SM8134A Datasheet, PDF (14/19 Pages) Nippon Precision Circuits Inc – White LED Driver IC

SM8134A
STARTUP SEQUENCE
After power is applied to the SM8134A or when a reset input occurs (reset register mode setting), the internal
power-ON reset circuit initializes all registers to their default value of 0. Consequently, all required data for
LED drive operation must be input using the serial interface. The registers can be addressed in arbitrary
sequence. Note that the registers are set in the same sequence as they are addressed.
Example 1. Set LED1 to LED4 to 20mA drive without group setting
Set EN HIGH, input “2AH” using the serial interface, set EN LOW (LED1 to 4 current setting 20mA), set EN
HIGH, input “58H”, set EN LOW, LED1 to LED4 turn ON after the soft start ends.
EN
SDA
Set LED1 to 4 current 20mA
2
A
001 01 010
LED1 to 4 ON
5
8
010 1100 0
SCK
LED1 to 4
20mA
Soft start time
EN = High
Send serial data "2AH"
2: DIN1 to 4 dimming command
A: Dimming data (20mA)
EN = Low
EN = High
Send serial data "58H"
5: LED ON command
8: LED1 to 4 ON
EN = Low
Example 1 input waveform
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