Hi,
I got unsubscribed to already ongoing thread hence raising the new case by attaching the previous reply.
Hi,
We are seeing part to part variation in supply current of around 10uA-20uA in microcontroller part MSP430FR5994 into Vcc Pin37, below are the operational details of the controller
• ADC is enabled
• DMA is enabled
• Operating Frequency-1Mhz(MODOSC)
• Operating mode- LPM2
• UART enabled
We are using 48Pin QFN package, we have configured unused GPIO as output low from S\W
In our application we take ADC samples in LPM2 every 1.2ms and the code comes out of LPM2 mode after every 10ms and then it goes to Active mode and then again goes to LPM2 mode.
Below is the current measured on the board
Board1à
Total board current- 140uA after replacing micro->127uA
Vcc pin current-102uA
Board2à
Total board current- 130uA
Vcc pin current -93uA
This we have verified on multiple boards.
We replaced two microcontroller on 1 board and measured current into vcc pin we could see a difference of 15uA.
Need your view on above observation that is this variation in current value is ok.
How much do you expect current variation in part to part.
Thanks & Regards
Rahul Wagh
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Hey Rahul, No, generally, I wouldn't expect much Vcc current draw from device to device. What does stands out to me though, is that you are using MODOSC. MODOSC is ~5 MHz clock source, but it's like +-10% accuracy. It's definitely going to vary from device to device, and this change in speed could affect how long between wake-ups which will also affect your average power draw. Can you check your wake-up periods somehow to confirm this might be the culprit for the variation? Thanks, JD |
Hi JD,
Thanks for the reply.
We are trying to measure wakeup time, tried with some option with directing output on GPIO for every interrupt.
we are working on it.(by directing the Oscillator output)
Could you suggest any method by which we can direct the MODOSC output on GPIO to check the variation in frequency.
Regards,
Rahul Wagh
You can put SMCLK or MCLK out on PJ.0 or PJ.1. [Ref Data Sheet (SLASE54C) Table 6-38.
BR
Bruce
Hi Bruce,
Thanks, we were able to check the clock frequency below is the results.
Board1->996KHz;measured board current->132uA
Board2->991KHz measured board current ->143uA
as we run on 1Mhz clock, though the board which is running on 996Khz is consuming less current which I guess should not be.
we performed below experiment as well to debug
1. Modified the code such that it work only in Active mode and does not go into LPM2 mode and measured board current
Board1->264uA
Board2->282uA
2.Modified the code such that after initialization of peripheral controller runs in infinite loop without executing any statement, interrupts are running as earlier
and below is Vcc pin current
Board1->151uA
Board2->171uA
So we could again see the device to device variation.
Please suggest.
Regards,
Rahul Wagh