A8513 ALLEGRO [Allegro MicroSystems], A8513 Datasheet - Page 20

• Manufacturer Part Number: A8513
• Description: Wide Input Voltage Range, High Efficiency Fault Tolerant LED Driver
• Manufacturer: ALLEGRO [Allegro MicroSystems]

A8513
STEP 7: Select the input capacitor. The input capacitor should be
selected such that it provides good filtering of the input voltage
waveform. A good rule of thumb is to set the input voltage ripple,
ΔV
input capacitor requirements are as follows:
IN
to be 1% of the minimum input voltage. The minimum
C
IN
=
=
8
8
2 MHz
f
SW
∆I
0.20 A
L
∆V
0.05 V
IN
Figure 21. A typical circuit designed using the example above in this section.
100 kΩ
4.7 μF
50 V
C
V
IN
IN
V
=
C
0.25 μF
8.66 kΩ
0.1 μF
C
R
VDD
ISET
Wide Input Voltage Range, High Efficiency
VIN
VDD
FAULT
EN/PWM
ISET
10 μH
L1
A8513
(26)
SW
GND
PAD
The rms current through the capacitor is given by:
A good ceramic input capacitor with ratings of 2.2 μF, 50V or
4.7 μF, 50 V will suffice for this application. Corresponding
capacitors include:
D1
COMP
OVP
LED
Vendor
Murata
Murata
120 pF
C
P
R
R
I
24.3 kΩ
422 kΩ
Fault Tolerant LED Driver
IN
OVP1
OVP2
rms =
4.7 μF 50 V
2.2 μF 50 V
=
Value
I
(1 – D(max))
OUT
0.120 ×
C
4.7 μF
(1 – 0.78)
VOUT
R
C
50 V
OUT
Z
Z
120 Ω
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
0.47 μF
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
×
I
IN
∆I
0.20 A
0.595 A
(max)
GRM32ER71H475KA88L
GRM31CR71H225KA88L
L
12
12
Part number
=
0.05 A
(27)
20