ZCU102 - VCC_PSBATT

[jff118]

Looking in the documentation 

https://www.xilinx.com/support/documentation/data_sheets/ds925-zynq-ultrascale-plus.pdf#page=4

https://www.xilinx.com/support/documentation/data_sheets/ds925-zynq-ultrascale-plus.pdf#page=8

VCC_PSBATT is 1.2 to 1.5 when using the RTC or BBRAM.  You are allowed to connect it to PSAUX when not using either of them.

The reference design however has an RTC on the board so I'm assuming the intent is to use it, but VBATT is powered at 1.8V.

Am I misreading the docs or was there perhaps an update since the schematics were generated

[gnarahar · Accepted solution]

@jff118 The battery is connected to 1.8V through a diode having a forward drop of 0.38V for charging. Below snippet from ZCU102 user guide UG1182 explains it