Datasheet

LTC3577/LTC3577-1
15
3577fa
LED Driver Effi ciency 6 LEDs LED Driver Effi ciency 4 LEDs
TYPICAL PERFORMANCE CHARACTERISTICS
T
A
= 25°C unless otherwise specifi ed
LED PWM
vs Constant Current Effi ciency
Too Hot BAT Discharge
DAC Code vs LED Current LED Boost Start-Up Transient
LED Boost Maximum Duty Cycle
vs Temperature
I
LED
(mA)
0
EFFICIENCY (%)
90
85
80
75
70
65
60
55
50
16
3577 G40
4 8 12 20142 6 10 18
3V
3.6V
4.2V
4.8V
5.5V
I
LED
(mA)
0
EFFICIENCY (%)
90
85
80
75
70
65
60
55
50
16
3577 G41
4 8 12 20142 6 10 18
3V
3.6V
4.2V
4.8V
5.5V
DAC CODE
0
40
50
70
30 50
3577 G43
30
20
10 20
40 60 70
10
0
60
CURRENT (dB)
60dB = 20mA
0dB = 20µA
R
LED_FS
= 20k
V
BAT
(V)
3.8
0
I
BAT
(mA)
20
60
80
100
200
140
3.9
4.0
3577 G48
40
160
180
120
4.1
4.2
V
NTC
< V
TOO_HOT
V
BUS
= 0V
LED Boost Current Limit
vs Temperature
TEMPERATURE (°C)
–40
CURRENT LIMIT (mA)
600
800
1000
1200
40
3577 G42
400
200
500
700
900
1100
300
100
0
–20
0
20
60 80 100 120
I
LED
10mA/DIV
V
BOOST
20V/DIV
I
L
200mA/DIV
2ms/DIV
3577 G44
TEMPERATURE (°C)
–50
95.7
MAX DUTY CYCLE (%)
95.8
96.0
96.1
96.2
50
96.6
3577 G45
95.9
0
–25
75 100
25 125
96.3
96.4
96.5
3V
3.6V
4.2V
5.5V
LED CURRENT (A)
20
EFFICIENCY (%)
30
50
60
80
90
1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 1.E-01
3577 G46
10
70
40
0
MAX PWM CONSTANT
CURRENT
Battery Discharge
vs Temperature
TEMPERATURE (°C)
50
BATTERY DISCHARGE CURRENT (mA)
175
80
3577 G47
100
50
60 70 90
25
0
200
150
125
75
100 110 120
V
BUS
= 5V
V
BUS
= 0V
V
BAT
= 4.1V
V
NTC
< V
TOO_HOT
5x MODE
I
VOUT
= 0mA