AD AD8178 Video crosspoint switch Datasheet

450 MHz, Triple 16 × 5
Video Crosspoint Switch
AD8178
FEATURES
RGB video switching
KVM
Professional video
D0 D1 D2 D3 D4 VPOS VNEG VDD
DGND
AD8178
A0
A1
A2
SERIN
CLR
SER/PAR
1
CLK
0
45-BIT SHIFT
REGISTER WITH
5-BIT PARALLEL
LOADING
25
CS
UPDATE
SEROUT
20
NO
CONNECT
SET INDIVIDUAL, OR
RESET ALL OUTPUTS TO OFF
WE
PARALLEL LATCH
RST
CMENC
25
5
DECODE
5 × 5:16 DECODERS
INPUT
RECEIVER
G = +2
R
G
B
80
OUTPUT
BUFFER
G = +1
2
2
2
2
2
2
R
G
B
R
G
B
2
V
2
2
2
2
2
5 x RGB, HV
CHANNELS
SWITCH
MATRIX
G = +2
ENABLE/DISABLE
H
R
G
B
H
V
VBLK
VOCM_CMENCON
VOCM_CMENCOFF
06608-001
APPLICATIONS
FUNCTIONAL BLOCK DIAGRAM
16 x RGB
CHANNELS
Large, triple 16 × 5 high speed, nonblocking switch array
Pin compatible with the AD8175 and AD8176 (16 × 9 switch
arrays) and the AD8177 (16 × 5 switch array)
Differential or single-ended operation
Supports sync-on common-mode and sync-on color
operating modes
RGB and HV outputs available for driving monitor directly
G = +4 operation (differential input to differential output)
Flexible power supplies: +5 V or ±2.5 V
Logic ground for convenient control interface
Serial or parallel programming of switch array
High impedance output disable allows connection of
multiple devices with minimal loading on output bus
Adjustable output CM and black level through external pins
Excellent ac performance
Bandwidth: 450 MHz
Slew rate: 1650 V/μs
Settling time: 4 ns to 1% to support 1600 × 1200 @ 85Hz
Low power of 2.3 W
Low all hostile crosstalk
−82 dB @ 5 MHz
−47 dB @ 500 MHz
Wide input common-mode range of 4 V
Reset pin allows disabling of all outputs
Fully populated 26 × 26 ball PBGA package
(27 mm × 27 mm, 1 mm ball pitch)
Convenient grouping of RGB signals for easy routing
Figure 1.
GENERAL DESCRIPTION
The AD8178 is a high speed, triple 16 × 5 video crosspoint switch
matrix. It supports 1600 × 1200 RGB displays @ 85 Hz refresh rate,
by offering a 450 MHz bandwidth and a slew rate of 1650 V/μs.
With −82 dB of crosstalk and −90 dB isolation (@ 5 MHz), the
AD8178 is useful in many high speed video applications.
The AD8178 supports two modes of operation: differential-in
to differential-out mode with sync-on CM signaling passed
through the switch and differential-in to differential-out mode
with CM signaling removed through the switch. The output CM
and black level can be conveniently set via external pins.
The outputs can be used single-ended in conjunction with
decoded H and V outputs to drive a monitor directly.
The independent output buffers of the AD8178 can be placed
into a high impedance state to create larger arrays by paralleling
crosspoint outputs. Inputs can be paralleled as well. The AD8178
offers both serial and a parallel programming modes.
The AD8178 is packaged in a fully-populated 26 × 26 ball
PBGA package and is available over the extended industrial
temperature range of −40°C to +85°C.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or 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.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
AD8178
TABLE OF CONTENTS
Features .............................................................................................. 1
Pin Configurations and Function Descriptions ............................8
Applications....................................................................................... 1
Truth Table and Logic Diagram ............................................... 17
Functional Block Diagram .............................................................. 1
Equivalent Circuits......................................................................... 19
General Description ......................................................................... 1
Typical Performance Characteristics ........................................... 21
Revision History ............................................................................... 2
Theory of Operation ...................................................................... 26
Specifications..................................................................................... 3
Applications Information .............................................................. 27
Timing Characteristics (Serial Mode) ....................................... 5
Operating Modes........................................................................ 27
Timing Characteristics (Parallel Mode) .................................... 6
Programming.............................................................................. 28
Absolute Maximum Ratings............................................................ 7
Differential and Single-Ended Operation............................... 29
Thermal Resistance ...................................................................... 7
Outline Dimensions ....................................................................... 38
Power Dissipation......................................................................... 7
Ordering Guide .......................................................................... 38
ESD Caution.................................................................................. 7
REVISION HISTORY
7/07—Revision 0: Initial Version
Rev. 0 | Page 2 of 40
AD8178
SPECIFICATIONS
VS = ± 2.5 V at TA = 25°C, G = +4, RL = 100 Ω (each output), VBLK = 0 V, output CM voltage = 0 V, differential I/O mode, unless
otherwise noted.
Table 1.
