DataSheet8.cn


PDF ( 数据手册 , 数据表 ) AD8142

零件编号 AD8142
描述 Triple Differential Drivers
制造商 Analog Devices
LOGO Analog Devices LOGO 


1 Page

No Preview Available !

AD8142 数据手册, 描述, 功能
Data Sheet
Low Cost, Triple Differential Drivers
for Wideband Video
AD8141/AD8142
FEATURES
Triple, high speed differential drivers
255 MHz, −3 dB large signal bandwidth
65 MHz, 0.1 dB flatness
1150 V/µs slew rate
12 ns settling time
Single 5 V or split supply operation
Fixed gain of 2
Internal common-mode feedback network
Output balance error −50 dB at 50 MHz
AD8142 has integrated sync-on-common-mode circuitry
High-Z output when disabled
Differential-to-differential or single-ended-to-differential
operation
High isolation between amplifiers: −100 dB at 10 MHz
Low power: 44 mA at 5 V
Available in space-saving packaging: 4 mm × 4 mm LFCSP
FUNCTIONAL BLOCK DIAGRAMS
DIS 1
VS–/GND 2
–IN A 3
+IN A 4
VS–/GND 5
–OUT A 6
24 23 22 21 20 19
+–
AD8141
–+
–+
18 VOCMC
17 VS+
16 –IN C
15 +IN C
14 VS–/GND
13 –OUT C
7 8 9 10 11 12
Figure 1.
APPLICATIONS
Keyboard-video-mouse (KVM) networking
Video distribution
Digital signage
Security cameras
GENERAL DESCRIPTION
The AD8141 and AD8142 are triple, low cost, differential or
single-ended-input-to-differential-output drivers. Each amplifier
has a fixed gain of 2 to compensate for the attenuation of the
line termination resistors. The AD8141 and AD8142 are
specifically designed for RGB signals but can be used for any
type of signals. The amplifiers have very fast slew rate and
settling time while being manufactured on a cost effective
CMOS process. They are optimized for high resolution video
performance with a 0.1 dB flatness of 65 MHz, which allows
driving high resolution video over any type of UTP cable.
The drivers have an internal common-mode feedback loop
that provides output amplitude and phase matching, achieving
−50 dB balance error at 50 MHz and thereby suppressing even-
order harmonics and minimizing radiated electromagnetic
interference (EMI).
24 23 22 21 20 19
AD8142
DIS 1
VS–/GND 2
–IN R 3
+IN R 4
VS–/GND 5
–OUT R 6
×2
+– –+ –+
18 SYNC LEVEL
17 VS+
16 –IN B
15 +IN B
14 VS–/GND
13 –OUT B
7 8 9 10 11 12
Figure 2.
The AD8142 includes a unique sync-on-common-mode feature
that allows the user to transmit balanced horizontal and vertical
video sync signals over the three common-mode channels.
Additionally, the AD8141 and AD8142 both have a disable
feature that, when asserted, produces high-Z outputs, allowing
line isolation and easy multiplexing.
The AD8141 and AD8142 are available in a 24-lead 4 mm × 4 mm
LFCSP and operate over a temperature range of −40°C to +85°C.
They can be used with the AD8145 triple differential-to-single-
ended receiver, AD8123 triple equalizer, AD8120 triple delay
line, and the AD8117 or AD8175 crosspoint switches to produce
a high resolution video distribution system.
Rev. A
Document Feedback
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibilityisassumedbyAnalogDevices for itsuse,nor foranyinfringementsofpatentsor other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2011–2013 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com







AD8142 pdf, 数据表
AD8141/AD8142
Data Sheet
TYPICAL PERFORMANCE CHARACTERISTICS
VS+ = 5 V, VS− = 0 V, RL,dm = 200 Ω, TA = 25°C, VOCM = 1.5 V (AD8141), HSYNC, VSYNC, and SYNC LEVEL = 0 V (AD8142), unless otherwise noted.
9
VOUT, dm = 200mV p-p
9
VOUT, dm = 2V p-p
66
33
00
–3
AD8141
AD8142
–6
1 10 100
FREQUENCY (MHz)
Figure 6. Small Signal Frequency Response
1k
9
VOUT, dm = 200mV p-p
6
3
0
–3
–6
–9
–12
1
10 100
FREQUENCY (MHz)
1k
Figure 7. Small Signal Frequency Response at VOCM = 2.5 V (AD8141)
6.7
VOUT, dm = 200mV p-p
6.6
6.5
6.4
6.3
6.2
6.1
6.0
5.9
5.8
5.7
1
AD8141
AD8142
10 100
FREQUENCY (MHz)
Figure 8. Small Signal 0.1 dB Flatness
1k
–3
AD8141
AD8142
–6
1 10 100
FREQUENCY (MHz)
Figure 9. Large Signal Frequency Response
1k
9
VOUT, dm = 2V p-p
6
3
0
–3
–6
–9
–12
1
10 100
FREQUENCY (MHz)
1k
Figure 10. Large Signal Frequency Response at VOCM = 2.5 V (AD8141)
6.7
VOUT, dm = 2V p-p
6.6
6.5
6.4
6.3
6.2
6.1
6.0
5.9
5.8
5.7
1
AD8141
AD8142
10 100
FREQUENCY (MHz)
Figure 11. Large Signal 0.1 dB Flatness
1k
Rev. A | Page 8 of 24







