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H-bridge circuit and a microcontroller problem

BlackMelon

Aug 7, 2012
188
Joined
Aug 7, 2012
Messages
188
Hello,

<How does the circuit work>
I am trying to drive the gates of power MOSFETs in an h-bridge configuration. My gate driver is HIP4080A, a full bridge driver. The circuits are shown by my attachments. At the HIP4080A, the DIS pin is pulled high, so the driver will be active only if there is a "green light" signal from the microcontroller. When Vin+ > Vin-, the power mosfet BL will be kept "ON". Then, if HEN = 1, the driver will turn AH on, and if HEN =0 the driver will turn AH off. So basically, the HEN is a pin to feed a PWM signal. The remaining MOSFETs are off. So, BL and AH together will make a motor rotate in one direction, and the duty ratio is determined by HEN. If Vin+ < Vin-, the motor will rotate in the other direction. HEN still determines the duty ratio

<My problem>
When I wire up everything except the 16V at the top of the H-bridge (there is still 16V at the input of 7805), the HEN, IN+, IN-, DIS logics are all correct. But if I hook the top of the H-bridge to 16V, it seems that my microcontroller can not start up. There is no PWM signal at HEN. Sometimes the voltage of HEN tries to go up but it suddenly drops down again. After I removed the 16V from the top of the H-bridge, everything works fine again.

What is the cause of this? How can I solve this?

Thank You
BlackMelon
 

Attachments

  • HIP Input.jpg
    HIP Input.jpg
    198.3 KB · Views: 61
  • HIP Output.jpg
    HIP Output.jpg
    161.4 KB · Views: 49
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