SM8133B Datasheet, PDF (15/20 Pages) Nippon Precision Circuits Inc – White LED Driver IC

SM8133B
STARTUP SEQUENCE
After power is applied to the SM8133B or when a reset input occurs (active-LOW input on RESETB or 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 LED6 to 30mA drive without group setting
Set EN HIGH, input “2FH” using the serial interface, set EN LOW (A group current setting 30mA), set EN
HIGH, input “58H”, set EN LOW (A group ON), LED1 to LED6 turn ON after the soft start ends.
EN
SCK
SDA
ILED1 to 6
Set A group current: 30mA (2FH)
123 45678
A group ON (58H)
12345678
Approx. 30mA
Soft start time
Example 1 input waveform
Example 2. Set LED1 to LED4 to A group, LED5 and LED6 to B group, and individual
group brightness
Input “13H” using the serial interface (group setting), input “25H” (A group current setting 10mA), input
“3AH” (B group current setting 20mA), input “5CH” (A and B groups ON) on successive EN cycles. LED1 to
LED6 turn ON after the soft start ends.
EN
SCK
SDA
ILED1 to 4
ILED5 to 6
Set grouping (13H)
LED1 to LED4 A group
LED5 to LED6 B group
123 45678
Set A group current: 10mA (25H)
12345678
Set B group current: 20mA (3AH)
12345678
Example 2 input waveform
A group, B group ON (5CH)
12345678
Soft start time Approx. 10mA
Approx. 20mA
NIPPON PRECISION CIRCUITS INC.—15