2.2 Detailed Design Procedure

2.2.1 Reducing IQ When LEDs are OFF

In many applications, the LEDs and the LP3943 share the same VDD, as shown in Figure 7-1. When the LEDs

are off, the LED pins are at a lower potential than VDD, causing extra supply current (ΔIQ). To minimize this

current, consider keeping the LED pins at a voltage equal to or greater than VDD.

Figure 7-2. Methods to Reduce IQ When LEDs are in OFF State

2.3 Application Curve

VIN (V)

2.3

2.6

2.9

3.2

3.5

3.8

4.1

4.4

4.7

5

25

28

31

34

37

40

43

46

49

D001

VLEDX = 0.4 V

VLEDX = 0.7 V

Figure 7-3. Typical LED Switch Resistance

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LP3943

SNVS256E – NOVEMBER 2003 – REVISED OCTOBER 2024

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