LT3495 Datasheet, PDF (9/16 Pages) Linear Technology – 650mA/350mA Micropower Low Noise Boost Converter with Output Disconnect

LT3495/LT3495B/
LT3495-1/LT3495B-1
APPLICATIONS INFORMATION
Inductor Selection
Several inductors that work well with the LT3495/LT3495B
are listed in Table 2 and those for the LT3495-1/LT3495B-1
are listed in Table 3. These tables are not complete, and
there are many other manufacturers and devices that can
be used. Consult each manufacturer for more detailed
information and for their entire selection of related parts,
as many different sizes and shapes are available.
Inductors with a value of 3.3μH or higher are recommended
for most LT3495 series designs. Inductors with low core
losses and small DCR (copper wire resistance) are good
choices for LT3495 series applications. For full output
power, the inductor should have a saturation current rating
higher than the peak inductor current. The peak inductor
current can be calculated as:
I_PK
= I_LIMIT
+
V_IN
•
200
L
• 10^–9
amps
where I_LIMIT is 0.65A and 0.35A for LT3495/LT3495B and
LT3495-1/LT3495B-1 respectively. L is the inductance
value in Henrys and V_IN is the input voltage to the boost
circuit.
Table 2. Recommended Inductors for LT3495/LT3495B
PART
L DCR
(μH) (mΩ) SIZE (mm) VENDOR
LPS4018-103ML 10 200 4.4 × 4.4 × 1.7 Coilcraft
MSS5131-103MLC 10 83 5.1 × 5.1 × 3.1 www.coilcraft.com
LPS3015-472MLC 4.7 200 3.0 × 3.0 × 1.5
LPS3015-682MLC 6.8 300 3.0 × 3.0 × 1.5
LQH43CN4R7M03 4.7 150 4.5 × 3.2 × 2.8 Murata
www.murata.com
CR32-6R8
6.8 202 4.1 × 3.7 × 3.0 Sumida
www.sumida.com
744031004
4.7 105 3.8 × 3.8 × 1.7 Wurth Elektronik
www.weonline.com
Capacitor Selection
The small size and low ESR of ceramic capacitors makes
them suitable for most LT3495 series applications. X5R
and X7R types are recommended because they retain
their capacitance over wider voltage and temperature
ranges than other types such as Y5V or Z5U. A 4.7μF
input capacitor and a 1μF to 10μF output capacitor are
sufficient for most applications. Always use a capacitor
with a sufficient voltage rating. Many capacitors rated at
1μF to 10μF, particularly 0603 case sizes, have greatly
reduced capacitance when bias voltages are applied. Be
sure to check actual capacitance at the desired output
voltage. Generally a 0805 or 1206 size capacitor will be
adequate. A 2.2μF capacitor placed on the CAP node is
recommended to filter the inductor current while a 1μF to
10μF capacitor placed on the V_OUT node will give excellent
transient response and stability. Table 4 shows a list of
several capacitor manufacturers. Consult the manufac-
turers for more detailed information and for their entire
selection of related parts.
Table 3. Recommended Inductors for LT3495-1/LT3495B-1
PART
L DCR
(μH) (mΩ) SIZE (mm) VENDOR
LPO4815-472MLC 4.7 150 4.8 × 4.8 × 1.5 Coilcraft
LPO4815-682MLC 6.8 180 4.8 × 4.8 × 1.5 www.coilcraft.com
LPO4815-103MLC 10 230 4.8 × 4.8 × 1.5
LPS3008-472MLC 4.7 350 3.0 × 3.0 × 0.8
LPS3008-682MLC 6.8 500 3.0 × 3.0 × 0.8
LPS3008-103MLC 10 650 3.0 × 3.0 × 0.8
LQH32CN4R7M53 4.7 150 3.2 × 2.5 × 1.6 Murata
LQH32CN100K33 10 300 3.2 × 2.5 × 2.0 www.murata.com
CDH28D09/S-6R2 6.2 369 3.3 × 3.0 × 1.0 Sumida
www.sumida.com
744030004
4.7 290 3.5 × 3.3 × 1.0 Wurth Elektronik
www.weonline.com
Table 4. Recommended Ceramic Capacitor Manufacturers
MANUFACTURER
PHONE
WEBSITE
Taiyo Yuden
[phone]
www.t-yuden.com
AVX
[phone]
www.avxcorp.com
Murata
[phone]
www.murata.com
Kemet
[phone]
www.kemet.com
TDK
[phone]
www.tdk.com
Diode Selection
Schottky diodes, with their low forward voltage drops and
fast switching speeds, are recommended for use with the
LT3495 series. The Diodes Inc. B0540WS-7 is a very good
choice. This diode is rated to handle an average forward
current of 0.5A with 40V reverse breakdown.
3495b1b1f
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