STM32F030: Current rises after putting TI CC1125 to SLEEP and entering STANDBY.

[Andrew Neil]

Cross-posting from CC1125 Sleep current rises to ~2mA on the TI forum.

I have a custom board with STM32F030 controlling a TI CC1125 sub-GHz radio transceiver via SPI plus a few GPIOs.

Everything is fine for normal operation (TX, RX, etc), but the system has a "Shutdown" mode where the CC1125 is put into its low-power SLEEP state, and the STM32 is in STANDBY.

In SLEEP the CC1125 should take under 1uA but, after sending the SLEEP command, I see the current rise over ~4s and eventually settle at ~2mA.

I have managed to reproduce this using a Nucleo-F030R8 (ST-Link removed) and a TI dev board:

The blue line is the total system current (STM32 + cc1125); red line is just the CC1125.

Zooming-in on the Shutdown part:

 

There seems to be something charging-up and then (partially?) switching-on?

With the CC1125 disconnected, the Nucleo alone takes a steady ~3.1uA with the STM32 in STANDBY.

So it looks like the issue is with the CC1125 somewhere; just posting here in case anyone has any suggestions.

Full details are in the TI forum post.

[waclawek.jan]

Just a blind shot: some floating pin?

JW

[Andrew Neil]

I don't think so - I think I've been through all the options!

[waclawek.jan]

Physically measuring them?

Like poking around with an oscilloscope probe during those 4 seconds, or maybe even beyond them?

[Andrew Neil]

Now I've got it reproduced on devboards with accessible pins, that's the next step...

[waclawek.jan]

oh, but that chip is QFN, the "pins" are basically accesible;  so that's just a sharp pin at the end of the probe, a steady hand, and possibly a good loupe... :):)

aren't most of the signals accessible at the surrounding resistors/capacitors anyway?

[EDIT]

also, is the chip completely "dumb" in the sleep/"high-current shutdown", or could it be queried through SPI from the STM32? I mean, not according to the manual, but try experimentally...