LTC3709 Datasheet, PDF (8/24 Pages) Linear Technology – Fast 2-Phase, No RSENSE Synchronous DC/DC Controller with Tracking/Sequencing

LTC3709
PI FU CTIO S
V_CC (Pin 17): Main Input Supply. Decouple this pin to
SGND with an RC filter (1Ω, 0.1µF).
DRV_CC (Pin 21): Driver Supply. Provides supply to the
driver for the bottom gate. Also used for charging the
bootstrap capacitor.
BG1, BG2 (Pins 22, 20): Bottom Gate Drive. Drives the
gate of the bottom N-channel MOSFET between ground
and DRV_CC.
PGND1, PGND2 (Pins 23, 19): Power Ground. Connect this
pin closely to the source of the bottom N-channel MOSFET,
the (–) terminal of C_DRVCC and the (–) terminal of C_IN.
SENSE1^–, SENSE2^– (Pins 24, 18): Current Sense Com-
parator Input. The (–) input to the current comparator is
used to accurately Kelvin sense the bottom side of the
sense resistor or MOSFET.
SENSE1⁺, SENSE2⁺ (Pins 25, 16): Current Sense Com-
parator Input. The (+) input to the current comparator is
normally connected to the SW node unless using a sense
resistor (see Applications Information).
SW1, SW2 (Pins 26, 15): Switch Node. The (–) terminal
of the bootstrap capacitor C_B connects here. This pin
swings from a Schottky diode voltage drop below ground
up to V_IN.
TG1, TG2 (Pins 27, 14): Top Gate Drive. Drives the top
N-channel MOSFET with a voltage swing equal to DRV_CC
superimposed on the switch node voltage SW.
BOOST1, BOOST2 (Pins 28, 13): Boosted Floating Driver
Supply. The (+) terminal of the bootstrap capacitor C_B
connects here. This pin swings from a diode voltage drop
below DRV_CC up to V_IN + DRV_CC.
PGOOD (Pin 29): Power Good Output. Open-drain logic
output that is pulled to ground when output voltage is not
within ±10% of the regulation point. The output voltage
must be out of regulation for at least 100µs before the
power good output is pulled to ground.
I_ON (Pin 30): On-Time Current Input. Tie a resistor from
V_IN to this pin to set the one-shot timer current and thereby
set the switching frequency.
FCB (Pin 31): Forced Continuous and External Clock
Input. Tie this pin to ground to force continuous synchro-
nous operation or to V_CC to enable discontinuous mode
operation at light load. Feeding an external clock signal
into this pin will synchronize the LTC3709 to the external
clock and enable forced continuous mode.
V_RNG (Pin 32): Sense Voltage Range Input. The voltage at
this pin is ten times the nominal sense voltage at maximum
output current and can be programmed from 0.5V to 2V.
The sense voltage defaults to 70mV when this pin is tied
to ground, 140mV when tied to V_CC.
3709f
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