AL9910S-13 Diodes Zetex, AL9910S-13 Datasheet - Page 11

• Manufacturer Part Number: AL9910S-13
• Manufacturer: Diodes Zetex

Specifications of AL9910S-13

• Lead Free Status / Rohs Status: Compliant

Applications Information
Input Bulk Capacitor
For Offline lamps an input bulk capacitor is required to ensure that the rectified AC voltage is held above twice the LED string
voltage throughout the AC line cycle. The value can be calculated from:
Where
If the capacitor has a 15% voltage ripple then a simplified formula for the minimum value of the bulk input capacitor
approximates to:
Power Factor Correction
If power factor improvement is required then for the input power less than 25W, a simple passive power factor correction
circuit can be added to the AL9910 typical application circuit. Figure 4 shows that passive PFC circuitry (3 current steering
diodes and 2 identical capacitors) does not significantly affect the rest of the circuit. Simple passive PFC improves the line
current harmonic distortion and achieves a power factor greater than 0.85.
Each of these identical capacitors should be rated for half of the input voltage and have twice as much capacitance as the
calculated C
For further design information please see AN75 from the Diodes website.
AL9910/AL9910A/AL9910-5
Document number: DS 35103 Rev. 3 - 2
V
V
C
C
D : Capacity charge work period, generally about
f : Input frequency for full range
Δ
L
AC
AC
MIN
V
IN
ch
DC
MIN
IN
IN
≥
=
_
max
of the buck converter circuit without passive PFC (see above section on bulk capacitor calculation).
I
LED
2
×
Should be set
V
×
Line
V
V
LEDs
P
IN
_
in
2
BR1
BR1
min
×
×
1 (
×
0.06
Fig. 4 Typical Application Circuit with passive PFC
−
f 2
D
L
10~15% of
(Continued)
ch
×
Passive PFC
Passive PFC
C1
C1
Δ
)
V
DC
(85~265V
C2
C2
_
max
2
UNIVERSAL HIGH VOLTAGE HIGH BRIGHTNESS LED
V
Line
RMS
C3
C3
_
www.diodes.com
)
min
V
V
LD
LD
PWM_D
PWM_D
11 of 15
DD
DD
R
R
0.2~0.25
AL9910/AL9910A/AL9910-5
OSC
OSC
AL9910/A
AL9910/A
GND
GND
V
V
IN
IN
GATE
GATE
R
R
OSC
OSC
CS
CS
Q1
Q1
R
R
D1
D1
SENSE
SENSE
L1
L1
C4
C4
© Diodes Incorporated
LED +
LED +
LED -
LED -
June 2011
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