SC4607
POWER MANAGEMENT
Pin Descriptions (Cont.)
Pin #
Pin Name
Pin Function
8
DRVL
Gate drive pin. DRVL drives the gate of the low side (synchronous rectifier) MOSFET. The
output driver is rated for 1A peak current. The PWM circuitry provides complementary drive
signals to the output stages. The cross conduction of the external MOSFETs is prevented
by monitoring the voltage on the DRVH and DRVL driver pins of the MOSFET pair in
conjunction with a time delay optimized for FET turn-off characteristics
9
PHASE
DRVH
The PHASE pin is used to limit current in the high side MOSFET. The SC4607 uses the
voltage across the Vin and ISET pins in order to set the current limit. The current limit
threshold is set by the value of an external resistor (R3 in the Typical Application Circuit
Diagram). Current limiting is performed by comparing the voltage drop across the sense
resistor with the voltage drop across the drain to source resistance of the high side
MOSFET during the MOSFET’s conduction period. The voltage drop across the drain to
source resistance of the high side MOSFET is obtained from the Vin and PHASE pins.
10
Gate drive pin. DRVH drives the gate of the high side (main switch) MOSFET. The output
driver is rated for 1A peak current. The PWM circuitry provides complementary drive
signals to the output stages. The cross conduction of the external MOSFETs is prevented
by monitoring the voltage on the DRVH and DRVL driver pins of the MOSFET pair in
conjunction with a time delay optimized for FET turn-off characteristics
2005 Semtech Corp.
5
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