UC2879DW

UC2879DW is a high-voltage, current‑mode PWM controller from TI/Unitrode, used in offline switch‑mode power supplies (SMPS) such as flyback, buck/forward topologies. It does not include a power MOSFET; an external MOSFET is required.
Key points:
- Primary-side control: drives the external switch based on current sense and error/voltage information.
- Built‑in high‑voltage startup and operating supply (charges Vcc from the input, enables startup, then runs off Vcc).
- Features: oscillator for PWM timing, current‑mode control, soft‑start, overcurrent/short‑circuit protection, undervoltage lockout, and various protections (lop-side, hiccup or latch behaviors depending on design).
- Applications: power adapters, low- to medium‑power offline supplies, LED drivers, and other offline SMPS topologies.
- Package: DW suffix indicates a specific packaging/reel option (e.g., small-outline or DIP/SOIC variant); exact pinout/parameters vary by revision—check the latest datasheet.
For precise electrical specs, pinout, and application notes, consult the UC2879DW datasheet.

Here are typical features of the UC2879DW (off-line PWM controller for SMPS):
- Off-line primary-side PWM controller for flyback/buck-boost converters
- Wide input range (AC ~85–265 V; DC ~120–370 V typical)
- High-voltage startup current source; internal Vcc regulator
- Peak-current mode control with slope compensation
- Programmable switching frequency via RT/CT (typical tens of kHz)
- Soft-start to limit inrush and inrush current
- Line sensing / feed-forward for improved regulation
- Protections: undervoltage lockout, overcurrent/short-circuit protection (often latch or hiccup), overvoltage protection, thermal shutdown
- Gate drive output for external MOSFET (drain/gate pins)
- 8-pin DW package (SOP-8 wide)
Note: exact parameters (e.g., frequency range, protection behavior) can vary by revision/variant. Refer to the TI UC2879DW datasheet for precise specifications.

UC2879DW is an 8-pin surface-mount device in an SOIC-8 package (8-pin Small Outline Integrated Circuit).

- Pin count: 8 pins (DW indicates an 8-pin small-outline/package).
- Function: UC2879DW is an 8-pin current‑mode PWM controller for switch‑mode power supplies. It provides:
- VCC supply and GND
- Feedback input (VFB) from the opto‑coupler
- Current-sense input (IS) for overcurrent protection
- Output drive (to switch the external MOSFET)
- Reference output (VREF) and timing/oscillator functionality
- Undervoltage/enable related functionality (UVLO) and typical control/compensation paths (COMP) via the error amplifier
This package is used to regulate duty cycle and maintain output voltage in SMPS designs.

- Manufacturer: Texas Instruments (TI).
- Company type: A multinational American semiconductor company that designs and manufactures analog, mixed-signal, and embedded processing ICs, including power-management devices.

UC2879DW is a high‑voltage, current‑mode PWM controller for offline switch‑mode power supplies. It is used in low‑ to medium‑power isolated SMPS. Common applications: flyback power supplies for AC‑DC adapters, set‑top boxes, TVs/monitors and computer peripherals; battery chargers; standby/auxiliary supplies; and LED driver circuits in consumer electronics.

Common cross‑refs for the UC2879DW (8‑pin, current‑mode PWM controller for flyback/off‑line supplies) are:
- TI UC3842/3843 (and UC3844/3845)
- KA3842/KA3843 (NXP/Philips)
Note: pinouts, UVLO, and startup currents vary; verify data sheets before substituting, as not all features are drop‑in compatible.