LTC3709 Linear Technology, LTC3709 Datasheet - Page 8

• Manufacturer Part Number: LTC3709
• Description: No RSENSE Synchronous DC/DC Controller
• Manufacturer: Linear Technology

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LTC3709
PI FU CTIO S
V
SGND with an RC filter (1Ω, 0.1µF).
DRV
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
PGND1, PGND2 (Pins 23, 19): Power Ground. Connect this
pin closely to the source of the bottom N-channel MOSFET,
the (–) terminal of C
SENSE1
parator Input. The (–) input to the current comparator is
used to accurately Kelvin sense the bottom side of the
sense resistor or MOSFET.
SENSE1
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
swings from a Schottky diode voltage drop below ground
up to V
TG1, TG2 (Pins 27, 14): Top Gate Drive. Drives the top
N-channel MOSFET with a voltage swing equal to DRV
superimposed on the switch node voltage SW.
8
CC
U
(Pin 17): Main Input Supply. Decouple this pin to
CC
IN
(Pin 21): Driver Supply. Provides supply to the
+
–
CC
.
, SENSE2
, SENSE2
U
.
+
–
U
DRVCC
(Pins 25, 16): Current Sense Com-
(Pins 24, 18): Current Sense Com-
and the (–) terminal of C
B
connects here. This pin
IN
.
CC
BOOST1, BOOST2 (Pins 28, 13): Boosted Floating Driver
Supply. The (+) terminal of the bootstrap capacitor C
connects here. This pin swings from a diode voltage drop
below DRV
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
V
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
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
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
ON
IN
RNG
to this pin to set the one-shot timer current and thereby
(Pin 30): On-Time Current Input. Tie a resistor from
(Pin 32): Sense Voltage Range Input. The voltage at
CC
up to V
IN
CC
+ DRV
to enable discontinuous mode
CC
.
CC
.
3709f
B