Parameter
DYNAMIC PERFORMANCE
−3 dB Bandwidth
Gain Flatness
Propagation Delay
Settling Time
Slew Rate, Differential Output
Slew Rate, RGB Common Mode
Slew Rate, HV Outputs
NOISE/DISTORTION PERFORMANCE
Crosstalk, All Hostile
Off Isolation, Input-Output
Input Voltage Noise
DC PERFORMANCE
Gain Error
Gain Matching
Gain Temperature Coefficient
OUTPUT CHARACTERISTICS
Output Offset Voltage
Output Offset Voltage,
RGB Common Mode
Output Impedance
Output Disable Capacitance
Output Leakage Current
Output Voltage Range
Output Current
INPUT CHARACTERISTICS
Input Voltage Range,
Differential Mode
Input Voltage Range,
Common Mode
CMR, RGB Input
CM Gain, RGB Input
Input Capacitance
Input Resistance
Input Offset Current
Conditions
Min
Typ
Max
Unit
200 mV p-p
2 V p-p
0.1 dB, 200 mV p-p
2 V p-p
1% , 2 V step
2 V step
2 V step, 10% to 90%
1 V step , 10% to 90%
Rail-to-rail, TTL load
450
420
17
1.3
4
1650
1450
300
400
MHz
MHz
MHz
ns
ns
V/μs
V/μs
V/μs
V/μs
f = 5 MHz
f = 10 MHz
f = 100 MHz
f = 500 MHz
f = 10 MHz, RL = 100 Ω, one channel
0.01 MHz to 50 MHz
−82
−74
−56
−47
−90
50
dB
dB
dB
dB
dB
nV/√Hz
R, G, B same channel
1
0.5
32
%
%
ppm/°C
CMENC on or off
Temperature coefficient
CMENC on or off
20
58
10
mV
μV/°C
mV
Temperature coefficient
Enabled, differential
Disabled, differential
Disabled
Disabled
No load, differential
Short circuit
−16
1.5
2.7
2
1
μV/°C
Ω
kΩ
pF
μA
V p-p
mA
4
45
1
V p-p
VIN = 1 V p-p
±2.25
V p-p
ΔVOUT, DM/ΔVIN, CM, ΔVIN, CM = ±0.5 V, CMENC off
ΔVOUT, DM/ΔVIN, CM, ΔVIN, CM = ±0.5 V, CMENC on
ΔVOUT, CM/ΔVIN, CM, ΔVIN, CM = ±0.5 V CMENC off
ΔVOUT, CM/ΔVIN, CM, ΔVIN, CM = ±0.5 V, CMENC on
Any switch configuration
Differential
–62
−45
−70
0
2
3.33
1
dB
dB
dB
dB
pF
kΩ
μA
Rev. 0 | Page 3 of 40
AD8178
Parameter
SWITCHING CHARACTERISTICS
Enable On Time
Switching Time, 2 V Step
POWER SUPPLIES
Supply Current
Supply Voltage Range
PSR
OPERATING TEMPERATURE RANGE
Temperature Range
θJA
Conditions
Min
Typ
Max
Unit
50% UPDATE to 50% output
50% UPDATE to 50% output
80
70
ns
ns
VPOS, outputs enabled, no load
Outputs disabled
VNEG, outputs enabled, no load
Outputs disabled
DVDD, outputs enabled, no load
ΔVOUT, DM/ΔVPOS, ΔVPOS = ±0.5 V
ΔVOUT, DM/ΔVNEG, ΔVNEG = ±0.5 V
460
290
460
290
4
4.5 to 5.5
−55
−55
mA
mA
mA
mA
mA
V
dB
dB
Operating (still air)
Operating (still air)
−40 to +85
15
°C
°C/W
Rev. 0 | Page 4 of 40
AD8178
TIMING CHARACTERISTICS (SERIAL MODE)
Table 2.
Parameter
Serial Data Setup Time
CLK Pulse Width
Serial Data Hold Time
CLK Pulse Separation
CLK to UPDATE Delay
UPDATE Pulse Width
CLK to SEROUT Valid
Propagation Delay, UPDATE to Switch On
Data Load Time, CLK = 5 MHz, Serial Mode
RST Time
Symbol
t1
t2
t3
t4
t5
t6
t7
Min
40
60
50
140
10
90
120
Limit
Typ
Max
Unit
ns
ns
ns
ns
ns
ns
ns
ns
μs
ns
80
9
140
t2
1
200
t4
CLK
LOAD DATA INTO
SERIAL REGISTER
ON FALLING EDGE
0
t1
t3
1
SERIN
OUT4 (D4)
OUT4 (D3)
OUT0 (D0)
0
t5
1 = LATCHED
t6
TRANSFER DATA FROM SERIAL
REGISTER TO PARALLEL
LATCHES DURING LOW LEVEL
UPDATE
0 = TRANSPARENT
t7
06608-002
1
SEROUT
0
Figure 2. Timing Diagram, Serial Mode
Table 3. Logic Levels, VDD = 3.3 V
VIH
SER/PAR, CLK,
SERIN, UPDATE
VIL
SER/PAR, CLK,
SERIN, UPDATE
VOH
SEROUT
VOL
SEROUT
IIH
SER/PAR, CLK,
SERIN, UPDATE
IIL
SER/PAR, CLK,
SERIN, UPDATE
IOH
SEROUT
IOL
SEROUT
2.0 V min
0.6 V max
2.8 V min
0.4 V max
20 μA max
–20 μA max
–1 mA min
1 mA min
Table 4. H and V Logic Levels, VDD = 3.3 V
VOH
2.7 V min
VOL
0.5 V max
IOH
–3 mA max
IOL
3 mA max
IIH
−60 μA max
IIL
−120 μA max
IIH
100 μA max
IOL
40 μA max
Table 5. RST Logic Levels, VDD = 3.3 V
VIH
2.0 V min
VIL
0.6 V max
Table 6. CS Logic Levels, VDD = 3.3 V
VOH
2.0 V min
VOL
0.6 V max
Rev. 0 | Page 5 of 40
AD8178
TIMING CHARACTERISTICS (PARALLEL MODE)
Table 7.
