STM32U375 current consumption at 80 Degrees temperature

[vishal12686]

Hello All,

I am current testing STM32U375RGT6Q at 80 degrees and I see that there is significant increase in the average current consumption at 80 degrees C. Average Current consumption increases from 290uA to 1mA. 

Also note that

1) Pull up and Pull down are 1Mega

2) MCU is in sleep mode for 50 percent of the time.

3) Internal oscillator MSI is used at 3MHz

4) Flash memory is 1MB

5) SMPS mode is used to reduce the current consumption.

Is there a way out to reduce the current consumption at high temperature. I know that STM32L4 series are more stable over temperature but they dont suite the current budget of 300uA 

[Andrew Neil]

Welcome to the forum.

Please give more details about your setup - see: How to write your question to maximize your chances to find a solution

[vishal12686]

I am using Power Profiler Kit II - nordicsemi.com which can measure upto nA current. The zero ohms R262 is removed and power profiler is connected. 

 

MCU current measurement

[Andrew Neil]

That's not the full schematic, is it?

What else is powered from VDD_MCU?

Have you checked the leakage vs temperature characteristics of all those capacitors ... ?

[AScha.3]

see ds for your cpu, similar :

This depends on the used chip process.

 

>Is there a way out to reduce the current consumption at high temperature.

no.

or choose other chip / manufac.

That kind of current rise at 80°C is pretty expected due to leakage increasing with temperature, especially when using MSI and sleep cycles, but you can still optimize by moving to deeper STOP modes, tightening GPIO states, and checking SMPS behavior at high temps since layout and load matter a lot there. I ran into a similar stability and performance tuning situation while working on a web tool project and documented some notes here on this app not MCU specific but the power and optimization approach mindset is similar and might give you a few ideas to test.

[Gyessine]

Hello @vishal12686 
Can you provide more details about your configuration?
Are all peripherals disabled?
Is SRAM enabled?
In general, can you specify in which use case are you? In some cases, the Datasheet states that the product's normal behavior can reach your mentioned consumption at 80 degrees Celsius and even more.
However, there is no harm in trying these tips to reduce consumption.
Ensure that you clear all debug mode-related bits and set all unused pins to analog mode.
Also, many bad hardware implementations can lead to an increase in power consumption so double check your PCB. (For this you can use one of our boards schematics as reference). 

BR
Gyessine

[vishal12686]

@Gyessine 

No, not all peripherals are disabled, we disable those that can be disabled when not used, maybe we can go through them more and make sure. For example ADC is not enabled more than necessary. Also SPI is turned off when not used to FRAM and MODAC. But UART where we are slave we need to detect when a message is coming. We use PWM on one led all the time so there we need timer for example.

Yes, we need RAM we don’t go to stop mode, only sleep mode is used. RTOS is handling the MCU to go to sleep possible.

pins not used are set to analog mode.

Also, many bad hardware implementations can lead to an increase in power consumption so double check your PCB.  

What is meant by bad hardware implementation? We have pull down which are very high ( 1Mega ohms).