MAX1984/MAX1985/MAX1986
Ultra-High-Efficiency White
LED Drivers
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1; V
IN
= 3.3V, SETI = BITA = BITB = BITC = SEL = IN, MODE = GND, C
OUT
= 4.7µF, C
REF
= 0.22µF, T
A
= -40°C to
+85°C, unless otherwise noted.) (Note 3)
PARAMETER CONDITIONS MIN TYP MAX UNITS
IN Supply Range 2.7 5.5 V
IN Undervoltage Lockout Threshold 50mV typical hysteresis 2.2 2.6 V
IN Quiescent Current BITA = BITB = BITC = IN, LD1 to LD8 = GND 600 µA
REF Output Voltage I
REF
= 0 1.230 1.270 V
REF Line Regulation 2.7V < V
IN
< 5.5V 5 mV
REF Load Regulation -1µA < I
REF
< +50µA 15 mV
Oscillator Frequency 0.8 1.2 MHz
OUT Overvoltage Protection
Threshold
V
LD1
to V
LD8
= 50mV, OUT rising, 100mV typical
hysteresis
5.1 5.5 V
INTERNAL MOSFET SWITCHES
N-Channel MOSFET On-Resistance I
LX
= 200mA 0.8 Ω
P-Channel MOSFET On-Resistance I
LX
= 200mA 1.0 Ω
MAX1984 0.50 0.81
MAX1985 0.40 0.65
N-Channel MOSFET Current Limit
MAX1986 0.30 0.52
A
CONTROL INPUTS
BITA, BITB, BITC Input Logic Low
Level
2.7V < V
IN
< 5.5V 0.4 V
BITA, BITB, BITC Input Logic High
Level
2.7V < V
IN
< 5.5V 1.6 V
MODE Input Logic Low Level 2.7V < V
IN
< 5.5V 0.4 V
MODE Input Logic High Level 2.7V < V
IN
< 5.5V V
IN
- 0.4 V
SEL Input Logic Low Level 2.7V < V
IN
< 5.5V 0.4 V
SEL Input Logic Midlevel 2.7V < V
IN
< 5.5V 0.50 1.85 V
SEL Input Logic High Level 2.7V < V
IN
< 5.5V 2.05 V
FULL-SCALE LED CURRENT ADJUSTMENT
V
LD
_ = 80mV, SETI = BITA = BITB = BITC = IN 16 20
V
LD
_ = 80mV, R
SETI
= 278kΩ ±1%, BITA = BITB =
BITC = IN
22 28
V
LD
_ = 80mV, R
SETI
= 1.8MΩ ±1%, BITA = BITB =
BITC = IN
11.5 16.0
V
LD_
= 80mV, R
SETI
= 697kΩ ±1%, BITA = BITB =
BITC = IN
15.5 20.0
LD1 to LD8 Output Current
SETI = GND 0.42 0.60
mA
