AN4374 datasheet(11/25 Pages) STMICROELECTRONICS

11 / 25 page

DocID025366 Rev 2

11/25

AN4374

LED power-on at maximum current and 50% duty cycle

Figure 11. LED1642GW and ALED1642GW brightness register: first word example

Figure 12. LED1642GW and ALED1642GW brightness register: last word example

•

As last pattern, the output switch power-on has to be sent. SDI=1 on switch register

has to be sent 16 times (see previous example) to have all 16 outputs ON.

The result of the above eighteen 16-bit words is the LED power-on at ILED=36 mA and 50%

duty cycle.

Clk

SDI

15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00

first bit

last bit

Brightness register : BRT output 15 (*) = 0x0800 – BRT outputs 14 to 0 (*) = TBD

(BRT reg. output 15 = 0x0800)

(*) We are assuming that this is the last 16 -bit data word in the 16 word data stream needed to load correctly the brightness register.

Global Latch

Key

AM16861v1

Clk

SDI

15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00

first bit

last bit

Brightness register : BRT Output 0 (*) = 0x0800 – BRT outputs 15 to 1(*) = already defined

(BRT reg. output 0 = 0x0800)

(*) We are assuming that this is the last 16 -bit data word in the 16 word data stream needed to load correctly the brightness register.

Global Latch

Key

AM16860v1

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