Microchip Technology SG3524BN

Overview

SG3524BN from Microsemi is a regulating pulse width modulator IC designed for switching power supplies, featuring 5 V reference trimmed to ±1%, 100 Hz–400 kHz oscillator range, dual 100 mA output transistors, undervoltage lockout, and full double-pulse suppression logic. It operates across 0 °C to 70 °C and delivers stable PWM control in DC-DC converters and offline SMPS.

For engineers reviewing the SG3524BN datasheet, SG3524BN pinout, SG3524BN application, or SG3524BN equivalent, key selection criteria include its 7–40 V input range, 60 V collector voltage rating, error amplifier common mode range (2.3 V to V_REF), current limit sense common mode range (0 V to V_IN + 2.5 V), and compatibility with pulse-by-pulse current limiting via shutdown pin.

Technical Context

The SG3524BN integrates a DC-coupled toggle flip-flop and PWM data latch to eliminate edge oscillations and triggering glitches. Its oscillator supports external synchronization and uses programmable R_T/C_T networks (R_T: 2–150 kΩ; C_T: 0.1–1 nF) to set frequency between 100 Hz and 400 kHz.

It features true digital shutdown with high-speed response, undervoltage lockout (4.2–4.9 V threshold), and dual emitter-follower outputs capable of sinking/source 100 mA each. The error amplifier provides 60–78 dB open-loop gain and 70–90 dB common-mode rejection over its operating range.

Key Specifications

Pinout & Package

SG3524BN is packaged in a 16-pin plastic dual inline package (PDIP, N package), with 0.300-inch body width and standard 0.100-inch lead pitch. Thermal resistance θ_JA is 65 °C/W under still-air conditions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UC3524N and TL494CN, SG3524BN offers tighter reference accuracy (±1%), wider current limit common-mode range, and enhanced reliability features including MIL-STD-883 qualification paths-making it suitable for mission-critical industrial and legacy aerospace power systems where long-term stability and ruggedness are prioritized over cost or feature count.

Availability

SG3524BN is available at Aetrix Electronics and suitable for AC-DC adapters, DC-DC buck converters, offline LED drivers, and industrial motor control supplies requiring stable component supply and long-lifecycle support.

Supply support for SG3524BN 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

Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog, mixed-signal, and power management ICs for aerospace, defense, and industrial markets.

The SG3524BN belongs to Microsemi's legacy regulating PWM controller product line, engineered for robust performance in harsh-environment switching power supplies where precision, stability, and long-term reliability are critical design requirements.

FAQ

What is the maximum oscillator frequency supported by SG3524BN?

The SG3524BN supports a maximum oscillator frequency of 400 kHz under recommended operating conditions. This is achieved using minimum timing resistor (2 kΩ) and capacitor (470 pF). At this frequency, sawtooth peak voltage remains stable at 3.5–3.9 V, and clock pulse width stays within 0.2–1.2 µs, enabling high-efficiency compact power designs without compromising control loop stability.

Does SG3524BN support external synchronization?

Yes, SG3524BN supports external synchronization via its OSC pin (Pin 13), which accepts TTL/CMOS-level clock inputs. When externally synchronized, the internal oscillator is disabled and the device locks to the external frequency, allowing precise phase alignment across multiple power stages-a key requirement in multi-rail or paralleled SMPS systems where ripple cancellation is critical.

What is the current limit threshold voltage for SG3524BN?

The current limit threshold voltage for SG3524BN is specified as 170–230 mV at the CL pin (Pin 12), depending on temperature and unit variation. This voltage corresponds to the differential sense voltage across an external shunt resistor. When exceeded, the device initiates immediate shutdown of both outputs, supporting reliable pulse-by-pulse current limiting in overload or short-circuit conditions.

Can SG3524BN drive MOSFET gates directly?

Yes, SG3524BN can drive MOSFET gates directly via its dual emitter-follower outputs (Pins 9 and 10), each rated for 100 mA sink/source current. With typical V_CE(sat) of 0.2–0.4 V at 10 mA and 0.4–2.0 V at 100 mA, it efficiently charges/discharge gate capacitance of medium-power MOSFETs (e.g., <1 nF total gate charge) without requiring external buffer transistors in most industrial applications.

Is SG3524BN RoHS compliant?

Yes, SG3524BN is RoHS compliant and features 100% matte tin lead finish on its PDIP (N) package. Per Microsemi's ordering information, the part meets RoHS directive requirements and is Pb-free, with solder reflow peak temperature rated at 260 °C (40 seconds max exposure), making it compatible with standard lead-free assembly processes.