BPI96 High Current Drain

Hi,
I bought a BPI96 board with BC95-g modem. I uploaded a code for it with stm32 shutdown mode and modem psm mode.
I removed the power led as well.
After the modem and stm32 go sleep mode, I got 3-4mA.
I need to get a few microamperes.
What can I do? Do you measure the modem in low power mode?
Thanks for the help!

How/where are you measuring current?

If you’re measuring it on the 5V input, then your measurement is going to include the quiescent current of the LM1117-3.3, which is 5 mA “typical” per the datasheet https://www.ti.com/lit/ds/symlink/lm1117.pdf

If you’re powering it via VBAT, it won’t leak through the LM1117-3.3, but it still regulates through the AP2127, which has a quiescent current of 60-90 uA, plus the drain through the voltage divider controlling feedback for voltage output adjustment, which will be another 41 uA for a total about 130 uA there, so even if you eliminate the LM1117-3.3, you aren’t going to get it down to “a few microamperes”.

First of all, thank you for your reply.
I am measuring during battery connector with constantly 3,8V. I use a multimeter to measure it.
I use STM32LowPower library to send shutdown mode the device.


Before that I got the +NPSMR:1 message from the modem, so theoretically it went to psm mode.
Unfortunately, I can’t measure only the modem or only the device current, but if it has any option to that, please let me know.

Do you have any idea for me to decrease current?