LT3798 LINER [Linear Technology], LT3798 Datasheet - Page 7

• Manufacturer Part Number: LT3798
• Description: Isolated No Opto-Coupler Flyback Controller
• Manufacturer: LINER [Linear Technology]

PIN FUNCTIONS
GATE (Pin 14): N-Channel FET Gate Driver Output. Switches
between INTV
state and stays high during low voltage states.
SENSE (Pin 15): The Current Sense Input for the Control
Loop. Kelvin connect this pin to the positive terminal of the
switch current sense resistor, R
NFET. The negative terminal of the current sense resistor
should be connected to the GND plane close to the IC.
BLOCK DIAGRAM
R9
R8
COMP
COMP
CTRL1
CTRL2
CTRL3
V
C6
OVP
R10
REF
VC
C4
FB
+
–
CC
1.22V
and GND. Driven to GND during shutdown
FB
–
+
+
–
A5
S&H
A8
A9
R12
1M
S&H
SENSE
R4
R5
MINIMUM
SW1
, in the source of the
+
–
DCM
R15
600mV
C1
+
–
A2
INTERNAL REG
STARTUP
L1C
A6
D2
EN/UVLO
SHOT
ONE
MULTIPLIER
R13
R14
A3
V
IN_SENSE
COMPARATOR
CURRENT
V
used for sensing the AC line voltage to perform power
factor correction. Connect a resistor in series with the
line voltage to this pin. If no PFC is needed, connect this
pin to INTV
GND (Exposed Pad Pin 17): Ground. The exposed pad
of the package provides both electrical contact to ground
and good thermal contact to the printed circuit board.
The exposed pad must be soldered to the circuit board
for proper operation.
IN_SENSE
+
–
A1
LOW OUTPUT
OSCILLATOR
CURRENT
1.22V
S
S
MASTER
(Pin 16): Line Voltage Sense Pin. The pin is
LATCH
CC
C3
R
with a 25k resistor.
–
+
A4
Q
A7
V
IN
R3
R7
R11
DRIVER
R1
3798 BD
V
RECTIFIED
C2
INTV
GATE
SENSE
GND
CC
L1A
C5
N:1
T1
R6
LT3798
L1B
D1
V
V
C7
OUT
OUT
7
3798f
+
–