Bidirectional electronic circuit breaker provides comprehensive protection against faults
Linear Technology Corporation introduces the LTC4368, a circuit protection controller ensuring safe voltage and current levels for 2.5V to 60V electronics in battery-powered automotive, industrial and portable systems. The device replaces fuses, transient voltage suppressors and discrete circuitry, enabling a compact and comprehensive solution for shielding electronics from damaging overcurrent and over-, under- and reverse-voltage conditions. It controls back-to-back N-channel MOSFETs to provide a low loss current path during normal operation, turning them off for overcurrent faults in the forward or reverse direction. The LTC4368-1 circuit breaker provides symmetric forward and reverse current thresholds to protect batteries from excessive charge and discharge currents. The LTC4368-2 circuit breaker trips off when reverse current is detected to prevent backfeeding and hold up the output.
The device quickly disconnects the load from input voltages exceeding an adjustable and precise overvoltage threshold. Adjustable undervoltage lockout disables operation for low input voltages, avoiding deeply discharged batteries. Reverse supply protection isolates the load from batteries inserted with incorrect polarity, eliminating a diode in the power path. The eliminated diode drop and the 2.5V operation provide sufficient margin for riding through automotive cold crank conditions. Device current consumption is just 80µA in normal operation and 5µA in shutdown mode, prolonging battery run and standby time. It also controls inrush current while hot plugging a circuit board’s power supply.
The circuit breaker is available in two options: the LTC4368-1 provides a 50mV reverse circuit breaker sense threshold, whereas the LTC4368-2 has a 3mV reverse threshold. After an overcurrent fault, a pin configuration determines if the MOSFETs are latched off or turned on after a delay. Specified over the 0C to 70C commercial, -40C to 85C industrial, and -40C to 125C automotive temperature ranges, the device is offered in 10-pin MSOP and 3mm x 3mm DFN packages.