Driver section
L6726A
5
Driver section
The integrated high-current drivers allow using different types of power MOSFET (also
multiple MOSFETs to reduce the equivalent R
dsON
), maintaining fast switching transition.
The driver for high-side MOSFET uses BOOT pin for supply and PHASE pin for return. The
driver for low-side MOSFET uses the VCC pin for supply and GND pin for return.
The controller embodies an anti-shoot-through and adaptive dead-time control to minimize
low side body diode conduction time, maintaining good efficiency while saving the use of
Schottky diode:
●
●
to check for high-side MOSFET turn off, PHASE pin is sensed. When the voltage at
PHASE pin drops down, the low-side MOSFET gate drive is suddenly applied;
to check for low-side MOSFET turn off, LGATE pin is sensed. When the voltage at
LGATE has fallen, the high-side MOSFET gate drive is suddenly applied.
If the current flowing in the inductor is negative, voltage on PHASE pin will never drop. To
allow the low-side MOSFET to turn-on even in this case, a watchdog controller is enabled: if
the source of the high-side MOSFET doesn't drop, the low side MOSFET is switched on so
allowing the negative current of the inductor to recirculate. This mechanism allows the
system to regulate even if the current is negative.
Power conversion input is flexible: 5 V, 12 V bus or any bus that allows the conversion (See
maximum duty cycle limitation and recommended operating conditions) can be chosen
freely.
10/35
Doc ID 12754 Rev 4
STMICROELECTRONICS [ STMICROELECTRONICS ]
