New Cool-ORing® Active ORing products provide fast fault current isolation for redundant 48 V and 12 V Applications

January 6, 2011
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As today’s businesses depend increasingly on electronic data processing, continuous availability of their servers and communications equipment is critical. Accordingly, the power architecture used to support such loads typically comprises two or more redundant power sources driving a common redundant bus. In such designs, the loads must be isolated from possibly harmful reverse currents if either of the power sources suffers a short circuit failure. Diode ORing provides the simplest solution, but it has limitations. These are overcome by Picor’s Active ORing family, which now has two new members – the P12127 and the P12007.

Although diodes are effective protection devices that will disconnect an input power source virtually instantaneously, they usually operate in forward conduction mode, where they have a relatively high forward voltage drop. This dissipates power and heat, creating a need for increased thermal management and therefore increased board space. Such requirements are no longer tolerable as onboard power levels and component densities continue to increase. By contrast, Vicor’s Active ORing solutions, comprising a MOSFET and controller, deliver the necessary performance. The MOSFET’s on-state resistance characteristic allows a forward conduction power loss typically 10 times less than a diode’s. The role of the controller is to accurately detect any fault current and turn off the MOSFET as fast as possible, before this reverse current has time to bring down or damage the system connected to the redundant bus.

The P12127 is a complete high-density, full function Active ORing solution with an integrated high-speed ORing MOSFET controller and a very low on-state resistance MOSFET. This integrated solution minimizes the system board real estate required to achieve the ideal ORing function, while minimizing overall design complexity. The 8.5 mΩ internal MOSFET provides very high efficiency and low power loss during steady state operation, while achieving very fast turn-off of the internal MOSFET, typically within 80 ns, during input power source fault conditions that cause reverse current flow. The PI2127 is packaged in an extremely small, thermally enhanced 7 mm x 8 mm land grid array System-in-Package platform, capable of delivering up to 12 Amps over a wide range of operating temperature. The PI2127 is a 60 V-rated solution with an integrated charge pump suitable for narrow-range high-side 48 V bus applications. The device provides an active low fault flag output to the system during reverse current, excessive forward over-current and UVLO fault conditions.

The PI2007 solution is a universal high-speed high-side Active ORing controller IC designed for use with N-channel MOSFETs in redundant power system architectures. The PI2007 controller is optimized for use in 12 V and 48 V high-side redundant power architectures, including systems that have a wide range input voltage of 36 V to 75 V and must operate during input voltage transients up to 100 V for 100 ms. The internal charge pump feature eliminates the need for a separate bias supply for high-side applications. The PI2007 controller enables an extremely low power loss solution with fast dynamic response to fault conditions, 80 ns reverse current turn-off delay time and 4 Amp gate peak discharge current capability to turn off the MOSFET very fast. The PI2007 controls either single or paralleled MOSFETs, allowing flexible optimization for different power levels. It provides an active low fault flag output to the system during reverse current, excessive forward over-current and UVLO fault conditions. It will also perform a FET-check upon initial system power-up to determine if the MOSFET is shorted. When paired with the PI2003 which is optimized for low side operation, a complete high-side/ low-side chip-set solution can be enabled for wide-range 48 V telecom applications.

With their 10 times power saving compared with conventional ORing diodes these Active ORing products eliminate the need for unnecessary thermal management overhead, while reducing board real estate by over 50%. Their 80 ns turn-off delay response time is significantly better than competing products which take 300 ns to recognize the failure and further 100s of ns to disconnect the failed source. This prevents very high currents, which can exceed 100 A, building up.

Samples, evaluation and demo boards are available from Vicor Sales or eCommerce facility.

For datasheet CLICK HERE

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