measuring shunt current

Anish N

Other Parts Discussed in Thread: INA282

Hello

Please suggest a Current shunt monitor with analog output with the specification as follows:

Shunt current to be measured - 0 to 330 mA
Range of voltage through shunt - 0 to 50 V
Analog output needed - 0 to 3.3 V

Shunt Current is bidirectional

Please help.

Regards,
Anish

over 8 years ago

0 Jason Bridgmon over 8 years ago

TI__Genius 14825 points

Anish,

Check out the INA282 family. Depending on the gain you need and the speed of the signal, it could well work for you. What kind of accuracy are you looking for?

I'm out on business travel for the week so Rabab Itarsiwala will be able to help you further.

0 Anish N over 8 years ago in reply to Jason Bridgmon

Intellectual 340 points

Hello Jason,

Thank you for the reply.

I am looking for an accuracy of 0.01 mA shunt current to be measured. Measuring range of 0-200 mA is acceptable too.

If possible please share some application circuits.

Regards,

Anish

0 Rabab Itarsiwala over 8 years ago in reply to Anish N

TI__Expert 4595 points

Hello Anish,
Like Jason suggested INA282 (Gain = 50 V/V) could work for your application. Assuming you are using 0-3.3 V supply, Vref = 1.65 V, Vcm = 12V, Rshunt = .1 ohm at room temperature the maximum error at full scale will be at ~1.45 % and typical error of about ~ 0.4%. These don't include the error introduced by Shunt resistor tolerance. Please take a look at the application section of INA282 datasheet for application diagrams. Also another good source for Current Shunt Monitors are the FAQs on top of this page. Link here : e2e.ti.com/.../401346
If you are looking for something in particular please let us know.

0 Anish N over 8 years ago in reply to Rabab Itarsiwala

Intellectual 340 points

Hello Rabab,

Thank you for the reply.

Just i want to clarify some points.

Vcm will vary from 5V to 48 V DC as in the application circuit, whether it will affect the precision?

Also is it feasible to switch the Rshunt to a higher value with the same circuit, for some time to measure a leakage current in the reverse polarity .

Regards,

Anish N

0 Rabab Itarsiwala over 8 years ago in reply to Anish N

TI__Expert 4595 points

Hi Anish,
INA282 has a very high CMRR specification so the effect on accuracy due to Common mode variation will be minimal. How much leakage current are you anticipating. May be this TI Reference Design may be of interest. It may not meet all your system requirements.
www.ti.com/.../tidu447.pdf

0 Anish N over 8 years ago in reply to Rabab Itarsiwala

Intellectual 340 points

Hello Rabab,

It is the diode reverse leakage current to be measured which is in the order of uA for ideal diodes and in mA for bad one.

We can expect a range of 0 to 100 uA in the case of ideal diodes, and 0 to 200 mA in the case of bad ones.

Regards,

Anish

0 Rabab Itarsiwala over 8 years ago in reply to Anish N

TI__Expert 4595 points

Hi Anish,

Please also take a look at this TI Design:

TIPD135 - 10uA-100mA, 0.05% Error, High-Side Current Sensing Solution Reference Design

Amplifiers

Amplifiers forum

measuring shunt current