Hi,
In the past I've used hall effect current feedback but now I want to move to a solution with shunt + op-amp. I'm an EE, but not very experienced with these amplifiers.
I'm pressing the "buy now" button on the HC (60V40A kit) any time now, but at the same time I'm starting designing a powerstage for volume production. The HC DRV3201 kit uses three tlv2781 op-amps with three 2mOhm shunts. In addition precision resistors set the gain is needed; as referenced from page 139 of the InstaSPIN FOC/MOTION user guide.
I've decided to use 300uOhm shunts (something along the line of this: http://www.mouser.com/ds/2/427/wsl2726-88189.pdf) and want to find a IC that preferably has a internal reference and fixed gain, basically doing the job a normal Op-amps does - but without the external resistors. This page shows some current shunt amplifiers made for high common voltage ranges - not what I need; but a step in the right direction with fixed gain. Could anyone point me in the right direction?
The motor I'll be driving is a ebike hub motor with about 170uH phase-phase inductance and 100mOhm phase-phase resistance. I will run 20kHz PWM.
The first 50 boards are being hand assembled and the extra cost of a IC can be justified with less parts to populate to the board.
Sincerely,