DAC8718: DAC8718 power supply problem

user5162383

Part Number: DAC8718

HI, I'm testing DAC8718.

I got a problem that DAC8718 outputs error after power-on, the error output is zero and the right ourput is -15V. then It always outputs +15V when I try to control it.

Before, due to the unusual sag in the 15V and 5V power up process，the anomaly occurred. So I adjust power-on sequencing.

CH1 is 3.3V for IOVDD,CH2 is 5V for DVDD, , CH3 is +15V for AVDD, CH4 is -15V for AVSS

It is meeting the manual sequencing requirements.

At the same time, I tested the voltage of OFFSET.

OFFSET-A is 0V

OFFSET-B is 2.983V.

Thanks for reading.

over 7 years ago

0 Kevin Duke over 7 years ago

TI__Mastermind 46290 points

Hello,

Would it be possible to further accentuate the power-supply sequencing and wait to apply the AVDD and AVSS rails until both IOVDD and DVDD are stable?

0 user5162383 over 7 years ago in reply to Kevin Duke

Prodigy 50 points

AVDD is applied by TPS7A4701RGW. AVSS is applied by TPS7A3301RGW. I can adjust the capacitance of the NR pin to accentuate the power-supply sequencing. But it is the cause of the problem, and can you provide a recommended time?

0 Kevin Duke over 7 years ago in reply to user5162383

TI__Mastermind 46290 points

Hello,

I would suggest that as a first experiment we try the simplest case and wait to begin to ramp the analog rails until both IOVDD and DVDD are stable supplies, what looks to be around 4ms in your oscilloscope capture.

0 Kevin Duke over 7 years ago in reply to Kevin Duke

TI__Mastermind 46290 points

Hello,

I also have received an email from the local FAE supporting this topic. Pending your preference I will take support via email, however should you prefer to keep a direct line on the E2E you can simply reply to this thread and the topic will be reopened.

Thanks.

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DAC8718: DAC8718 power supply problem