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Fully integrated current-limited load switch simplifies hot swap management

11th March 2009

Advanced Analogic Technologies Inc., Europe

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Datasheet

While designers of advanced portable systems with hot swap capabilities often need programmability to maximize protection, reverse blocking to control reverse current potentials and a fault flag to indicate over-current or over-temperature conditions, until now they could only add all three functions with a complex discrete approach. By integrating all three features into a single monolithic device, a power switch from AnalogicTech 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 percent 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 which 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 very fast 1 micro second 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 130 milli Ohms typical.

To conserve power, quiescent current on the AAT4614 is only 10 micro A. In shutdown mode, supply current decreases to < 1 micro A. 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 to +85 degree C temperature range, the AAT4614 is available in a Pb-free 8-pin SC70JW, a 6-pin SOT23 or a 5-pin SOT23 package.