Hello,
I am working on LLC converter design where UCD7138DRST is used as gate driver for synchronous MOSFETs (two in parallel).
I have disabled DTC input and also grounded the CTRL pin externally so PWM output is in line with input (refer the schematic image) and gate resistance is 2.2 ohms each.
As noticed, the output of gate driver is irregular, i.e., the pulse width varies and also the PWM is absent at times.
Also, the auxiliary power supply reads fluctuations in current drawn. The current drawn is nearly 130mA under normal operation for two UCD7138 gate drivers. Whereas, it drops nearly to zero at times when PWM is output is missing.
Further, the peak amplitude of input pulses (at IN pin) is reduced when current drawn is reduced, while the IC draws 130mA when input pulses (at IN pin) are of peak amplitude 3.3V (that is correct).
What is the cause of such behavior of the IC? Any suggestions?
