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White LED Step-Up Converter
PT6937
PTC PT6937 (4 LEDs)
L1
22 H
VIN
3V ~ 5V
D1
85%
EFFICIENCY (%)
C
IN
1 F
VIN
SW
90K
PT6937
/SHDN
FB
GND
5K
R1
3
VDC
DIMMING
C
OUT
0.22 F
80%
75%
70%
65%
60%
55%
50%
2
5
10
15
20
VIN = 3V
VIN = 3.6V
D1: FAIRCHILD 1N5819
L1: 3L Electronic Corp. SMTSDR322520C-220K
LED CURRENT (mA)
Li-Ion to Four White LEDs
L1
22 H
VIN
3V ~ 5V
C
IN
1 F
VIN
SW
90K
PT6937
/SHDN
FB
GND
5K
R1
3
C
OUT
0.22 F
D1
PTC PT6937 (5 LEDs)
85%
80%
EFFICIENCY (%)
VDC
DIMMING
75%
70%
65%
60%
55%
50%
2
5
10
15
LED CURRENT (mA)
VIN = 3V
VIN = 3.6V
D1: FAIRCHILD 1N5819
L1: 3L Electronic Corp. SMTSDR322520C-220K
Li-Ion to Five White LEDs
PT6937 V1.1
-9-
March, 2006
PTC [ PRINCETON TECHNOLOGY CORP ]
