OPA862: looking for SE to differential AMP for ADS52J90

Ben Kuo

Part Number: OPA862
Other Parts Discussed in Thread: INA210, ADS52J90, , THP210, THS4561, THS4509

Dear team,

We are looking for SE to differential amp for our application.

Our input signal is INA210 and use ADS52J90 to monitor system current information.

Since INA210 is SE output and ADC only support differential input, we will need a SE to DIFF. (Current signal->INA210->OPA862->ADS52J90)

Is OPA862 suitable for this application? If not, Could you share your comments and solution with us? thanks.

Regards,

Ben

over 4 years ago

0 Michael Steffes over 4 years ago

Guru 48395 points

morning Ben,

That is a pretty fast ADC for an INA type channel, but in any case the FDA's families were developed to support diff input ADC's. You pick a part based on signal bandwidth and dynamic range issues - and supplies. I would maybe start with the THS4561 or THP210.

The OPA862 is also a valid choice if your FDA cannot drive the input resistor of an FDA design.

0 Sima Jalaleddine over 4 years ago

TI__Mastermind 30170 points

Hello Ben,

It really does depend on signal bandwidth and supplies as Michael mentioned. The ADS52J90 does have an EVM that uses the THS4509, a 1.9GHz Fully Differential Amplifier. The EVM uses the popular RGT package for the amplifier driver which should be easy to replace with other FDAs for testing.

Thank you,

Sima

0 Michael Steffes over 4 years ago in reply to Sima Jalaleddine

Guru 48395 points

For perspective Ben, the THS4509 was at the time a breakthough FDA for pipeline ADC interface - so it was applied everywhere whether needed or not.

Since that time (circa 2005) quite a few slower, more power efficient, devices have been developed - kind of need to match your device to the need, but this is non-trivial in the best of cases (and impossible without performance targets).

0 Ben Kuo over 4 years ago in reply to Michael Steffes

TI__Expert 7580 points

Hi Michael and Sima,

Thanks for your information. I found an app note for SE to differential with FDA.

https://www.ti.com/lit/an/sbaa246a/sbaa246a.pdf

Regards,

Ben

0 Sima Jalaleddine over 4 years ago in reply to Ben Kuo

TI__Mastermind 30170 points

Hello Ben,

This configuration works as well if you are looking to buffer the signal to the FDA using a precision amplifier. This is not necessary for all applications; but, since you are using the INA210 due to the current input, the app note would be beneficial for this type of design.

Here are additional resources on designing FDA circuits:

1. Single Ended to Differential with FDA (mid-supply reference)

2. Fully Differential Amplifiers

3. Brief Overview on FDAs

4. Video Series on FDAs (Includes Stability)

Thank you,

Sima