LTC3789 Datasheet, PDF (9/28 Pages) Linear Technology – High Efficiency, Synchronous, 4-Switch Buck-Boost Controller

LTC3789
Pin Functions (SSOP/QFN)
V_OUTSNS (Pin 11/Pin 8): V_OUT Sense Input to the Buck-
Boost Transition Comparator. Connect this pin to the drain
of the top N-channel MOSFET on the output side.
I_LIM (Pin 12/Pin 9): Input/Output Average Current Sense
Range Input. This pin tied to SGND, INTV_CC or left floating,
sets the maximum average current sense threshold.
I_OSENSE+ (Pin 13/Pin 10): The (+) Input to the Input/Output
Average Current Sense Amplifier.
I_OSENSE– (Pin 14/Pin 11): The (–) Input to the Input/Output
Average Current Sense Amplifier.
TRIM (Pin 15/Pin 12): Tie this pin to GND for normal
operation. Do not allow this pin to float.
EXTV_CC (Pin 20/Pin 17): External Power Input to an
Internal LDO Connected to INTV_CC. This LDO supplies
INTV_CC power, bypassing the internal LDO powered from
V_IN whenever EXTV_CC is higher than 4.8V. See EXTV_CC
Connection in the Applications Information section. Do
not exceed 14V on this pin.
INTV_CC (Pin 21/Pin 18): Output of the Internal Linear Low
Dropout Regulator. The driver and control circuits are
powered from this voltage source. Must be bypassed to
power ground with a minimum of 4.7µF tantalum, ceramic,
or other low ESR capacitor.
V_IN (Pin 22/Pin 19): Main Supply Pin. A bypass capa-
citor should be tied between this pin and the signal
ground pin.
BG1, BG2 (Pins 23, 19/Pins 20, 16): High Current Gate
Drives for Bottom (Synchronous) N-Channel MOSFETs.
Voltage swing at these pins is from ground to INTV_CC.
PGND (Pin 24/Pin 21): Driver Power Ground. Connects
to C_OUT and R_SENSE (–) terminal(s) of C_IN.
BOOST1, BOOST2 (Pins 25, 18/Pins 22, 15): Bootstrapped
Supplies to the Top Side Floating Drivers. Capacitors
are connected between the BOOST and SW pins and
Schottky diodes are tied between the BOOST and INTV_CC
pins. Voltage swing at the BOOST pins is from INTV_CC to
(V_IN + INTV_CC).
TG1, TG2 (Pins 26, 17/Pins 23, 14): High Current Gate
Drives for Top N-Channel MOSFETs. These are the outputs
of floating drivers with a voltage swing equal to INTV_CC
– 0.5V superimposed on the switch node voltage SW.
SW1, SW2 (Pins 27, 16/Pins 24, 13): Switch Node
Connections to Inductors. Voltage swing at these pins
is from a Schottky diode (external) voltage drop below
ground to V_IN.
PGOOD (Pin 28/Pin 25): Open-Drain Logic Output. PGOOD
is pulled to ground when the voltage on the V_FB pin is not
within ±10% of its regulation window, after the internal
20µs power-bad mask timer expires.
3789f
9