LOAD

Implementation

Backplane

PowerBuses

Plug-InUnit

Common

Buses

Concept

Hotswap

DC/DC

Converter

Concept

Input

Voltage

Power

Bus

Implementation

DC/DC

Converter

DC/DC

Converter

TPS2412, TPS2413

www.ti.com

SLVS728C – JANUARY 2007 – REVISED NOVEMBER 2015

Feature Description (continued)

It is possible for a malfunctioning converter in an ORed topology to create a bus overvoltage if the loading is less

than the converter's capacity (for example, N = 1). The ORed topology shown cannot protect the bus from this

condition, even if the ORing MOSFET can be turned off. One common solution is to use two MOSFETs in a

back-to-back configuration to provide bidirectional blocking. The TPS2412/13 does not have a provision for

forcing the gate off when the overvoltage condition occurs, use of the TPS2410/11 is recommended.

ORed supplies are usually designed to share power by various means, although the desired operation could

implement an active and standby concept. Sharing approaches include both passive, or voltage droop, and

active methods. Not all of the output ORing devices may be ON depending on the sharing control method, bus

loading, distribution resistances, and TPS2412/13 settings.

Figure 9. N+1 Power Supply Example

8.3.4 Input ORing – Typical Connection

Figure 10 shows how redundant buses may be ORed to a common point to achieve higher reliability. It is

possible to have both MOSFETs ON at once if the bus voltages are matched, or the combination of tolerance

and regulation causes both TPS2412/13 circuits to see a forward voltage. The ORing MOSFET disconnects the

lower-voltage bus, protecting the remaining bus from potential overload by a fault.

Figure 10. Example ORing of Input Power Buses

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