Parameter
Parallel Data Setup Time
WE Pulse Width
Parallel Hold Time
WE Pulse Separation
WE to UPDATE Delay
UPDATE Pulse Width
Propagation Delay, UPDATE to Switch On
RST Time
Symbol
t1
t2
t3
t4
t5
t6
t2
1
Min
80
110
150
90
10
90
Limit
Typ
Max
80
140
200
Unit
ns
ns
ns
ns
ns
ns
ns
ns
t4
WE
0
t1
t3
1
D0 TO D4
A0 TO A2
0
t5
t6
06608-003
1 = LATCHED
UPDATE
0 = TRANSPARENT
Figure 3. Timing Diagram, Parallel Mode
Table 8. Logic Levels, VDD = 3.3 V
VIH
SER/PAR, WE,
D0, D1, D2, D3,
D4, A0, A1, A2,
A3, UPDATE
VIL
SER/PAR, WE,
D0, D1, D2, D3,
D4, A0, A1, A2,
A3, UPDATE
VOH
SEROUT
VOL
SEROUT
IIH
SER/PAR, WE,
D0, D1, D2, D3,
D4, A0, A1, A2,
A3, UPDATE
IIL
SER/PAR, WE,
D0, D1, D2, D3,
D4, A0, A1, A2,
A3, UPDATE
IOH
SEROUT
IOL
SEROUT
2.0 V min
0.6 V max
Disabled
Disabled
20 μA max
−20 μA max
Disabled
Disabled
Table 9. H and V Logic Levels, VDD = 3.3 V
VOH
2.7 V min
VOL
0.5 V max
IOH
–3 mA max
IOL
3 mA max
IIH
−60 μA max
IIL
−120 μA max
IIH
100 μA max
IOL
40 μA max
Table 10. RST Logic Levels, VDD = 3.3 V
VIH
2.0 V min
VIL
0.6 V max
Table 11. CS Logic Levels, VDD = 3.3 V
VOH
2.0 V min
VOL
0.6 V max
Rev. 0 | Page 6 of 40
AD8178
ABSOLUTE MAXIMUM RATINGS
POWER DISSIPATION
Table 12.
Parameter
Analog Supply Voltage (VPOS – VNEG)
Digital Supply Voltage (VDD – DGND)
Ground Potential Difference
(VNEG – DGND)
Maximum Potential Difference
(VDD – VNEG)
Common-Mode Analog Input Voltage
Differential Analog Input Voltage
Digital Input Voltage
Output Voltage
(Disabled Analog Output)
Output Short-Circuit Duration
Storage Temperature Range
Operating Temperature Range
Lead Temperature
(Soldering, 10 sec)
Junction Temperature
Rating
6V
6V
+0.5 V to –2.5 V
The AD8178 is operated with ±2.5 V or +5 V supplies and can
drive loads down to 100 Ω, resulting in a large range of possible
power dissipations. For this reason, extra care must be taken
when derating the operating conditions based on ambient
temperature.
8V
Packaged in a 676-lead BGA, the AD8178 junction-to-ambient
thermal impedance (θJA) is 15°C/W. For long-term reliability,
the maximum allowed junction temperature of the die should
not exceed 150°C. Temporarily exceeding this limit may cause
a shift in parametric performance due to a change in stresses
exerted on the die by the package. Exceeding a junction
temperature of 175°C for an extended period can result in
device failure. The curve in Figure 4 shows the range of allowed
internal die power dissipations that meet these conditions over
the −40°C to +85°C ambient temperature range. When using
Table 13, do not include external load power in the maximum
power calculation, but do include load current dropped on the
die output transistors.
(VNEG – 0.5 V) to
(VPOS + 0.5 V)
±2 V
VDD
(VPOS – 1 V) to (VNEG + 1 V)
Momentary
−65°C to +125°C
−40°C to +85°C
300°C
150°C
10
TJ = 150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
MAXIMUM DIE POWER (W)
9
THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
6
5
3
15
25
35
45
55
65
AMBIENT TEMPERATURE (°C)
Unit
°C/W
75
85
06608-004
θJA
15
7
4
Table 13. Thermal Resistance
Package Type
PBGA
8
Figure 4. Maximum Die Power Dissipation vs. Ambient Temperature
ESD CAUTION
Rev. 0 | Page 7 of 40
AD8178
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
A
VNEG
VNEG
VNEG
NC
NC
VNEG
OPR4
ONB4
VPOS
IPR8
INB8
VNEG
IPR9
INB9
VPOS
IPR10
INB10
VNEG
IPR11
INB11
VPOS
IPR12
INB12
VNEG
VNEG
VNEG
A
B
VNEG
VNEG
VNEG
NC
NC
VNEG
ONR4
OPB4
VPOS
INR8
IPB8
VNEG
INR9
IPB9
VPOS
INR10
IPB10
VNEG
INR11
IPB11
VPOS
INR12
IPB12
VNEG
VNEG
VNEG
B
C
VNEG
VNEG
VNEG
NC
NC
VNEG
OPG4
ONG4
VPOS
IPG8
ING8
VNEG
IPG9
ING9
VPOS
IPG10
ING10
VNEG
IPG11
ING11
VPOS
IPG12
ING12
VNEG
VNEG
VNEG
C
D
VNEG
VNEG
VNEG
NC
NC
VPOS
H4
V4
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
IPG13
INR13
IPR13
D
E
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VPOS
DGND
VDD
SEROUT
CS
CLK
SERIN
SER/PAR
A2
A1
A0
CLR
VDD
DGND
VPOS
VPOS
ING13
IPB13
INB13
E
F
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
F
G
ONB3
OPB3
ONG3
V3
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
G
H
OPR3
ONR3
OPG3
H3
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
IPG14
INR14
IPR14
H
J
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
ING14
IPB14
INB14
J
K
NC
NC
NC
NC
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
K
L
NC
NC
NC
NC
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
IPG15
INR15
IPR15
L
M
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
