Chip
SG3525
chip de control PWM usadas en módulos de control de soldadoras inverter, arranque suave, compensación y diagnóstico sin PWM.
soldadora-specific role
SG3525 appears in many ZX7-style y older módulos de control de soldadoras inverter. It normally generates push-pull PWM para a driver transformador etapa, while external amplifiers y comparadors handle current regulation, thermal protección, overcurrent y shutdown.
Application flow
Corriente setting pot
↓
Corriente realimentación amplifier
↓
SG3525 error amp / compensación
↓
Oscillator y soft start
↓
PWM salidas
↓
Driver transistor pair
↓
compuerta-drive transformador
↓
MOSFET / IGBT etapa de potencia
Measurement table
| Comprobación | Normal / valor esperado | Significado si es anormal |
|---|---|---|
| VCC | Stable supply | Auxiliary supply o falla de conector |
| Referencia voltage | Stable | IC o load problem |
| arranque suave pin | Ramps up | arranque suave clamp o capacitor falla |
| pin shutdown | Inactive | Protection path active |
| salida pins | Complementary PWM | SG3525 disabled o damaged |
| Driver transistor salidas | Drive forma de onda | Z24/9Z24/S8050/S8550 etapa falla |
Common fallas
- SG3525 has potencia but sin salida because shutdown is active.
- arranque suave capacitor o clamp path prevents arranque.
- CA3140/LM324 realimentación de corriente pulls the control loop abnormal.
- salida pins are normal but driver transistors o transformador entrada are abnormal.
Caso de reparación pattern
Many SG3525 casos are not solved by replacing the SG3525. The failure may be in the realimentación amplifier, arranque suave path, driver transistor pair o protección entrada.