LT3782 Linear Technology, LT3782 Datasheet - Page 5

• Manufacturer Part Number: LT3782
• Description: 2-Phase Step-Up DC/DC Controller
• Manufacturer: Linear Technology

PI FU CTIO S
SGATE2 (Pin 1): Second Phase Synchronous Drive Sig-
nal. An external driver buffer is needed to drive the top
synchronous power FET.
SGATE1 (Pin 2): First Phase Synchronous Drive Signal.
An external driver buffer is needed to drive the top syn-
chronous power FET.
NC (Pin 3): Not Connected. Can be connected to GND.
GND (Pin 4): Chip Ground.
SYNC (Pin 5): Synchronization Input. The pulse width can
range from 10% to 70%. Note that the operating frequency
is half of the sync frequency.
DELAY (Pin 6): When synchronous drivers are used, the
programmable delay that delays BGATE turns on after
SGATE turns off.
DCL (Pin 7): This pin programs the limit of the maximum
duty cycle. When connected to V
maximum duty cycle, approximately 90%.
SENSE1
Positive Input. An RC filter is required across the current
sense resistor. Current limit threshold is set at 60mV.
SENSE1
Negative Input. An RC filter is required across the current
sense resistor.
SLOPE (Pin 10): A resistor from SLOPE to GND increases
the internal current mode PWM slope compensation.
R
oscillator charging current and the operating frequency.
SENSE2
Negative Input. An RC filter is required across the current
sense resistor.
SENSE2
Positive Input. An RC filter is required across the current
sense resistor. Current limit threshold is set at 60mV.
SS (Pin 14): Soft-Start. A capacitor on this pin sets the
output ramp up rate. The typical time for SS to reach the
programmed level is (C • 2.44V)/10µA.
SET
U
(Pin 11): A resistor from R
+
–
–
+
(Pin 12): Second Phase Current Sense Amplifier
(Pin 13): Second Phase Current Sense Amplifier
(Pin 8): First Phase Current Sense Amplifier
(Pin 9): First Phase Current Sense Amplifier
U
U
RSET
SET
, it operates at natural
to GND sets the
V
control signal of the current loop of the current-mode
PWM. Switching starts at 0.7V, and higher V
corresponds to higher inductor current.
FB (Pin 16): Error Amplifier Inverting Input. A resistor
divider to this pin sets the output voltage.
RUN (Pin 17): LT3782 goes into shutdown mode when
V
mode when V
NC (Pin 18): Not Connected. Can be connected to GND.
VEE2 (Pin 19): Gate Driver BGATE2 Ground. This pin
should be connected to the ground side of the second
current sense resistor.
BGATE2 (Pin 20): Second Phase MOSFET Driver.
GBIAS2 (Pin 21): Bias for Gate Driver BGATE2. Should be
connected to GBIAS or an external power supply between
12V to 14V. A bypass low ESR capacitor of 2µF or larger
is needed and should be connected directly to the pin to
minimize parasitic impedance.
GBIAS1 (Pin 22): Bias for Gate Driver BGATE1. Should be
connected to GBIAS2.
BGATE1 (Pin 23): First Phase MOSFET Driver.
VEE1 (Pin 24): Gate Driver BGATE1 Ground. This pin
should be connected to the ground side of the second
current sense resistor.
NC (Pin 25): Not Connected. Can be connected to GND.
NC (Pin 26): Not Connected. Can be connected to GND.
V
is required.
GBIAS (Pin 28): Internal 11V regulator output for biasing
internal circuitry. Should be connected to GBIAS1 AND
GBIAS2.
EXPOSED PAD (Pin 29): The exposed package pad is
fused to internal ground and is for heat sinking. Solder the
bottom metal plate onto expanded ground plane for opti-
mum thermal performance.
C
RUN
CC
(Pin 15): The output of the gm error amplifier and the
(Pin 27): Chip Power Supply. Good supply bypassing
is below 2.2V and goes to low bias current shutdown
RUN
is below 0.3V.
LT3782
C
voltages
3782fa
5