Ultra-High-Efficiency White

LED Drivers

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9

Pin Description (continued)

PIN

MAX1984

MAX1985

MAX1986

NAME

FUNCTION

16

16

12

BITA

Brightness Control Input (Multimode):

DPWM Mode: DPWM control signal input.

Analog Mode: Connect to IN.

2- or 3-Bit Parallel Mode: Digital input. Most significant bit (MSB).

17

17

13

BITC

Brightness Control Input:

DPWM Mode: Connect to IN.

Analog Mode: Connect to IN.

2-Bit Parallel Mode: Connect to GND.

3-Bit Parallel Mode: Digital input (LSB).

18

18

14

IN

Input Supply. IN provides power to the internal control circuitry and MOSFET

drivers. Bypass IN to GND with a minimum 0.1µF ceramic capacitor.

19

19

15

MODE

Brightness Control Mode Selection Input. Connect MODE and BITC to IN for

DPWM control. Connect MODE, BITA, and BITC to IN for analog control. For 2-bit

parallel control, connect MODE to IN and BITC to ground. For 3-bit parallel control,

connect MODE to GND.

20

20

16

SEL

LED Selection Input. Connect SEL to IN to turn on all LEDs. Connect SEL to ground

to turn on only LED1–LED5 (MAX1984), LED1–LED4 (MAX1985), or LED1 to LED3

(MAX1984), LED3–LED6 (MAX1985), or LED4 (MAX1986).

MAX1984

D1

LD1

D2

4

LD2

1

OUT

D3

5

LD3

D4

6

LD4

D5

7

LD5

D6

9

LD6

D7

10

11

LD7

D8

12

8

20

19

17

15

16

13

14

LD8

SETI

REF

GND

LX

IN

BITA

BITB

BITC

MODE

SEL

LDG

C4

2 x 2.2

µF

LED SELECT

BRIGHTNESS

CONTROL

C3

0.22

µF

C1

2 x 2.2

µF

L1

10

µH

18

2

3

2.7V TO 5.5V

C2

0.1

µF

Figure 1. Standard Application Circuit of the MAX1984