current sensing - back to the schematics

Time to go back to the schematics.

I have previously checked that I have correct values for all the components. I will check again and document what values are correct and where I got the info for their values from.

Looking at figure 1 in the application note:


I need to choose: R, R_sense, C_bs, D_bs and the diode from V_s to COM (D_vs).

R_sense calculations are shown earlier in this blog.


R and D_vs are present to eliminate any negative transients from the Vs pin. (see app note p4)

R should be 10 - 20 ohm (see app note p4)

D_vs should be a 1A diode that has a recovery time of less than 100ns.

WHAT DIODE DID I CHOOSE?


C_bs and D_bs are needed for the bootstrap circuit.

HOW DID I CHOOSE THE SIZE OF THESE COMPONETS?



I also need a 1 - 10K pullup on the PO (app not p1).

done with 10K


I also need to choose and determine the location for a filter cap(0.1uF).

here i have found a problem. The filter cap (decoupling cap) has beed added between Vcc and Vs rather than Vcc and COM.

I have moved the filter cap to the correct place and connected them both directly to the pins of the chip to ensure that they are as close as possible as the app note recommends.



not much seems to have been fixed.