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IMX287 Power Supply Issues

Question asked by christian vieira on Sep 24, 2014
Latest reply on Sep 30, 2014 by CarlosCasillas

Hello all!


We are facing some problems with the Power Module Unit of the iMX287. Considering that our product is fed through a main source of +5V and a LiIon battery is used to allow controlled shutdown of the processor, allowing the application layer receives a software signal (from the Linux Kernel) when the absence of mains power, so that it can be saved all critical information. Then, the processor should enter into powerdown, in which only the internal RTC is powered by the battery. Under these conditions, is expected to battery consumption of about 15 ~ 20uA. However, the following behaviour is observed:


1). Sometimes, even with the main power supply connected and having the correct nominal value, it is seen through a current meter that the battery powers the entire circuit because we perceive a current of about 200mA on the meter current connected to the battery and a current less than 10mA in current meter connected to the main power supply. This causes a depletion of the battery, and when the circuit suffers a power down and then a power up, the processor is not agreed, giving the impression of being caught.

2). When the main power is disconnected and the circuit becomes fed (iMX287, DDR2, SDCard and few other peripherals) by LiIon battery, a signal is sent from the kernel to the application layer. The application layer is the received signal, and finally the method: static void mx28_pm_power_off (void) in pm.c file is invoked. However, the processor does not come in freeze mode, since the current measured on the current meter connected to the battery indicates approximately 35mA, well above the expected 15 to 20uA (only necessary to maintain the internal RTC).

Anyone faced those same problems? Any help is welcome!

Thanks in advance,