Datasheet

N+1 POWER SUPPLY – TYPICAL CONNECTION
CommonBus
Concept
V
DD
A
C
GND
GATE
Power Conversion Block
Input
Voltage
Power
Bus
Implementation
C
(BYP)
BYP
DC/DC
Converter
DC/DC
Converter
TPS2410
TPS2411
SLVS727C – NOVEMBER 2006 – REVISED JUNE 2009 .................................................................................................................................................. www.ti.com
The N+1 power supply configuration shown in Figure 12 is used where multiple power supplies are paralleled for
either higher capacity, redundancy or both. If it takes N supplies to power the load, adding an extra, identical unit
in parallel permits the load to continue operation in the event that any one of the N supplies fails. The supplies
are ORed together, rather than directly connected to the bus, to isolate the converter output from the bus when it
is plugged-in or fails short. The TPS2410/11 with an external MOSFET emulates the function of the ORing diode.
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 (e.g. 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. See the section on BIDIRECTIONAL BLOCKING AND
PROTECTION OF C.
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 active depending on the sharing control method, bus
loading, distribution resistences, and TPS2410/11 settings.
Figure 12. N+1 Power Supply Example
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