AD8142 equivalent, schematic
AD8141/AD8142
Data Sheet
INPUT COMMON-MODE VOLTAGE RANGE IN
SINGLE-SUPPLY APPLICATIONS
The driver inputs are designed to facilitate level-shifting of ground
referenced input signals on a single power supply. For a single-
ended input, this implies, for example, that the voltage at VIN in
Figure 36 is 0 V when the amplifier’s negative power supply
voltage is also set to 0 V.
It is important to ensure that the common-mode voltage at the
amplifier inputs, VAP and VAN, stays within its specified range.
Because the VAP and VAN voltages are driven to be essentially
equal by negative feedback, the amplifier’s input common-mode
voltage can be expressed as a single term, VACM. VACM can be
calculated as
VACM
=
VOCM
+ 2VICM
3
where VICM is the common-mode voltage of the input signal,
that is,
VICM
=
VIP
+ VIN
2
TERMINATING A SINGLE-ENDED INPUT
Each driver has a nominal fixed gain of 2, with RF = 2.0 kΩ and
RG = 1.0 kΩ. A typical single-ended video signal source applied to
the AD8141/AD8142 input has a maximum terminated output
voltage of 0.7 V p-p and source resistance of 75 Ω. Because the
terminated output voltage of the source is 0.7 V p-p, the open-
circuit output voltage of the source is 1.4 V p-p. The source shown
in Figure 37 indicates this open-circuit voltage. The following
three steps illustrate how to terminate a signal from a typical
single-ended 75 Ω video source.
1. The single-ended input impedance is calculated as
RIN = 1.5 kΩ.
VIDEO SOURCE
RS
75Ω
VS
1.4V p-p
RIN
1.5kΩ
RG
1kΩ
RG
1kΩ
RF
2kΩ
+5V
+
AD8141/
AD8142
RL VOUT, dm
VS
1.4V p-p
RS
75Ω
RIN
75Ω
RT
80.6Ω
RG
1kΩ
RG
1kΩ
RF
2kΩ
+VS
+
AD8141/
AD8142
RL VOUT, dm
–VS
RF
2kΩ
Figure 38. Adding Termination Resistor RT
3. It can be seen from Figure 38 that the effective RG in the
upper feedback loop is now greater than the RG in the
lower loop due to the addition of the termination resistors.
To compensate for the imbalance of the gain resistors, a
correction resistor (RTS) is added in series with RG in the
lower loop. RTS is the closest 1% resistor to the Thevenin
equivalent of the source resistance RS and the termination
resistance RT, equal to RS||RT.
VS
1.4V p-p
RS
75Ω
RT
80.6Ω
VTH
0.725V p-p
RTH
38.8Ω
Figure 39. Calculating the Thevenin Equivalent
RTH = RS||RT = 38.8 Ω, and RTS = 38.3 Ω. Note that VTH is
greater than 0.7 V p-p, which was obtained with RT = 75 Ω
alone. The modified circuit with the Thevenin equivalent of
the terminated source and RTS in the lower feedback loop is
shown in Figure 40.
RF
2kΩ
VTH
0.725V p-p
RTH
38.8Ω
RTS
38.3Ω
RG
1kΩ
RG
1kΩ
+VS
+
AD8141/
AD8142
–VS
RF
2kΩ
RL VOUT, dm
Figure 40. Thevenin Equivalent and Matched Gain Resistors
RF Figure 40 presents a tractable circuit with matched feedback
2kΩ loops that can be easily evaluated.
Figure 37. Calculating Single-Ended Input Impedance, RIN
2. To match the 75 Ω source resistance, the termination resistor,
RT, is calculated using RT||1.125 kΩ = 75 Ω. The closest
standard 1% value for RT is 80.6 Ω.
It is useful to point out two effects that occur with a terminated
input. The first is that the value of RG is increased in both loops,
lowering the overall closed-loop gain. The second is that VTH is
a little larger than 0.7 V p-p, as it is if RT = 75 Ω alone. These
two effects have opposite impacts on the output voltage, and for
large resistor values in the feedback loops, the effects essentially
cancel each other out. For smaller RF and RG, however, the
diminished closed-loop gain is not canceled completely by the
increased VTH.
Rev. A | Page 16 of 24










页数 24 页
下载[ AD8142.PDF 数据手册 ]


分享链接

Link :

推荐数据表

零件编号描述制造商
AD8141Triple Differential DriversAnalog Devices
Analog Devices
AD8142Triple Differential DriversAnalog Devices
Analog Devices
AD8143Triple Differential ReceiverAnalog Devices
Analog Devices
AD8145Triple Differential ReceiverAnalog Devices
Analog Devices

零件编号描述制造商
STK15C88256-Kbit (32 K x 8) PowerStore nvSRAMCypress Semiconductor
Cypress Semiconductor
NJM4556DUAL HIGH CURRENT OPERATIONAL AMPLIFIERNew Japan Radio
New Japan Radio
EL1118-G5 PIN LONG CREEPAGE SOP PHOTOTRANSISTOR PHOTOCOUPLEREverlight
Everlight


DataSheet8.cn    |   2020   |  联系我们   |   搜索  |  Simemap