OR’ing controller raises reliability of shared power systems

17th March 2009

ES Admin

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Datasheet

Diodes Incorporated has announced an active OR’ing controller chip enabling shared power system designers to replace heat-dissipating blocking diodes with high efficiency MOSFETs. As a result, in up-time critical telecom, server and mainframe applications, the ZXGD3102 will ensure cooler running, lower maintenance and higher reliability operation.

The heat dissipated by the Schottky blocking diodes traditionally used to protect a load from faulty power supplies is high, relating directly to its hefty 0.5V forward voltage drop. Replacing the diodes with low on-resistance MOSFETs, with typical forward voltages of under 100mV, means power dissipation is greatly reduced. The ZXGD3102 is therefore purpose designed to control MOSFETs in high-reliability N+1 redundant power systems.

Sinking a peak turn-off current of 5A, the controller’s gate drive is able to achieve a typical MOSFET turn-off time of 160ns, ensuring the rapid load protection that’s needed to avoid any variation in bus voltage in the event of a power supply failure and hot-swapping. To meet the fault handling requirements, turn-on time can be adjusted to enable a smooth hand over between supplies. The ZXGD3102’s input voltage blocking capability is 180V.

The chip is housed in the compact SM8 package and requires a minimal external component count. It uses a 5 to 15V low current bias rail, which is easily derived using a miniature zener diode. The ZXGD3102 active OR’ing controller is priced at $0.98USD in quantities of 1K.