Kinetis Microcontrollers中的主题 Re: Overheated problem of K60

Overheated problem of K60

wangfukai — Thu, 10 Jul 2014 09:11:52 GMT

Hi all,

I am using MK60FX512VLQ12 in bare-metal mode. Every 0.833ms it will perform ADC . The loop in the main() do some Key Scanning and

Uart Sending. No other features in its code. Now the K60 chip will be overheated(may be 60℃) after 20 minutes' running. If debug K60 with

J-link, it will be overheated(may be 90℃) in less time.

The chip runs well and can be debugged.

What could be the problem and how can I identify it?

Bests

Fukai from BeiJing

Re: Overheated problem of K60

chris_brown — Thu, 10 Jul 2014 14:52:16 GMT

Hi Fukai,

What is the ambient temperature near the part?

Can you measure the current draw of the part when this happens?

Can you also post a schematic? At least a snippet of the device and the power capacitors and other power supply circuitry? That may help to provide some clues.

Thanks,

Chris

Re: Overheated problem of K60

wangfukai — Sat, 12 Jul 2014 01:06:38 GMT

Hi Chris,

Thanks for your kind help firstly.

That's how the cpu board should be used, in a box with other boards. Initially, I guess the over heated problem

was caused by the power board. There is a big AC/DC module on power board.

So I pluged the CPU board out and soldered a 5V power on LM1117 pin directly as showed after.

And the over heated problem still exist. The ambient temperature is 27℃ and we have an air-conditioner in our school lab

so this should not be the cause.

I measured current of the whole CPU board and it is 0.341A.

There are four modules on the CPU board: Internet port, RS485 port, EEPROM, IO port. But none of these modules were

used in the project code. The CPU only do A/D conversation every 0.833ms with the internal ADC.

Thanks

Fukai

Re: Overheated problem of K60

vicentegomez — Tue, 29 Jul 2014 21:17:56 GMT

Would be possible that you send me your schematics?

Please check if you do not have any electrical short or wrong component?

What happens if you load a empty project, the board gets hot?

I believe that you are using a LQFP package, can you please check that there is not any solder short between the pins

Have a great day,
Vicente

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Re: Overheated problem of K60

wangfukai — Wed, 30 Jul 2014 02:20:25 GMT

Hi Vicente,

I soldered another board and no overheat problem occurred. So that MCU on the overheat board

may has something wrong.

I checked the MCU and no pins was shorted. And the MCU still can be linked with Jlink.

So, it is strange. The temperature in the box which contains the MCU board is a little bit hot, So I guess

may that cause the MCU to be destroyed but not totally destroyed.

Regards.

Fukai

Re: Overheated problem of K60

vicentegomez — Fri, 01 Aug 2014 18:49:59 GMT

Hi, you can check the impedance between the good part and the failed part, I do not know if this is possible but what happened if you place a new MCU on the failed board, I am thinking that the problem is on the board (hardware), probably a wrong or missing component. If you place a new MCU and the board still did not work, I will check the hardware.

Have a great day,
Vicente

Re: Overheated problem of K60

wangfukai — Fri, 01 Aug 2014 23:55:41 GMT

Hi Vicente,

Actually, the board was good in the beginning. And days later it went to wrong so I soldered another MCU on the board. It keeped well

for another days and then went wrong again.

So I suppose the box's high temperature is the cause.

I chang another new board with new MCU and check what will happen.

Thank you,

Fukai

Re: Overheated problem of K60

daweiyou — Sun, 03 Aug 2014 14:33:31 GMT

Hi Fukai:

300mA current is large enough to make chip overheated.

Maybe something short, you could check every pin to clear the short pin to GND.

Do you use internal USB regulator module?

Dawei You（尤大为）

Mobile: +86 13675169919

Re: Overheated problem of K60

wangfukai — Mon, 04 Aug 2014 00:28:13 GMT

Hi Dawei,

I thought I find the problem. The box we use is made of metal and it let two boards be shorted.

Thanks.

Fukai