Until now we have a problem with the UCC27211 MOSFET drivers that don’t behave as expected.
We use conventional H-Bridges with asymmetrical gate resistors:
- R_g_on = 4,7Ohm
- R_g_off = 3,2Ohm
but the High-Side is shutting off and on shortly after switching on (about 50ns later). Vdd is quite low at 9V but is required to limit switching losses.
The MOSFETs are IPD90N08S405 so nothing hard to switch. The only workaround was to increase R_g_on to 15Ohm but the switching losses are increasing accordingly and we are clearly under the UCC27211 specifications…
We ordered the pin compatible MAX15019 to check if the problem comes from the design. It is not our first design though and it is following all the classical recommended design rules.
Would a noisy Vdd during high du/dt trigger the UVLO?
Regards,
Bernd