ING15
IPB15
INB15
M
N
ONB2
OPB2
ONG2
V2
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VOCM_
CMENCON
VPOS
VPOS
VPOS
VPOS
N
P
OPR2
ONR2
OPG2
H2
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VBLK
VPOS
VPOS
VPOS
VPOS
P
R
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VOCM_
CMENCOFF
VPOS
IPG7
INR7
IPR7
R
T
NC
NC
NC
NC
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
ING7
IPB7
INB7
T
U
NC
NC
NC
NC
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
U
V
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
IPG6
INR6
IPR6
V
W
ONB1
OPB1
ONG1
V1
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
ING6
IPB6
INB6
W
Y
OPR1
ONR1
OPG1
H1
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
Y
AA
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
AA
AB
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VPOS
DGND
VDD
RST
UPDATE
WE
CMENC
D4
D3
D2
D1
D0
VDD
DGND
VPOS
VPOS
IPG5
INR5
IPR5
AB
AC
VNEG
VNEG
VNEG
NC
NC
VPOS
V0
H0
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
ING5
IPB5
INB5
AC
AD
VNEG
VNEG
VNEG
NC
NC
VPOS
ONG0
OPG0
VNEG
ING0
IPG0
VPOS
ING1
IPG1
VNEG
ING2
IPG2
VPOS
ING3
IPG3
VNEG
ING4
IPG4
VNEG
VNEG
VNEG
AD
AE
VNEG
VNEG
VNEG
NC
NC
VPOS
OPB0
ONR0
VNEG
IPB0
INR0
VPOS
IPB1
INR1
VNEG
IPB2
INR2
VPOS
IPB3
INR3
VNEG
IPB4
INR4
VNEG
VNEG
VNEG
AE
AF
VNEG
VNEG
VNEG
NC
NC
VPOS
ONB0
OPR0
VNEG
INB0
IPR0
VPOS
INB1
IPR1
VNEG
INB2
IPR2
VPOS
INB3
IPR3
VNEG
INB4
IPR4
VNEG
VNEG
VNEG
AF
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
Figure 5. Pin Configuration, Package Bottom View
Rev. 0 | Page 8 of 40
06608-055
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
A
VNEG
VNEG
VNEG
INB12
IPR12
VPOS
INB11
IPR11
VNEG
INB10
IPR10
VPOS
INB9
IPR9
VNEG
INB8
IPR8
VPOS
ONB4
OPR4
VNEG
NC
NC
VNEG
VNEG
VNEG
A
B
VNEG
VNEG
VNEG
IPB12
INR12
VPOS
IPB11
INR11
VNEG
IPB10
INR10
VPOS
IPB9
INR9
VNEG
IPB8
INR8
VPOS
OPB4
ONR4
VNEG
NC
NC
VNEG
VNEG
VNEG
B
C
VNEG
VNEG
VNEG
ING12
IPG12
VPOS
ING11
IPG11
VNEG
ING10
IPG10
VPOS
ING9
IPG9
VNEG
ING8
IPG8
VPOS
ONG4
OPG4
VNEG
NC
NC
VNEG
VNEG
VNEG
C
D
IPR13
INR13
IPG13
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
V4
H4
VPOS
NC
NC
VNEG
VNEG
VNEG
D
E
INB13
IPB13
ING13
VPOS
VPOS
DGND
VDD
CLR
A0
A1
A2
SER/PAR
SERIN
CLK
CS
SEROUT
VDD
DGND
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
E
F
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
F
G
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
V3
ONG3
OPB3
ONB3
G
H
IPR14
INR14
IPG14
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
H3
OPG3
ONR3
OPR3
H
J
INB14
IPB14
ING14
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
J
K
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
NC
NC
K
L
IPR15
INR15
IPG15
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
NC
NC
L
M
INB15
IPB15
ING15
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
M
VPOS
VOCM_
CMENCON
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
V2
ONG2
OPB2
ONB2
N
N
VPOS
VPOS
VPOS
P
VPOS
VPOS
VPOS
VPOS
VBLK
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
H2
OPG2
ONR2
OPR2
P
R
IPR7
INR7
IPG7
VPOS
VOCM_
CMENCOFF
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
R
T
INB7
IPB7
ING7
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
NC
NC
T
U
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
NC
NC
U
V
IPR6
INR6
IPG6
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
V
W
INB6
IPB6
ING6
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
V1
ONG1
OPB1
ONB1
W
Y
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
H1
OPG1
ONR1
OPR1
Y
AA
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
AA
AB
IPR5
INR5
IPG5
VPOS
VPOS
DGND
VDD
D0
D1
D2
D3
D4
CMENC
WE
UPDATE
RST
VDD
DGND
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
AB
AC
INB5
IPB5
ING5
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
H0
V0
VPOS
NC
NC
VNEG
VNEG
VNEG
AC
AD
VNEG
VNEG
VNEG
IPG4
ING4
VNEG
IPG3
ING3
VPOS
IPG2
ING2
VNEG
IPG1
ING1
VPOS
IPG0
ING0
VNEG
OPG0
ONG0
VPOS
NC
NC
VNEG
VNEG
VNEG
AD
AE
VNEG
VNEG
VNEG
INR4
IPB4
VNEG
INR3
IPB3
VPOS
INR2
IPB2
VNEG
INR1
IPB1
VPOS
INR0
IPB0
VNEG
ONR0
OPB0
VPOS
NC
NC
VNEG
VNEG
VNEG
AE
AF
VNEG
VNEG
VNEG
IPR4
INB4
VNEG
IPR3
INB3
VPOS
IPR2
INB2
VNEG
IPR1
INB1
VPOS
IPR0
INB0
VNEG
OPR0
ONB0
VPOS
NC
NC
VNEG
VNEG
VNEG
AF
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Figure 6. Pin Configuration, Package Top View
Rev. 0 | Page 9 of 40
06608-056
AD8178
AD8178
Table 14. Ball Grid Description
Ball No.
