SC4607 データシートの表示（PDF） - Semtech Corporation

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SC4607

Very Low Input, MHz Operation,High Efficiency Synchronous Buck

Semtech Corporation 

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

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

DRVH

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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