STMicroelectronics SG3524P

Overview

SG3524P from STMicroelectronics is a fixed-frequency PWM controller IC for switching power supplies, featuring dual uncommitted transistor outputs, an internal 5 V ±1% reference, programmable oscillator (up to 300 kHz), error amplifier, current-limiting comparator, and pulse-steering flip-flop. It supports single-ended or push-pull topologies in DC-DC converters, inverters, and polarity converters.

For engineers reviewing the SG3524P datasheet, SG3524P pinout, SG3524P application, or SG3524P equivalent, key selection considerations include oscillator timing accuracy (±5%), temperature-stable reference (±1% over 0–70°C), output dead-time control via CT, and dual-output drive capability with 40 V collector-emitter rating.

Technical Context

The SG3524P integrates a linear ramp oscillator driven by RT/CT, feeding a high-gain comparator whose output is steered by a synchronous flip-flop to produce complementary or paralleled outputs. Its error amplifier shares a common node with current-limit and shutdown circuitry, enabling override control of duty cycle.

Reference regulation is achieved via on-chip 5 V bandgap source (±1% max temp variation), stable under 8–40 V supply and 0–20 mA load. Oscillator frequency follows f ≈ 1.18/(RT × CT), supporting 120 Hz–500 kHz range with practical RT (1.8–100 kΩ) and CT (0.001–0.1 µF) values.

Key Specifications

Pinout & Package

SG3524P is housed in a 16-pin SOIC (SO16) package with 1.27 mm pitch, 10 mm × 4 mm body, and 1.75 mm max height. Thermal resistance junction-to-ambient is 50 °C/W when soldered to alumina substrate.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UC3524N and TL494CN, SG3524P offers tighter reference stability (±1% vs ±2%) and lower quiescent current (8 mA vs 12 mA), making it optimal for cost-sensitive, commercial-temperature, single-reference switching supplies where simplicity and thermal efficiency are prioritized.

Availability

SG3524P is available at Aetrix Electronics and suitable for flyback converters, push-pull DC-DC supplies, and voltage-doubler circuits requiring stable component supply, long-lifecycle availability, and consistent electrical performance across production batches.

Supply support for SG3524P 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering silicon solutions for automotive, industrial, and power management applications.

The SG3524P belongs to ST's legacy analog power control product line, engineered specifically for fixed-frequency voltage-mode PWM regulation in isolated and non-isolated DC-DC conversion systems.

FAQ

What is the maximum allowable timing capacitor (CT) value for stable SG3524P operation?

The datasheet specifies CT between 0.001 µF and 0.1 µF for reliable oscillator function and blanking pulse control. Using CT > 0.1 µF risks insufficient ramp amplitude, leading to erratic duty cycle and potential output instability. Values near 0.1 µF require careful PCB layout to minimize stray capacitance and ensure monotonic ramp linearity.

Can SG3524P drive MOSFETs directly without external gate drivers?

SG3524P's outputs are uncommitted NPN emitters rated for 100 mA collector current and 40 V V_CEO. They can directly drive small-signal MOSFETs (e.g., < 1 nF gate charge) at ≤100 kHz, but for power MOSFETs or frequencies >200 kHz, external gate drivers are required to ensure fast turn-on/turn-off and avoid shoot-through.

How does the DIS (pin 5) shutdown function interact with current limiting?

Pin 5 (DIS) is an active-low shutdown that forces COMP low, overriding both error amplifier and current-limit signals to halt all output pulses. It operates independently of I_SENSE (pin 9); current limiting remains active during normal operation but is disabled entirely when DIS is asserted, providing fail-safe system-level disable.

Is the SG3524P compatible with synchronous rectification schemes?

No-SG3524P lacks dedicated synchronous rectifier control outputs or adaptive timing logic. Its dual outputs are fixed-phase and lack programmable delay or sensing inputs needed for MOSFET-based secondary-side rectification. For synchronous designs, consider controllers like UC384x or newer STNRG series with dedicated SR gate drive and sensing interfaces.