INA240: How to calculate output levels

Tomer Bruchiel

Intellectual 640 points

Part Number: INA240
Other Parts Discussed in Thread: INA181,

Hi,

I could not find in the datasheet any reference as to how output is changed based on the input (and other parameters).

For example in part INA181 I can see the following equation:

Vout = (Iload x Rsense X GAIN) + Vref.

What is the equivalent in INA240?

Thanks

over 8 years ago

0 Peter Iliya over 8 years ago

TI__Mastermind 32395 points

Hello Tomer,

The INA240 Vout equation is the same as the INA181, but how Vref is generated differs.

Vref = |Vref1 + Vref2|/2 for INA240.

Thus, Vout = (ILOAD*Rsense*GAIN) + |Vref1 + Vref2|/2

Pins REF1 and REF2 are functionally the same thing because their input resistances (resistors of the internal voltage divider) are the same. This is why it does not matter if you connect REF1 to 5V and REF2 to 1V or REF1 to 1V and REF2 to 5V; the Vout will still be referenced to 3V in both scenarios. Just make sure you do not connect either REF1 or REF2 to voltages > Vs or < GND.

Hope this helps.

Best,
Peter Iliya
Current Sense Applications