Occasionally our WP7609s won’t wake from ULPM using the POWER_ON_N pin. We have to first trigger a module reset using RESET_IN_N, then triggering the POWER_ON_N pin will power the module on. It seems to be occurring about 20-30% of attempts to power on.
Has anyone experienced this behaviour? I can’t find any documents which discuss enabling/disabling the POWER_ON_N pin. Is there a configuration option anyone knows of which could be causing this?
Another possibility I’m considering is that the module’s MCU might be crashing…?
POWER_ON_N
The AirPrime WP76XX module requires a low level signal (POWER_ON_N) that is used to switch the module ON. The signal is connected internally to the permanent 1.8V supply regulator inside the module via a pull-up resistor. Once VBAT_BB is supplied to the module, this 1.8V supply regulator will be enabled and so the POWER_ON_N signal is by default at high level.
The module can be powered ON when VBATT is applied then POWER_ON_N is asserted
Thank you for your response. I appriciate the documentation you have provided.
We are supplying VBAT_BB continuously to the module via an attached battery, so pulling POWER_ON_N low should power on the module. Unfortunately though, occasionally this doesn’t occur. We first have to pull RESET_IN_N low, then pulling POWER_ON_N low will power on the module (as expected).
Please let me know if you have any more tips/tests for us to try
Assertion time is the time required to keep POWER_ON_N at LOW level to ensure the module
can be powered ON successfully.
You can try with POWER_ON_N assertion time Minimum is 200 ms.
