Chip
UC3846
chip PWM en modo corriente usadas en soldadoras inverter placas de control, realimentación de corriente pico, compensación de pendiente y diagnóstico de shutdown.
soldadora-specific role
UC3846 is widely usadas en current-mode placas de soldadoras inverter de control. In these máquinas it is not just a generic PWM chip: it sits between the current command, realimentación de corriente, peak-current sampling, shutdown chain y driver etapa.
Application flow in a soldadora
Corriente setting / commy
↓
Corriente realimentación y compensación de pendiente
↓
UC3846 PWM comparador
↓
shutdown / protección compuerta
↓
PWM salidas
↓
Driver transformador o opto driver
↓
IGBT / MOSFET driver de compuerta
Key diagnóstico points
| Comprobación | Normal / valor esperado | Significado si es anormal |
|---|---|---|
| VCC | Stable operating voltage | Auxiliary supply falla if missing |
| Referencia | Stable reference | IC o loading falla |
| Peak-current entrada | Low/normal during idle | False overcurrent if high |
| shutdown entrada | Inactive during normal operation | Protection path blocking salida |
| salida pins | PWM forma de onda | No drive if missing |
Common sin salida causes
- pin shutdown is active because an optocoupler o transistor path is pulling it.
- Peak-realimentación de corriente pin sees abnormal voltage due to sampling resistencia o CT circuit falla.
- The chip has supply but no reference due to IC damage o excessive load.
- Salidas are present but driver transformador o compuerta etapa is open.
Caso de reparación pattern
A typical UC3846 caso de reparación registros fuente auxiliar as normal, PWM salida as missing, a shutdown/realimentación node as abnormal, y a small transistor, optocoupler o sensado de corriente part as the actual cause.