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Texas Instruments UC3842D8 — Power Management (PMIC / Gate Driver)

UC3842D8 Current-Mode PWM Controller, up to 500 kHz, 8-SOIC

MPNUC3842D8
Active

Texas Instruments UC3842D8 current-mode PWM controller, 8-SOIC (0.154", 3.90mm Width), Tube, 12V~28V supply, up to 500 kHz switching, 97% max duty cycle, 0°C~70°C.

$0.9325Ref. price · indicative, final on quote
Texas Instruments UC3842D8 datasheet (PDF)
Packaging8-SOIC (0.154", 3.90mm Width)
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Aug 2026

Specifications

UC3842D8 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
Case8-SOIC (0.154\", 3.90mm Width)
Control featuresFrequency Control
Output configurationPositive, Isolation Capable
Synchronous rectifierNo

Product details

Current-mode PWM controller in an 8-SOIC — what you get

It handles step-up, step-down, and step-up/step-down topologies including boost, buck, buck-boost, flyback, and forward converters. The single transistor-driver output delivers a 97% maximum duty cycle, switching at up to 500 kHz. Supply range is 12 V to 28 V, and it includes frequency control on the pinout.

The 97% maximum duty cycle is the standout parameter for flyback and buck converters where you need to squeeze every volt out of a low input-to-output differential. At near-100% on-time the controller keeps the switch on almost the whole cycle, which reduces the transformer turns ratio needed. The 500 kHz switching ceiling lets you shrink the magnetics and output capacitors compared to a 100 kHz controller, but the trade-off is tighter layout — the 8-SOIC package has limited copper area for heat sinking, and at high switching frequencies the gate-drive losses add up. Keep the feedback loop compensation stable across the full duty range; current-mode control gives good line transient response but needs a slope-compensation ramp above 50% duty to avoid subharmonic oscillation.

For volume or reel requirements, confirm the reel-pack variant (typically UC3842D8TR) separately.

Frequently asked questions

Is UC3842D8 equivalent to UC3842N?

The UC3842N is the same controller in a PDIP-8 through-hole package, while the UC3842D8 is the 8-SOIC surface-mount variant. Functionally identical — same current-mode PWM control, same 97% duty cycle, same 500 kHz switching ceiling. The choice is purely package-dependent: the SOIC version takes less board space and suits automated assembly; the PDIP is easier to hand-prototype and rework.

What is the maximum duty cycle of UC3842D8?

The maximum duty cycle is 97%. That near-100% on-time allows the controller to operate with very low input-to-output headroom in flyback and buck converters, but above 50% duty you need slope compensation to prevent subharmonic oscillation — standard practice with current-mode control.

What is UC3842D8 used for?

It is a current-mode PWM controller for switch-mode power supplies. Typical applications include AC-DC adapters, battery chargers, off-line flyback supplies, and DC-DC converters in commercial-grade equipment where the ambient temperature stays within 0°C to 70°C. The 500 kHz switching frequency suits compact magnetics designs.