ame5144 AME, Inc., ame5144 Datasheet - Page 9

• Manufacturer Part Number: ame5144
• Description: High Efficiency, 37v Step-up Converter For 2 To 10 White Leds
• Manufacturer: AME, Inc.

are recommended for stable operation over the entire op-
erating temperature range. The exact values of input and
output capacitors are not critical. The typical value for
input capacitor is 2.2 F, and the typical value for output
capacitor is 0.1 F. Higher values capacitors can be used
to reduce input and output ripple, but at the expense of
size and higher cost. C
control soft-start. Connect a 0.1 F capacitor from COMP
to GND.
ductor optimizes the efficiency for most applications while
maintaining low 12mVp-p input ripple. Inductor with low
DCR can be more efficiency. To prevent core saturation,
ensure that the inductor-saturation current rating exceeds
the peak inductor current for the application. Calculate
the peak inductor current with the following formula:
Sumida CDRH5D16NP- 220MB are recommended.
AME5144
Rev.D.01
I
PEAK
Capacitor Selection
Ceramic capacitors with X5R, X7R, or better dielectric
Inductor Selection
Inductor values range from 10 H to 47 H. A 22 H in-
22 H, 250mA inductor Murata LQH32CN220K and
V
OUT
0
AME
(
MAX
9 .
)
V
IN
I
(
LED
MIN
COMP
(
)
MAX
stabilizes the converter and
)
V
IN
(
MIN
2
)
L
0
9 .
us
i e
C
Converter for 2 to 10 White LEDs
a high-speed rectification diode (D1) for optimum efficiency.
A Schottky diode is recommended due to its fast recovery
time and low forward-voltage drop. Ensure that the diode's
average and peak current rating exceed the average out-
put current and peak inductor current. In addition, the
diode's reverse breakdown voltage must exceed V
RMS diode current can be approximated from:
200mA, 40V Schottky diode SOD-523 or Central Semi-
conductor CMOSH-4E are recommended for applications.
careful PC board layout is required. When laying out a
board, minimum trace lengths between the IC and R
the inductor, the diode, the input capacitor and output ca-
pacitor. Keep trace short and wide. Keep noisy traces,
such as the SW node trace, away from CS.
to the IC as possible. This will reduce copper trace resis-
tance, which effect the input voltage ripple of the IC. The
output capacitor, C
IC and connected directly between the OUT and GND pins.
PGND and GND should be connected directly to the ex-
posed paddle underneath the IC. The ground connections
of C
Any copper trace connections with the C
increase the series resistance which directly effects out-
put ripple and efficiency. The current setting resistor,
R
copper trace connections that can inject noise in to the
system. The traces from IN to the inductor and from
Schottky diode to the LEDs can be longer.
I
The input bypass capacitor C
Schottky Diode Selection
The high switching frequency of the AME5144 demands
Layout Consideration
Due to fast switching waveforms and high-current paths,
DIODE
SENSE
IN
, should be kept close to the CS pin to minimize
and C
(
RMS
High Efficiency, 37V Step-Up
)
OUT
should be as close together as possible.
I
OUT
OUT
, should also be placed close to the
I
PEAK
IN
should be placed as close
OUT
capacitor can
OUT
. The
SENSE
9
,