LTC3704_15 Datasheet, PDF (18/28 Pages) Linear Technology – Wide Input Range, No RSENSE Positive-to-Negative DC/DC Controller

LTC3704
APPLICATIO S I FOR ATIO
I_RMS(COUT) ≥
1 _• (1– D_MAX) _• V_O
12
f
L2
It should be noted that these equations assume no cou-
pling between the inductors. If the inductors are wound on
the same core, the ripple currents at the input and output
can be tuned to very low values, and so the equations
above would be extremely conservative. It is highly rec-
ommended that the user experiment in the lab with the
same magnetics and capacitors which will be used in
production.
Note that the ripple current ratings from capacitor manu-
facturers are often based on only 2000 hours of life. This
makes it advisable to further derate the capacitor or to
choose a capacitor rated at a higher temperature than
required. Several capacitors may also be placed in parallel
to meet size or height requirements in the design.
Manufacturers such as Nichicon, United Chemicon and
Sanyo should be considered for high performance through-
hole capacitors. The OS-CON semiconductor dielectric
capacitor available from Sanyo has the lowest product of
ESR and size of any aluminum electrolytic, at a somewhat
higher price.
In surface mount applications, multiple capacitors may
have to be placed in parallel in order to meet the ESR or
RMS current handling requirements of the application.
18
Table 1. Recommended Component Manufacturers
VENDOR
COMPONENTS
TELEPHONE
AVX
Capacitors
[phone]
BH Electronics
Inductors, Transformers [phone]
Coilcraft
Inductors
[phone]
Coiltronics
Inductors
[phone]
Diodes, Inc
Diodes
[phone]
Fairchild
MOSFETs
[phone]
General Semiconductor
Diodes
[phone]
International Rectifier
MOSFETs, Diodes
[phone]
IRC
Sense Resistors
[phone]
Kemet
Tantalum Capacitors [phone]
Magnetics Inc
Toroid Cores
[phone]
Microsemi
Diodes
[phone]
Murata-Erie
Inductors, Capacitors [phone]
Nichicon
Capacitors
[phone]
On Semiconductor
Diodes
[phone]
Panasonic
Capacitors
[phone]
Sanyo
Capacitors
[phone]
Sumida
Inductors
[phone]
Taiyo Yuden
Capacitors
[phone]
TDK
Capacitors, Inductors [phone]
Thermalloy
Heat Sinks
[phone]
Tokin
Capacitors
[phone]
Toko
Inductors
[phone]
United Chemicon
Capacitors
[phone]
Vishay/Dale
Resistors
[phone]
Vishay/Siliconix
MOSFETs
[phone]
Vishay/Sprague
Capacitors
[phone]
Zetex
Small-Signal Discretes [phone]
WEB ADDRESS
avxcorp.com
bhelectronics.com
coilcraft.com
coiltronics.com
diodes.com
fairchildsemi.com
generalsemiconductor.com
irf.com
irctt.com
kemet.com
mag-inc.com
microsemi.com
murata.co.jp
nichicon.com
onsemi.com
panasonic.com
sanyo.co.jp
sumida.com
t-yuden.com
component.tdk.com
aavidthermalloy.com
tokin.com
tokoam.com
chemi-com.com
vishay.com
vishay.com
vishay.com
zetex.com
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