LNBH24
Dual LNB supply and control IC with step-up and I²C interface
Features
■
■
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Complete interface between LNBS and I²C bus
Built-in DC-DC converter for single 12 V supply
operation and high efficiency (typ. 93%@0.5 A)
Selectable output current limit through external
resistor
Compliant with main satellite receivers output
voltage specification
New accurate built-in 22 kHz tone generator
meets widely accepted standards (patent
pending)
Fast oscillator start-up facilitates DiSEqC™
encoding
Built-in 22 kHz tone detector supports bi-
directional DiSEqC™ 2.0
Very low-drop post regulator and high
efficiency step-up PWM with integrated power
N-MOS allow low power losses
Two output pins suitable for bypassing the
output R-L filter and avoiding tone distortion (R-
L filter as per DiSEqC™ 2.0 specs, see typ.
application circuits)
Overload and over-temperature internal
protections with I²C diagnostic bits
Output voltage and output current level
diagnostic feedback by I²C bits
LNB short circuit dynamic protection
+/- 4 kV ESD tolerant on output power pins
PowerSSO-36 (ePad)
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designed to provide the 13/18 V power supply and
the 22 kHz tone signalling for two independent
LNB down-converters in the antenna dishes
and/or multi-switch box. In this application field, it
offers a dual tuner STBs with extremely low
component count, low power dissipation together
with simple design and I²C standard interfacing.
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Description
Intended for analog and digital dual satellite
receivers/sat-TV, sat-PC cards, the LNBH24 is a
monolithic voltage regulator and interface IC,
assembled in PowerSSO-36 ePad, specifically
Table 1.
Device summary
Order code
LNBH24PPR
April 2009
Package
PowerSSO-36 (Exposed pad)
Rev 3
Packaging
Tape and reel
1/30
www.st.com
30
Contents
LNBH24
Contents
1
2
Block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1
2.2
2.3
2.4
2.5
2.6
2.7
2.8
2.9
2.10
2.11
2.12
2.13
2.14
Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
DiSEqC™ data encoding and decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
DiSEqC™ 2.0 implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
DiSEqC™ 1.X implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Data encoding through external tone generator (EXTM) . . . . . . . . . . . . . . 6
I²C interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Output voltage selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Diagnostic and protection functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Output voltage diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
22 kHz tone diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Minimum output current diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Output current limit selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Over-current and short-circuit protection and diagnostic . . . . . . . . . . . . . . 8
Thermal protection and diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3
4
5
6
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
I²C bus interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1
6.2
6.3
6.4
6.5
Data validity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Start and stop condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Byte format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Transmission without acknowledge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7
LNBH24 software description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1
Interface protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2/30
LNBH24
Contents
7.2
7.3
7.4
7.5
7.6
7.7
System register (SR, 1 Byte for each section A and B) . . . . . . . . . . . . . . 16
Transmitted data (I²C bus write mode) for each section A/B . . . . . . . . . . 16
Diagnostic received data (I²C read mode) for both sections A/B . . . . . . . 17
Power-on I²C interface reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Address pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
DiSEqC™ implementation for each section A/B . . . . . . . . . . . . . . . . . . . 18
8
9
10
11
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3/30
Block diagram
LNBH24
1
Figure 1.
Block diagram
Block diagram
TTX-A
-
ISEL -A
ADDR -A
SDA SCL
ADDR -B
V
CC
Byp
V
CC
-L
ISEL -B TTX-B
-
LX -A
PWM
Controller
Rsense
P-GND-A
-
-
PWM
Controller
Preregulator
+U.V.lockout
+P.ON reset
EN-
A
-
VSEL-
A
-
TEN-
A
-
EN-
A
-
-
VSEL-
A
TTX-
A
-
TEN-
B
-
EN-
B
-
EN-
B
-
-
VSEL-
B
LX -B
Rsense
P-GND-B
-
I²C interface
²
-
VSEL-
B
TTX-
B
ITEST-
B
-
VOUT-
B
Control
-
ISEL-
B
-
V
UP
-B
V
UP
-A
ISEL-
A
-
ITEST-
A
VOUT-
A
Control
VoRX -A
VCTRL -A
VoTX -A
TTX-
A
-
EXTM -A
DSQIN -A
DETIN -A
22KHz Tone
.
Amp. Diagn
22KHz Tone
Freq. Det.
DSQOUT
-
A
Linear Post -
-reg
+Protections
+Diagnostics
I²C Diagnostics
²
Linear Post -
-reg
+Protections
+Diagnostics
VoRX -B
VCTRL -B
VoTX -B
22KHz
Oscill.
Oscill.
TTX-
B
-
EXTM -B
DSQIN -B
22KHz Tone
Amp. Diagn
.
22KHz Tone
Freq. Det.
DETIN -B
TEN-
A
-
TEN-
B
-
LNBH24
A-GND
-
DSQOUT
-
B
4/30
LNBH24
Introduction
2
Introduction
The LNBH24 includes two completely independent sections. Except for the V
CC
and I²C
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).
2.1
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
UP
) that allow the linear post-regulator to work at a minimum
dissipated power of 0.375 W Typ. @ 500 mA load (the linear post-regulator drop voltage is
internally held at V
UP
-V
OUT
=0.75 V typ.). An under voltage lockout circuit will disable the
entire circuit when the supplied V
CC
drops below a fixed threshold (6.7 V typically).
Note:
In this document the V
OUT
is intended as the voltage present at the linear post-regulator
output (V
oRX
pin).
2.2
DiSEqC™ data encoding and decoding
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™ data encoding, or
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.
2.3
DiSEqC™ 2.0 implementation
The built-in 22 kHz Tone detector completes the fully bi-directional DiSEqC™ 2.0 (see
Note:)
interfacing. Its input pin (DETIN) must be AC coupled to the DiSEqC™ bus, and
extracted PWK data are available on the DSQOUT pin. To comply with the bi-directional
DiSEqC™ 2.0 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
oRX
) and one
for the 22 kHz tone transmission (V
oTX
). The V
oTX
must be activated only during the tone
transmission while the V
oRX
provides the 13/18 V output voltage. This allows the 22 kHz
Tone to pass without any losses due to the R-L filter impedance (see
Figure 4).
During the
22 kHz transmission, in DiSEqC™ 2.0 applications, activated by DSQIN pin or by the TEN
bit, the V
oTX
pin must be preventively set ON by the TTX function. This can be controlled
both through the TTX pin and the I²C bit. As soon as the tone transmission is expired, the
V
oTX
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
oRX
pin through
the R-L filter.
2.4
DiSEqC™ 1.X implementation
When the LNBH24 is used in DiSEqC™ 1.x applications the R-L filter is always needed for
the proper operation of the 22 kHz tone generator (patent pending. See
Figure 4).
Also in
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
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