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18
A19
A20
A21
A22
A23
A24
A25
A26
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
B11
B12
B13
B14
B15
B16
B17
B18
B19
B20
B21
B22
B23
B24
B25
Mnemonic
VNEG
VNEG
VNEG
INB12
IPR12
VPOS
INB11
IPR11
VNEG
INB10
IPR10
VPOS
INB9
IPR9
VNEG
INB8
IPR8
VPOS
ONB4
OPR4
VNEG
NC
NC
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
IPB12
INR12
VPOS
IPB11
INR11
VNEG
IPB10
INR10
VPOS
IPB9
INR9
VNEG
IPB8
INR8
VPOS
OPB4
ONR4
VNEG
NC
NC
VNEG
VNEG
Description
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 12, Negative Phase.
Input Number 12, Positive Phase.
Positive Analog Power Supply.
Input Number 11, Negative Phase.
Input Number 11, Positive Phase.
Negative Analog Power Supply.
Input Number 10, Negative Phase.
Input Number 10, Positive Phase.
Positive Analog Power Supply.
Input Number 9, Negative Phase.
Input Number 9, Positive Phase.
Negative Analog Power Supply.
Input Number 8, Negative Phase.
Input Number 8, Positive Phase.
Positive Analog Power Supply.
Output Number 4, Negative Phase.
Output Number 4, Positive Phase.
Negative Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 12, Positive Phase.
Input Number 12, Negative Phase.
Positive Analog Power Supply.
Input Number 11, Positive Phase.
Input Number 11, Negative Phase.
Negative Analog Power Supply.
Input Number 10, Positive Phase.
Input Number 10, Negative Phase.
Positive Analog Power Supply.
Input Number 9, Positive Phase.
Input Number 9, Negative Phase.
Negative Analog Power Supply.
Input Number 8, Positive Phase.
Input Number 8, Negative Phase.
Positive Analog Power Supply.
Output Number 4, Positive Phase.
Output Number 4, Negative Phase.
Negative Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
Negative Analog Power Supply.
Ball No.
B26
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16
C17
C18
C19
C20
C21
C22
C23
C24
C25
C26
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
D16
D17
D18
D19
D20
D21
D22
D23
D24
Rev. 0 | Page 10 of 40
Mnemonic
VNEG
VNEG
VNEG
VNEG
ING12
IPG12
VPOS
ING11
IPG11
VNEG
ING10
IPG10
VPOS
ING9
IPG9
VNEG
ING8
IPG8
VPOS
ONG4
OPG4
VNEG
NC
NC
VNEG
VNEG
VNEG
IPR13
INR13
IPG13
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
V4
H4
VPOS
NC
NC
VNEG
Description
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 12, Negative Phase.
Input Number 12, Positive Phase.
Positive Analog Power Supply.
Input Number 11, Negative Phase.
Input Number 11, Positive Phase.
Negative Analog Power Supply.
Input Number 10, Negative Phase.
Input Number 10, Positive Phase.
Positive Analog Power Supply.
Input Number 9, Negative Phase.
Input Number 9, Positive Phase.
Negative Analog Power Supply.
Input Number 8, Negative Phase.
Input Number 8, Positive Phase.
Positive Analog Power Supply.
Output Number 4, Negative Phase.
Output Number 4, Positive Phase.
Negative Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 13, Positive Phase.
Input Number 13, Negative Phase.
Input Number 13, Positive Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 4, V Sync.
Output Number 4, H Sync.
Positive Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
AD8178
Ball No.
D25
D26
E1
E2
E3
E4
E5
E6
E7
E8
E9
E10
E11
E12
E13
E14
E15
E16
E17
E18
E19
E20
E21
E22
E23
E24
E25
E26
F1
F2
F3
F4
F5
F6
F7
F8
F9
F10
F11
F12
F13
F14
F15
F16
F17
F18
F19
F20
F21
F22
F23
F24
Mnemonic
VNEG
VNEG
INB13
IPB13
ING13
VPOS
VPOS
DGND
VDD
CLR
A0
A1
A2
SER/PAR
SERIN
CLK
CS
SEROUT
VDD
DGND
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
Description
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 13, Negative Phase.
Input Number 13, Positive Phase.
Input Number 13, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Digital Power Supply.
Digital Power Supply.
Internal Register Clearing
Control Pin 0, Output Address Bit 0.
Control Pin 1, Output Address Bit 1.
Control Pin 2, Output Address Bit 2.
Control Pin: Serial Parallel Select Mode.
Control Pin: Serial Data In.
Control Pin: Serial Data Clock.
Control Pin: Chip Select.
Control Pin: Serial Data Out.
Digital Power Supply.
Digital Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Ball No.
F25
F26
G1
G2
G3
G4
G5
G6
G7
G8
G9
G10
G11
G12
G13
G14
G15
G16
G17
G18
G19
G20
G21
G22
G23
G24
G25
G26
H1
H2
H3
H4
H5
H6
H7
H8
H9
H10
H11
H12
H13
H14
H15
H16
H17
H18
H19
H20
H21
H22
H23
H24
Rev. 0 | Page 11 of 40
Mnemonic
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
V3
ONG3
OPB3
ONB3
IPR14
INR14
IPG14
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
H3
OPG3
Description
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 3, V Sync.
