Datasheet LT3798 (Analog Devices)

LT3798 Isolated No Opto-Coupler Flyback Controller with Active PFC
FEATURES DESCRIPTION
n
Isolated PFC Flyback with Minimum Number of
The LT®3798 is a constant-voltage/constant-current iso-
External Components
lated flyback controller that combines active power factor n
VIN and VOUT Limited Only by External Components
correction (PFC) with no opto-coupler required for output n
Active Power Factor Correction
voltage feedback into a single-stage converter. A LT3798 n
Low Harmonic Distortion
based design can achieve a power factor of greater than 0.97 n
No Opto-Coupler Required
by actively modulating the input current, allowing compli- n
Constant-Current and Constant-Voltage Regulation
ance with most Harmonic Current Emission requirements. n Accurate Regulated Voltage and Current (±5% Typical) The LT3798 is well suited for a wide variety of off-line n Energy Star Compliant (<0.5W No Load Operation) applications. The input range can be scaled up or down, n Thermally Enhanced 16-lead MSOP Package depending mainly on the choice of external components. Efficiencies higher than 86% can be achieved with output
APPLICATIONS
power levels up to 100W. In addition, the LT3798 can easily n Offline 5W to 100W+ Applications be designed into high DC input applications. n High DC VIN Isolated Applications L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear n Offline Bus Converter (12V, 24V or 48V Outputs) Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5438499 and 7471522.
TYPICAL APPLICATION Universal Input 24W PFC Bus Converter VOUT vs IOUT
24.50 90V TO 265V AC 24.25 499k 100k D2 20Ω (V) 4:1:1 24.00 0.1µF 499k 100k 4.7pF V OUT 10µF 2k D3 23.75 VAC = 90V VAC = 120V V 90.9k D4 IN DCM 1M 24V VAC = 220V VIN_SENSE FB Z1 1A VAC = 265V 23.50 EN/UVLO 560µF 0 0.2 0.4 0.6 0.8 1 95.3k 4.99k 22pF × 2 IOUT (A) LT3798 D1 3798 TA01b VREF 20Ω 100k 40.2k CTRL3 GATE Z2 CTRL2 SENSE CTRL1 INTVCC 0.05Ω OVP 4.7µF GND 2.2nF 221k 16.5k COMP+ VC COMP– 2.2µF 0.1µF 3798 TA01a 3798fa 1 Document Outline Description Features Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Typical Applications Package Description Revision History Typical Application Related Parts