Topfield TF4000FI, Service Manual, Page: 21 / 62

LNBP10 SERIES - LNBP20
2/18
input pin is available (EXTM). An appropriate DC
blocking capacitor must be used to couple the
modulating signal source to the EXTM pin. When
external modulation is not used, the relevant pin
can be left open.
Two pins are dedicated to the overcurrent
protection/monitoring:
CEXT and OLF. The
overcurrent protection circuit works dynamically:
as soon as an overload is detected in either LNB
output, the output is shut-down for a time t
off
determined by the capacitor connected between
CEXT and GND. Simultaneously the OLF pin, that
is an open collector diagnostic output flag, from
HIGH IMPEDANCE state goes LOW.
After the time has elapsed, the output is resumed
for a time t
on
=1/15t
off
(typ.) and OLF goes in HIGH
IMPEDANCE. If the overload is still present, the
protection circuit will cycle again through t
off
and
ton until the overload is removed. Typical t
on
+t
off
value is 1200ms when a 4.7
µ
F external capacitor
is used.
This dynamic operation can greatly reduce the
power dissipation in short circuit condition, still
ensuring excellent power-on start up even with
highly capacitive loads on LNB outputs.
The device is packaged in Multiwatt15 for
thru-holes mounting and in PowerSO-20 for
surface mounting. When a limited functionality in a
smaller package matches design needs, a range
of cost-effective PowerSO-10 solutions is also
offered.
All versions have built-in thermal
protection against overheating damage.
(*): External components are needed to comply to level 2.x and above (bidirectiona) DiSEqC bus hardware requirements. DiSEqC is a
trademark or EUTELSAT.
ORDERING CODES
(*) Available on request
PIN CONFIGUARATION (top view)
TYPE Multiwatt-15 PowerSO-20 PowerSO-10
LNBP10 LNBP10SP-TR (*)
LNBP11 LNBP11SP-TR (*)
LNBP12 LNBP12SP-TR (*)
LNBP13 LNBP13SP-TR (*)
LNBP14 LNBP14SP-TR (*)
LNBP15 LNBP15SP-TR (*)
LNBP16 LNBP16SP-TR (*)
LNBP20 LNBP20CR LNBP20PD-TR
PowerSo-20 PowerSO-10 Multiwatt-15