LNBP10 Datasheet, PDF (1/18 Pages) STMicroelectronics – LNB SUPPLY AND CONTROL VOLTAGE REGULATOR PARALLEL INTERFACE

LNBP10 SERIES
®
LNBP20
LNB SUPPLY AND CONTROL VOLTAGE
REGULATOR (PARALLEL INTERFACE)
s COMPLETE INTERFACE FOR TWO LNBs
REMOTE SUPPLY AND CONTROL
s LNB SELECTION AND STAND-BY FUNCTION
s BUILT-IN TONE OSCILLATOR FACTORY
TRIMMED AT 22KHz
s FAST OSCILLATOR START-UP
FACILITATES DiSEqC™ ENCODING
s TWO SUPPLY INPUTS FOR LOWEST
DISSIPATION
s BYPASS FUNCTION FOR SLAVE
OPERATION
s LNB SHORT CIRCUIT PROTECTION AND
DIAGNOSTIC
s AUXILIARY MODULATION INPUT EXTENDS
FLEXIBILITY
s CABLE LENGTH COMPENSATION
s INTERNAL OVER TEMPERATURE
PROTECTION
s BACKWARD CURRENT PROTECTION
DESCRIPTION
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 satellite
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 regulator outputs are disabled to
allow the antenna downconverters to be
supplied/controlled by others satellite receivers
sharing the same coaxial lines. In this occurrence
the device will limit at 3 mA (max) the backward
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 the Master Input pin
(MI) and the LNBA pin, thus leaving all LNB
powering and control functions to the Master
Receiver. This electronic switch is closed when
the device is powered and EN pin is LOW.
Multiwatt-15
PowerSo-20
10
1
PowerSO-10
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 the coaxial cable (LLC pin HIGH).
In order to reduce the power dissipation of the
device when the lowest output voltage is
selected, the regulator has two Supply Input pins
VCC1 and VCC2. They must be powered
respectively at 16V (min) and 23V (min), and an
internal switch automatically will select the
suitable supply pin according to the selected
output voltage. If adequate heatsink is provided
and higher power losses are acceptable, both
supply pins can be powered by the same 23V
source without affecting any other circuit
performance.
The ENT (Tone 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
September 1998
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