Typical operating characteristics – Rainbow Electronics MAX1554 User Manual
Page 4
MAX1553/MAX1554
High-Efficiency, 40V Step-Up
Converters for 2 to 10 White LEDs
4
_______________________________________________________________________________________
Typical Operating Characteristics
(MAX1553 driving six white LEDs, V
CC
= V
EN
= 3.6V, Circuit of Figure 1, T
A
= +25°C, unless otherwise noted.)
EFFICIENCY vs. LOAD CURRENT
DRIVING 6 WHITE LEDS
MAX1553/54 toc01
LOAD CURRENT (mA)
EFFICIENCY (%)
15
10
5
60
70
80
90
100
50
0
20
V
CC
= 5V
V
CC
= 4V
V
CC
= 3.6V
V
CC
= 3V
L1 = 22
µH
NO CAPACITOR ACROSS LEDs
EFFICIENCY vs. LOAD CURRENT
DRIVING 6 WHITE LEDS
MAX1553/54 toc02
LOAD CURRENT (mA)
EFFICIENCY (%)
15
10
5
60
70
80
90
100
50
0
20
V
CC
= 5V
V
CC
= 4V
V
CC
= 3.6V
V
CC
= 3V
L1 = 33
µH
4700pF ACROSS LEDs
EFFICIENCY vs. LOAD CURRENT
DRIVING 6 WHITE LEDS
MAX1553/54 toc03
LOAD CURRENT (mA)
EFFICIENCY (%)
15
10
5
60
70
80
90
100
50
0
20
V
CC
= 5V
V
CC
= 4V
V
CC
= 3.6V
V
CC
= 3V
L1 = 47
µH
4700pF ACROSS LEDs
EFFICIENCY vs. LOAD CURRENT
WITH MAX1554 DRIVING 9 WHITE LEDS
MAX1553/54 toc04
LOAD CURRENT (mA)
EFFICIENCY (%)
15
10
5
60
70
80
90
100
50
0
20
V
CC
= 5V
V
CC
= 4V
V
CC
= 3.6V
CIRCUIT OF FIGURE 3
LED CURRENT
vs. INPUT VOLTAGE
MAX1553/54 toc05
INPUT VOLTAGE (V)
LED CURRENT (mA)
5.0
4.5
4.0
3.5
3.0
14
17
20
23
26
11
2.5
5.5
L1 = 22
µH, NO CAPACITOR ACROSS LEDs
L1 = 47
µH,
4700pF ACROSS LEDs
L1 = 33
µH, 4700pF ACROSS LEDs
R1 = 10
Ω, V
BRT
= 1.25V
LED CURRENT
vs. INPUT VOLTAGE
MAX1553/54 toc06
INPUT VOLTAGE (V)
LED CURRENT (mA)
5.0
4.5
4.0
3.5
3.0
14
17
20
23
26
11
2.5
5.5
L1 = 22
µH, NO CAPACITOR ACROSS LEDs
L1 = 47
µH,
4700pF ACROSS LEDs
L1 = 33
µH, 4700pF ACROSS LEDs
R1 = 14
Ω, V
BRT
= 3.3V
LED CURRENT vs. INPUT VOLTAGE
WITH MAX1554 DRIVING 9 LEDS
MAX1553/54 toc07
INPUT VOLTAGE (V)
LED CURRENT (mA)
5.0
4.5
4.0
3.5
14
17
20
23
26
11
3.0
5.5
CIRCUIT OF FIGURE 3
LED CURRENT
vs. BRT VOLTAGE
MAX1553/54 toc08
BRT VOLTAGE (V)
LED CURRENT (mA)
3.0
2.4
1.8
1.2
0.6
5
10
15
20
25
30
35
0
0
3.6
LED CURRENT
vs. BRT DUTY CYCLE
MAX1553/54 toc09
BRT DUTY CYCLE (%)
LED CURRENT (mA)
80
60
40
20
5
10
15
20
25
30
0
0
100