RCV420: Alternative device

franziskus

Expert 7759 points

Part Number: RCV420
Other Parts Discussed in Thread: INA317

Tool/software:

Hi,

my customer found RCV420 to be a technical fit for their application, but they cannot use the PDIP package.

I also would like to guide them towards a more modern device.

Do you have suggestens where to start?

Best regards

2 months ago

+1 Clemens Ladisch 2 months ago

Guru 296910 points

What are the actual requirements?

The RCV420 takes effort to map the 4 mA … 20 mA range to 0 V … 5 V. But it would be much easier to use a simple precision resistor to generate the voltage drop; for example, 250 Ω would result in an output range of 1 V … 5 V. This voltage can be buffered with any opamp. If you cannot connect the shunt resistor to ground or want to shift the output voltage range, use an instrumentation amplifier like the INA317.

0 Robert Clifton56 2 months ago in reply to Clemens Ladisch

TI__Mastermind 25100 points

Hi Franziskus,

Adding to Clemens comments, depending on the customer needs, we also have 4-20mA current loop devices can be switched to output both current and voltage. However, depending on the applications the current loop might be necessary to traverse the long cables.

As Clemens mentioned, we could also suggest a transimpedance amplifier design that might be able to help. It won't be as integrated as the RCV420. Here's a document going over the general circuit design: https://www.ti.com/lit/an/sboa268b/sboa268b.pdf

0 franziskus 1 month ago in reply to Robert Clifton56

TI__Expert 7759 points

Thanks Robert and Clemens!
My customer mainly wants to avoid having an external shunt resistor, that's why the RCV420 is interesting.

Robert,
Is there any reason not to use the RCV420 in a new project?

The app note seems not helpful for them. Do we have any other examples using a transimpedance amplifier?

Best regards

+1 Robert Clifton56 1 month ago in reply to franziskus

TI__Mastermind 25100 points

Franziskus,

I see no problem with using this device in your project.

Without an external shunt, it removes most other solutions. However, there are integrated current-sense resistors available. I'm not an expert in the current sense selection but here's the parts with an integrated shunt. https://www.ti.com/amplifier-circuit/current-sense/products.html#-3=Analog%20current-sense%20amplifiers%20with%20integrated%20shunt%20resistor&

Best Regards,

Robert Clifton

0 franziskus 1 month ago in reply to Robert Clifton56

TI__Expert 7759 points

Thank you Robert and Clemens!

0 Robert Clifton56 1 month ago in reply to franziskus

TI__Mastermind 25100 points

Hi Franziskus,

Glad we could help!

Best Regards,

Robert Clifton

Amplifiers

Amplifiers forum

RCV420: Alternative device