i use dspic micro and ir2104 to drive half bridge mosfet

i use 12 volt , 150 watt switching power supply and lm2576 3.3 for dspic.

when the mosfet load is 10 watt no problem but when the load is 50 watt ,micro Continuous

reset and power up.the mosfet is irfz44

i pullup mclr pin with 10k resistor and put 100 nf cap for each vcc gnd.

i think when the mosfet goes on the high load, generate noise and the mclr pin reset.

because i dont have Voltage drop on vcc of micro but when i see gnd line with oscop its noisy when the micro is in reset

how to solve problem?

thank you

i separate gnd and vcc of dspic with 2 ferrite bead and add 100 nf cap series with mclr pin but yet dspic Continuous in reset

  • \$\begingroup\$ Add a 100nF cap directly across the power supply pins of the microcontroller. Same for all digital chips in your circuit. Keep tracks short between microcontroller and MOSFET, this includes the ground path. \$\endgroup\$
    – jippie
    Jan 13, 2015 at 7:07
  • \$\begingroup\$ what is the part number of your device? \$\endgroup\$ Jan 14, 2015 at 6:02

1 Answer 1


You may need to separate grounds for dspic and the power stage. They need to be connected at one point, like a sense resistor if you have it. Also, adding a ferrite bead in series with dspic ground may help, as well as another one on the input of the linear regulator.

Also, some dspics have a register which contains a cause of the last reset. You may want to find the name of this register in the datasheet of your dspic and check its contents to see if a reset was due to MCLR line or BOR or something else.


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