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SILICON TOUCH TECHNOLOGY INC

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16-channel 12-bit PWM Constant Current LED Driver

Version:A.003

Page 10

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DM631

Serial Data Interface

The serial-in data (DAI) will be clocked into 16 × 12 bit shift registers synchronized on the

rising edge of the clock (DCK). The data will be transferred into the 16 × 12 bit latch registers

when the strobe signal (

LAT ) is kept at high level (level trigger); otherwise, the data will be held.

The latch pulse should be sent after the falling edge of the last clock within a frame data. The trigger

timing of the serial-out data (DAO) will be shifted out on synchronization to the rising edge of the

clock if serial out selection (SOMODE) is kept at low level. And if serial out selection (SOMODE)

is kept at high level, the serial-out data (DAO) will be shifted out on synchronization to the falling

edge of the clock (DCK).

Input Data Format

LED Open Detection

DM631 provides a real time monitor of LED open detection function without extra components

or circuit design. It will be identified as a LED open failure when the output is turned on but the

output voltage is below 0.3V. The test result of each channel will write to its correspondent shift

refer to timing diagram on page13. Detecting report could be retrieved from serial-out (DAO) data.

If the system reads ‘1’ back, that indicates LED is in normal status. But if ‘0’ was retrieved then

LED open failure has occurred. In order to make sure LED open detection function is in well

operating condition, it is recommended that all the luminance data are wrote to ‘1’ then almost

turning on the outputs during detection process.