Output Number 3, Negative Phase.
Output Number 3, Positive Phase.
Output Number 3, Negative Phase.
Input Number 14, Positive Phase.
Input Number 14, Negative Phase.
Input Number 14, Positive Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 3, H Sync.
Output Number 3, Positive Phase.
AD8178
Ball No.
H25
H26
J1
J2
J3
J4
J5
J6
J7
J8
J9
J10
J11
J12
J13
J14
J15
J16
J17
J18
J19
J20
J21
J22
J23
J24
J25
J26
K1
K2
K3
K4
K5
K6
K7
K8
K9
K10
K11
K12
K13
K14
K15
K16
K17
K18
K19
K20
K21
K22
K23
K24
Mnemonic
ONR3
OPR3
INB14
IPB14
ING14
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
Description
Output Number 3, Negative Phase.
Output Number 3, Positive Phase.
Input Number 14, Negative Phase.
Input Number 14, Positive Phase.
Input Number 14, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
No Connect.
No Connect.
Ball No.
K25
K26
L1
L2
L3
L4
L5
L6
L7
L8
L9
L10
L11
L12
L13
L14
L15
L16
L17
L18
L19
L20
L21
L22
L23
L24
L25
L26
M1
M2
M3
M4
M5
M6
M7
M8
M9
M10
M11
M12
M13
M14
M15
M16
M17
M18
M19
M20
M21
M22
M23
M24
Rev. 0 | Page 12 of 40
Mnemonic
NC
NC
IPR15
INR15
IPG15
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
NC
NC
INB15
IPB15
ING15
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
Description
No Connect.
No Connect.
Input Number 15, Positive Phase.
Input Number 15, Negative Phase.
Input Number 15, Positive Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
No Connect.
No Connect.
No Connect.
No Connect.
Input Number 15, Negative Phase.
Input Number 15, Positive Phase.
Input Number 15, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
AD8178
Ball No.
M25
M26
N1
N2
N3
N4
N5
N6
N7
N8
N9
N10
N11
N12
N13
N14
N15
N16
N17
N18
N19
N20
N21
N22
N23
N24
N25
N26
P1
P2
P3
P4
P5
P6
P7
P8
P9
P10
P11
P12
P13
P14
P15
P16
P17
P18
P19
P20
P21
P22
P23
P24
Mnemonic
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VOCM_
CMENCON
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
V2
ONG2
OPB2
ONB2
VPOS
VPOS
VPOS
VPOS
VBLK
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
H2
OPG2
Description
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output CM Reference with CM
Encoding On.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 2, V Sync.
Output Number 2, Negative Phase.
Output Number 2, Positive Phase.
Output Number 2, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Blank Level.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 2, H Sync.
Output Number 2, Positive Phase.
Ball No.
P25
P26
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R16
R17
R18
R19
R20
R21
R22
R23
R24
R25
R26
T1
T2
T3
T4
T5
T6
T7
T8
T9
T10
T11
T12
T13
T14
T15
T16
T17
T18
T19
T20
T21
T22
T23
T24
Rev. 0 | Page 13 of 40
Mnemonic
ONR2
OPR2
IPR7
INR7
IPG7
VPOS
VOCM_
CMENCOFF
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
INB7
IPB7
ING7
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
Description
Output Number 2, Negative Phase.
Output Number 2, Positive Phase.
Input Number 7, Positive Phase.
Input Number 7, Negative Phase.
Input Number 7, Positive Phase.
Positive Analog Power Supply.
Output Reference with CM
Encoding Off.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 7, Negative Phase.
Input Number 7, Positive Phase.
Input Number 7, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
No Connect.
No Connect.
AD8178
Ball No.
T25
T26
U1
U2
U3
U4
U5
U6
U7
U8
U9
U10
U11
U12
U13
U14
U15
U16
U17
U18
U19
U20
U21
U22
U23
U24
U25
U26
V1
V2
V3
V4
V5
V6
V7
V8
V9
V10
V11
V12
V13
V14
V15
V16
V17
V18
V19
V20
V21
V22
V23
V24
Mnemonic
NC
NC
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
NC
NC
NC
NC
IPR6
INR6
IPG6
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
VPOS
VPOS
Description
No Connect.
No Connect.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
No Connect.
No Connect.
No Connect.
No Connect.
Input Number 6, Positive Phase.
Input Number 6, Negative Phase.
Input Number 6, Positive Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Ball No.
V25
V26
W1
W2
W3
W4
W5
W6
W7
W8
W9
W10
W11
W12
W13
W14
W15
W16
W17
W18
W19
W20
W21
W22
W23
W24
W25
W26
Y1
Y2
Y3
Y4
Y5
Y6
Y7
Y8
Y9
Y10
Y11
Y12
Y13
Y14
Y15
Y16
Y17
Y18
Y19
Y20
Y21
Y22
Y23
Y24
Rev. 0 | Page 14 of 40
Mnemonic
VPOS
VPOS
INB6
IPB6
ING6
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
VPOS
VPOS
V1
ONG1
OPB1
ONB1
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
H1
OPG1
Description
Positive Analog Power Supply.
Positive Analog Power Supply.
Input Number 6, Negative Phase.
Input Number 6, Positive Phase.
Input Number 6, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 1, V Sync.
Output Number 1, Negative Phase.
Output Number 1, Positive Phase.
