LED7708 datasheet(42/53 Pages) STMICROELECTRONICS

Part #	LED7708

Description	16 channels x 85 mA LED driver with boost controller and 4-wire serial interface

PDF	53 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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42 / 53 page

Recommended operating conditions

LED7708

42/53

Doc ID 022698 Rev 1

8.6.3

Grayscale synchronization

Grayscale sync (GSSY) used as synchronization output

When the DSYS bit of the DEVCFG1 register is set low, the GSSY pin of the LED7708 is set

as output. A 4xTGSC high level pulse is provided at the GSSY pin at the end of each

dimming cycle (latency followed by a dimming period).

Figure 15.

Dimming waveform and GSSY output pulse

Grayscale sync (GSSY) used as synchronization input

When the DSYS bit of the DEVCFG1 register is set high, the GSSY pin of the LED7708 is

set as input. This option can be used to lock the dimming cycles (latency followed by a

dimming period) to the vertical sync signal (VSYNC) coming from the video processor. The

minimum pulse duration is 2xTGSC. As soon as the GSSY signal goes high, the ongoing

dimming sequence is stopped and the grayscale counter is reset. A new dimming sequence

is triggered when the GSSY pin goes low.

Figure 16.

Dimming waveform triggered by GSSY input

LED7708 Datasheet(PDF) 42 Page - STMicroelectronics