Datasheet

OUT
IN
GND
FAULT
ILIM
EN
Input
TPS2551
PowerPad
Output
10kW
STAT
ExternalLogic
EnableSignal
SN74HC00D
0.1 Fm
0.1 Fm
R
10k
FAULT
W
15kW
C
LOAD
R
LOAD
TWO-LEVEL CURRENT-LIMIT CIRCUIT
OUT
IN
GND
FAULT
ILIM
EN
ControlSignal
Input
TPS2550/51
FAULT Signal
PowerPad
Output
CurrentLimit
ControlSignal
0.1 Fm
R
100k
FAULT
W
R1
80.6kW
R2
20kW
C
LOAD
R
LOAD
Q1
2N7002
TPS2550
TPS2551
SLVS736B – FEBRUARY 2008 – REVISED NOVEMBER 2008 ........................................................................................................................................ www.ti.com
Figure 24. Overcurrent Latch-Off Using a Quad-NAND Gate
Some applications require different current-limit thresholds depending on external system conditions. Figure 25
shows an implementation for an externally controlled, two-level current-limit circuit. The current-limit threshold is
set by the total resistance from ILIM to GND (see previously discussed "Programming the Current-Limit
Threshold" section). A logic-level input enables/disables MOSFET Q1 and changes the current-limit threshold by
modifying the total resistance from ILIM to GND. Additional MOSFETs/resistor combinations can be used in
parallel to Q1/R2 to increase the number of additional current-limit levels.
NOTE:
ILIM should never be driven directly with an external signal.
Figure 25. Two-Level Current-Limit Circuit
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