AMC3330: Voltage Sensing

parth kalaria

Part Number: AMC3330

Tool/software:

Hello TI Team,

We are designing a board that incorporates three isolated DC-DC modules: 24VDC Digital, +24VDC Analog, and -24VDC Analog. All output supplies are galvanically isolated.

We aim to measure the voltage of all power supplies using an ADC powered by the 24VDC Digital supply. We prefer not to use any isolated circuits (such as isolated amplifiers or isolated ADCs). The isolated ground is intended to prevent noise coupling.

Kindly suggest any reference design or circuit for the measurement. Attached simple block diagram of power supply and ADC for your reference.

Thank you for answer and your time.

Regards,

Parth

7 months ago

0 Saleh Ahmad 7 months ago

TI__Expert 5330 points

Hi Parth,

If you want to keep the analog domains isolated you will need an isolated measurement solution for those 2 nodes. You can use 2 AMC3330's to measure the analog supplies, with the low side outputs being measured by the ADC in the digital domain.

To measure the voltages you will want voltage dividers on the supply to divide the voltage down to the input range of the AMC device and ADC.

Since the AMC3330 has differential outputs, you'll probably want a differential to single ended conversion before going to the ADC. Or, depending on the accuracy needs, you can just send 1 of the differential outputs to the ADC.

Thanks.

0 parth kalaria 7 months ago in reply to Saleh Ahmad

Prodigy 70 points

Hello Ahmad,

Thank you for the quick feedback.

The provided solution is with the isolated domain. But we need non-isolated solution (ex. op-amp based) for measurement of voltage and current. As voltages are less we don't want to use isolated solution. Also, we require some cost effective solution to measure the same.

The main purpose of using isolated supply is to prevent noise coupling in each supply by other supply.

Regards,

Parth

0 Saleh Ahmad 7 months ago in reply to parth kalaria

TI__Expert 5330 points

Hi Parth,

If you don't need isolation, you could just use a voltage divider and feed the output into your ADC. If you need an op-amp, I can move this thread over to the non-isolated op-amp team.

Thanks.

0 parth kalaria 7 months ago in reply to Saleh Ahmad

Prodigy 70 points

Hello Ahmad,

I appreciate you can shift the thread to the non-isolated op-amp team.

Regards,

Parth

0 Ron Michallick 7 months ago in reply to parth kalaria

TI__Guru**** 159701 points

Parth,

If there is less than 1/2 volt difference between the grounds then this could work. For high difference between ground then all the switches should be SSR (solid state relays). As drawn below only -24V power uses a SSR. The main ground is digital ground. The selection for +24V Digital (SD+) should be logic high for on and low for off. The selection for +24V Analog (SA+) and -24V analog (SA-) is best to be logic High for on, and High Z for off. That way the select output can go a little below digital ground.