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SG3524N

Texas Instruments

Texas Instruments SG3524N, PWM controller IC, step-up/step-down/step-up/step-down function, buck/boost/flyback/forward/full-bridge/half-bridge/push-pull topology, 450kHz switching frequency, 45% max duty cycle, 8V-40V supply, 0°C to 70°C, 16-DIP through-hole package.

Texas Instruments SG3524N
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[IN STOCK] In Stock: 652 pcs
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MOQ 5 · Tube · RoHS · EIA-481 · DAP/DDP · T/T

[ORIGINAL SEALED] [PRE-SHIP HD PHOTOS] [30D WARRANTY · COC] [TRACKED DAP/DDP]

Technical specifications

SG3524N specifications
Parameter / AttributeSpecification / Value
Output typeTransistor Driver
MountingThrough Hole
Voltage - supply (Vcc (Vdd))8V ~ 40V
Frequency - switching450kHz
I/O channels2
Output phases1
Duty cycle45%
Operating temperature0°C ~ 70°C (TA)
PackageTube
FunctionStep-Up, Step-Down, Step-Up/Step-Down
TopologyBuck, Boost, Flyback, Forward Converter, Full-Bridge, Half-Bridge, Push-Pull
Clock syncNo
Case16-DIP (0.300\", 7.62mm)
Control featuresCurrent Limit, Frequency Control
Output configurationPositive, Isolation Capable
Synchronous rectifierNo
100% Footprint Match · Solder-Ready (No PCB Redesign Needed)

Need Stock or a Drop-in Second-Source for SG3524N?

Package: DIP-16 / SOIC-16 · Pin-compatible replacements with immediate Shenzhen spot stock

Footprint Match 98%
Supply Chain & Allocation Reality:

The SG3525A is the voltage-mode PWM controller that runs the push-pull and half-bridge stages of welder inverters, offline inverters, UPS and battery chargers: 8V to 35V operation, a trimmed 5.1V reference, 100Hz to 400kHz, and +/-400mA totem-pole outputs strong enough to drive MOSFET gates without an external driver - the exact reason welder designers chose it over the TL494 class. Its identity is a triangle of pin-pure second sources (UC3525 from Unitrode, KA3525A from the Fairchild line), and its standing trap is the SG3524, a first-generation ancestor whose name sits digits away and whose control pins do not map.

Verified Pin-Compatible Replacements (3 verified alternatives)

UC3525A TI (Unitrode lineage) DIP-16 / SOIC-16
100% Drop-in (Zero Code Change)
Availability & Target Pricing:

The Original Unitrode Second Source

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The pin-and-function-identical original: every controller pin in place, the same 5.1V reference, the same oscillator programming through RT, CT and the discharge pin, the same soft-start and shutdown behavior.

8V to 35V operation; the output stage sinks and sources the same +/-400mA class.

Compatibility & Drop-In Notes: Substitution inside the triangle is pin-pure in both directions: stock whichever lot prices best, keep one tube of each as bench spares.
Package & Solder Footprint: DIP-16 / SOIC-16 shared across the family.
Shenzhen Warehouse Stock & MOQ: Continuous multi-fab supply; quote across the triangle.
Request Volume Quote for UC3525A Compare SG3524N vs UC3525A Spec Matrix
TL494 TI (original) / onsemi / Fairchild line DIP-16 / SOIC-16
Functional Equivalent
Availability & Target Pricing:

The Rival Standard in the Same Body

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The other inverter PWM generation in a 16-pin body: two error amplifiers instead of one, 250mA-class drive, about 200kHz top oscillator - and a completely different pin assignment inside the same plastic.

Similar supply envelope; the control architecture differs - dead-time and output-control pins exist where the SG3525 puts sync and discharge.

Compatibility & Drop-In Notes: The substitution rule is the reason both get their own pages: same body, same job description, incompatible pinouts. "16-pin PWM controller" is not a part number.
Package & Solder Footprint: DIP-16 shared; pin functions are not.
Shenzhen Warehouse Stock & MOQ: Stocked; match the controller the schematic was drawn around.
Request Volume Quote for TL494 Compare SG3524N vs TL494 Spec Matrix
SG3524 TI (original) / multiple DIP-16
Functional Equivalent
Availability & Target Pricing:

The First Generation - Similar Name, Different Pins

Shenzhen Spot Stock (24-48h Dispatch)

Electrical & Core Specs:

The ancestor: same voltage-mode push-pull idea, weaker oscillator drive, untrimmed reference, and no soft-start or dedicated discharge pin - the control functions the 3525 added are exactly the ones repairs touch.

