NCP5010(2005) データシートの表示（PDF） - ON Semiconductor
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NCP5010 Datasheet PDF : 18 Pages
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NCP5010
Multiple LEDs String
Since the output voltage in limited at 22 V (nom.), one
can arrange the LEDs in 2 or more string. Figure 31 shows
VBat
2.7 to 5.5 V
C1
4.7 mF 0603
X5R 6.3 V
X5R 6.3 V
L1
22 mH
two LEDs branches where the constant current is regulated
in primary branch and the secondary branch is selected by
Q1. The number of LED in each string have to be the same.
C2
LED
LED
1 mF 0805
X5R 25 V
ENABLE
A2 CTRL VOUT C1
NCP5010
PRIMARY BRANCH
ENABLE SECONDARY BRANCH
LED
R1
24
LED
R2
L1: TDK VLF4012AT−220MR51
24
C1: TDK C1608X5R0J475MT
C2: TDK C2012X5R1E105MT
Q1
N
Figure 31. Multiple LED String Application
Matched LEDs Branches
Should one need to control precisely the current in two
LEDs branches the schematic Figure 32 can be used. An
dual NPN BC847BD is used to form a current mirror Q1
like this the current in the secondary branch I2 equal the
current in primary branch I1. Thank to this current mirror
the number of LEDs in secondary branch could be lower or
equal than primary one.
VBat
2.7 to 5.5 V
C1
4.7 mF 0603
X5R 6.3 V
X5R 6.3 V
L1
22 mH
C2
LED
LED
1 mF 0805
X5R 25 V
ENABLE
A2 CTRL VOUT C1
LED
I1
NCP5010
R1
24
LED
I2 NPN Duals
Q1
R2
24
Q1: ON SEMICONDUCTOR BC847BDW1T1
L1: TDK VLF4012AT−220MR51
C1: TDK C1608X5R0J475MT
C2: TDK C2012X5R1E105MT
Figure 32. Matched 2 Branches of LEDs
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