SM8133B Datasheet, PDF (16/20 Pages) Nippon Precision Circuits Inc – White LED Driver IC

SM8133B
Example 3. Set LED1 to LED6 to 30mA drive, temporarily turn OFF, turn ON again,
and reset using RESETB input without group setting
Input “2FH”(A group current setting 30mA) and “58H” (A group ON) from the serial interface. LED1 to
LED6 turn ON after the soft start ends. While the LEDs are ON, input “50H” (A group OFF) to turn the LEDs
OFF and transfer the SM8133B to standby mode. The internal register setting “2FH” (A group current setting
30mA) data is retained during standby mode, so you need to input “58H” (A group ON) only to turn the LEDs
ON again. At this point, the charge pump soft start circuit operates again, taking a soft start time of approxi-
mately 1.3ms from when the data is input to when the LEDs turn ON. If RESETB is connected to the micro-
controller power supply and the supply goes LOW, the SM8133B is reset, the LEDs turn OFF, and operation
transfers to standby mode.
RESETB
LED mode
EN
SCK
SDA
ILED1 to 6
Reset mode
Set A Group current : 30mA (2FH)
12345678
A group ON (58H)
LED ON mode
12 3 45 6 78
A group OFF (50H)
12 3 45678
Soft start time
Approx. 30mA
A group ON (58H)
12 3 45 6 7 8
Reset
Reset mode
Soft start time
Approx. 30mA
Example 3 input waveform
NIPPON PRECISION CIRCUITS INC.—16