SG3525

SG3525 is a classic dual PWM controller IC used in switch‑mode power supplies. It provides a 5V reference, two error amplifiers, an on‑chip oscillator, a PWM comparator, and dead‑time control. The oscillator frequency is set with external RT/CT, and its two outputs can be wired in push‑pull or single‑ended configurations to drive MOSFETs/IGBTs (often via driver transistors). Protection features include undervoltage lockout and current‑limit via a sense input. Typical applications are flyback, forward, half‑bridge and full‑bridge regulators in PC PSUs, adapters, etc. Feedback from the secondary side is fed through an optocoupler into the error amps, which modulate the PWM to regulate the output. It is powered from a DC supply (roughly 8–40 V) with a 5V reference.

Common equivalents/substitutes for SG3525:
- TL494 (TI) — 16-pin PWM controller with dual error amps
- SG3524 — older 16-pin PWM controller in the same family
- KA3524 / KA3525 — 16-pin PWM controllers in the SG352x family
- UC3842 / UC3843 (TI) — widely used current‑mode PWM controllers (not pin‑for‑pin compatible; verify circuit)
Note: pinout and features differ; confirm with the datasheet before swapping.

Here are the key features of the SG3525 PWM controller (concise):
- Dual error amplifiers with a fixed 5V reference for feedback and error sensing.
- Internal error-amplifier inputs and compensation network suitable for voltage-mode control.
- External oscillator using RT/CT to set switching frequency (adjustable over a wide range; typical tens of kHz).
- PWM comparator driving two high-current outputs; outputs can be used in push-pull or paralleled for higher drive.
- Dead-time control input to prevent shoot-through in the output stage.
- Current-sense input with protection: cycle-by-cycle current limit and latch protection for faults.
- Soft-start behavior via the error amplifier/modulation ramp.
- Wide input/supply range (suitable for various SMPS topologies, e.g., flyback/forward).
- Built-in protections: overcurrent/short-circuit protection with latch, fault indication options.
- Suitable for offline or low-voltage SMPS applications; commonly used in flyback/forward regulators.

- Pin count: 16 pins (DIP16/SO16).
- Function: SG3525 is a PWM controller for switch-mode power supplies. It provides two error amplifiers, a 5V reference, an oscillator (RT/CT) for switching frequency, a dead-time control input, a PWM comparator, and dual outputs (O1, O2) that can be configured push-pull or parallel. Feedback from the output is fed to the error amplifiers to regulate the output.

- Manufacturer: Sanyo Electric Co., Ltd. (Sanyo Semiconductor) – the SG3525 was produced by Sanyo.
- What kind of company: A Japanese multinational electronics manufacturer that produced consumer electronics and semiconductors; its semiconductor business is now part of Panasonic after Sanyo was acquired in 2009.

Common application areas of SG3525:
- PWM controller for switch‑mode power supplies
- Topologies: flyback, forward, push‑pull, half‑bridge, full‑bridge (isolated or non‑isolated)
- Applications: offline AC–DC adapters and power supplies, computer/monitor/TV SMPS, telecom and industrial power supplies
- Other: battery chargers, DC–DC converters, LED drivers, UPS/inverter front ends

SG3525 is a 16-pin PWM controller. It’s available in DIP-16 and SO-16 (SOP-16) packages. The “N” suffix typically denotes the DIP version (e.g., SG3525N).