LT3799-1_15 Datasheet, PDF (1/20 Pages) Linear Technology – Offline Isolated Flyback LED Controller with Active PFC

LT3799-1
Offline Isolated Flyback
LED Controller with Active PFC
FEATURES
n _{Isolated PFC LED Driver with Minimum Number of}
External Components
n _{VIN and VOUT Limited Only by External Components}
n _{Active Power Factor Correction (Typical PFC > 0.97)}
n _{Low Harmonic Content}
n _{No Opto-Coupler Required}
n _{Accurate Regulated LED Current (±5% Typical)}
n _{Open LED and Shorted LED Protection}
n _{Thermally Enhanced 16-Lead MSOP Package}
APPLICATIONS
n _{Offline 4W to 100W+ LED Applications}
n _{High DC VIN LED Applications}
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
True Color PWM is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Patents pending.
DESCRIPTION
The LT^®3799-1 is an isolated flyback controller with power
factor correction specifically designed for driving LEDs.
The controller operates using critical conduction mode
allowing the use of a small transformer. Using a novel
current sensing scheme, the controller is able to deliver a
well regulated current to the secondary side without using
an opto-coupler. A strong gate driver is included to drive
an external high voltage MOSFET. Utilizing an onboard
multiplier, the LT3799-1 typically achieves power factors
of 0.97. The FAULT pin provides notification of open and
short LED conditions. The LT3799-1 offers improved line
regulation over the LT3799, but is not designed for use
with a TRIAC dimmer.
The LT3799-1 uses a micropower hysteretic start-up to
efficiently operate at offline input voltages, with a third
winding to provide power to the part. An internal LDO
provides a well regulated supply for the part’s internal
circuitry and gate driver.
TYPICAL APPLICATION
20W LED Driver
90V
TO 150V
AC
100k
FAULT
100k
0.22μF 499k _100k
499k
20Ω
4.7pF
10μF
2k
4:1:1
6.34k
V_IN
V_{IN_SENSE}
LT3799-1
DCM
FB
32.4k 40.2k
100k
NTC _15.8k
V_REF
CTRL3
CTRL2
CTRL1
GATE
SENSE
INTV_CC
GND
FAULT CT COMP⁺ COMP^–
0.1μF
0.1μF
100k
4.99k
170V
20Ω
560μF
×2
4.7μF
0.05Ω
2.2nF
1A
20W
33V
LED
POWER
LED Current vs Input Voltage
1.20
1.15
1.10
1.05
1.00
0.95
0.90
0.85
0.80
90 100 110 120 130 140 150
V_IN (V_AC)
37991 TA01b
37991 TA01a
37991f
1