UCC28C43P

UCC28C43P is a TI (Unitrode) PWM controller in the UCC28Cxx family, used in off-line flyback switch‑mode power supplies. The “P” denotes an 8‑pin package (DIP-8).
What it is:
- A primary-side, peak-current/current‑mode controller for flyback converters.
- Provides high-voltage startup current, undervoltage lockout, overcurrent protection, soft-start, and feedback/enable options.
- Drives an external N‑channel MOSFET that switches the transformer primary; it does not include the power MOSFET.
Typical usage:
- Drives low- to mid‑power offline flyback supplies (wall adapters, small SMPS).
- Feedback usually comes from an optocoupler or auxiliary winding.
Key notes:
- Requires external MOSFET, external sense resistor, and appropriate compensation network.
- Includes protections and timing features to regulate output with standard transformer design and snubber/eyeballing for stability.
- Refer to the TI datasheet for exact pinout, recommended circuits, and design guidelines.

Equivalent products: In TI/UCC family: UCC28C40, UCC28C41, UCC28C42, UCC28C44 (pin‑compatible variants). Common substitutes: UC3842/UC3843 (and UC3844/UC3845) from Intersil/TI; ON Semiconductor NCP1250, NCP1251, NCP1252, NCP1253. Note: verify HV startup, reference voltage, slope compensation, and pinout; not every variant is a drop‑in. For exact cross, consult TI cross reference.

Here are the key features of UCC28C43P:
- Fixed‑frequency, current‑mode PWM controller for offline flyback converters.
- Internal high‑voltage startup current source and bias regulator for universal input (no bias winding required).
- Undervoltage lockout with a precise internal reference.
- Pulse‑by‑pulse current limit with leading‑edge blanking and slope compensation.
- Overcurrent/short‑circuit protection with latch and auto‑restart (hiccup) behavior.
- Overvoltage protection and robust line/load fault handling.
- Thermal shutdown protection for rugged operation.
- External compensation via feedback network (optoisolator) for regulation.
- 8‑pin package (P denotes plastic DIP/SOIC variant) suitable for compact designs.
- Applications: cost‑effective off‑line flyback SMPS, adapters, chargers, and small power supplies.

Pin count: 8 pins (PDIP/SOIC).
Function: TI UCC28C43P is an off-line, fixed-frequency, current-mode PWM controller for switch‑mode power supplies (no integrated FET). It drives an external MOSFET, provides high-voltage startup, UVLO, overcurrent protection, and slope compensation, and uses opto‑coupled feedback (VFB/COMP) to regulate the output.

- Manufacturer: Texas Instruments Incorporated (TI).
- What kind of company: TI is an American multinational semiconductor company that designs and manufactures analog and embedded processing integrated circuits (ICs), including power management, op-amps, audio, and DSP/MCU products.

UCC28C43P is TI’s high‑voltage current‑mode PWM controller for off‑line isolated flyback converters. Typical applications include:
- Isolated AC‑DC adapters and chargers (5–60 W class)
- Constant‑current LED drivers using flyback topology
- Low/medium‑power standby and auxiliary supplies for consumer electronics (TVs, monitors, set‑top boxes)
- Telecom and industrial power supplies
- Battery charging circuits that use flyback regulation
Note: Designed for primary‑side regulation and flyback topologies in off‑line SMPS.

8-pin plastic DIP (PDIP) package.