The PX3511x is a high frequency MOSFET driver specifically
designed to drive upper and lower power N-channel
MOSFETs in a synchronous rectified buck converter topology.
These drivers combined with the PX3535 or PX3538 Digital
Multi-phase Controllers and N-channel MOSFETs form a
complete core-voltage regulator solution for advanced
microprocessors.
The PX3511A drives the upper gate to +12V, while the lower
gate can be independently driven over a range from +5V to
+12V. The PX3511B and PX3511D drive both upper and
lower gates over a range of +5V to +12V. This drive-voltage
provides the flexibility needed to optimize applications
involving trade-offs between gate charge and conduction
losses.
Adaptive zero shoot-through protection is integrated into the
PX3511x to minimize dead time and prevent both upper and
lower MOSFETs from conducting simultaneously. An overvoltage
protection feature is operational before VCC exceeds
its turn-on threshold, where the PHASE node is connected to
the gate of the low-side MOSFET (LGATE). The output
voltage of the converter is then limited by the threshold of the
low-side MOSFET. This protects the microprocessor if the
upper MOSFET is shorted during initial startup.
The PX3511x also features a three-state PWM input that,
when used together with Primarion’s Digital Multiphase
Controllers, prevents a negative transient on the output
voltage when the output is shut down. This feature eliminates
the need for Schottky diodes that are used to protect the load
from reverse output voltage events.