TSC888A gain is low

john_schimandle · ‎2013-01-02

Posted on January 02, 2013 at 19:50

I'm using the TSC888A current sensing amplifier in BLDC (brushless DC) motor controller current limit circuit. I'm seeing a gain of about 10 from the amplifier instead of the published typical value of 20. The data sheet does not specify a min or max gain but does state an output accuracy of 6%. With a 0.05 ohm series resistor and 1.2A current I am seeing an output voltage of 650mV. According to my calculations I should be seeing 1.2V (1.2*0.05*20).

Vcc and Vp are both connected to same 12V power bus.

Has anyone else seen this problem?

#tsc888

john_schimandle · ‎2013-01-02

Posted on January 03, 2013 at 02:22

This was pilot error. Gain is correct per the data sheet.

Anthony BOIMOND · ‎2013-01-06

Posted on January 06, 2013 at 11:13

Hello John,

You were able to find the solution by yourself: thanks for sharing with us!

I can add one information: the gain for TSC888 is ''hard-trimmed'' and tested in production line so it's very unlikely to see gain values out of specified values (trimming can hardly change after programming).

Best wishes for 2013 and Best regards,

Anthony