LT3582 LINER [Linear Technology], LT3582 Datasheet - Page 18

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

LT3582/LT3582-5/LT3582-12
APPLICATIONS INFORMATION
Choosing Inductors
Several series of inductors that work well with the LT3582
series are listed in Table 3. This table is not complete, and
there are many other manufacturers and parts 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.
Table 3: Inductor Manufacturers
Coilcraft
Murata
Sumida
TDK
Würth
Elektronik
Inductances of 2.2μH-10μH typically result in a good
tradeoff between inductor size and system performance.
More inductance typically yields an increase in effi ciency
at the expense of increased output ripple. Less inductance
may be used in a given application depending on required
effi ciency and output current. For higher effi ciency, choose
inductors with high frequency core material, such as ferrite,
to reduce core losses. Also to improve effi ciency, choose
inductors with more volume for a given inductance. The
inductor should have low DCR (copper-wire resistance)
to reduce I
18
10. Read the OTP data and verify the contents.
11. Write 00h to CMDR. This enables the power switches
12. Float the V
and the chip will operate from the OTP confi gura-
tion.
after step 8.
2
LPS3008-LPS4018 Series,
XPL2010 Series
LQH32C, LQH43C Series
CDRH26D09, CDRH26D11,
CDRH3D14 Series
VLF and VLCF Series
WE-TPC Series Type T, TH,
XS and S
R losses, and must be able to handle the peak
PP
pin. This can be done at any time
www.coilcraft.com
www.murata.com
www.sumida.com
www.tdk.com
www.we-online.com
inductor current without saturating. To minimize radiated
noise, use a toroidal or shielded inductor (note that the
inductance of shielded types will drop more as current
increases, and will saturate more easily).
Peak Current Rating: Real inductors can experience
a drop in inductance as current and temperature
increase. The inductors should have saturation cur-
rent ratings higher than the peak inductor currents.
The peak inductor currents can be calculated as:
where:
Maximum Load Currents: Use one of the following equa-
tions to estimate the maximum output load current for the
positive and negative output voltages:
I
⎛
⎜
⎝
or I
⎛
⎜
⎜
⎝
OUTP
V
V
V
IN(MIN)
IN(MIN)
I
I
L
V
T
I
OUTP
PK
LIMIT
OUTN
PK
OS
LSWON
=
V
≅ I
IN(MIN)
+ |V
⎞
⎟ • I
⎠
=
LIMIT
⎛
⎜
⎝
= Peak inductor current
= Typically 350mA for Boost and 600mA for
= Inductance in μH
= Maximum inductor voltage when the
= 100 for Boost and 125 for Inverting
OUTN
PK
Inverting
power switch is “on”. Typically max V
for the Boost and Inverting converters.
+
–
|
V
T
⎞
⎟
⎟ • I
⎠
LSWON
OFF _ MIN
⎛
⎜
⎝
PK
L
–
• T
T
• (V
OFF _ MIN
OS
OUTP
mA
2 • L
+ 0.5 – V
• (|V
2 • L
OUTN
IN(MIN)
| +0.5)
)
⎞
⎟ • 0.8η
⎠
⎞
⎟ • 0.8η
⎠
3582512f
IN