AD7848 Power Sequence requirement

Keiichi Kajino

Expert 2365 points

Other Parts Discussed in Thread: ADS7948

Hi folks,

Is there any restriction of power sequence between AVDD and DVDD?

Our customer will use AVDD=5.0V and DVDD=3.3V. Since application is power sensitive, will try to shut down AVDD.

In this case, there is of DVDD=3.3V and AVDD=0.0V(Of course AVDD realated signal input should be 0V).

We can not find any restriction between AVDD and DVDD. Is there any DVDD -> AVDD parasitic diode into ADS7848?

over 10 years ago

0 Luis Chioye over 10 years ago

TI__Guru 55466 points

Hi Keiichi,

AD7848 is not a TI device and I don't believe we have an ADS7848 device. Please clarify the device you are referring to.

Thanks,

Luis

0 Keiichi Kajino over 10 years ago in reply to Luis Chioye

Expert 2365 points

Hi, Luis

I am very sorry. The device should be ADS7948.

0 Luis Chioye over 10 years ago in reply to Keiichi Kajino

TI__Guru 55466 points

Hi Keiichi,

The digital supply voltage range is 1.65<DVDD < AVDD; therefore the DVDD voltage is to be kept below AVDD at all times. The standard requirements per the Absolute Maximum RatingsTable is that the digital signals must remain low prior DVDD starting up; and the analog inputs and REF pin should not exceed AVDD during the sequence.

In seldom cases, the device was reported to power up in 32-CLK mode (instead of 16-CLK mode). One way to guarantee that the device is set in 16-CLK mode after power-up, is to always use 15 falling clock edges on the first frame immediately after power-up. After the first 15-CLK frame is issued, a 14 CLK frame may be used for the second and subsequent frames. Please review the previous post below.

https://e2e.ti.com/support/data_converters/precision_data_converters/f/73/p/438143/1588168

Please let me know if you have questions.

Thank you and Best Regards,

Luis

0 Keiichi Kajino over 10 years ago in reply to Luis Chioye

Expert 2365 points

Hi, Luis

I missed to see electric char. section, Thank you.

Data converters

Data converters forum

AD7848 Power Sequence requirement