Datasheet

BIDIRECTIONAL BLOCKING AND PROTECTION OF C
UV
OV
V
DD
A
C
GND
GATE
Power
Bus
BY P
1kW
SST270
Control
Switchable
Input
C
(BYP)
TPS2410
TPS2411
SLVS727C – NOVEMBER 2006 – REVISED JUNE 2009 .................................................................................................................................................. www.ti.com
The TPS2410/11 may be used in applications where bidirectional blocking is desired. This may occur in
situations where two different voltages are ORed together, and operation from the lower voltage is desired.
Another important application allows isolation of a redundant unit that is generating too high an output voltage.
There are two considerations, first is the selection of the V
DD
source, and second is protection of the C pin from
excessive current. Figure 18 provides an example of this type of application.
V
DD
needs to have voltage applied when A is to be connected to the load. Connecting V
DD
to C only works when
voltage on C is always present before A is connected. V
DD
may be connected to A, a separate supply, or have
voltage from A ORed with voltage from C. OV may be used to force GATE low, even when V
(A)
is greater than
V
(C)
, by driving OV to a voltage between 0.6 V and less than 5.25 V.
The C pin must be protected from excessive current if V
(A)
can exceed V
(C)
by more than 5.5 V. With a single
MOSFET, V
(C)
will never be more than a diode drop lower than V
(A)
. When V
(AC)
is greater than a diode drop, a
small current flows out of the C pin into the load. If V
(AC)
exceeds 5.5 V, a current limiting circuit should be used
to protect C. Figure 18 provides an example circuit. Inserting this protection circuit creates a small offset in the
forward regulation and threshold voltage.
Figure 18. Bidirectional Blocking Example
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