DC current sensing!

Following a discussion with Friso, we decided that it would be best to make a circuit that used the IR2175 in a DC situation. This will allow me to callibrate the sensors by supplying a fixed current from a digital power supply.

The problem with this approach is that I will need a separate power supply to achive Vbs as there will be no switching to charge up the bootstrap circuit.

CALCULATIONS

Shunt resistor

I only want to use a current of 2A

V = IR = 0.260

therfore

R = 0.260/2

= 0.13

or 7 x 1 ohm in series.

and for the power:

P = IV

V = IR

I = V/R

therfore

P = V^2/R

= 0.26*0.26*1
= 0.0676

so quarter watt will be fine.


Motor simulation resistors

These resistors need to drop 12V using 2A

V = IR

R = V/I
= 6 ohms


total power

P = IV
= 2*12
= 24 W

I need 3 10W 19R in series