ADS8685: similar price and performance ADC which can support 2.5v external reference in. (16bit, 500ksps)

Frank Xiao

Genius 12055 points

Part Number: ADS8685
Other Parts Discussed in Thread: ADS8860

Hi team,

My customer is using the ADS8685 now. As you know the internal and external reference is 4.096v. My customer input signal is below 2.5V. We want to check whether we have similar price and performance ADC which can support 2.5v external reference in. (16bit, 500ksps)Thanks.

over 3 years ago

0 Dale Li over 3 years ago

TI__Mastermind 37955 points

Hi Frank,

Is the signal in the customer's system bipolar or unipolar? ADS8685 can support +/-2.56V input range, only one command is needed to program the Range_Sel_REG register from the default +/-3Vref range to +/-0.625Vref range.

Regards,

Dale

0 Frank Xiao over 3 years ago in reply to Dale Li

TI__Genius 12055 points

Hi Dale,

You are correct. Our concerns is the accuracy derating of smaller input with current reference voltage. If the input max is similar as reference, we can set the gain to 1 to improve the design. How the device can solve it? Thanks.

0 Dale Li over 3 years ago in reply to Frank Xiao

TI__Mastermind 37955 points

Hi Frank,

There is a precision PGA inside, it implements the change on the gain.

Regards,

Dale

0 Frank Xiao over 3 years ago in reply to Dale Li

TI__Genius 12055 points

HI Dale,

sorry for forgetting to mention the information, the input is unipolar. Thanks..

0 Dale Li over 3 years ago in reply to Frank Xiao

TI__Mastermind 37955 points

Hi Frank,

The lowest unipolar input range on ADS8685 is 0-5.12V, you will lose some dynamic range if your signal is 0~2.5V. The best solution for you is using an amplifier+ low voltage precision ADC(e.g. ADS8860 family: ADS8860-1Msps, ADSADS8862-680ksps SE input).

Regards,

Dale

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ADS8685: similar price and performance ADC which can support 2.5v external reference in. (16bit, 500ksps)