Serial-Input, Constant-Current Latched

LED Drivers with Open LED Detection

A6279

8

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

The A6278 and A6279 allow the user to set the magnitude of

the constant current to the LEDs. Once set, the current remains

constant regardless of the LED voltage variation, the supply

voltage variation, or other circuit parameters that could otherwise

affect LED current. The output current is determined by the value

these parameters is shown in figure 1. Typical characteristics for

100

200

300

500

700

1K

2K

3K

5K

Figure 1. Output Current versus Current Control Resistance

90

80

70

60

50

40

30

20

10

0

100

200

300

500

700

1k

2k

3k

5k

Figure 2. Output Current versus Device Voltage Drop

90

80

70

60

50

40

30

20

10

0

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0