OPA462: Application for HV capacitance measurement

Hi David,

David Huang said:

Do we have any reference design or application notes for the power management of HV amplifier? The customer is using industrial 24V.

Your last sentence confuses me. The OPA462 allows to be powered with a supply voltage of +180V. And you want to power it with +24V? Why taking the OPA462 then and not any other OPAmp?

Can you please give more details on the measurement setup? And can you please show a schematic?

Kai

Hi Huang,

Could you share the schematic with us? 

We would like to know the type of circuit you use to measure capacitance in 100's volt. The following application note may or may not be applicable. Are you measuring a capacitance by injecting a constant current to a capacitor and measure dV/dt Peak value or some other measurement technique. Please let us know. 

https://www.ti.com/lit/an/sboa510/sboa510.pdf?ts=1626284512764&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FOPA462

Best,

Raymond

Hi Raymond

Thanks for the reply.

We don't have the schematic yet.

I noticed that Jonathan has included you in our email discussion, I think we can carry on the discussion by email.

Regards

Hi kai

Thanks for answering.

Sorry for making confusion there.

My guess is that their HV circuit is not used to power up the op-amp(it's 100s volts, too high for the OPA462), the op-amp is only used for measuring the capacitance of this circuit and they are designing another circuit for the power rail of the OPA462.

I think the reason why they need higher voltage supply op-amp is simply because they need higher output voltage. Then the power management they are looking for is probably something to convert 24V to 90V split-rail.

Do we have such power solution?

Regards

Hi David,

you might want to have a look at this thread:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/954668/ina105-ina105-to-make-a-low-noise-howland-current-source

Kai