OPA1678: Input current limiting resistor.

Kengo.Y

Part Number: OPA1678
Other Parts Discussed in Thread: OPA205, OPA206, RC4580

Tool/software:

I'd like to consider using OPA1678.
However, when using it with a voltage follower, I cannot put in a current limiting resistor due to input amplitude issues.
Do you have any devices that has the same functionality as this device but does not require a current limiting resistor at input when used with a voltage follower?

BR,
Kengo.

2 months ago

0 Chris Featherstone 2 months ago

TI__Mastermind 25180 points

Hi Kengo,

The input protection diodes are designed for ESD events and should be kept to 10mA or less. We have some devices that have input protection using JFETs and my colleague actually wrote an article on this topic. Please see the link here: Op-amp input protection can be noisy. The OPA205 and OPA206 are two options presented in this paper.

Outside of that the only option would be to protect the input with a resistor for current and TVS diodes for voltage. We have a section on electrical overstress in our video training series that discusses how to select components.

https://www.ti.com/video/series/precision-labs/ti-precision-labs-op-amps.html

I hope this information is helpful.

Best Regards,

Chris Featherstone

0 Kengo.Y 2 months ago in reply to Chris Featherstone

Guru 11255 points

Hi Chris,

Which OPA1678 alternative has no input protection circuit like OPA205?
Because the input signal is very small and greatly affected by thermal noise due to resistance.

BR,
Kengo.

+1 Chris Featherstone 2 months ago in reply to Kengo.Y

TI__Mastermind 25180 points

Hi Kengo,

The OPA205 doesn't have back to back diodes. The RC4580 doesn't either. Nearly all other audio amplifiers will have the back to back diodes.

Best Regards,

Chris Featherstone

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OPA1678: Input current limiting resistor.