Datasheet

MAX1574
180mA, 1x/2x, White LED Charge Pump
in 3mm x 3mm TDFN
_______________________________________________________________________________________ 3
Note 1: Limits are 100% production tested at T
A
= +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: LED current matching is defined as: (I
LED
- I
AVG
) / I
AVG
Note 3: Dropout voltage is defined as the LED_-to-GND voltage at which current into LED_ drops 10% from the value at V
LED_
= 0.2V.
ELECTRICAL CHARACTERISTICS (continued)
(V
IN
= 3.6V, V
GND
= 0V, EN = IN, R
SET
= 13.7kΩ, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
(Note 1)
PARAMETER CONDITIONS MIN TYP MAX UNITS
EN = GND or 5.5V, T
A
= +25°C 0.01 1
EN Input Current
EN = GND or 5.5V, T
A
= +85°C 0.1
µA
EN Low Shutdown Delay 1.0 2 3.3 ms
EN t
LO
(Figure 1) 0.5 500 µs
EN t
HI
(Figure 1) 0.5 µs
Initial EN t
HI
(Figure 1) Only required for first EN_ pulse 50 µs
Thermal-Shutdown Threshold +160 °C
Thermal-Shutdown Hysteresis 20 °C
Typical Operating Characteristics
(Circuit of Figure 2, V
IN
= 3.6V, EN = IN, driving three white LEDs, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. INPUT VOLTAGE
MAX1574 toc01
INPUT VOLTAGE (V)
EFFICIENCY (%)
3.93.63.33.0
10
20
30
40
50
60
70
80
90
100
0
2.7 4.2
I
LED
= 2mA
I
LED
= 8mA
I
LED
= 20mA
I
LED
= 40mA
V
IN
FALLING
INPUT CURRENT vs. INPUT VOLTAGE
MAX1574 toc02
INPUT VOLTAGE (V)
INPUT CURRENT (mA)
3.93.63.33.0
50
100
150
200
250
300
0
2.7 4.2
V
IN
FALLING
I
LED
= 40mA
I
LED
= 20mA
I
LED
= 8mA
I
LED
= 2mA
INPUT RIPPLE vs. SUPPLY VOLTAGE
MAX1574 toc03
SUPPLY VOLTAGE (V)
INPUT RIPPLE (mV
P-P
)
5.04.54.03.53.0
5
10
15
20
25
0
2.5 5.5
60mA/LED
20mA/LED
8mA/LED
2mA/LED