Microchip Technology SG3524D

Overview

SG3524D from Microchip Technology is a monolithic PWM controller IC designed for regulating power supply inverters and switching regulators. It integrates voltage reference, error amplifier, oscillator, pulse width modulator, pulse steering flip-flop, dual 50 mA output transistors, and current-limiting/shutdown circuitry in a 16-pin SOIC package. It supports single-ended or push-pull topologies for DC-DC converters, voltage doublers, and polarity converters operating from 0 °C to +70 °C ambient.

For engineers reviewing the SG3524D datasheet, SG3524D pinout, SG3524D application, or SG3524D equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternatives with functional distinctions, and supply support for industrial power design programs requiring stable component sourcing.

Technical Context

The SG3524D implements a fixed-frequency PWM architecture with an internal oscillator (100 Hz–300 kHz) driven by external RT/CT components, generating a linear sawtooth waveform for precise duty-cycle control. Its dual alternating outputs are steered by a flip-flop, enabling push-pull operation at half the oscillator frequency or parallel single-ended operation up to 90% duty cycle.

It features a 5 V ±2% reference with 0.4% line/load regulation, a high-gain error amplifier (60 dB open-loop gain), and a dedicated current-limit amplifier with 200 mV threshold and ±0.3 V common-mode range. Shutdown is triggered by a 0.5–1.2 V logic-level input, and output transistors deliver 50 mA each with <2 V saturation voltage.

Key Specifications

Pinout & Package

SG3524D uses a 16-pin narrow-body plastic SOIC (D-package) with standard 1.27 mm pitch, 10.0 mm × 6.0 mm footprint, and 1.52 mm max height - compatible with automated SMT assembly and IPC-7351B land patterns.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PWM controller applications.

Compared with UC3524N and TL494CN, the SG3524D offers guaranteed commercial-temperature operation with integrated reference and simpler oscillator setup, making it optimal for cost-sensitive, single-rail 0–70 °C power supplies where layout reuse and BOM minimization are critical.

Availability

SG3524D is available at Aetrix Electronics and suitable for AC-DC adapters, industrial DC-DC converters, battery chargers, and voltage doubler circuits requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for SG3524D includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology is a global semiconductor company specializing in microcontrollers, analog devices, and power management ICs, with ISO 9001-certified manufacturing and broad industrial qualification.

The SG3524D belongs to Microchip's legacy PWM controller product line, designed specifically for discrete transistor-based switching power supplies in commercial and industrial applications where reliability, simplicity, and proven topology support are essential.

FAQ

What is the maximum switching frequency supported by the SG3524D?

The SG3524D supports an oscillator frequency range of 100 Hz to 300 kHz, as specified in its Recommended Operating Conditions. At the upper limit, the device maintains stable PWM operation with typical initial oscillator accuracy of ±4 kHz at 40 kHz and ±10 kHz across the full 300 kHz range. The SG3524D datasheet confirms this maximum under all guaranteed conditions for the D-package commercial variant.

Does the SG3524D include an internal voltage reference?

Yes, the SG3524D integrates a precision 5 V bandgap reference with ±0.4 V tolerance over temperature and load, delivering up to 20 mA. This reference appears on Pin 2 (VREF) and serves as the error amplifier non-inverting input reference (Pin 12) and bias source for external circuitry - eliminating the need for an external reference IC in most designs.

Can the SG3524D drive MOSFETs directly without external buffers?

The SG3524D provides dual 50 mA open-collector NPN output transistors (Pins 7 and 13), capable of directly driving the gate of low-to-mid Qg MOSFETs (e.g., ≤5 nC) at ≤100 kHz. For higher gate charge or faster switching, external buffer transistors or gate drivers are recommended to ensure adequate dV/dt and minimize shoot-through risk.

What is the purpose of the SYNC pin (Pin 15) on the SG3524D?

The SYNC pin (Pin 15) accepts external TTL/CMOS clock pulses to synchronize the internal oscillator. When driven with a logic-high ≥2.4 V and logic-low ≤0.3 V, the SG3524D locks its frequency to the external source - useful for noise reduction in multi-converter systems or line-frequency coordination in AC-input doublers. The internal oscillator must be set to run at ~90% of the sync frequency for reliable locking.

How does the current limit function work on the SG3524D?

The SG3524D implements current limiting via Pins 4 (CL+) and 5 (CL–), which form a differential input to an internal amplifier with a 200 mV threshold. It requires a sense resistor placed in the ground or return path, with common-mode voltage constrained to ±0.3 V around ground. The amplifier's 300 Hz bandwidth provides moderate-speed protection against overload while avoiding false triggering from transient spikes.