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| 型號(hào)： | AD8177ABPZ |
| 廠商： | Analog Devices Inc |
| 文件頁數(shù)： | 24/40頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC VIDEO CROSSPOINT SWIT 676BGA |
| 標(biāo)準(zhǔn)包裝： | 1 |
| 功能： | 視頻交叉點(diǎn)開關(guān) |
| 電路： | 3 x 16:5 |
| 電壓電源： | 單/雙電源 |
| 電壓 - 電源，單路/雙路(±)： | 4.5 V ~ 5.5 V，±2.5V |
| 電流 - 電源： | 460mA |
| 工作溫度： | -40°C ~ 85°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 676-BGA |
| 供應(yīng)商設(shè)備封裝： | 676-BGA（27x27） |
| 包裝： | 管件 |
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AD8177
Rev. 0 | Page 30 of 40
DIFFERENTIAL AND SINGLE-ENDED OPERATION
Although the AD8177 has fully differential inputs and outputs,
it can also be operated in a single-ended fashion. Single-ended
and differential configurations are discussed in the following
sections, along with implications on gain, impedances, and
terminations.
Differential Input
Each differential input to the AD8177 is applied to a differential
receiver. These receivers allow the user to drive the inputs with
an uncertain common-mode voltage, such as from a remote
source over twisted pair. The receivers respond only to the
differences in input voltages and restore an internal common-
mode suitable for the internal signal path. Noise or crosstalk,
which affect the inputs of each receiver equally, are rejected by
the input stage, as specified by its common-mode rejection ratio
(CMRR).
Furthermore, the overall common-mode voltage of all three
differential pairs comprising an RGB channel is processed and
rejected by a separate circuit block. For example, a static discharge
or a resistive voltage drop in a middle-of-Cat-5-run with sync-
on CM signaling coupling into all three pairs in an RGB channel
are rejected at the output of the AD8177, and the sync-on
CM signals are allowed through the switch.
The circuit configuration used by the differential input receivers
is similar to that of several Analog Devices general-purpose
differential amplifiers, such as the AD8131. The topology is that
of a voltage-feedback amplifier with internal gain resistors. The
input differential impedance for each receiver is 5 kΩ in parallel
with 10 kΩ or 3.33 kΩ, as shown in Figure 50.
IN+
IN–
RG
RCM
RCVR
RF
OUT–
OUT+
TO SWITCH
MATRIX
0
660
5-
0
23
Figure 50. Input Receiver Equivalent Circuit
This impedance creates a small differential termination error
if the user does not account for the 3.33 kΩ parallel element.
However, this error is less than 1% in most cases. Additionally,
the source impedance driving the AD8177 appears in parallel
with the internal gain-setting resistors, such that there may be
a gain error for some values of source resistance. The AD8177
is adjusted such that its gain is correct when driven by a back-
terminated Cat-5 cable (25 Ω effective impedance to ground at
each input pin, or 100 Ω differential source impedance across
pairs of input pins). If a different source impedance is presented,
the differential gain of the AD8177 can be calculated as
S
dm
R
G
+
=
kΩ
5
.
2
kΩ
525
.
2
where RS is the effective impedance to ground at each input pin.
When operating with a differential input, care must be taken to
keep the common-mode, or average, of the input voltages
within the linear operating range of the AD8177 receiver. For
the AD8177 receiver, this common-mode range can extend rail-
to-rail, provided the differential signal swing is small enough to
avoid forward biasing the ESD diodes (it is safest to keep the
common-mode plus differential signal excursions within the
supply voltages of the part).
The input voltage of the AD8177 is linear for ±1 V of differential
input voltage difference (this limitation is primarily due to
ability of the output to swing close to the rails because the
differential gain through the part is +2). Beyond this level,
the signal path saturates and limits the signal swing. This is not
a desired operation, because the supply current increases and
the signal path is slow to recover from clipping. The absolute
maximum allowed differential input signal is limited by long-
term reliability of the input stage. The limits in the Absolute
Maximum Ratings section of the data sheet should be observed
to avoid degrading device performance permanently.
AC Coupling of Inputs
It is possible to ac-couple the inputs of the AD8177 receiver,
so that bias current does not need to be supplied externally.
A capacitor in series with the inputs to the AD8177 creates
a high-pass filter with the input impedance of the device. This
capacitor needs to be sized large enough so that the corner
frequency includes all frequencies of interest.
Single-Ended Input
The AD8177 input receiver can be driven single-endedly
(unbalanced). Single-ended inputs apply a component of
common-mode signal to the receiver inputs, which is then
rejected by the receiver (see the Specifications section for
common-mode-to-differential-mode ratio of the part).
The single-ended input resistance, RIN, differs from the
differential input impedance, and is equal to
)
(
2
1
F
G
F
G
IN
R
+
×
=
Note that this value is smaller than the differential input
resistance, but it is larger than RG. The difference is due to the
component of common-mode level applied to the receiver by
single-ended inputs. A second, smaller component of input
inputs in both single-ended and differential operation.
In single-ended operation, an input is driven, and the undriven
input is often tied to midsupply or ground. Because signal-
frequency current flows at the undriven input, such input
should be treated as a signal line in the board design.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD8177-EVALZ | 制造商:AD 制造商全稱:Analog Devices 功能描述:500 MHz, Triple 16 】 5 Video Crosspoint Switch |
| AD8178 | 制造商:AD 制造商全稱:Analog Devices 功能描述:450 MHz, Triple 16 】 5 Video Crosspoint Switch |
| AD8178ABPZ | 功能描述:IC VIDEO CROSSPOINT SWIT 676BGA RoHS:是 類別:集成電路 (IC) >> 接口 - 模擬開關(guān)，多路復(fù)用器，多路分解器 系列:- 其它有關(guān)文件:STG4159 View All Specifications 標(biāo)準(zhǔn)包裝:5,000 系列:- 功能:開關(guān) 電路:1 x SPDT 導(dǎo)通狀態(tài)電阻:300 毫歐 電壓電源:雙電源 電壓 - 電源，單路/雙路(±):±1.65 V ~ 4.8 V 電流 - 電源:50nA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:7-WFBGA，F(xiàn)CBGA 供應(yīng)商設(shè)備封裝:7-覆晶 包裝:帶卷 (TR) |
| AD8178ABPZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:450 MHz, Triple 16 】 5 Video Crosspoint Switch |
| AD8178-EVALZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:450 MHz, Triple 16 】 5 Video Crosspoint Switch |
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