ADS8688A: what is the definition of AVDD impedance for Input Overvoltage Protection

Noriyuki Takahashi

Part Number: ADS8688A

Hi team,

Overvoltage protection voltage varies depending on the AVDD, but I am not sure the meaning of the impedance in the electrical characteristics.

Could you tell the detail of it?

Regards,

Noriyuki Takahashi

over 3 years ago

0 Dale Li over 3 years ago

TI__Mastermind 35590 points

Hi Noriyuki-san,

The reason is this ADC has a special analog front-end (AFE) including a 1Mohm high input impedance. In order to understand it simply, <30kohm impedance can be considered as the condition that the AVDD is available and >30kohm is the condition that the AVDD is turned off.

Best regards,

Dale

0 Noriyuki Takahashi over 3 years ago in reply to Dale Li

TI__Genius 9245 points

Dale,

Sorry, I am still not sure yet about the impedance the datasheet mentions.

For example, in the datasheet electrical characteristics, we can see the below description.

AVDD = 5 V or offers low impedance < 30 kΩ, all input ranges

Which impedance does this mention?

Regards,

Noriyuki Takahashi

0 Dale Li over 3 years ago in reply to Noriyuki Takahashi

TI__Mastermind 35590 points

Hi Noriyuki-san,

That's the condition for power supply, which is same as the ADVDD is on or off.

Regards,

Dale

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ADS8688A: what is the definition of AVDD impedance for Input Overvoltage Protection