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DAC8760 very very hot

Other Parts Discussed in Thread: DAC8760

Below is my circuit

Where the -10V is actually -12V

the ouput is connect to an OPAMP

I use 2MHz SPI to operate it. Update frequency is 50KHz.

The register setting is

Write_DAC_reg(0x55,0x1092);

That is :

OUTEN = 1;

SRCLK = 0; eg .250KHz Slew rate clock
SRSTEP = 4; eg. Slew Rate Step-Size 16
Slew Rate Enable.
OUTPUT RANGE  ±5 V

Other registers use default values.

After several minites of operation, the DAC8760 will become very hot and then stop operation. I am wondering any error in my circuit or code. I have tried by removing C36 and C37 with no improvement.

Please help!

  • Hello Steve,

    The person that currently supports this device is out on travel, but I may be able to assist you with your question. Can you provide answers to the questions below, thanks.

    - Is the V5_ANALOG supply sourced through an external supply, are there any bypass capacitors included on this supply?
    - Does the AVSS supply have any bypass cap arrangement?
    -Can you measure the current through the supply pins/DAC output while this issue appears?
    -Measure DAC output voltage while issue occurs?

    Thanks,
    Matt
  • Steve,

    In addition to the questions Matt has asked, I would like to know what net the thermal pad is connected to. As noted on page 9 of the datasheet, the thermal pad should be connected to the same net as AVSS, in this case your -12V rail. If the thermal pad is connected to ground or another potential it is possible for current to conduct to/from AVSS that will heat the device and eventually cause damage.
  • Dear Kevin

    I did connect thermal pad to the GND,  I will try as you said

  • Hi Matthew
    There are bypass capacitors on all the supply
    DAC output voltage is normal in the begin of heating, and eventually to an fixed level (maybe 0)
    I will first try as Kevin said, if still cannot solve the problem. I will measure the current
    Thanks
  • Hi Steve,

    It is more than likely as Kevin pointed out. The Thermal Pad is internally connected to the AVSS supply. Connecting GND to the thermal pad will create a short between AVSS and ground, which would draw large current and heat up the device.

    Best Regards,
    Matt
  • Steve,

    Were you able to confirm the root cause of this issue?