SHORT _ min

1.037

ILIMx

48000

I

R

=

SHORT _ max

0.962

ILIMx

48000

I

R

=

0

750

3000

3250

1250

2000

0

20

40

120 140

180 200

R

100

80

220

2750

2500

2250

1750

1500

1000

500

250

160

60

I

SHORT_min

I

SHORT_max

500

1250

1750

2500

10

15

20

35

40

50

55

R

30

60

3250

3000

2750

2250

2000

1500

1000

750

45

25

I

SHORT_min

I

SHORT_max

TPS2540, TPS2540A

TPS2541, TPS2541A

SLVSAG2C

– OCTOBER 2010 – REVISED OCTOBER 2011

www.ti.com

APPLICATION INFORMATION

Programming the Current Limit Threshold

There

are

two

overcurrent

thresholds,

which

are

user

programmable

via

TPS2540/40A/41/41A uses an internal regulation loop to provide a regulated voltage on the ILIM0 and ILIM1

pins. The current-limit thresholds are proportional to the current sourced out of ILIM0 and ILIM1. The

internal regulation loop, although not exceeding 210 k

Ω results in a better accuracy. Many applications require

that the minimum current limit is above a certain current level or that the maximum current limit is below a certain

current level, so it is important to consider the tolerance of the overcurrent threshold when selecting a value for

reduce parasitic effects on the current-limit accuracy.

The equations and the graph below can be used to estimate the minimum and maximum variation of the current

limit threshold for a predefined resistor value. This variation is an approximation only and does not take into

account the resistor tolerance or the variation of ILIM. For exact variation of ILIM, refer to the current limit section

of the electrical specification table.

(4)

(5)

Current Limit Threshold

Current Limit Threshold

vs

vs

Current Limit Resistance

Current Limit Resistance

Figure 40.

Figure 41.

28

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Product Folder Link(s): TPS2540, TPS2540A TPS2541, TPS2541A