MAX1984/MAX1985/MAX1986
Ultra-High-Efficiency White
LED Drivers
8 _______________________________________________________________________________________
Pin Description
PIN
MAX1984 MAX1985 MAX1986
NAME FUNCTION
1 1 1 OUT Step-Up Regulator Output. Bypass OUT to GND with a 4.7µF capacitor.
222LX
Inductor Connection. LX is connected to the drains of the internal N-channel and
P-channel MOSFETs.
3 3 3 GND Ground
—
4, 12
—
N.C. No Connection. Not internally connected.
454LD1
LED1 Cathode Connection. LD1 is the open-drain output of an internal current
regulator for controlling the current through LED1. It is able to sink up to 25mA.
If not used, connect LD1 to GND.
565LD2
LED2 Cathode Connection. LD2 is the open-drain output of an internal current
regulator for controlling the current through LED2. It is able to sink up to 25mA.
If not used, connect LD2 to GND.
677LD3
LED3 Cathode Connection. LD3 is the open-drain output of an internal current
regulator for controlling the current through LED3. It is able to sink up to 25mA.
If not used, connect LD5 to GND.
798LD4
LED4 Cathode Connection. LD4 is the open-drain output of an internal current
regulator for controlling the current through LED4. It is able to sink up to 25mA.
If not used, connect LD4 to GND.
886LDG
Common Ground Connection for Internal Current Regulators. Connect LDG to
GND.
910— LD5
LED5 Cathode Connection. LD5 is the open-drain output of an internal current
regulator for controlling the current through LED5. It is able to sink up to 25mA.
If not used, connect LD5 to GND.
10 11 — LD6
LED6 Cathode Connection. LD6 is the open-drain output of an internal current
regulator for controlling the current through LED6. It is able to sink up to 25mA.
If not used, connect LD6 to GND.
11 ——LD7
LED7 Cathode Connection. LD7 is the open-drain output of an internal current
regulator for controlling the current through LED7. It is able to sink up to 25mA.
If not used, connect LD7 to GND.
12 ——LD8
LED8 Cathode Connection. LD8 is the open-drain output of an internal current
regulator for controlling the current through LED8. It is able to sink up to 25mA.
If not used, connect LD8 to GND.
13 13 9 SETI
Maximum LED Current Set Input. SETI sets the maximum current through each
LED. Connect SETI to IN for a default maximum current of 18mA; connect SETI to
GND for the 0.5mA LED test mode. Connect a resistor from SETI to GND to adjust
the maximum current between 12mA to 25mA (see the Setting the Maximum LED
Current section).
14 14 10 REF
1.25V Reference Output. Bypass REF to GND with a minimum 0.22µF ceramic
capacitor.
15 15 11 BITB
Brightness Control Input (Multimode):
DPWM Mode: Leave unconnected for greater than 50kHz operation. Add a
capacitor from BITB to ground for lower frequency operation.
Analog Mode: Analog control signal input.
2- or 3-Bit Parallel Mode: Digital input. Least significant bit (LSB) for 2-bit mode.
