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Texas Instruments UC3844DTR — Power Management (PMIC / Gate Driver)

UC3844DTR Current-Mode PWM Controller, 48% Duty Cycle

MPNUC3844DTR
Active

Texas Instruments UC3844DTR current-mode PWM controller, 14-SOIC, 48% max duty cycle, switching up to 500 kHz, 12V~28V supply, 0°C~70°C.

$1.3600Ref. price · indicative, final on quote
Texas Instruments UC3844DTR datasheet (PDF)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

UC3844DTR specifications
ParameterValue
Output typeTransistor Driver
MountingSurface Mount
Voltage - supply (Vcc (Vdd))12V ~ 28V
Frequency - switchingUp to 500kHz
I/O channels1
Output phases1
Duty cycle48%
Operating temperature0°C~70°C(TA)
PackageTape & Reel (TR); Cut Tape (CT)
FunctionStep-Up, Step-Down, Step-Up/Step-Down
TopologyBoost, Buck, Buck-Boost, Flyback, Forward
Clock syncNo
Case14-SOIC (0.154\", 3.90mm Width)
Control featuresFrequency Control
Output configurationPositive, Isolation Capable
Synchronous rectifierNo

Product details

Current-mode PWM controller for flyback and forward converters

The Texas Instruments UC3844DTR is a current-mode PWM controller designed for single-ended topologies including boost, buck, buck-boost, flyback, and forward converters. It delivers a single transistor-driver output with a maximum duty cycle of 48%, which sets the practical input-output voltage ratio for the transformer in isolated designs.

48% duty cycle — the topology gate

The 48% duty cycle ceiling is the key parametric constraint. In a flyback converter, this limits the reflected voltage and the maximum step-up ratio from input to output. For a forward converter, the reset winding must clamp the transformer within the off-time, and the 48% duty ensures the core resets fully before the next cycle. Switching frequency reaches up to 500 kHz, which allows smaller magnetics and output capacitors compared to lower-frequency controllers. The practical switching speed is bounded by the 12V to 28V supply range and the gate-drive current available from the transistor driver output.

Frequently asked questions

What is the maximum duty cycle of UC3844DTR?

The maximum duty cycle is 48%. This is a fixed limit for the current-mode PWM controller and governs the transformer turns ratio in flyback and forward designs.

Can UC3844DTR be used for flyback converters?

Yes. The UC3844DTR supports flyback topology directly, along with boost, buck, buck-boost, and forward converters. The 48% duty cycle is well-suited for single-switch flyback converters operating in discontinuous conduction mode.

What is the difference between UC3842 and UC3844?

The primary difference is the maximum duty cycle: the UC3842 offers up to 96% duty, while the UC3844 is limited to 48%. The UC3844 is preferred for forward converters where the transformer must reset within the off-time.