Power on reset

Hi Kumar!

Which processor do you mean? MSP430F47187? Anyway, use 47k for R and 2n2 for C and you're fine.

Dennis

Hi Denis,

In production some of the Microcontrollers  are (MSP430F47187)  not loading the codes

We suspect the Power ON reset problem we are using 47K for R and 100nF for C

Kumar

Since you cannot use SBW for that chip, a larger capacity does no harm. Look for some other reason.

kumar sivaraman said:

In production some of the Microcontrollers  are (MSP430F47187)  not loading the codes

What do you mean by that? If you cannot program the device (load your program into the MSP430), then this large capacitance might be the reason for that. Once the program is inside the microcontroller, a larger capacitance is no problem any more.

Dennis

For some MSP430 chips, the nRST pin is also shared with SBWTDIO. A 100nF capacitor there will impede SBW operation. In that case, if you use SBW to download firmware, there will be problems.

MSP430F47187 does not have SBW and you have to use either 4-wire JTAG or BSL to download firmware. A 100nF capacitor at nRST pin does no harm to 4-wire JTAG or BSL operations.

Hi,

I will clearly explain the problem what i am facing

We are using MSP430F47187 controller In our Protection relay product for more than 3Years about more than 5K+ after complete testing of product we involve Dry heat chamber tests at 55C  for 5-8hours with cyclic timer ON (1Min) / OFF(30Secs)  for the product.

During this test most of the Relay product not getting  ON during the ON time.

After removing from Heat chamber  the same problematic relay product  is tested in Ambient temperature with the cyclic timer ON (1Min) / OFF(30Secs)  sometimes it getting ON and sometimes Not

So only we suspect the RESET/ section since we are using 47K for R and 100nF for C.Is this value is correct or we have to alter as 2n2 for C 

Suggest me

kumar

Convinced! Kumar, old_cow_yellow is right! 4-wire JTAG only capable devices do not use the RST pin, so it's value for C does not affect programming.

Dennis