The LTC4380 from Linear Technology is an ultra-low quiescent current surge stopper, providing compact over-voltage and over-current protection for always-on 4 V to 72 V electronics in automotive, industrial and avionic systems.
It replaces traditional shunt circuits composed of bulky inductors, capacitors, transient voltage suppressors (TVS) and fuses with a simple IC and series N-channel MOSFET solution, saving board space and enabling continuous operation through transient voltage or current surges.
The device protects downstream electronics from input over-voltage up to the MOSFET rating, while also protecting the power supply from output overload. Device current consumption is a mere 8 μA in normal operation and 6 μA in shutdown mode, prolonging battery run and standby time. The low current allows a large filtering resistor to the device supply pin, enabling operation through automotive cold crank and over-voltage transients above 100 V.
During an input voltage surge, such as automotive load dump, the LTC4380 drops the excess voltage across the external MOSFET while clamping its gate and therefore the output to a safe voltage. This enables the use of lower voltage rated electronics downstream, saving costs. The clamp voltage is pin-selectable for 12 V and 24 V systems, or adjustable with an input Zener diode.
During an output overload or short circuit, the device regulates the forward path to a current limit set by a sense resistor. For sustained over-voltage or over-current conditions, a MOSFET stress-accelerated timeout ensures safe turn-off of the MOSFET. In contrast, traditional protection circuits may blow a fuse or burn out the TVS, requiring repairs.
The LTC4380 withstands a reversed input, such as an incorrectly inserted battery, to -60 V. Adjustable input under-voltage lockout threshold blocks start-up for out-of-range voltages, avoiding deeply discharged batteries. The device also controls inrush current during hot plug of a circuit board’s power supply.
The device is available in four options: the LTC4380-1 and LTC4380-2 have a pin-selectable clamp voltage, whereas the LTC4380-3 and LTC4380-4 clamp voltage is set with an input Zener diode. After a fault, the LTC4380-1 and LTC4380-3 latch the MOSFET off, while the LTC4380-2 and LTC4380-4 automatically turn on with a 0,1% duty cycle. Specified over the 0°C to 70°C commercial, -40°C to 85°C industrial and -40°C to 125°C automotive temperature ranges, the LTC4380 is offered in 10-pin MSOP and 3 x 3 mm DFN packages
For more information contact Conrad Coetzee, Arrow Altech Distribution, +27 (0)11 923 9600, [email protected], www.arrow.altech.co.za
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| Email: | [email protected] |
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