LTC1709 datasheet(8/28 Pages) LINER

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LTC1709

PI FU CTIO S

AMPMD (Pin 23): This Logic Input pin controls the

connections of internal precision resistors that configure

the operational amplifier as a unity-gain differential

amplifier.

TG2, TG1 (Pins 24, 35): High Current Gate Drives for Top

N-Channel MOSFETS. These are the outputs of floating

drivers with a voltage swing equal to INTVCC superim-

posed on the switch node voltage SW.

SW2, SW1 (Pins 25, 34): Switch Node Connections to

Inductors. Voltage swing at these pins is from a Schottky

diode (external) voltage drop below ground to VIN.

BOOST 2, BOOST 1 (Pins 26, 33): Bootstrapped Supplies

to the Topside Floating Drivers. External capacitors are

connected between the Boost and Switch pins, and Schottky

diodes are connected between the Boost and INTVCC pins.

BG2, BG1 (Pins 27, 31): High Current Gate Drives for

Bottom N-Channel MOSFETS. Voltage swing at these pins

is from ground to INTVCC.

PGND (Pin 28): Driver Power Ground, connect to sources

of bottom N-channel MOSFETS and the (–) terminals of

CIN.

INTVCC (Pin 29): Output of the Internal 5V Linear Low

Dropout Regulator and the EXTVCC Switch. The driver and

control circuits are powered from this voltage source.

Decouple to power ground with a 1

µF ceramic capacitor

placed directly adjacent to the IC and minimum of 4.7

µF

additional tantalum or other low ESR capacitor.

EXTVCC (Pin 30): External Power Input to an Internal

Switch . This switch closes and supplies INTVCC, bypass-

ing the internal low dropout regulator whenever EXTVCC is

higher than 4.7V. See EXTVCC Connection in the Applica-

tions Information section. Do not exceed 7V on this pin

and ensure VEXTVCC ≤ VIN.

VIN(Pin 32): Main Supply Pin. Should be closely decoupled

to the IC’s signal ground pin.

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