TLV333: High Side Current Shunt Op-Amp Circuit to Single-Ended ADC for Cost-Optimized Monitor

oben enes sucu

Intellectual 265 points

Part Number: TLV333

Tool/software:

Hello All,

I have a system like 48V input and max 25A, if I use this circuit for this values is it okay?

https://www.ti.com/lit/an/sbaa353a/sbaa353a.pdf?ts=1729192792070

Regards

1 month ago

+1 Ron Michallick 1 month ago

TI__Guru**** 151566 points

Hello Oben,

The load is high side and the current sense is low side. +15V or +48V doesn't matter, unless the 1mili ohm resistor opens up. Then a larger Rg

25A is a 'large' 25mV input so the gain need to be lowered. If full ADC range is 27A; then gain should be 5V/0.027= 185.2, so increase both Rg to 690k/185.2 = 3.73k ; closest 1% is 3.74k

If 1mili ohm did open up, (48V - 5.6V) / 3.74k = 11.3mA; just over the ABS MAX input current. So if this is possible, go further.

(48V-5.6V) / 10mA = 4.24k ; so pick Rg bigger than that. Then pick Rf resistors based on what max current range to measure.

0 oben enes sucu 1 month ago in reply to Ron Michallick

Intellectual 265 points

Hello Ron!

Thank you for your good feedback.

I made my voltage supply 3.3V for TLV333 and I made 1.5k Ohms resistors to 6.8k Ohms and when I calculated the max A is 32.52A.

What do you think about this is this works right?

Regards

0 Ron Michallick 1 month ago in reply to oben enes sucu

TI__Guru**** 151566 points

Oben,

Checking fault current, (48V -3.3V - 0.6V) / 6.8k = 6.4mA input pin current (this flows to 3.3V bus that has to absorb this current); that is under 10mA. 3.3V / (690k/6.8k) = 32.52mV = 32.52A

690k is an odd value, 680k is far more popular. 3.3V / (680k/6.8k) = 32.52mV = 33A

0 oben enes sucu 1 month ago in reply to Ron Michallick

Intellectual 265 points

Ron,

So 680k and 6.8k is okay for my wants right?

Regards

0 Ron Michallick 1 month ago in reply to oben enes sucu

TI__Guru**** 151566 points

Oben,

Yes this satisfies the DC performance.

Amplifiers

Amplifiers forum

TLV333: High Side Current Shunt Op-Amp Circuit to Single-Ended ADC for Cost-Optimized Monitor