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URL: http://www.princeton.com.tw
White LED Step-Up Converter
PT6937
TYPICAL APPLICATIONS
L1
22 H
VIN
3V ~ 5V
C1
1 F
VIN
D1
PTC PT6937 (3 LEDs)
C2
0.22 F
15mA
LED 1
SW LED 2
EFFICIENCY (%)
90%
80%
70%
60%
50%
2
5
10
15
20
LED CURRENT (mA )
V IN = 3V
V IN = 3.6V
OFF ON
LED 3
PT6937
/SHDN
FB
GND
R1
6.43
D1: FAIRCHILD 1N5819
L1: 3L Electronic Corp. SMTSDR322520C-220K
Li-Ion Powered Driver for Three White LEDs
PTC PT6937 (2 LEDs)
L1
22 H
VIN
3V ~ 5V
C
IN
1 F
VIN
SW
90K
PT6937
/SHDN
FB
GND
5K
R1
2.2
D1
VDC
DIMMING
C
OUT
1 F
85%
80%
75%
70%
65%
60%
55%
50%
2
5
10
15
20
LED CURRENT (mA)
EFFICIENCY (%)
VIN = 3V
VIN = 3.6V
D1: FAIRCHILD 1N5819
L1: 3L Electronic Corp. SMTSDR322520C-220K
Li-Ion to Two White LEDs
PTC PT6937 (3 LEDs)
L1
22 H
VIN
3V ~ 5V
C
IN
1 F
VIN
SW
90K
PT6937
/SHDN
FB
GND
5K
R1
4.75
D1
90%
VDC
DIMMING
C
OUT
0.22 F
EFFICIENCY (%)
80%
70%
60%
50%
2
5
10
15
20
LED CURRENT (mA)
VIN = 3V
VIN = 3.6V
D1: FAIRCHILD 1N5819
L1: 3L Electronic Corp. SMTSDR322520C-220K
Li-Ion to Three White LEDs
PT6937 V1.1
-8-
March, 2006
PTC [ PRINCETON TECHNOLOGY CORP ]
