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Unused inputs

Other Parts Discussed in Thread: UCD9244, UCD9220

For the UCD9244, what should i do with any unused input pins?  Specifically, I'm wondering about unused VID pins, unused inputs to the 12-bit ADC (CS, temp/aux, etc) and unused inputs to power peripherals (EAp, EAn, FLT, etc).  Does the UCD9244 insert a pullup or pulldown on these inputs if programmed to be not used, or should I short these to GND?

  • Pins (DPWM, EA_P/_N, CS, FLT, SRE, VID) that are associated with unconfigured rails or phases can be left floating.  The temperature was expected to be used always and the input will be monitored whether the function is used or not, you may want to tie the TEMP input to ground through a resistor if unused.

    Attached is a Hardware Configuration Guide which explains many of the pin requirements, this is from the original UCD9220/40 controllers but still applies to the newer devices as well.  This information should have been updated and included with the Design Guide that was published in April.