I am facing an issue in wakeup pin functionality of my STM32F407VG (LQFP100) device after entering to standby mode. The PA0/wakeup pin voltage is dropping from 3.3V to 1.8V when the EWUF bit in power control register is enabled. Due to this reason the WKUP pin is not able receive a low to high interrupt in standby mode. The reason we found out for this voltage drop was that PA0 pin is taking a current 90uA(After testing in stm32f407 discovery board) when EWUF pin is SET. While in my application I should not exceed this current above 5uA as mine is a battery powered application.
None of the STM32F datasheets are mentioning about the current requirements of WKUP pin to enable this functionality for standby mode. Please provide me a necessary solution.