Datasheet

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SLUS495H − SEPTEMBER 2001 − REVISED AUGUST 2007
9
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FUNCTIONAL DESCRIPTION
enable function (CS+, CS−)
The two inputs of the current sense amplifier are also used for implementing an ENABLE function. During
normal operation CS− = CS+ and the internal offset added between the CS− voltage and the inverting input of
the enable comparator ensures that the UCC39002 is always enabled. By forcing the CS− pin approximately
0.5-V above the CS+ pin, the UCC39002 can be forced into a disable mode. While disabled, the UCC39002
disconnects itself from the load share bus and its adjust current is zero.
UDG−02087
1CS−
2CS+
+
ENABLE
+
0.5 V
Figure 1. Enable Comparator
fault protection
Accidentally, the load share bus might be shorted to ground or to the positive bias voltage of the UCC39002.
These events might result in erroneous output voltage adjustment. For that reason, the load share bus is
continuously monitored by a window comparator as shown in Figure 2.
UDG−02088
8CSO
7LS
+
+
FAULT
R
2R
V
DD
− 0.7 V
Figure 2. Fault Protection Comparators
The FAULT signal is handled by the start up and adjust logic which pulls the non-inverting input of the adjust
amplifier low when the FAULT signal is asserted.