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UC3844D8TRG4

UC3844D8TRG4 PWM Controller, 48% Duty, 500 kHz, 8-SOIC

MPNUC3844D8TRG4
End of Life

Texas Instruments UC3844D8TRG4 current-mode PWM controller, 48% max duty cycle, up to 500 kHz switching, 12V to 28V supply, 8-SOIC surface-mount package, 0°C to 70°C commercial temperature range.

Texas Instruments UC3844D8TRG4 datasheet (PDF)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

UC3844D8TRG4 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)
FunctionStep-Up, Step-Down, Step-Up/Step-Down
TopologyBoost, Buck, Buck-Boost, Flyback, Forward
Clock syncNo
Case8-SOIC (0.154\", 3.90mm Width)
Control featuresFrequency Control
Output configurationPositive, Isolation Capable
Synchronous rectifierNo

Product details

The UC3844D8TRG4 is a current-mode PWM controller from Texas Instruments, built for single-ended topologies — boost, buck, buck-boost, flyback, and forward converters. Its 48% maximum duty cycle is the hard stop that defines the transformer turns ratio and output regulation range in isolated designs; a flyback winding that needs more than 48% on-time at minimum input voltage forces a different controller or a two-switch topology. The part switches up to 500 kHz, letting you shrink the magnetic core and output capacitor relative to 100 kHz designs, but that edge frequency demands careful layout — the sense resistor and gate-drive loop parasitics become the limit.

Supply rails and temperature — where this part fits the BOM

Vcc range of 12 V to 28 V covers the common bias rail from an auxiliary flyback winding or a bootstrap supply in a buck converter — no extra linear regulator needed in most offline AC-DC designs.

TI lists the UC3844D8TRG4 as Active.

Frequently asked questions

What is the difference between UC3844 and UC3842?

The primary parametric difference is the maximum duty cycle. The UC3844 family is clamped at 48% duty cycle, while the UC3842 family allows up to 96% duty. Both are current-mode PWM controllers in the same pin-compatible 8-pin SOIC footprint, but the 48% ceiling on the UC3844 limits its use to flyback and forward converters where the transformer reset time demands a duty cycle below 50%. The UC3842 is the part to choose for boost or push-pull topologies that need a wider on-time.