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PDF LNBH23L Data sheet ( Hoja de datos )
| Número de pieza | LNBH23L | |
| Descripción | LNB supply and control IC | |
| Fabricantes | STMicroelectronics | |
| Logotipo |  |
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LNBH23L
LNB supply and control IC with step-up and I²C interface
Features
■ Complete interface between LNB 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 by external
resistor
■ Compliant with main satellite receivers output
voltage specification
■ Auxiliary modulation input (EXTM pin)
facilitates DiSEqC™ 1.X encoding
■ Accurate built-in 22 kHz tone generator suits
widely accepted standards
■ Low-drop post regulator and high efficiency
step-up PWM with integrated power NMOS
allow low power losses
■ Overload and over-temperature internal
protections with I²C diagnostic bits
■ LNB short circuit dynamic protection
■ ± 4 kV ESD tolerant on output power pins
Applications
■ STB satellite receivers
■ TV satellite receivers
■ PC card satellite receivers
QFN32 (5 x 5 mm)
(Exposed pad)
Description
Intended for analog and digital satellite receivers,
the LNBH23L is a monolithic voltage regulator
and interface IC, assembled in QFN32 5 x 5
specifically designed to provide the 13 / 18 V
power supply and the 22 kHz tone signalling to
the LNB down-converter in the antenna dish or to
the multi-switch box. In this application field, it
offers a complete solution with extremely low
component count, low power dissipation together
with simple design and I²C standard interfacing.
Table 1.
Device summary
Order code
LNBH23LQTR
Package
QFN32 (5 x 5 mm) Exposed pad
November 2010
Doc ID 15335 Rev 4
Packaging
Tape and reel
1/25
www.st.com
25
Free Datasheet http://www.datasheet4u.com/
1 page  
LNBH23L
2 Application information
Application information
Note:
2.1
This IC has a built-in DC-DC step-up converter that, from a single source from 8 V to 15 V,
generates the voltages (VUP) that let the linear post-regulator to work at a minimum
dissipated power of 0.55 W typ. @ 500 mA load (the linear post-regulator drop voltage is
internally kept at VUP - VOUT = 1.1 V typ.). An under voltage lockout circuit will disable the
whole circuit when the supplied VCC drops below a fixed threshold (6.7 V typically).
In this document the VOUT is intended as the voltage present at the linear post-regulator
output (VoRX pin).
DiSEqC™ data encoding
The internal 22 kHz tone generator is factory trimmed in accordance to the standards, and
can be selected by I²C interface TTX bit (or TTX pin) and activated by a dedicated pin
(DSQIN) that allows immediate DiSEqC™ data encoding, or through TEN I²C bit in case the
22 kHz presence is requested in continuous mode. In stand-by condition (EN bit LOW) The
TTX function must be disabled setting TTX to LOW. Besides the internal 22 kHz tone
generator, the auxiliary modulation pin (EXTM) can be driven by an external 22 kHz source
and in this case TTX must be set to low.
2.2 DiSEqC™ 1.X implementation by EXTM pin
In order to improve design flexibility and reduce the total application cost, an analogic
modulation input pin is available (EXTM) to generate the 22 kHz tone superimposed to the
VoRX DC output voltage. An appropriate DC blocking capacitor must be used to couple the
modulating signal source to the EXTM pin. If the EXTM solution is used the output R-L filter
can be removed (see Figure 5) saving the external components cost. If this configuration is
used keep TTX set to low.
The pin EXTM modulates the VoRX voltage through the series decoupling capacitor, so that:
VoRX(AC) = VEXTM(AC) x GEXTM
Where VoRX(AC) and VEXTM(AC) are, respectively, the peak to peak voltage on the VoRX and
EXTM pins while GEXTM is the voltage gain from EXTM to VoRX.
2.3 DiSEqC™ 1.X implementation with VOTX and EXTM pin
connection
If an external 22 kHz tone source is not available, it is possible to use the internal 22 kHz
tone generator signal available through the VoTX pin to drive the EXTM pin. The VoTX pin
internal circuit must be preventively set ON by setting the TTX function to High. This can be
controlled both through the TTX pin or by I²C bit. By this way the VoTX 22 kHz signal will be
superimposed to the VoRX DC voltage to generate the LNB output 22 kHz tone (see
Figure 3). After TTX is set to High the internal 22 kHz tone generator available through the
VoTX pin can be activated during the 22 kHz transmission either by DSQIN pin or by the TEN
bit.The DSQIN internal circuit activates the 22 kHz tone on the VoTX output with 0.5 cycles ±
25 µs delay from the TTL signal presence on the DSQIN pin, and it stops with 1 cycles ± 25
µs delay after the TTL signal is expired. As soon as the tone transmission is expired, the
Doc ID 15335 Rev 4
5/25
5 Page 
LNBH23L
5 Typical application circuit
Figure 3. DiSEqC 1.x using internal 22 kHz tone generator
D3
Typical application circuit
Vin
12V
C4
470nF
D1
L1
Vup
C3 C6
470nF
LX
VoTX
LNBH23L
EXTM
VoRX
Vcc
C1
Tone Enable control
TTL
C8
220nF
Vcc-L
{I2C Bus
SDA
SCL
ADDR
DSQIN
P-GND
A-GND
PDC
TTX
ISEL
Byp
R9
1.5KOhm
C15
47nF
to LNB
500mA max
C10
220nF
D2
C11
220nF
R2 (RSEL)
15kOhm
Figure 4. DiSEqC 1.x using internal 22 kHz tone generator and "optional" PDC circuit
D3
Vin
12V
C4
470nF
D1
L1
Vup
C3 C6
470nF
LX
VoTX
LNBH23L
EXTM
VoRX
Vcc
C1
Tone Enable control
TTL
C8
220nF
Vcc-L
{I2C Bus
SDA
SCL
ADDR
DSQIN
P-GND
A-GND
PDC
TTX
ISEL
Byp
R9
1.5KOhm
C15
47nF
to LNB
500mA max
C10
220nF
D2
Diode
1N4148
*R5
2.2K Ohm
3.3V
*C14
1nF
*R8
150 Ohm
*TR1
*R7
22 Ohm
(*) OPTIONAL components.
To be used only in case
of heavy capacitive load
C11
220nF
R2 (RSEL)
15kOhm
Doc ID 15335 Rev 4
11/25
11 Page | ||
| Páginas | Total 25 Páginas | |
| PDF Descargar | [ Datasheet LNBH23L.PDF ] | |
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