Self-resetting electronic circuit breaker

In related article "Electronic circuit breaker with current detection amplifier" I introduced that breaker can be reset by turning on the power again or resetting by the LE terminal (temporarily set to low) after removing the fault. However, in the case of the master unit which supplies power to multiple slave units remotely, it may be difficult to set the reset terminal for each slave unit port or it may be convenient to automatically reset.

In such cases, it is useful to retry periodically and return automatically.  This can be achieved with the additional circuit in LT6118, but it can be more easily achieved with LT1910.

The LT1910 is an N-channel MOSFET driver with a built-in booster circuit and has a current detection circuit for short - circuit protection, so it can be applied to a circuit breaker of a power supply.  Since the power supply voltage is 8V to 48V, it cannot be used for 3.3V or 5V low power supply voltage systems. However, the built - in timer allows the automatic reset time to be programmed.

LT1910 features and functional block diagram are shown below.

• Supply voltage range : 8V to 48V
• Protected from –15V to 60V Supply Transients
• Short circuit protection
• Automatic Restart Timer
• Open Collector Fall Flag
• Fully Enhances N-channel MOSFET switch
• Programmable current limits, delay time and auto-restart period
• Voltage - limited gate drive
• Defaults to Off State with Open Input
• Available in SO-8 package

Below is an example of a circuit using LT1910 with LTspice. Current detection is performed with shunt resistor R1, and the voltage drop is limited when it reaches 50 mV. To prevent detection by spike current, delay time is given to detection at R3, C3 and C4. The restart time can be programmed by the capacitor connected to the Timer terminal. In the above circuit example, a retry is performed every 0.7 seconds, which greatly reduces heat generation when an output short circuit occurs.

It is also possible to disable automatic recovery by pulling up to about 5 V with a 2.2K Ω resistor. The fault terminal is pulled up by 5 V, but this is to check the status, so it can be used open if the status display is not required.  D1 is used to suppress the Vgs voltage for gate protection of MOSFET M1.

The IN terminal is originally a logic signal that drives the gate, but it is used for the UVLO (Under Voltage Lockout) function.