lp5526tlx National Semiconductor Corporation, lp5526tlx Datasheet - Page 26

• Manufacturer Part Number: lp5526tlx
• Description: Lighting Management Unit With High Voltage Boost Converter With Up To 150ma Serial Flash Led Driver
• Manufacturer: National Semiconductor Corporation

www.national.com
Recommended External Components
OUTPUT CAPACITOR, C
The output capacitor C
the output ripple voltage. In general, the higher the value of
C
ramic capacitors with low ESR are the best choice. At the
lighter loads, the low ESR ceramics offer a much lower V
ripple that the higher ESR tantalums of the same value. At
the higher loads, the ceramics offer a slightly lower V
ripple magnitude than the tantalums of the same value.
However, the dv/dt of the V
much lower that the tantalums under all load conditions.
Capacitor voltage rating must be sufficient, 25V or greater is
recommended. Examples of suitable capacitors are: TDK
C3216X5R1E475K,
ECJMFB1E475K and ECJ4YB1E475K.
Some ceramic capacitors, especially those in small
packages, exhibit a strong capacitance reduction with
the increased applied voltage (DC bias effect). The ca-
pacitance value can fall below half of the nominal ca-
pacitance. Too low output capacitance can make the
boost converter unstable. Output capacitors DC bias
effect should be better than –50% at 20V.
INPUT CAPACITOR, C
The input capacitor C
input ripple voltage and to a lesser degree the V
higher value C
age rating must be sufficient, 10V or greater is recom-
mended.
OUTPUT DIODE, D
A schottky diode should be used for the output diode. Peak
repetitive current should be greater than inductor peak cur-
LIST OF RECOMMENDED EXTERNAL COMPONENTS
Symbol
Note: See Application Note AN-1442 "Design and Programming Examples for Lighting Management Unit LP5526" for more
information on how to design with LP5526
C
C
C
C
C
R
LEDs
OUT
C
R
VDDIO
R
C
VDDA
VREF
D
VDD
OUT
L
RGB
SW
SW
RT
IN
1
1
, the lower the output ripple magnitude. Multilayer ce-
Symbol explanation
C between VDD1,2 and GND
C between VDDIO and GND
C between VDDA and GND
C between FB and GND
Maximum DC bias effect
C between battery voltage and GND
L between SW and V
Saturation current
C between V
R between I
R between I
Rectifying diode (Vf
Reverse voltage
Repetitive peak current
C in EMI filter
R in EMI filter
IN
will give a lower V
1
IN
OUT
IN
directly affects the magnitude of the
RGB
RT
Panasonic
OUT
REF
directly affects the magnitude of
OUT
and GND
and GND
and GND
ripple with the ceramics is
@
BAT
IN
maxload)
ripple. Capacitor volt-
@
20V
ECJ3YB1E475K,
OUT
ripple. A
2 x 4.7 or 1 x 10
OUT
OUT
0.3-0.5
Value
1300
1500
100
100
100
100
390
-50
26
2.4
10
10
82
30
1
rent (1500mA) to ensure reliable operation. Schottky diodes
with a low forward drop and fast switching speeds are ideal
for increasing efficiency in portable applications. Choose a
reverse breakdown voltage of the schottky diode signifi-
cantly larger ( ~ 30V) than the output voltage. Do not use
ordinary rectifier diodes, since slow switching speeds and
long recovery times cause the efficiency and the load regu-
lation to suffer. Examples of suitable diodes are: Central
Semiconductor CMMSH1-40, Infineon BAS52-02V.
EMI FILTER COMPONENTS C
EMI filter (R
suppress EMI caused by fast switching. These components
should be as near as possible to the SW pin to ensure
reliable operation. 50V or greater voltage rating is recom-
mended for capacitor.
INDUCTOR, L
A 10uH shielded inductor is suggested for LP5526 boost
converter. The inductor should have a saturation current
rating higher than the rms current it will experience during
circuit operation (1300mA). Less than 300mΩ ESR is sug-
gested for high efficiency and sufficient output current. Open
core inductors cause flux linkage with circuit components
and interfere with the normal operation of the circuit. This
should be avoided. For high efficiency, choose an inductor
with a high frequency core material such as ferrite to reduce
the core losses. To minimize radiated noise, use a toroid, pot
core or shielded core inductor. The inductor should be con-
nected to the SW pin as close to the IC as possible. Ex-
amples of suitable inductors are: TDK SLF6028T-100M1R3,
Coilcraft MSS6122-103MLB.
Unit
mA
mA
µH
kΩ
kΩ
nF
nF
µF
µF
µF
nF
pF
%
V
V
Ω
SW
1
and C
User Defined
Ceramic, X7R / X5R
Ceramic, X7R / X5R
Ceramic, X7R / X5R
Ceramic, X7R / X5R, tolerance +/-10%
Ceramic, X7R / X5R
Shielded inductor, low ESR
Ceramic, X7R / X5R
±
±
Schottky diode
Ceramic, X7R / X5R, 50V
±
1%
1%
1%
SW
) on the SW pin can be used to
SW
, R
SW
Type