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

Andrew Neil · ‎2026-05-12

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.

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

waclawek.jan · ‎2026-05-12

Just a blind shot: some floating pin?

JW

Andrew Neil · ‎2026-05-12

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

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

waclawek.jan · ‎2026-05-12

Physically measuring them?

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

Andrew Neil · ‎2026-05-12

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

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

waclawek.jan · ‎2026-05-12

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...

Andrew Neil · ‎2026-05-26

The problem seems to be that, in STANDBY, the STM32F0 outputs are hi-Z - and the CC1125 does not like this.

If I use STOP mode instead, and set the used outputs to be all high (or low), I get down to 5.6uA for the Nucleo + CC1125.

From the STM32F0 point-of-view, is there any advantage to choosing to force the outputs low or high?

PS - for completeness:

In STOP mode, I did try just enabling the pullups on the STM32 outputs - and got down to 120uA.

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

waclawek.jan · ‎2026-05-26

Nice find. Thanks for coming back with the solution.

> From the STM32F0 point-of-view, is there any advantage to choosing to force the outputs low or high?

As in choosing between external pullup or pulldown? I don't think there's anything significant, but I am no low-power expert.

Btw. in newer STM32 families - you may want to have a look perhaps at 'G0/C0 or even 'U0 - there's an option to switch on internal pullups/pulldowns during Standby. Again, no personal experience.

JW