Same supply family; the differences live in the control pins, not the rails.

Compatibility & Drop-In Notes: Repair-list rule: SG3524 to SG3525 is a board modification, not a substitution. Map every control pin against the schematic before fitting the newer part into a genuine 3524 design.
Package & Solder Footprint: Both 16-pin DIP; the similar body is the whole trap.
Shenzhen Warehouse Stock & MOQ: Stocked; tell us the controller generation the board was designed around.
Request Volume Quote for SG3524 Compare SG3524N vs SG3524 Spec Matrix
Buyer & Quality Checklist for Sourcing Alternatives
  • The SG3525A / UC3525A / KA3525A triangle is pin-pure - genuine multi-fab second sourcing. The SG3524 name neighbor is not: it is the first generation with different control pins, and treating the two as one part is the classic repair-list error.
  • Soft-start (pin 8) and shutdown (pin 10) are the welder-repair functions: a shorted soft-start capacitor, or an external overcurrent comparator latching shutdown, presents as a dead controller. Check the protection chain before condemning the IC.
  • Deadtime is programmed through the discharge pin into CT: that resistor sets the minimum off-time between the two outputs. A wrong value after repair is shoot-through waiting for the first real load.
  • The trimmed 5.1V reference on pin 16 feeds the error amplifier and often the external setpoints: measure it first. A collapsed reference explains every downstream symptom in one probe.
  • The +/-400mA totem-pole outputs drive MOSFET gates directly; a board that "needs" an external gate driver after a controller swap usually got the wrong controller generation (the 250mA-class part instead).
  • Oscillator range reaches 400kHz where the TL494 class stops near 200kHz: cross-family swaps change the switching frequency and every timing constant around it - stay inside the triangle for repairs.
Frequently Asked Technical Questions

Q: Is the SG3525 pin-compatible with the SG3524?

A: No. The 3525 is the second generation with control pins the 3524 does not have in the same places - sync, oscillator output, the discharge pin for programmable deadtime, and soft-start. Repair lists that treat them as one part produce boards running with deadtime and soft-start unwired.

Q: Can a TL494 replace an SG3525?

A: No - both are 16-pin voltage-mode PWM controllers, but the pinouts and feature sets differ: the TL494 has two error amplifiers and 250mA-class drive; the SG3525 one error amplifier, a trimmed 5.1V reference and +/-400mA totem-pole outputs. The swap is a redesign, not a repair.

Q: Why does the inverter shut down immediately after a controller replacement?

A: Start at the protection chain: the shutdown pin latched by an external overcurrent comparator, a shorted soft-start capacitor on pin 8, or the 5.1V reference not coming up. The controller is usually reporting a fault, not causing it.

Technical details

The Texas Instruments SG3524N is a pulse-width modulation (PWM) control IC designed for a wide range of DC-DC converter topologies. It handles step-up, step-down, and step-up/step-down configurations, supporting buck, boost, flyback, forward converter, full-bridge, half-bridge, and push-pull designs. The part integrates the oscillator, error amplifier, reference, and dual transistor drivers on a single die, making it a self-contained controller for isolated and non-isolated supplies up to 450 kHz switching frequency. The 16-pin DIP through-hole package (16-PDIP) suits prototyping, legacy board repairs, and designs where wave-solder assembly is preferred over surface-mount. Control features include current limiting and frequency control, giving the designer basic loop compensation without external timers. The output configuration is positive and isolation-capable, so the SG3524N can drive a transformer in flyback or forward topologies with optocoupler feedback on the secondary side.

45% duty cycle — the topology gate

The maximum duty cycle per output is 45%.

450 kHz switching — magnetics sizing trade-off

The maximum oscillator frequency is 450 kHz.

The 8V to 40V supply range covers unregulated rectified AC (e.g., 12V or 24V nominal rails) and industrial bus voltages. The two transistor-driver outputs each source and sink enough current to drive a power MOSFET gate directly for low-to-medium power levels. For higher gate charge, an external driver stage is advisable.

For volume production or BOM freeze, the active status means no imminent LTB risk.

SG3524N
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