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congatec
AG
TR44m17
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5.1.12
Power Control
PWR_OK
Power OK from main power supply or carrier board voltage regulator circuitry. A high value indicates that the power is good and the module
can start its onboard power sequencing. The PWR_OK is a 3.3V signal according to the COM Express Specification. The use of this input is
optional.
Carrier board hardware must drive this signal low until all power rails and clocks are stable. Releasing PWR_OK too early or not driving it low
at all can cause numerous boot up problems. It is a good design practice to delay the PWR_OK signal a little (typically 100ms) after all carrier
board power rails are up, to ensure a stable system. Although the PWR_OK input is not mandatory for the onboard power-up sequencing, it is
strongly recommended that the carrier board hardware drives the signal low until it is safe to let the module boot-up.
A sample screenshot is shown below:
Note
1. The module is kept in reset as long as PWR_OK is driven by carrier board hardware.
2. PWR_OK must be kept low before rising to 12V.
