LTC1871 Linear Technology, LTC1871 Datasheet - Page 18

• Manufacturer Part Number: LTC1871
• Description: Wide Input Range/ No RSENSE Current Mode Boost/ Flyback and SEPIC Controller
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
LTC1871
continuous (see Figure 12b). The input voltage source im-
pedance determines the size of the input capacitor, which
is typically in the range of 10 F to 100 F. A low ESR capaci-
tor is recommended, although it is not as critical as for the
output capacitor.
The RMS input capacitor ripple current for a boost con-
verter is:
Please note that the input capacitor can see a very high
surge current when a battery is suddenly connected to the
input of the converter and solid tantalum capacitors can
fail catastrophically under these conditions. Be sure to
specify surge-tested capacitors!
18
I
RMS CIN
(
)
0 3
. •
Table 1. Recommended Component Manufacturers
VENDOR
AVX
BH Electronics
Coilcraft
Coiltronics
Diodes, Inc
Fairchild
General Semiconductor
International Rectifier
IRC
Kemet
Magnetics Inc
Microsemi
Murata-Erie
Nichicon
On Semiconductor
Panasonic
Sanyo
Sumida
Taiyo Yuden
TDK
Thermalloy
Tokin
Toko
United Chemicon
Vishay/Dale
Vishay/Siliconix
Vishay/Sprague
Zetex
U
V
IN MIN
L f
(
•
U
)
•
D
MAX
W
Inductors, Transformers
Small-Signal Discretes
Inductors, Capacitors
Capacitors, Inductors
Tantalum Capacitors
MOSFETs, Diodes
Sense Resistors
COMPONENTS
Toroid Cores
Capacitors
Capacitors
Capacitors
Capacitors
Capacitors
Heat Sinks
Capacitors
Capacitors
Capacitors
Inductors
Inductors
MOSFETs
Inductors
Inductors
MOSFETs
Resistors
Diodes
Diodes
Diodes
Diodes
U
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
Burst Mode Operation and Considerations
The choice of MOSFET R
determines the load current at which the LTC1871 enters
Burst Mode operation. When bursting, the controller clamps
the peak inductor current to approximately:
which represents about 20% of the maximum 150mV
SENSE pin voltage. The corresponding average current
depends upon the amount of ripple current. Lower induc-
tor values (higher I
Burst Mode operations begins, since it is the peak current
that is being clamped.
TELEPHONE
I
BURST PEAK
(
generalsemiconductor.com
)
aavidthermalloy.com
component.tdk.com
bhelectronics.com
fairchildsemi.com
R
chemi-com.com
WEB ADDRESS
microsemi.com
coiltronics.com
panasonic.com
30
L
nichicon.com
DS ON
avxcorp.com
coilcraft.com
mag-inc.com
murata.co.jp
t-yuden.com
onsemi.com
sumida.com
tokoam.com
diodes.com
sanyo.co.jp
) will reduce the load current at which
kemet.com
vishay.com
vishay.com
vishay.com
zetex.com
tokin.com
irctt.com
mV
irf.com
(
DS(ON)
)
and inductor value also