Testing a DAC MCP4822 (data sheet here) I noticed it hot to touch with 2V at the A output. Last settings transmitted through the SPI interface were to have just 0,5V at VoutA.
Additional consumption current with that IC in-circuit was as of about 50 mA. No surprise it was hot.
After discarding a short, I found that:
From all the above, what could be the reason for the damage? Maybe the abrupt changes with a big charged cap at the output and no resistor to drain it?
I expect to learn something from all this. Comments are welcome.
Successful design, let me tell you...
Additional consumption current with that IC in-circuit was as of about 50 mA. No surprise it was hot.
After discarding a short, I found that:
- VoutA - pin 1 (and VoutB - pin 3 for the case) had no load resistors.
- Both outputs had 4u7F tantalium caps as filters.
- The software had an error that never latched VoutA when values were being progressively decreased. In other words, after going high, VoutA never came down.
- The test I designed, involved cyclic alternative reset of both outputs, starting with very low values. There, VoutA was effectively (and abruptly) updated.
From all the above, what could be the reason for the damage? Maybe the abrupt changes with a big charged cap at the output and no resistor to drain it?
I expect to learn something from all this. Comments are welcome.
Successful design, let me tell you...