Output Number 1, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 1, H Sync.
Output Number 1, Positive Phase.
AD8178
Ball No.
Y25
Y26
AA1
AA2
AA3
AA4
AA5
AA6
AA7
AA8
AA9
AA10
AA11
AA12
AA13
AA14
AA15
AA16
AA17
AA18
AA19
AA20
AA21
AA22
AA23
AA24
AA25
AA26
AB1
AB2
AB3
AB4
AB5
AB6
AB7
AB8
AB9
AB10
AB11
AB12
AB13
AB14
AB15
AB16
AB17
AB18
AB19
AB20
AB21
AB22
AB23
AB24
Mnemonic
ONR1
OPR1
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
VNEG
VNEG
IPR5
INR5
IPG5
VPOS
VPOS
DGND
VDD
D0
D1
D2
D3
D4
CMENC
WE
UPDATE
RST
VDD
DGND
VPOS
VPOS
VPOS
VPOS
VPOS
VNEG
Description
Output Number 1, Negative Phase.
Output Number 1, Positive Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 5, Positive Phase.
Input Number 5, Negative Phase.
Input Number 5, Positive Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Digital Power Supply.
Digital Power Supply.
Control Pin, Input Address Bit 0.
Control Pin, Input Address Bit 1.
Control Pin, Input Address Bit 2.
Control Pin, Input Address Bit 3.
Control Pin, Input Address Bit 4.
Control Pin, Pass/Stop CM Encoding.
Control Pin, 1st Rank Write Strobe.
Control Pin, 2nd Rank Write Strobe.
Control Pin, 2nd Rank Data Reset.
Digital Power Supply.
Digital Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Negative Analog Power Supply.
Ball No.
AB25
AB26
AC1
AC2
AC3
AC4
AC5
AC6
AC7
AC8
AC9
AC10
AC11
AC12
AC13
AC14
AC15
AC16
AC17
AC18
AC19
AC20
AC21
AC22
AC23
AC24
AC25
AC26
AD1
AD2
AD3
AD4
AD5
AD6
AD7
AD8
AD9
AD10
AD11
AD12
AD13
AD14
AD15
AD16
AD17
AD18
AD19
AD20
AD21
AD22
AD23
AD24
Rev. 0 | Page 15 of 40
Mnemonic
VNEG
VNEG
INB5
IPB5
ING5
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
VPOS
H0
V0
VPOS
NC
NC
VNEG
VNEG
VNEG
VNEG
VNEG
VNEG
IPG4
ING4
VNEG
IPG3
ING3
VPOS
IPG2
ING2
VNEG
IPG1
ING1
VPOS
IPG0
ING0
VNEG
OPG0
ONG0
VPOS
NC
NC
VNEG
Description
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 5, Negative Phase.
Input Number 5, Positive Phase.
Input Number 5, Negative Phase.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Positive Analog Power Supply.
Output Number 0, H Sync.
Output Number 0, V Sync.
Positive Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 4, Positive Phase.
Input Number 4, Negative Phase.
Negative Analog Power Supply.
Input Number 3, Positive Phase.
Input Number 3, Negative Phase.
Positive Analog Power Supply.
Input Number 2, Positive Phase.
Input Number 2, Negative Phase.
Negative Analog Power Supply.
Input Number 1, Positive Phase.
Input Number 1, Negative Phase.
Positive Analog Power Supply.
Input Number 0, Positive Phase.
Input Number 0, Negative Phase.
Negative Analog Power Supply.
Output Number 0, Positive Phase.
Output Number 0, Negative Phase.
Positive Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
AD8178
Ball No.
AD25
AD26
AE1
AE2
AE3
AE4
AE5
AE6
AE7
AE8
AE9
AE10
AE11
AE12
AE13
AE14
AE15
AE16
AE17
AE18
AE19
AE20
AE21
AE22
AE23
AE24
AE25
Mnemonic
VNEG
VNEG
VNEG
VNEG
VNEG
INR4
IPB4
VNEG
INR3
IPB3
VPOS
INR2
IPB2
VNEG
INR1
IPB1
VPOS
INR0
IPB0
VNEG
ONR0
OPB0
VPOS
NC
NC
VNEG
VNEG
Description
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 4, Negative Phase.
Input Number 4, Positive Phase.
Negative Analog Power Supply.
Input Number 3, Negative Phase.
Input Number 3, Positive Phase.
Positive Analog Power Supply.
Input Number 2, Negative Phase.
Input Number 2, Positive Phase.
Negative Analog Power Supply.
Input Number 1, Negative Phase.
Input Number 1, Positive Phase.
Positive Analog Power Supply.
Input Number 0, Negative Phase.
Input Number 0, Positive Phase.
Negative Analog Power Supply.
Output Number 0, Negative Phase.
Output Number 0, Positive Phase.
Positive Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
Negative Analog Power Supply.
Ball No.
AE26
AF1
AF2
AF3
AF4
AF5
AF6
AF7
AF8
AF9
AF10
AF11
AF12
AF13
AF14
AF15
AF16
AF17
AF18
AF19
AF20
AF21
AF22
AF23
AF24
AF25
AF26
Rev. 0 | Page 16 of 40
Mnemonic
VNEG
VNEG
VNEG
VNEG
IPR4
INB4
VNEG
IPR3
INB3
VPOS
IPR2
INB2
VNEG
IPR1
INB1
VPOS
IPR0
INB0
VNEG
OPR0
ONB0
VPOS
NC
NC
VNEG
VNEG
VNEG
Description
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
Input Number 4, Positive Phase.
Input Number 4, Negative Phase.
Negative Analog Power Supply.
