Datasheet

OUT
IN
GND
FAULT
ILIM
EN
ControlSignal
Input
Fault Signal
PowerPad
Output
CurrentLimit
ControlSignal
0.1 Fm
R
100k
FAULT
W
C
LOAD
R
LOAD
R1
210kW
R2
22.1kW
Q1
2N7002
TPS2552, TPS2553
TPS2552-1, TPS2553-1
SLVS841E –NOVEMBER 2008– REVISED FEBRUARY 2012 www.ti.com
TWO-LEVEL CURRENT-LIMIT CIRCUIT
Some applications require different current-limit thresholds depending on external system conditions. Figure 27
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 the 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 MOSFET/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 27. Two-Level Current-Limit Circuit
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