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STMicroelectronics UC3844BN — Power Management (PMIC / Gate Driver)

UC3844BN STMicroelectronics PWM Controller – Obsolete

MPNUC3844BN
Obsolete

STMicroelectronics UC3844BN, current-mode PWM controller, 8-DIP (0.300", 7.62 mm), 48% max duty cycle, switching frequency up to 500 kHz, 0°C to 70°C operation.

$1.0200Ref. price · indicative, final on quote
STMicroelectronics UC3844BN datasheet (PDF)
Packaging8-DIP (0.300", 7.62mm)
RoHSROHS3 Compliant
Independent supplier — new & surplus stockAuthenticity-screened · ESD-safe packingListing updated Jul 2026

Specifications

UC3844BN specifications
ParameterValue
Output typeTransistor Driver
MountingThrough Hole
Voltage - supply (Vcc (Vdd))10V ~ 30V
Frequency - switchingUp to 500kHz
I/O channels1
Output phases1
Duty cycle48%
Operating temperature0°C ~ 70°C (TJ)
PackageTube
FunctionStep-Up, Step-Up/Step-Down
TopologyBoost, Flyback
Clock syncNo
Case8-DIP (0.300\", 7.62mm)
Control featuresFrequency Control
Output configurationPositive, Isolation Capable
Synchronous rectifierNo

Product details

What the UC3844BN does in a flyback supply

It drives a single external transistor with a maximum duty cycle of 48%, which sets the practical step-up ratio in a flyback converter. Switching frequency reaches up to 500 kHz, allowing the use of smaller magnetics at the cost of tighter layout and higher switching losses.

STMicroelectronics lists the UC3844BN as Obsolete. We can source and quote to order against your quantity — confirm the BOM position count and we will search available inventory across our supplier network.

Duty-cycle ceiling and flyback design fit

The 48% max duty cycle is the key parametric difference from the UC3842 family (which allows up to 96%). In a flyback, this limits the maximum output voltage for a given input and turns ratio — a designer moving from a UC3842-based design to the UC3844BN must recalculate the transformer. The UC3844BN is pin-compatible with the UC3842/3/5 series in the same 8-DIP package, but the duty-cycle clamp is hard-wired at 48% — it is not adjustable.

Package and mounting — through-hole DIP

Supplied in a Tube, the 8-DIP (0.300", 7.62 mm) package with 2.54 mm pitch is a standard through-hole footprint. No MSL concern — the DIP body is robust against reflow and hand-soldering.

Frequently asked questions

How can I order the UC3844BN or check stock?

The UC3844BN is obsolete, so stock is limited to distributor and broker inventory. Submit an RFQ with your target quantity — we will source across our network and return a quote. Pricing and availability are confirmed at quote time.

What is the difference between UC3844BN and UC3842?

The primary difference is the maximum duty cycle: UC3844BN is clamped at 48%, while the UC3842 allows up to 96%. Both are current-mode PWM controllers in the same 8-DIP footprint, but the UC3844BN is intended for applications requiring a duty-cycle limit below 50%, such as certain flyback designs.

What is the replacement for UC3844BN?

STMicroelectronics has not published an official direct replacement under the UC3844 base number. A pin-compatible alternative in the same 8-DIP package would be the UC3842 series, but note the duty-cycle difference (96% vs 48%). For a drop-in with the same 48% clamp, look for UC3844 variants from other manufacturers or consider a redesign with a newer controller.