High voltage surge stoppers ensure reliable operation during power surges: Page 4 of 5

March 28, 2012 //By Alison Steer, Linear Technology Corp.
High voltage surge stoppers ensure reliable operation during power surges
In automotive, industrial and avionic applications, high voltage power supply spikes with durations ranging from a few microseconds to hundreds of milliseconds are commonly encountered. The electronics within these systems must not only survive transient voltage spikes, but in many cases also operate reliably throughout the event. Recent surge stopper designs help to maintain these devices in the safe zone.
  • provide advance warning of impending power-off due to an overvoltage or overcurrent fault condition.

Overcurrent Protection

  • The LT4363 features an adjustable current limit that protects against short circuits or excessive load current. Voltage drop is monitored across an external current sense resistor on the output to protect against overcurrent faults. During an overcurrent event, the GATE pin is regulated to limit the current through this resistor. Charging of the TIMER pin is accelerated with increasing voltage across the MOSFET. This turns the MOSFET off faster, since more power is dissipated during this condition.

Inrush Current Limiting

  • Eliminates current spikes propagating through the MOSFET to the output during power-up by controlling the GATE pin slew rate.

Reverse Input Protection to -60V          

  • The LT4363 is designed to withstand reverse voltage of up to -60V without damage to itself or the load (using back-to-back FET). This eliminates the need for a blocking diode which causes extra power loss, generates heat, and reduces the available supply voltage range. During cold crank, the extra voltage drop is particularly undesirable.

Low Shutdown Current (<20uA)

  • Prevents automobile battery from discharging when parked for long periods. Offers additional power savings for improved battery life in portable applications.

Strong Gate Sink Current

  • Strong current pull-down (>150mA) on the GATE during a fault ensures fast response time.

 -40oC to +125oC Operating Range

  • High Temperature rating allows operation in automotive and industrial applications. Contact Linear Technology for details on -55oC military plastic versions.

Target Markets:

Linear Technology's surge stopper products have wide appeal for the industrial, avionics and automotive markets due to their ability to provide solid high voltage front-end protection in a very small solution size.

LTC4366 applications include fuel cells, industrial and military systems, and high voltage DC distribution in servers.

LT4363 applications include all consumer, automotive, industrial, avionics, communications, and military applications that operate from a battery or a badly behaving supply.

Table 1: Linear Technology's High Voltage

Design category: 

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