Datasheet
OS_min
0.98422
ILIM_XX
45,661
I (mA) = - 30
(R (kΩ) + 0.1)
OS_max
1.0143
ILIM_XX
55,639
I (mA) = + 30
(R (kΩ) + 0.1)
0
500
1000
1500
2000
2500
3000
3500
0 10 20 30 40 50 60 70 80 90 100
Current-Limit Programming Resistor (kΩ)
OUT Short Circuit Current Limit (mA)
Min I
OS
Typ I
OS
Max I
OS
Lower R
ILIM_XX
Range
G019
0
100
200
300
400
500
600
100 150 200 250 300 350 400 450 500 550 600 650 700 750
Current-Limit Programming Resistor (kΩ)
OUT Short Circuit Current Limit (mA)
Min I
OS
Typ I
OS
Max I
OS
Upper R
ILIM_XX
Range
G020
TPS2543
www.ti.com
SLVSBA6 –FEBRUARY 2012
Many applications require that the current limit meet specific tolerance limits. When designing to these tolerance
limits, both the tolerance of the TPS2543 current limit and the tolerance of the external programming resistor
must be taken into account. The following equations approximate the TPS2543 minimum / maximum current
limits to within a few mA and are appropriate for design purposes. The equations do not constitute part of TI’s
published device specifications for purposes of TI’s product warranty. These equations assume an ideal - no
variation - external programming resistor. To take resistor tolerance into account, first determine the minimum /
maximum resistor values based on its tolerance specifications and use these values in the equations. Because of
the inverse relation between the current limit and the programming resistor, use the maximum resistor value in
the I
OS_min
equation and the minimum resistor value in the I
OS_max
equation.
(2)
(3)
CURRENT LIMIT SETTING CURRENT LIMIT SETTING
vs vs
PROGRAMMING RESISTOR PROGRAMMING RESISTOR
Figure 35. Figure 36.
The traces routing the R
ILIM_XX
resistors should be a sufficiently low resistance as to not affect the current-limit
accuracy. The ground connection for the R
ILIM_XX
resistors is also very important. The resistors need to reference
back to the TPS2543 GND pin. Follow normal board layout practices to ensure that current flow from other parts
of the board does not impact the ground potential between the resistors and the TPS2543 GND pin.
FAULT Response
The FAULT open-drain output is asserted (active low) during an over-temperature or current limit condition. The
output remains asserted until the fault condition is removed. The TPS2543 is designed to eliminate false FAULT
reporting by using an internal deglitch circuit for current limit conditions without the need for external circuitry.
This ensures that FAULT is not accidentally asserted due to normal operation such as starting into a heavy
capacitive load. Over-temperature conditions are not deglitched and assert the FAULT signal immediately.
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