DGD2136

Document Number DS38611 Rev. 7 - 4

12 of 14

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November 2021

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DGD2136

Design Notes (continued)

Solution 2

If the 3-phase current sensing configuration is similar to Figure 33, then the best solution is to add a ceramic capacitor (0.022 to 0.1uF) between

VSS and COM directly at the IC. This provides a more stable ground at the IC, and the current sense circuit operates normally (see Figures 34

and 35).

Summary

To improve the performance of the DGD2136 during high current operation of 3-phase motor applications, it is best to make a more stable IC

ground. Depending on the current sense circuit arrangement in the 3-phase motor driver application, two solutions are provided: one that shorts

the connection between COM-VSS and another is adding a ceramic capacitor between COM-VSS. In a compressor application, there were no

fault conditions seen at the MCU and the COM-VSS noise was significantly less with the solutions provided.

Figure 31. During startup, current is high, with

shorted COM-VSS, noise is less, fault conditions do

not occur, compressor will not stall, 2ms/div

Figure 32. During startup, current is high, with

shorted COM-VSS, noise is less, fault conditions do

not occur, compressor will not stall, 100us/div

Figure 33. Adding capacitor between VSS-COM at IC

for current sense configuration C

Figure 34. During startup current is high, with cap

between COM-VSS, noise is less, fault conditions do

not occur, compressor will not stall, 2ms/div

Figure 35. During startup current is high, with cap

between COM-VSS, noise is less, fault conditions do

not occur, compressor will not stall, 100us/div