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Controller offers over-voltage protection of up to 80V

Posted: 04 May 2010     Print Version  Bookmark and Share

Keywords:over-voltage protector  over-current controller  portable electronics  power supply 

Linear Technology Corp. rolls out the LTC4361, a protection controller that is targeted for mobile electronics with multiple power supply options like cell phones, MP3/MP4 players, digital cameras that charge via wall and car battery adapters and USB ports. The 2.5V to 5.5V over-voltage and over-current protection controller designed to safeguard low voltage, portable electronics from damaging input voltage transients and current surges.

The LTC4361 uses a 2 per cent accurate 5.8V over-voltage threshold to detect an over-voltage event and responds quickly within 1µs (max) to isolate the downstream components from the input. Overvoltage protection of up to 80V can be achieved without the need of additional external components such as capacitors or transorbs at the input. In addition, the LTC4361 monitors voltage drop across a current sense resistor at the input of the circuit to protect against over-current faults.

The LTC4361 controls a low cost external n-channel MOSFET so that under normal operation it provides a low loss path from the input to the load. Inrush current limiting is achieved by controlling the voltage slew rate of the gate. If the voltage at the input exceeds the over-voltage threshold of 5.8V, the GATE is pulled low within 1µs to protect the load. While the IC operates from supplies between 2.5V and 5.5V, the input pins can withstand 80V transients or DC over-voltages.

The LTC4361 features a soft shutdown controlled by the ON pin and provides a gate drive output for an optional external P-channel MOSFET for reverse voltage protection. A power good output pin indicates gate turn on. Following an over-voltage condition, the LTC4361 automatically restarts with a start-up delay.

The LTC4361 is available in two options; the LTC4361-1 latches off after an over-current event, where as the LTC4361-2 performs an auto-retry following a 130ms delay.

The new LTC4360 over-voltage protection controller is recommended for applications that do not require over-current protection. While offering many of the same features as the LTC4361, the two LTC4360 versions are differentiated by pin functions. The LTC4360-1 features soft shutdown control with low shutdown current of 1.5µA, while the LTC4360-2 can drive an optional external p-channel MOSFET for negative voltage protection.

Specified over the full commercial and industrial temperature ranges, the LTC4361 is offered in 8-lead (2mm x 2mm) DFN and SOT-23 packages, and the LTC4360 is offered in a tiny 8-lead SC70 package. Evaluation boards and samples are available online.

The LTC4360 is priced at Rs.53.10 ($1.15) each and the LTC4361 is priced at Rs.64.65 ($1.40) each, respectively in 1,000-piece quantities.

- Ismini Scouras

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