LTC3727-1 Linear Technology, LTC3727-1 Datasheet - Page 8

• Manufacturer Part Number: LTC3727-1
• Description: 2-Phase Synchronous Step-Down Switching Regulators
• Manufacturer: Linear Technology

LTC3727/LTC3727-1
PI FU CTIO S
PLLFLTR (Pin 5): The phase-locked loop’s lowpass filter
is tied to this pin. Alternatively, this pin can be driven with
an AC or DC voltage source to vary the frequency of the
internal oscillator.
PLLIN (Pin 6): External Synchronization Input to Phase
Detector. This pin is internally terminated to SGND with
50k . The phase-locked loop will force the rising top gate
signal of controller 1 to be synchronized with the rising
edge of the PLLIN signal.
FCB (Pin 7): Forced Continuous Control Input. This input
acts on both controllers and is normally used to regulate
a secondary winding. Pulling this pin below 0.8V will
force continuous synchronous operation. Do not leave
this pin floating.
I
ing Regulator Compensation Points. Each associated chan-
nels’ current comparator trip point increases with this
control voltage.
SGND (Pin 9): Small Signal Ground common to both
controllers, must be routed separately from high current
grounds to the common (–) terminals of the C
capacitors.
3.3V
supplying 10mA DC with peak currents as high as 50mA.
PGND (Pin 20): Driver Power Ground. Connects to the
sources of bottom (synchronous) N-channel MOSFETs, an-
odes of the Schottky rectifiers and the (–) terminal(s) of C
INTV
Dropout Regulator and the EXTV
8
TH1,
U
OUT
CC
I
TH2
(Pin 21): Output of the Internal 7.5V Linear Low
(Pin 10): Output of a linear regulator capable of
(Pins 8, 11): Error Amplifier Outputs and Switch-
U
U
CC
Switch. The driver and
OUT
IN
.
control circuits are powered from this voltage source. Must
be decoupled to power ground with a minimum of 4.7 F
tantalum or other low ESR capacitor.
EXTV
Switch Connected to INTV
supplies V
regulator, whenever EXTV
EXTV
8.5V on this pin.
BG1, BG2 (Pins 23, 19): High Current Gate Drives for
Bottom (Synchronous) N-Channel MOSFETs. Voltage
swing at these pins is from ground to INTV
V
be tied between this pin and the signal ground pin.
BOOST1, BOOST2 (Pins 25, 18): Bootstrapped Supplies
to the Top Side Floating Drivers. Capacitors are connected
between the boost and switch pins and Schottky diodes
are tied between the boost and INTV
at the boost pins is from INTV
SW1, SW2 (Pins 26, 17): Switch Node Connections to
Inductors. Voltage swing at these pins is from a Schottky
diode (external) voltage drop below ground to V
TG1, TG2 (Pins 27, 16): High Current Gate Drives for Top
N-Channel MOSFETs. These are the outputs of floating
drivers with a voltage swing equal to INTV
superimposed on the switch node voltage SW.
PGOOD (Pin 28): Open-Drain Logic Output. PGOOD is
pulled to ground when the voltage on either V
not within 7.5% of its set point.
IN
(Pin 24): Main Supply Pin. A bypass capacitor should
CC
CC
connection in Applications section. Do not exceed
(Pin 22): External Power Input to an Internal
CC
power, bypassing the internal low dropout
CC
CC
. This switch closes and
CC
is higher than 7.3V. See
www.DataSheet4U.com
to (V
CC
pins. Voltage swing
IN
+ INTV
CC
OSENSE
.
CC
CC
IN
– 0.5V
.
).
pin is
3727f