Programmable fuse integrates safety and reliability with MOSFET

Extending the benefits of fast-acting overload protection to applications at higher power ratings, the STEF01 is a programmable electronic fuse from STMicroelectronics.

The STEF01 is capable of sustaining up to 4A continuous current over a wide operating input voltage range of eight to 48V, with low insertion loss thanks to its integrated low-RDS (ON) VIPower MOSFET, claims STMicro.

The programmable electronic fuse extends the benefits of fast-acting overload protection to applications at higher power ratings. When connected in series to the main power rail, the STEF01 protects the load against over-current and over-voltage. The voltage is clamped to a user-defined maximum, preset with external resistors. Excessive current is restricted to the programmed safe limit by controlling the internal power MOSFET, and folds back to a lower limit if a strong over-current or short-circuit is detected.

The STEF01 is based on ST’s BCD8 high voltage process to integrate value-added features, including dV/dt control to prevent excessive inrush current during start-up or hot-swap insertion. This slows the output-voltage ramp-up time to at least three milliseconds, which can be increased by connecting an external capacitor.

Programmable under-voltage lockout (UVLO) can also be set using external components, and allows the user to fine-tune the desired voltage-rail minimum value to suit the load requirements.

There is also thermal shutdown with latching or auto-retry, and maximum dissipated-power protection. Each features prevents exceptionally high power from damaging the STEF01 when starting up into heavy capacitive loads, or during large load transients or short-circuits at high voltage. There is also a power-good indicator, and an enable/fault pin that can be used as either a status monitor or to control the device. A dedicated gate-driver output for controlling an external n-channel MOSFET simplifies implementation of reverse-current protection.

The STEF01 can protect a range of applications, including industrial hot-swap boards and control equipment, circuit breakers, power buses, security or lighting systems, telecom power modules, or distributed power systems.

The STEF01 is available now in 14-pin HTSSOP14 package.

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