Hi Dave,
[A1] Yes, it is required to disconnect the on-board processor I2C bus for programming, does not matter if you are using a Zynq Z7020 or an i.Mx. This is made to avoid any supply to the possessor thought the I2C lines while it is turned-off, this could cause damage on it.
What you can probably do it’s to ask your distributor to pre-program your PMICs with your desire configuration before they send them to your fabric. Some distributors can program the parts for a cost.
[A2] An input voltage of 3.3 V at the VIN pin is one of the requirements to allow programming of the OTP fuses. Does not matter where it comes from, but VIN should have 3.3.V
9.5V is the voltage needed to program the fuses, but the 3.3V are still needed to maintain the system operation. Please find more details on Section 3 of the Application note AN4536: http://www.nxp.com/assets/documents/data/en/application-notes/AN4536.pdf
[A3] After the fuses are programmed, their values may be loaded into the digital control logic without toggling VIN or PWRON, however, it is recommendable to perform a toggling on PWRON to avoid any issue after the OTP programming.
Have a great day,
Jose
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