Schematic for the NCP1028LED Evaluation Board
R1
4R7 2W
AC
input
D1, 2, 3, 4
1N4007 x 4
L1, 1 mH
C1
4.7 or
10 nF
"x"
C2
10uF,
400Vdc
x2
1
7,8
C4
1.5 nF
1 kV
C3
+
T1
D6
MBR160
R2
47K,
1W
E1
C5A C5B
1
2
R3B
Iout
0.5 W
470uF
25V
D5
MUR160
C6
10 nF
3
R11
10K
5,6
D8
C11
0.1uF
4
5
+
Output
_
6
4
3
_ E2
1N4148A
R8
3M, 0.5W
J1
R3A
Q1
PN2907
2
R10
100
C9 ("Y" cap)
D7
Vmax
2.2 nF
NCP1028
5
3
R7
18K
R9
(see
note 10)
R4
U1
2
4
7
1
4
C10
1nF
R6
1M
8
+ C8
10uF
25V
U2
1
R5
200
C7
100pF
100
3
opto
2
NOTES:
1. L1 is Coilcraft part RFB0807-102 (1 mH @ 250 mA) for EMI compliance.
2. U2 is 4 pin optocoupler with CTR of 50% minimum(Vishay)
3. See Magnetics Data Sheet for T1 construction details (EF-16 core & horizontal bobbin.)
4. U1 is NCP1028 (15W max).
5. D7 zener sets Vout max: Vout = Vz + 0.85V (should not exceed 25V).
6. R3A, R3B set max current: Imax = 0.65/(Rtotal), use both resistors for I>0.5A
7. Fuse resistor recommended for R1.
8. Crossed schematic lines are not connected.
9.R7, R8, C10 provide brownout protection
10. D8, C11, R9 and xfmr winding (2-3) necessary for NCP1028. For specified xfmr
,R9 = 1.5K.
11. C5B optional depending on output ripple requirements.
12. J1 is Tyco # 535676-5 connector for demo board applications.
2/15/2008
-1-
NCP1028LED Constant Current
LED Driver (Universal Input)
Final Rev2
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