topic K32W0xx voltage ripple problems in Wireless MCU

K32W0xx voltage ripple problems

MVWare — Fri, 25 Jul 2025 12:13:04 GMT

We now have problems with two issues with K32W041:

Voltage ripple at Vbat

Voltage ripple at Vbat

We have followed up the power design for the K21W041 according AN12893, Using the DC-DC Feature. So the correct decoupling capacitors, the PCB design rules. No concessions on that.

We measure upto 40mVpp ripple on Vbat. This is caused by the DCDC of the chip.

We need extra information to reduce this ripple.

What type of DCDC regulator is used?
What is the value of the switching current?
How is the switching current controlled?
What type of feedback controller is used?
Provide an block diagram / architecture of the DCDC

We need to reduce the ripple and switching current

Re: K32W0xx voltage ripple problems

sofiaurueta — Tue, 29 Jul 2025 19:04:02 GMT

Hello,

Hope you are doing well.

The internal DCDC module in K32W061/41 is a buck converter which converts an input supply voltage to a fixed output voltage.

I would recommend checking the K32W Hardware Design User Guide, which can be found under the K32W061/41 Product Page > Design Resources > K32W061 Manufacturing package

The DCDC load current configuration depends on the inductance value in reference design and can be optimized to suit the load current of the application, the DC-DC inductor for K32W041A/AM-based schematics is 2.2 μH, see K32W Hardware Design User Guide section 4.1 Schematics design.

You could also check sections 4.9 "DC-DC components" and 4.11.2 "VDD (radio), FB, VDD_PMU, VDDE, and VBAT decoupling", which have relevant information.

On the User Manual section 4.2.1 you will find the DCDC system diagram. On the Data Sheet section 9.2 Schematic diagram you will find the Application diagram – battery powered solution.

Could you help us review the schematics of your board following these recommendations? The best way to build a PCB the first time right with K32W061, QN9090 or JN5189

Best Regards,

Sofia.

Re: K32W0xx voltage ripple problems

MVWare — Thu, 31 Jul 2025 09:14:15 GMT

Hi Sofia, thanks for your response.

The hints you give, were already studied by me. Thats the reason, I started this post.
Sorry to say, but that information does not answere any of my questions in this post.
I need expert information to optimse the DCDC implementation to improve our application.
Answeres to the first questions will help for that..

Re: K32W0xx voltage ripple problems

sofiaurueta — Mon, 04 Aug 2025 21:24:05 GMT

Hello,

Could you please help us check if this issue is also present on the EVK?

Let me know your findings.

Best Regards,

Ana Sofia,