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Adjustable current load switch with fault flag

Posted: 16 Mar 2009     Print Version  Bookmark and Share

Keywords:power switch  hot swap  monolithic device  high side load switching 


Designers of advanced portable systems with hot swap capabilities often need programmability to maximise protection, reserve blocking to control reverse current potentials and a fault flag to indicate over-current or over-temperature conditions. Until now, they could only add three functions with a complex discrete approach.

By integrating all three features into a single monolithic device, a power switch from Advanced Analogic Technologies Inc. offers designers the highest level of protection available for hot swap in a simple, seamless solution that requires up to one-third less board space than discrete alternatives

The AAT4614 is a current-limited P-channel MOSFET power switch for high side load switching applications. Designed to protect peripheral ports from short-circuit and over-voltage events, the load switch combines reverse current blocking with programmable current limit capability and an integrated fault flag in a silicon footprint up to 30 per cent smaller than traditional implementations.

Operating across an input range of 2.4V to 5.5V, the AAT4614 can be used in both 3V and 5V systems. When the input drops below 2.4V, an under-voltage lockout circuit automatically shuts down operation to avoid saturation.

To protect the device against large input currents that could cause the supply to fall out of regulation, the load switch features an over current threshold, which is programmable up to 1.6A via a resistor from SET to ground. A fast 1µs current limit transient response reduces the requirements for local supply bypassing.

The AAT4614 adds a reverse current blocking capability to protect the device from reverse current potentials when disabled. In addition, the device features an open drain FAULT flag to indicate an over-current or over-temperature condition. A 4ms blanking time prevents false reporting during charge of a capacitive load.

The AAT4614 also features an RDS(ON) of 130mΩ typical.

To conserve power, quiescent current on the AAT4614 is only 10µA. In shutdown mode, supply current decreases to < 1µA. The switch also features an over-temperature protection circuit that automatically switches the device off if die temperature exceeds a pre-defined limit.

Qualified over a -40°C to +85°C temperature range, the AAT4614 is available in a Pb-free 8-pin SC70JW, a 6-pin SOT23 or a 5-pin SOT23 package.

- Henri Arnold
EE Times Europe

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