RT9629A_15 Datasheet, PDF (4/14 Pages) Richtek Technology Corporation – Triple-Channel Synchronous Rectified Buck MOSFET Driver

RT9629A
Operation
POR (Power On Reset)
POR block detects the voltage at VCC1 pin and VCC2
pin. When the VCC1 and VCC2 pin voltage is higher than
POR rising threshold, POR pin output voltage (POR output)
is high. POR output is low when VCC1 and VCC2 are not
both higher than POR rising threshold. When the POR
pin voltage is high, UGATEx and LGATEx can be controlled
by ENx pin and PWMx pin voltage. With low POR pin
voltage, both UGATEx and LGATEx will be pulled to low.
Enable Detect
When ENx pin input voltage is higher/lower than EN rising
threshold, MOSFET driver is enabled/disabled. When the
ENx input and POR output are high, UGATEx and LGATEx
can be controlled by PWMx input voltage. When ENx
input is low, both UGATEx and LGATEx are pulled to low.
Tri-State Detect
When both POR block output and ENx pin voltages are
high, UGATEx and LGATEx can be controlled by PWMx
input. There are three PWMx input modes, which are high,
low, and shutdown state. If PWMx input is within the
shutdown window, both UGATEx and LGATEx output are
low. When PWMx input is higher than its rising threshold,
UGATEx is high and LGATEx is low. When PWMx input
is lower than its falling threshold, UGATEx is low and
LGATEx is high.
Bootstrap Control
Bootstrap control block controls the integrated bootstrap
switch. When LGATEx is high (low side MOSFET is
turned on), the bootstrap switch is turned on to charge
the bootstrap capacitor connected to BOOTx pin. When
LGATEx is low (low side MOSFET is turned off), the
bootstrap switch is turned off to disconnect VCCx pin and
BOOTx pin.
Turn-Off Detection
Turn-off detection block detects whether high side
MOSFET is turned off by monitoring PHASEx pin voltage.
To avoid shoot through between high side and low side
MOSFETs, low side MOSFET can be turned on only after
high side MOSFET is effectively turned off.
Shoot-Through Protection
Shoot-through protection block implements the dead time
when both high side and low side MOSFETs are turned
off. With shoot-through protection block, high side and
low side MOSFET are never turned on simultaneously.
Thus, shoot through between high side and low side
MOSFETs is prevented.
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is a registered trademark of Richtek Technology Corporation.
DS9629A-05 July 2015