Hello dear community,
in a university project we are developing a 48V/12V buck converter using the LTC4444-5 as driver (picture 1: schematic).We currently have the problem that it is not possible to control the high and low side MOSFET with a PWM logic of 3.3V (Figure 2: Gate-source voltage at 3.3V logic voltage). If the amplitude of the PWM is increased to 5V, the driver works (Figure 3: gate-source voltage at 5V logic voltage).The problem is independent of the duty cycle and the frequency of the PWM (Figure 4). When permanently applying 3.3V to the BINP pin the low side MOSFET is driven correctly. Do you have experience with this problem or a possible solution?
Thanks for your help!