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Texas Instruments UC3842D — Power Management (PMIC / Gate Driver)

UC3842D Current-Mode PWM Controller, up to 500kHz, 14-SOIC

MPNUC3842D
Obsolete

Texas Instruments UC3842D current-mode PWM controller, 14-SOIC package, supports boost/buck/buck-boost/flyback/forward topologies, up to 500kHz switching, 97% max duty cycle, 12V~28V supply, 0°C~70°C.

$0.9325Ref. price · indicative, final on quote
Texas Instruments UC3842D datasheet (PDF)
Packaging14-SOIC (0.209", 5.30mm Width)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

UC3842D specifications
ParameterValue
Output typeTransistor Driver
MountingSurface Mount
Voltage - supply (Vcc (Vdd))12V ~ 28V
Frequency - switchingUp to 500kHz
I/O channels1
Output phases1
Duty cycle97%
Operating temperature0°C~70°C(TA)
PackageTube
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

What this PWM controller does

The UC3842D: It drives an external transistor switch with a single output, operating from a 12V to 28V supply rail and switching at up to 500kHz. The 97% maximum duty cycle gives headroom for converters where the output voltage is significantly higher than the input, like a 5V-to-12V boost or a flyback generating an isolated rail.

Where it fits — and where it doesn't

Lifecycle reality — obsolete, not dead

The UC3842D is listed as obsolete by Texas Instruments. That means the factory no longer builds it, and no last-time-buy window remains.

Frequently asked questions

Where can I buy UC3842D?

The UC3842D is obsolete from the factory, but we source it through independent distribution channels. Submit an RFQ — we confirm availability and current pricing at quote time. No stock numbers or lead-time promises on the page; the quote is the real answer.

Is UC3842D obsolete?

Yes, Texas Instruments lists the UC3842D as obsolete. No factory production or last-time-buy window remains. Sourcing is through surplus and broker inventory.

What is the replacement for UC3842D?

There is no official TI replacement with the exact UC3842D order code. The UC3843 family is a common functional cross-shop — it offers the same current-mode PWM control with a slightly different undervoltage lockout threshold (8.4V/7.6V vs 16V/10V on the UC3842). Check your startup and UVLO requirements before substituting.

Does UC3842D have a cross reference to UC3843?

The UC3843 is a functional equivalent in the same current-mode PWM controller family, but the UVLO thresholds differ: UC3842 turns on at 16V and off at 10V; UC3843 turns on at 8.4V and off at 7.6V. The pinout is the same (14-SOIC), so it is a drop-in replacement if your design's startup voltage and hysteresis budget allow the lower thresholds.

What is UC3842D's listed function?

The UC3842D is a current-mode PWM controller supporting step-up, step-down, and step-up/step-down topologies — specifically boost, buck, buck-boost, flyback, and forward converters. It outputs a transistor driver signal from a single phase.