Hi people,
Im using IR2011 gate driver to drive top and bottm MOSFETs on one side of a H-bridge. The circuit I used is quite simple. Basically, im just following the circuit in its datasheet. The input signal for both high and low sides is a 5V-25kHz PWM signal. I tested the output of the driver by inputing that PWM signal to HIN and LIN separately. I can get the same PWM signal with a higher magnitude (almost Vcc of gate driver) at the the low side output (LO). BUT, the only thing I can get is roughly 11.3V DC (gate driver Vcc=12V)at high side output (HO), I also measured the source voltage of the top MOSFET, the voltage level is quite close with its gate voltage, which means the top MOSFET will never be turned ON. Can someone help me out?

 

Yes, but we need the other half of the circuit.

Timescope

 

12V - forward voltage drop of the diode = 11.3V.

Post pictures of the output gate signals.

What is the duty cycle? Where is the rest of the schematic?

 

Hi thanks to people who was trying to help. The top trace is input PWM to the HIN port and bottom trace is the actual output from the HO port.

 

Thanks, but the schematic is still not complete. What is the lower end of pickup coil L connected to ?

Timescope

 

BUT, the only thing I can get is roughly 11.3V DC (gate driver Vcc=12V)at high side output (HO), I also measured the source voltage of the top MOSFET, the voltage level is quite close with its gate voltage,

Wait a second, are u saying the high side output is constantly ON? and there is no voltage from gate to source of the top Mosfet? Something isn't right here.

Just to make sure:
Is the voltage from pin 2 to pin 4 11.3V?
Did you measure the HO voltage from pin 3 to pin 4?
Is the Mosfet ok? Is the gate resistor ok?

 

Hi people,
Problem solved. Because I didnt connect the load into the circuit, the high side driver remains a high output when there is no load. Once the load is switched, the problem is gone. Still appretiate those people who was offering help.
Thanks,

 

i's like to ask something. do u use the same ground for both mosfet driver supply and mosfet supply?