LT3582 LINER [Linear Technology], LT3582 Datasheet - Page 19

• Manufacturer Part Number: LT3582
• Description: I2C Programmable Boost and Single Inductor Inverting DC/DC Converters with OTP
• Manufacturer: LINER [Linear Technology]

Where…
For example, if V
L = 4.7μH then I
Note: The 155mA (Typ) current limit of the output dis-
connect PMOS (see Electrical Characteristics) may limit
maximum I
Improving Boost Converter Effi ciency.
Maximum Slew Rate: Lower inductance causes higher
current slew rates which can lead to current limit over-
shoot. Choose an inductance higher than L
the overshoot:
where V
previous example V
Capacitor Selection
The small size and low ESR of ceramic capacitors makes
them suitable for most LT3582 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 capaci-
tor and a 2.2μF-10μF output capacitor are suffi cient for
APPLICATIONS INFORMATION
V
V
I
η
T
I
L
PK
OUT
OFF_MIN
OUT
IN(MIN)
MIN
IN(MAX)
= V
OUTP
IN(MAX)
= Regulation voltage
= Minimum input voltage.
= Peak inductor current. See prior section
= Power conversion effi ciency (about 88%
= Minimum switch off time. Typically
= Output load current
rating for these calculations.
for Boost or 78% for Inverting)
Peak Current Rating. Use minimum I
100ns for Boost and 125ns for Inverting.
OUTP
is the maximum input voltage. Using the
OUTP
unless CAPP is shorted to V
• 0.2µH
IN
= 117mA and I
= 10V, V
= 3V, L
MIN
OUTN
= 0.6μH.
= –10V, V
OUTN
= 105mA.
IN
MIN
OUTP
= 5V, and
to limit
. See
Limit
most LT3582 series applications. Always use a capacitor
with a suffi cient voltage rating. Many capacitors rated at
2.2μF to 10μF, particularly 0805 or 0603 case sizes, have
greatly reduced capacitance at the desired output voltage.
Generally a 1206 capacitor will be adequate. A 0.22μF to
1μF capacitor placed on the CAPP node is recommended
to fi lter the inductor current while the larger 2.2μF to 10μF
placed on the V
transient response and stability. Avoid placing large value
capacitors (generally > 6.8μF) on both CAPP and V
This confi guration can be less stable since it creates two
poles, one at the CAPP pin and the other at the V
pin, which can be near each other in frequency. Table 4
shows a list of several capacitor manufacturers. Consult
the manufacturers for more detailed information and for
their entire selection of related parts.
Table 4: Ceramic Capacitor Manufacturers
MANUFACTURER
Kemet
Murata
Taiyo Yuden
TDK
Diode Selection
Schottky diodes, with their low forward voltage drops
and fast switching speeds, are recommended for use with
the LT3582 series. The Diodes Inc. B0540WS is a very
good choice in a small SOD-323 package. This diode is
rated to handle an average forward current of 500mA and
performs well across a wide temperature range. Schottky
diodes with very low forward voltage drops are also avail-
able. These diodes may improve effi ciency at moderate
and cold temperatures, but will likely reduce effi ciency
at higher temperatures due to excessive reverse leakage
currents.
LT3582/LT3582-5/LT3582-12
OUTP
PHONE
408-986-0424
814-237-1431
408-573-4150
847-803-6100
& V
OUTN
URL
www.kemet.com
www.murata.com
www.t-yuden.com
www.tdk.com
nodes will give excellent
19
3582512f
OUTP
OUTP
.