IR3651SPBF
06/08/2011
Pin Description
Pin Name Description
1 Fb Inverting input to the error amplifier. This pin is connected directly to the
output of the regulator via resistor divider to set the output voltage and
provide feedback to the error amplifier.
2 Comp Output of error amplifier. An external resistor and capacitor network is
typically connected from this pin to ground to provide loop compensation.
3 SS/SD Soft start / shutdown. This pin provides user programmable soft-start
function. Connect an external capacitor from this pin to ground to set the
start up time of the output voltage. The converter can be shutdown by
pulling this pin below 0.3V.
4 SYNC The internal oscillator can be synchronized to an external clock via this
pin.
5 PGnd Power Ground. This pin serves as a separate ground for the MOSFET
driver and should be connected to the system’s power ground plane.
6 LDrv Output driver for low side MOSFET.
7 DRVcc This pin provides biasing for the internal low side driver. A minimum of
0.1uF, high frequency capacitor must be connected from this pin to power
ground.
8 Vb This pin powers the high side driver and must be connected to a voltage
higher than bus voltage. A minimum of 0.1uF, high frequency capacitor
must be connected from this pin to switch node.
9 HDrv Output driver for high side MOSFET
10 Vs Switch node. Connect this pin to the source of the upper MOSFET and
the drain of the lower MOSFET. This pin is return path for the upper gate
driver.
11 Vcc This pin provides power for the internal blocks of the IC. A minimum of
0.1uF, high frequency capacitor must be connected from this pin to
ground.
12 OCSet Current limit set point. A resistor from this pin to drain of low side
MOSFET will set the current limit threshold.
13 Gnd Signal ground for internal reference and control circuitry.
14 Rt Connecting a resistor from this pin to ground sets the oscillator frequency.
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