ST1208
!
Typical Operating Characteristics
Condition: VIN = VEN1 = VEN2 = 3.6 V, CIN = C1 = C2 = COUT = 1 uf, dropout current is 60 mA. ( 20 mA / LED X 3 ), LED
forward voltage Vf = 3.3 V, ISET = 125 uA
90
EFFICIENCY ( %
EFFICIENCY ( PLEDs / PBATT ) vs.
Li + BATTERY DISCHARGE
80
70
60
50
40
4.2
4.1
4.0
3.9
3.8
3.7
3.6
3.5
3.4
Li+ BATTERY VOLTAGE,
TIME-WEIGHTED ( V )
45mA
60mA
90mA
100mA
IIN ( mA )
Under-Voltage Protection
LED CURRENT ( mA
LED CURRENT vs. SUPPLY VOLTAGE
60
50
40
30
20
10
0
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 3.2 3.3
VIN ( V )
19
18
17
16
15
14
13
12
2.1 2.3 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5
Increase
Reduce
LED1
LED2
LED3
SUPPLY VOLTAGE ( V )
ILED vs. ISET
50
ILED ( mA )
40
30
20
10
0
10
30
VIN > 3.3 V
ILED = 30 mA @ Iset = 190
VIN = 3.0 V
VIN = 2.7 V
60
90
0
12
0
15
0
18
0
21
0
24
ISET ( uA )
VIN = 2.7 V
VIN = 3.6 V
VIN = 3.0 V
VIN = 4.2 V
VIN = 3.3 V
VIN = 5.0 V
V1.1
9/12
2004/10/27
SITRONIX [ SITRONIX TECHNOLOGY CO., LTD. ]
