Datasheet

TPS2458
Backplane
SUM3SUM12
R
SUM3
R
SUM12
PowerSource1
TPS2458
SUM3SUM12
PowerSource2
TPS2458
SUM3SUM12
PowerSource1
TPS2458
SUM3SUM12
PowerSource2
MicroTCA
TM
Redundancy
MultiswapRedundancy
Backplane
R
SUM12
R
SUM3
m C
R
SUM3
R
SUM12
m C
TPS2458
www.ti.com SLUS916B –FEBRUARY 2009–REVISED MAY 2010
Multiswap Operation in Redundant Systems
TheTPS2458 features an additional mode of operation called Multiswap redundancy. This technique does not
require a microcontroller, making it simpler and faster than the redundancy schemes described in the
MicroTCA™standard. Multiswap is especially attractive for AdvancedMC™ applications that require redundancy
but need not comply with the MicroTCA™ power module standard.
In order to implement Multiswap redundancy, connect the SUM pins of the redundant channels together and tie a
single R
SUM
resistor from this node to ground. The current limit thresholds now apply to the sum of the currents
delivered by the redundant supplies. When implementing Multiswap redundancy on 12-V channels, all of the
channels must use the same values of resistors for R
SENSE
and R
SET
.
Figure 20 compares the redundancy technique advocated by the MicroTCA™ specification with Multiswap
redundancy. MicroTCA™ redundancy independently limits the current delivered by each power source. The
current drawn by the load cannot exceed the sum of the current limits of the individual power sources. Multiswap
redundancy limits the current drawn by the load to a fixed value regardless of the number of operational power
sources. Removing or inserting power sources within a Multiswap system does not affect the current limit seen
by the load.
Figure 20. MicroTCA Redundancy vs. Multiswap Redundancy
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