Unknown problem with ir2103 gate driver

Thread Starter


Joined Jul 1, 2017
Hey guys.
Im using 3 half bridge with ir2103 as gate driver to drive a bldc motor(foc).
As you can see in the picture i sent, after a low level on HIN input of ir2103 the gate of the mosfet has a 1 us delay to get low and mosfet turns off.And this will cause 2 mosfets in one bridge turn on.
Whats the problem?
Yello is high side gate signal.blue is low side gate signal.prple is hin input from mcu.

Here is schematics of gate driver.


Joined Sep 17, 2013
Try increasing the dead-time in software.
Why do RB2 and RB5 have different values?
QLB source isn't grounded.


Joined Apr 7, 2016
I don't like RB4, RB7, CB5, CB6 and DB2.
The resistors are redundant as the driver has push / pull outputs and no high impedance mode. RB4 also unnecessarily discharges the bootstrap capacitor CB2.
The capacitors sits parallel to the gate capacitance of the MOS transistors, and increases the switching time.
The diode is parallel to the QLB body diode, and can have a hard time if the PCB is not optimal.