LNBH24_0808 STMICROELECTRONICS [STMicroelectronics], LNBH24_0808 Datasheet - Page 5

• Manufacturer Part Number: LNBH24_0808
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

2
2.1
Note:
2.2
2.3
2.4
Introduction
The LNBH24 includes two completely independent sections. Except for the V
inputs, each circuit can be separately controlled and have independent external
components. The specification that follow should be considered equally for both sections
(A/B).
Application information
This IC has a built-in DC-DC step-up converter which, from a single 8 V to 15 V source,
generates the voltages (V
dissipated power of 0.375 W Typ. @ 500 mA load (the linear post-regulator drop voltage is
internally held at V
entire circuit when the supplied V
In this document the V
output (V
DiSEqC
The new internal 22 kHz tone generator (patent pending) is factory trimmed in accordance
with the standards, and can be selected through I²C interface TTX bit (or TTX pin) and
activated by a dedicated pin (DSQIN) which allows immediate DiSEqC
through TEN I²C bit in case the 22 kHz presence is requested in continuous mode. In
standby condition (EN bit LOW). The TTX function must be disabled setting TTX to LOW.
DiSEqC
The built-in 22 kHz Tone detector completes the fully bi-directional DiSEqC
interfacing. Its input pin (DETIN) must be AC coupled to the DiSEqC
PWK data are available on the DSQOUT pin. To comply with the bi-directional DiSEqC
bus hardware requirements an output R-L filter is needed. The LNBH24 is provided with two
output pins for each section, one for the DC voltage output (V
tone transmission (V
while the V
without any losses due to the R-L filter impedance (see
transmission, in DiSEqC
V
through the TTX pin and the I²C bit. As soon as the tone transmission is expired, the V
must be disabled by setting the TTX to LOW to set the device in the 22 kHz receiving mode.
The 13/18 V power supply is always provided to the LNB from the V
filter.
DiSEqC
When the LNBH24 is used in DiSEqC
the proper operation of the 22 kHz tone generator (patent pending. See
this case, the TTX function must be preventively enabled before to start the 22 kHz data
transmission and disabled as soon as the data transmission has been expired. The tone can
oTX
pin must be preventively set ON by the TTX function. This can be controlled both
oRX
oRX
™
™
™
pin).
data encoding and decoding
2.0 implementation
1.X implementation
provides the 13/18 V output voltage. This allows the 22 kHz Tone to pass
UP
oTX
-V
OUT
OUT
). The V
™
UP
2.0 applications, activated by DSQIN pin or by the TEN bit, the
is intended as the Voltage present at the linear post-regulator
=0.75 V typ.). An under voltage lockout circuit will disable the
) that allow the linear post-regulator to work at a minimum
oTX
CC
must be activated only during the tone transmission
drops below a fixed threshold (6.7 V typically).
™
1.x applications the R-L filter is always needed for
Figure
oRX
4). During the 22 kHz
) and one for the 22 kHz
oRX
™
™
bus, and extracted
pin through the R-L
Figure
data encoding, or
™
2.0 (see Note:)
CC
4). Also in
and I²C
™
oTX
5/30
2.0