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Getting started with EVAL-AD5535BSDZ

Category: Hardware
Product Number: EVAL-AD5535BSDZ
Software Version: None

I have purchased an eval board EVAL-AD5535BSDZ with an application of driving a multi-mirror MEMS array. I plan to use it in stand-alone mode, using an SPI interface to provide SYNCB, SCLK and DIN signals, as I need to drive all 32 DAC channels independently. I have verified the timing of my signals meets the requirement, and I have connected these to the SMB connectors on the board.

I have applied a 5V signal to the AVCC line and 100V to the Vpp line, and I have configured LK4 and LK5  to be connected (connects DVCC and V++) and I am using a scaled reference of 2.048V (LK1=C and LK2=B) . When the power supplies are turned on I can verify 2.05V on the EXT REF test point and I can change this to 3V, 1V or 4V by changing the LK1 and LK2 settings. So the Eval board appears to be functioning.

However it does not appear that the AD5535B chip is turning on. I do not see any voltage across the temperature controller diode ANODE-CATHODE test points, and I never see any voltages on any of the DAC output lines or test points.

Furthermore the board usually turns on drawing about 60mA of current on the 5V supply. But sometimes (randomly,  about once per 5 starts) it starts up drawing 0.8-1.1A of current on the 5V line, and the AD5535B chip rapidly heats up to a dangerous level. When this happens I have to switch it off quickly to prevent the DAC chip from overheating. In the over-heating mode there is still no temperature diode or DAC activity.

I would appreciate suggestions as to what I could be doing wrong.

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