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AD5206 occasional setting error

Question asked by ricky on Jan 18, 2015
Latest reply on Feb 13, 2015 by ricky

Hi All,

 

My customer is testing the operation of his first prototype unit.

The unit consists of two boards, one is processor board and the other one is analog output board.

The analog output board contains AD5206 digi-pot for adjusting amplitude and offset of analog output signal.

He has a trouble of AD5206 operation now.

SPI bus line and GND line between processor and AD5206 is connected by around 10cm long wire.

When setting the wiper position through SPI bus, its wiper position moved different position from set data, occasionally.

When he insert shumitt-trigger (TC74HC14) between microcontroller and AD5206 on CLK and SDI line, it works well, it can always be set to correct wiper position.

He doesn’t want insert the schumitt-trigger device for his production unit.

He tried to insert 22ohm series resister and 1,000pF capacitor to CLK and SDI terminal to GND, it reduced occurrence of error, however couldn’t be disappeared, it still occur although in a very few frequency.

Clk frequency is 250 kHz in his system.

Do you know the similar experience with the AD5206?

If you have any advice for resolution, please let me know.

 

Thank you for your help.

  Ricky

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