The power controller is disabled internally when UFM access is enabled by issuing command 0x74 (Enable Configuration).
So, the Standby signal is not available when the UFM interface is enabled.
The power controller functionality is restored after the Flash Memory (UFM/Configuration) Interface is disabled using Disable Configuration Interface command 0x26 followed by Bypass command 0xFF.
For more details, refer to the Flash Memory Design Tips section in TN1205, Using User Flash Memory and Hardened Control Functions in MachXO2 Devices Technical Note.
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