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dgrimes
dgrimes
Associate II
January 7, 2015
Question

EMC filtering with L6235

  • January 7, 2015
  • 2 replies
  • 629 views
Posted on January 07, 2015 at 18:41

Hello,

Is there a best practice for EMC filtering on the L6235? In applications with other drivers we've added RC filters on the outputs between switches and motor to dampen the switching noise. Is this recommended for the L6235? Should these components NOT be included (does the device have proper filtering internally?)

-D

#l6235
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2 replies

scope
scope
Associate
January 16, 2015
Posted on January 16, 2015 at 02:33

''EMI'' not EMC. C means Compatibility.

Cant guess at it. What if there is no noise, then why add RC components?

Minimum test equipment is a 60-100 MHz oscilloscope or spectrum analyser to check the lines.

dgrimes
dgrimesAuthor
Associate II
January 16, 2015
Posted on January 17, 2015 at 00:25

With standard H-bridge and MOSFETs you would normally have fly back diodes, high and low side gate RC, and RC filters for both high and low side source. A monolithic IC like L6229 or L6235 must have internal flyback diode and probably manages gate signals (it would be difficult for these to be external.)

My question was, does the IC also have some internal RC between VSA/VSB and OUT 1, 2, 3 (also VGND and OUT1, 2, 3)?

The ''typical applications'' shows these pins straight to motor, J5, or CN3 (depending on the document you are looking at) these might either be internal or were left out to simplify the schematics.

-D

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