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參數(shù)資料
| 型號： | LNBS21PD |
| 廠商： | 意法半導(dǎo)體 |
| 英文描述： | LNB SUPPLY AND CONTROL IC WITH STEP-UP CONVERTER AND I2C INTERFACE |
| 中文描述： | LNB電源與控制集成電路升壓轉(zhuǎn)換器和I2C接口 |
| 文件頁數(shù)： | 2/19頁 |
| 文件大?。?/td> | 637K |
| 代理商： | LNBS21PD |
LNBS21
2/19
post-regulator to work at a minimum dissipated
power. An UnderVoltage Lockout circuit
disable the whole circuit when the supplied V
CC
drops below a fixed threshold (6.7V typically). The
internal 22KHz tone generator is factory trimmed
in accordance to the standards, and can be
controlled either by the I
2
C
TM
dedicated pin (DSQIN) that allows immediate
DiSEqC
TM
data encoding (*). All the functions of
this IC are controlled via I
2
C
TM
bus by writing 6
bits on the System Register (SR, 8 bits) . The
same register can be read back, and two bits will
report the diagnostic status. When the IC is put in
Stand-by (EN bit LOW), the
disabled
and the loop-through switch between
LT1 and LT2 pins is closed, thus leaving all LNB
powering and control
functions to the Master
Receiver (**). When the regulator blocks are
active (EN bit HIGH), the output can be logic
controlled to be 13 or 18 V (typ.) by mean of the
VSEL bit (Voltage SELect) for remote controlling
of non-DiSEqC LNBs. Additionally, it is possible
to increment by 1V (typ.) the selected voltage
value to compensate for the excess voltage drop
along the coaxial cable (LLC bit HIGH). In order to
minimise the power dissipation, the output voltage
of the internal step-up converter is adjusted to
allow the linear regulator to work at minimum
dropout. Another bit of the SR is addressed to the
remote control of non-DiSEqC LNBs: the TEN
(Tone ENable) bit. When it is set to HIGH, a
continuous 22KHz tone is generated regardless
of the DSQIN pin logic status. The TEN bit must
be set LOW when the DSQIN pin is used for
DiSEqC
TM
encoding. The fully bi-directional
DiSEqC
TM
interfacing is completed by the built-in
22KHz tone detector. Its input pin (DETIN) must
be AC coupled to the DiSEqC
TM
extracted
PWK
data
DSQOUT pin (*).
will
interface or by a
power blocks are
bus, and the
available
are
on
the
In order to improve design flexibility and to allow
implementation of newcoming LNB remote control
standards, an analogic modulation input pin is
available (EXTM). An appropriate DC blocking
capaci-tor 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.
The current limitation block has two thresholds
that can be selected by the I
SEL
bit of the SR; the
lower threshold is between 650 and 900mA
(I
SEL
=HIGH),
while
the
between 750 and 1000mA (I
SEL
=LOW).
The current protection block is SOA type. This
limits the short circuit current (Isc) typically at
300mA with I
SEL
=HIGH and at 400mA with
I
SEL
=LOW when the output port is connected to
ground.
higher
threshold
is
It is possible to set the Short Circuit Current
protection either statically (simple current clamp)
or dy-namically by the PCL bit of the SR; when
the PCL (Pulsed Current Limiting) bit is set to
LOW, the overcurrent protection circuit works
dynamically: as soon as an overload is detected,
the output is shut-down for a time t
off
, typically
900ms. Simultaneously the OLF bit of the System
Register is set to HIGH. After this time has
elapsed, the output is resumed for a time t
on
=1/
10t
off
(typ.). At the end of t
on
, if the overload is still
detected, the protection circuit will cycle again
through Toff and Ton. At the end of a full Ton in
which no overload is detected, normal operation is
resumed and the OLF bit is reset to LOW. Typical
Ton+Toff time is 990ms and it is determined by an
internal timer. This dynamic operation can greatly
reduce the power dissipation in short circuit
condition, still ensuring excellent power-on start
up in most conditions (**) .
However, there could be some cases in which an
highly capacitive load on the output may cause a
difficult start-up when the dynamic protection is
chosen. This can be solved by initiating any power
start-up in
static mode (PCL=HIGH) and then
switching to the dynamic mode (PCL=LOW) after
a chosen amount of time. When in static mode,
the OLF bit goes HIGH when the current clamp
limit is reached and returns LOW when the
overload condition is cleared.
This IC is also protected against overheating:
when the junction temperature exceeds 150°C
(typ.), the step-up converter and the linear
regulator are shut off, the loop-trough switch is
opened, and the OTF bit of the SR is set to HIGH.
Normal operation is resumed and the OTF bit is
reset to LOW when the junction is cooled down to
140°C (typ.).
(*): External components are needed to comply to bi-directional DiSEqC
TM
bus hardware require-ments. Full compliance of the whole appli-
cation to DiSEqC
TM
specifications is not implied by the use of this IC.
(**): The current limitation circuit has no effect on the loop-through switch. When EN bit is LOW, the current flowing from LT1 to LT2 must
be externally limited.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| LNBS21PD-TR | 功能描述:其他電源管理 LNB Supply/Cont IC RoHS:否 制造商:Texas Instruments 輸出電壓范圍: 輸出電流:4 mA 輸入電壓范圍:3 V to 3.6 V 輸入電流: 功率耗散: 工作溫度范圍:- 40 C to + 110 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-48 封裝:Reel |
| LNBTVS3-220 | 功能描述:TVS 二極管 - 瞬態(tài)電壓抑制器 3kV 1500W Ppp Lightning Protection RoHS:否 制造商:Vishay Semiconductors 極性:Bidirectional 工作電壓: 擊穿電壓:58.9 V 鉗位電壓:77.4 V 峰值浪涌電流:38.8 A 系列: 封裝 / 箱體:DO-214AB 最小工作溫度:- 55 C 最大工作溫度:+ 150 C |
| LNBTVS3-220S | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Lightning protection for LNB power supply |
| LNBTVS3-220U | 功能描述:TVS 二極管 - 瞬態(tài)電壓抑制器 3kV 1500W Ppp Lightning Protection RoHS:否 制造商:Vishay Semiconductors 極性:Bidirectional 工作電壓: 擊穿電壓:58.9 V 鉗位電壓:77.4 V 峰值浪涌電流:38.8 A 系列: 封裝 / 箱體:DO-214AB 最小工作溫度:- 55 C 最大工作溫度:+ 150 C |
| LNBTVS3-221 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Lightning protection for LNB power supply |
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