Reset for AD5592RBCBZ-1-RL7

Question

I&rsquo;m planning to use the AD5592RBCBZ-1-RL7 in my design, with Vlogic at 1.8V and VDD at 3.3V. Since the AD5592RBCBZ-1-RL7 doesn&rsquo;t have a dedicated reset pin, how can we reset the SPI bus if we encounter any issues with SPI communication? 
 I understand that the AD5592RBCBZ-1-RL7 has an internal reset command via the SPI bus. However, how can we reset the device if we face issues with the SPI bus itself while using the AD5592RBCBZ-1-RL7?

dendalisay · Accepted Answer

Hi Techq , 
 No problem. Just a quick note, the observation that SDO is likely in high impedance when VLOGIC is off is based on the datasheet&rsquo;s &ldquo;Floating-State Output Capacitance&rdquo; spec of 10 pF, which implies the pin isn&rsquo;t actively driven and should not interfere with the SPI bus. So to be on the safe side, I'd stilll recommend adding a pull‑up resistor to keep things stable during power transitions. Also, as I've mentioned before, after powering VLOGIC back on, wait at least 250 &micro;s for the POR to complete. Closing this thread for now, but let me know if you have any more questions. 
 Br, 
 Den)

dendalisay · Answer

Hi Techq , 
 Oh I see. So when VLOGIC is powered off, the AD5592R‑1&rsquo;s SDO pin goes into a high impedance state, which means it won&rsquo;t drive the SPI bus. This matches the datasheet&rsquo;s &ldquo;Floating-State Output Capacitance&rdquo; spec of 10 pF, indicating the pin is meant to avoid interference when not active. 
 After powering VLOGIC back on, basically the device goes through a 250 &micro;s POR, and during this time, SDO could brieflyoutput undefined data. To keep your SPI bus clean, wait at least 250 &micro;s before resuming communication, and consider adding a pull-up resistor to SDO to prevent it from floating. 
 Br, 
 Den

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Reset for AD5592RBCBZ-1-RL7

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