At 02:49 AM 4/22/2012, Forrest Christian wrote: >I'm currently using an INA196 high side shunt amplifier in a couple of >applications. As I asked/discussed a couple of weeks ago, one of them >involves current monitoring the currents through some P-channel FETS, >and am looking at moving the sensing from a sense resistor to sensing >across the FETS. Can I suggest a somewhat different approach? Allegro makes some fine hall-effect current sensors for probably less=20 money than the INA196 op-amp that you are currently using. The=20 larger units are intended for high current operation (200A plus) but=20 the tiny units are rated for plus minus 5A full-scale. And a whole=20 whack of current ratings in-between. For example, the Allegro ACS712ELCTR-05B-T (Digikey # 620-1189-1-ND)=20 sells for Can $4.84 in singles but drops down to just over Can $3 in hundre= ds. The advantage of using a current sensor like this is that the current=20 loop is galvanically isolated from the measurement side. The ACS712=20 datasheet says that the current loop is about 1.2 milli-ohms and the=20 device is rated at 2.1kV minimum isolation between the loop and the=20 sensor. Frequency response is stated at 80KHz. There may be reasons why these parts aren't suitable but I think that=20 they are worth a look. dwayne PS - I have another suggestion that I will post after this one. dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .