Intended for analog and digital satellite receivers,
the LNBP is a monolithic linear voltage regulator,
assembled in Multiwatt-15, PowerSO-20 and
PowerSO-10, specifically designed to provide the
powering voltages and the interfacing signals to
the LNB downconverter situated in the antenna
via the coaxial cable. Since most satel lite
receivers have two antenna ports, the output
voltage of the regulator is available at one of two
logic-selectable output pins (LNBA, LNBB ). When
the IC is powered and put in Stand-by (EN pin
LOW), both regulat or outputs are disabled to allow
the antenna downconverters to be supplied/
controlled by others satellite receivers sharing the
same coaxial lines. I n this oc c urrence the device
will limit at 3 mA (max) the backw ard current that
could flow from LNBA and LNBB output pins to
GND.
For slave operation in single dish, dual receiver
systems, the bypass function is implemented by
an electronic switch between t he Master Input pin
(MI) and the LNBA pin, thu s leaving all LNB
powering and control functions to the Master
Receiver. This electronic switch is close d when
the device is powered and EN pin is LOW.
ENCODING
LNBP10 SERIES
LNBP20
Multiwatt-15
10
1
Power SO-20
The regulator outputs can be logic controlled to be
13 or 18 V (typ.) by mean of the VSEL pin for
remote controlling of LNBs. Additionally, it is
possible to increment by 1V (typ.) the selected
voltage value to compensate the excess voltage
drop along th e c oax ial c able (LLC pin HIGH).
In orde r to reduc e the power dissipation of the
device when the l owes t output voltage is selected,
the regulator has two Supply Input pins V
V
. They must be powered respec ti v ely at 16V
CC2
(min) and 23V (min), and an internal switch
automatically will select the suitable supply pin
according to the s elected output voltage. If
adequate heatsink is provided and higher power
losses are ac ceptable, both supply pins can be
powered by the same 23V source without
affecting any other circuit performance.
The ENT (T one Enable) pin activates the internal
oscillator so that the DC output is modulated by a
±0.3 V , 22KHz (typ.) square wave. This internal
oscillator is factory trimmed within a tolerance of
±2KHz, thus no further adjustments neither
external components are required.
A burst coding of the 22KHz tone can be
accomplished thanks to the fast response of the
ENT i nput and the prompt oscillator start-up. This
helps designers who want to implement the
DiSEqC
protocols (*).
In order to improve design flexibility and to allow
implementation of newcoming LNB remote contro l
standards, an analogic modulation
PowerSO-10
CC1
and
1/20June 2003
LNBP10 SERIES - LNBP20
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:CEXTandOLF. T he
overcurrent protection circuit works dynamically:
as soon as an overload i s detected in either LNB
output, th e output is shut-down for a time t
off
determined by t he 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 t he time has elapsed, the output is resumed
for a time t
(*): External components are needed to comply to level 2.x and above (bidirectional) DiSEqCbus hardware requirements. DiSEqCis a
trademark or EUTELSAT.
=1/15t
on
(typ.) and OLF goes in HIG H
off
IMPEDANCE. If the overload is still present, the
protection circuit will cycle again through t
ton until the ov erload is removed. Typical t
and
off
on+toff
value is 1200ms when a 4.7µF 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 out puts.
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.Allversionshavebuilt-inthermal
protection agains t overheating damage.