SG3525ADWR2G - onsemi
IC REG CTRLR PUSH-PULL 16SOIC
Full Technical Specifications
16 Parameters| Parameter / Attribute | Specification / Value |
|---|---|
| Output type | Transistor Driver |
| Mounting | Surface Mount |
| Voltage - supply (Vcc (Vdd)) | 8V ~ 35V |
| Frequency - switching | 100Hz ~ 400kHz |
| I/O channels | 2 |
| Output phases | 1 |
| Duty cycle | 49% |
| Operating temperature | 0°C ~ 70°C (TA) |
| Package | Tape & Reel (TR) Cut Tape (CT) |
| Function | Step-Up/Step-Down |
| Topology | Push-Pull |
| Clock sync | Yes |
| Case | 16-SOIC (0.295\", 7.50mm Width) |
| Control features | Enable, Frequency Control, Soft Start |
| Output configuration | Positive |
| Synchronous rectifier | Yes |
Need Stock or a Drop-in Second-Source for SG3525ADWR2G?
Package: DIP-16 / SOIC-16 · Pin-compatible replacements with immediate Shenzhen spot stock
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)
The Original Unitrode Second Source
Shenzhen Spot Stock (24-48h Dispatch)
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.
The Rival Standard in the Same Body
Shenzhen Spot Stock (24-48h Dispatch)
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.
The First Generation - Similar Name, Different Pins
Shenzhen Spot Stock (24-48h Dispatch)
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.
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.