA = 16, ILED =

0mA and the LED drive circuit shuts down.

EN1 input

11 12 13 14 15 16 17 18 19 20 21

ILED

disable signal

ILED

off

LED current

12345

11 12 13 14 15 16

LED drive current setting disable interval

When both EN1 and EN2 are held LOW for an extended interval, the internal enable signal âCEâ goes LOW

and the device enters power-save mode. In this mode, the EN input internal counter is reset and subsequent ris-

ing-edge pulses on EN restart the counter from DATA = 1.

SEL inputs and LED control groups

The DIN1 to DIN6 6-channel LED drive pins can be divided into two groups of drive pins (EN1 control and

EN2 control drive pins) by the state of select inputs SEL1 and SEL2. Two groups with separate LED drive cur-

rent control using EN1 and EN2 allows a single device to independently adjust the backlight brightness of 2

screens. With a MODE 6:0 setting, EN2 is not used and should be connected to GND. Also, any unused DIN

LED drive pins should be connected to GND.

Table. SEL setting and LED drive pin grouping

SEL input

LED control signal

MODE

SEL1

SEL2

DIN1

DIN2

DIN3

DIN4

DIN5

DIN6

6:0 setting

EN1

5:1 setting

EN1

EN2

4:2 setting

EN1

EN2

3:3 setting

EN1

EN2

NIPPON PRECISION CIRCUITS INC.â8

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