ilc6383 Fairchild Semiconductor, ilc6383 Datasheet - Page 9

• Manufacturer Part Number: ilc6383
• Description: 1-cell To 3-cell Boost Dc-dc Converter With True Load Disconnect, 3.3v, 5v Or Adjustable Output
• Manufacturer: Fairchild Semiconductor

PRODUCT SPECIFICATION
External Component Selection
Inductors
The ILC6383 is designed to work with a 15µH inductor in
most applications. There are several vendors who supply
standard surface mount inductors to this value. Suggested
suppliers are shown in Table 1. Higher values of inductance
will improve efficiency, but will reduce peak inductor current
and consequently ripple and noise, but will also limit output
current.
Capacitors
Input Capacitor
The input capacitor is necessary to minimize the peak
current drawn from the battery. Typically a 10µF tantalum
capacitor is recommended. Low equivalent series resistance
(ESR) capacitors will help to minimize battery voltage
ripple.
Output Capacitor
Low ESR capacitors should be used at the output of the
ILC6383 to minimize output ripple. The high switching
speeds and fast changes in the output capacitor current, mean
that the equivalent series impedance of the capacitor can
contribute greatly to the output ripple. In order to minimize
these effects choose an output capacitor with less than 10nH
of equivalent series inductance (ESL) and less than 100mΩ
of equivalent series resistance (ESR). Typically these charac-
teristics are met with ceramic capacitors, but may also be
met with certain types of tantalum capacitors. Suitable
vendors are shown in Table 2.
REV. 1.2.6 6/13/02
Coilcraft
muRata
Sumida
TDK
T495 series tantalum
595D series tantalum
TAJ, TPS series
tantalum
X5R, X7R Ceramic
Vendor
Description
D03308P-153
D03316P-153
D01608C-153
LQH4N150K
LQH3C150K
CDR74B-150MC
CD43-150
CD54-150
NLC453232T-150K
Part No.
Kemet
Sprague
AVX
TDK
AVX
muRata
Vendor
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
www.murata.com
Contact
Contact
Layout and Grounding Considerations
High frequency switching and large peak currents means
PCB design for DC-DC converters requires careful consider-
ation. As a general rule, place the DC-DC converter
circuitry well away from any sensitive RF or analog compo-
nents. The layout of the DC-DC converters and its external
components are also based on some simple rules to minimize
EMI and output voltage ripple.
Layout
1. Place all power components, ILC6383, inductor, input
2.
3.
4.
Grounding
1. Use a star grounding system with separate traces for the
2.
capacitor and output capacitor as close together as
possible.
Keep the output capacitor as close to the ILC6383 as
possible with very short traces to the V
pins. Typically it should be within 0.25 inches or 6mm.
Keep the traces for the power components wide,
typically >50mil or 1.25mm.
Place the external networks for LBI and V
ILC6383, but away from the power components as far as
possible.
power ground and the low power signals such as LBI/
SD and V
power supply enters the PCB.
On multilayer boards use component side copper for
grounding around the ILC6383 and connect back to a
quiet ground plane using vias.
ON/OFF
47µF
V
C
IN
IN
Recommended application circuit
schematic for ILC6383CIR-ADJ
FB
PWM
. The star should radiate from where the
15µH
L1
PFM
1
2
4
3
Local "Quiet" Ground
LBI/SD
SEL
V
Power Ground
IN
L
ILC6383
X
GND
V
LBO
V
OUT
FB
8
7
6
5
+
OUT
C
47µF
FB
OUT
and GND
close to the
R1
R2
ILC6383
R3
V
OUT
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