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Texas Instruments UC3845ADWTRG4 — Power Management (PMIC / Gate Driver)

UC3845ADWTRG4 PWM Controller, 48% Duty Cycle, 500 kHz

MPNUC3845ADWTRG4
Obsolete

Texas Instruments UC3845ADWTRG4, current-mode PWM controller, 48% max duty cycle, up to 500 kHz switching, 7.6 V to 30 V supply, 16-SOIC, 0°C to 70°C.

Texas Instruments UC3845ADWTRG4 datasheet (PDF)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

UC3845ADWTRG4 specifications
ParameterValue
Output typeTransistor Driver
MountingSurface Mount
Voltage - supply (Vcc (Vdd))7.6V ~ 30V
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, Flyback, Forward
Clock syncNo
Case16-SOIC (0.295\", 7.50mm Width)
Control featuresFrequency Control
Output configurationPositive, Isolation Capable
Synchronous rectifierNo

Product details

Current-mode PWM controller — why the 48% duty cycle matters

The UC3845ADWTRG4 has a 48% maximum duty cycle. In a flyback converter, that limit sets the transformer turns ratio and the reflected voltage across the primary switch.

Switching frequency and supply voltage — the operating envelope

The controller switches at up to 500 kHz. The 48% duty cycle applies at any frequency within that range.

A pin-compatible alternative within the UC3845 family would need to be verified against the specific supply and duty-cycle requirements of your application.

Frequently asked questions

Can UC3845ADWTRG4 be used in a buck converter?

Yes, the UC3845ADWTRG4 supports buck topology. The 48% maximum duty cycle limits the step-down ratio — for a 12 V input, the minimum output voltage is roughly 5.8 V at 48% duty, assuming continuous conduction mode. A higher step-down ratio requires a higher-duty-cycle controller.

What is the difference between UC3845ADW and UC3845ADWTRG4?

The UC3845ADW and UC3845ADWTRG4 are the same silicon in the same 16-SOIC package. The suffix TRG4 indicates tape-and-reel packaging; UC3845ADW ships in tube or tray. Both are obsolete.

What is the duty cycle of UC3845ADWTRG4?

The maximum duty cycle is 48%. This is a fixed limit for the UC3845 variant; the UC3844 offers a 50% maximum, and the UC3846 goes above 50%.