Datasheet LTC3857-1 (Analog Devices) - 9

LTC3857-1
PIN FUNCTIONS BOOST1, BOOST2 (Pin 24, Pin 17):
Bootstrapped Supplies
PGOOD1 (Pin 27):
Open-Drain Logic Output. PGOOD1 is to the Topside Floating Drivers. Capacitors are connected pulled to ground when the voltage on the VFB1 pin is not between the BOOST and SW pins and Schottky diodes are within ±10% of its set point. tied between the BOOST and INTVCC pins. Voltage swing
TRACK/SS1, TRACK/SS2 (Pin 28, Pin 14):
External Track- at the BOOST pins is from INTVCC to (VIN + INTVCC). ing and Soft-Start Input. The LTC3857-1 regulates the
SW1, SW2 (Pin 25, Pin 16):
Switch Node Connections VFB1,2 voltage to the smaller of 0.8V or the voltage on the to Inductors. TRACK/SS1,2 pin. An internal 1μA pull-up current source is connected to this pin. A capacitor to ground at this
TG1, TG2 (Pin 26, Pin 15):
High Current Gate Drives for pin sets the ramp time to final regulated output voltage. Top N-Channel MOSFETs. These are the outputs of float- Alternatively, a resistor divider on another voltage supply ing drivers with a voltage swing equal to INTVCC – 0.5V connected to this pin allows the LTC3857-1 output to track superimposed on the switch node voltage SW. the other supply during start-up. 38571fc 9 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS