Managing power

Texas Instruments has announced what it claims are the industry’s first hot swap power managers featuring programmable power and current limit functions for positive 9-V to 80-V systems.

Simplifying high voltage system design, the 10-pin, 3 mm x 5 mm controllers take advantage of TI’s new 0.7-µm silicon-on-insulator analog process to ensure complete MOSFET safe operating area (SOA) protection.

The TPS2490 and TPS2491 hot swap managers are suited to support and protect emerging positive high voltage distributed power systems, such as 12-V, 24-V and 48-V server backplanes, storage area networks, medical systems, plug-in modules and wireless base stations.

‘One of the major concerns for power designers of positive high-voltage power systems is maximising voltage operation while achieving low channel resistance,’ said Rich Valley, vice president of TI’s system power management business. ‘These new hot swap devices give designers peace of mind by following the power curve and guaranteeing the FET is safe, no matter how harsh the operating conditions.’

The TPS2490 and TPS2491 devices’ programmable power limiting feature helps make certain the external FET never operates outside its SOA in applied voltage, current and time. During normal operation, the external FET works with the gate-to-source voltage maximised to provide the lowest possible channel resistance. During start-up and short-circuit events, the gate-to-source voltage is modulated to provide a defined turn-on time and to prevent damage to the external FET.

A timer function limits how long the device will be in power-limit mode. The power-limit circuitry, which monitors the drain current and drain-to-source voltage of the external FET, computes the power dissipation and controls the gate-to-source voltage to prevent the FET from dissipating power greater than the user-programmed level. When the drain-to-source voltage of the external FET is low, the circuitry operates in a current-limit mode, preventing the drain current from surpassing the user-programmed level.

The TPS2490 and TPS2491 are shipping in volume today in lead-free, 10-pin MSOP, and are priced at $1.70 per 1,000 units.

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