Input Number 3, Positive Phase.
Input Number 3, Negative Phase.
Positive Analog Power Supply.
Input Number 2, Positive Phase.
Input Number 2, Negative Phase.
Negative Analog Power Supply.
Input Number 1, Positive Phase.
Input Number 1, Negative Phase.
Positive Analog Power Supply.
Input Number 0, Positive Phase.
Input Number 0, Negative Phase.
Negative Analog Power Supply.
Output Number 0, Positive Phase.
Output Number 0, Negative Phase.
Positive Analog Power Supply.
No Connect.
No Connect.
Negative Analog Power Supply.
Negative Analog Power Supply.
Negative Analog Power Supply.
AD8178
TRUTH TABLE AND LOGIC DIAGRAM
Table 15. Operation Truth Table
SERIN
X
SEROUT
X
RST
SER/PAR
CS
0
X
X
CMENC
X
SERINi
SERINi-45
1
0
0
X
1
X
X
1
1
0
X
0
1
X
X
1
X
0
X
X
X
X
X
1
1
0
X
WE
UPDATE
CLK
X1
X
X
1
1
0
1
1
1
1
X = don’t care.
Rev. 0 | Page 17 of 40
Operation/Comment
Asynchronous reset. All outputs
are disabled. Contents of the
45-bit shift register are
unchanged.
Serial mode. The data on the
SERIN line is loaded into the
45-bit shift register. The first bit
clocked into the shift register
appears at SEROUT 45 clock
cycles later. Data is not applied
to the switch array.
Parallel mode. The data on
parallel lines D0 through D4 is
loaded into the shift register
location addressed by A0
through A2. Data is not applied
to the switch array.
Switch array update. Data in
the 45-bit shift register is transferred to the parallel latches
and applied to the switch array.
No change in logic.
A0
A1
A2
OUTPUT
ADDRESS
3 TO 5 DECODER
CS
CLK
WE
SERIN
Figure 7. Logic Diagram
Rev. 0 | Page 18 of 40
D4
D0
D1
D2
D3
RST
CS
UPDATE
OUT4 EN
OUT3 EN
OUT2 EN
OUT1 EN
OUT0 EN
(OUTPUT ENABLE)
SER/PAR
PARALLEL DATA
OUT0
B0
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUT0
B1
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUT0
B2
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUT0
EN
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
80
SWITCH MATRIX
OUT0
B3
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUT1
B0
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
DECODE
OUT4
EN
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUT4
B0
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
5
OUT4
B2
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUTPUT ENABLE
OUT4
B1
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUT4
B3
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
OUT4
EN
CLR Q
ENA D
S
D1
Q D Q
D0 CLK
SEROUT
AD8178
06608-028
AD8178
EQUIVALENT CIRCUITS
VPOS
10kΩ
0.1pF
OPn, ONn
VBLK,
VOCM_CMENCOFF
10kΩ
06608-013
0.1pF
1kΩ
06608-008
1kΩ
(VPOS – VNEG)
2
VNEG
Figure 13. VBLK and VOCM_CMENCOFF Inputs
(see also ESD Protection Map, Figure 19)
Figure 8. Enabled Output (see also ESD Protection Map, Figure 19)
VPOS
VPOS
20kΩ
OPn
20kΩ
0.3pF
3.4pF
0.4pF
VNEG
3.1kΩ
3.33kΩ
VOCM_CMENCON
VPOS
3.4pF
0.3pF
20kΩ
3.33kΩ
06608-009
VNEG
VNEG
)
)
Figure 9. Disabled Output (see also ESD Protection Map, Figure 19
Figure 14. VOCM_CMENCON Input (see also ESD Protection Map, Figure 19
5050Ω
2500Ω
IPn
06608-014
ONn
20kΩ
VDD
1.3pF
25kΩ
06608-010
10kΩ
1.3pF
INn
2500Ω
5050Ω
1kΩ
RST
DGND
Figure 10. Receiver Differential (see also ESD Protection Map, Figure 19)
06608-015
0.3pF
Figure 15. RST Input (see also ESD Protection Map, Figure 19)
IPn
1.3pF
2500Ω
06608-011
2500Ω
1.3pF
INn
CLK, SER/PAR, WE,
UPDATE, SERIN
A[2:0], D[4:0],
CMENC
10kΩ
1kΩ
DGND
Figure 11. Receiver Simplified Equivalent Circuit When Driving Differentially
06608-016
0.3pF
Figure 16. Logic Input (see also ESD Protection Map, Figure 19)
IPn
1kΩ
CS
25kΩ
DGND
Figure 12. Receiver Simplified Equivalent Circuit When Driving Single-Ended
Rev. 0 | Page 19 of 40
06608-030
INn
2.5kΩ
06608-012
1.6pF
Figure 17. CS Input (see also ESD Protection Map, Figure 19)
VDD
VDD
VNEG
DGND
IPn, INn,
OPn, ONn, VBLK,
VOCM_CMENCOFF
VOCM_CMENCON
06608-017
SEROUT,
H, V
DGND
VPOS
Figure 18.SEROUT, H, V Logic Outputs
(see also ESD Protection Map, Figure 19)
Figure 19. ESD Protection Map
Rev. 0 | Page 20 of 40
CLK, RST,
SER/PAR,
WE,
UPDATE,
SERIN,
SEROUT,
A[2:0],
D[4:0],
CMENC,
CS
06608-018
AD8178
AD8178
TYPICAL PERFORMANCE CHARACTERISTICS
VS = ±2.5 V at TA = 25°C, G = +2, RL = 100 Ω (each output), VBLK = 0 V, output CM voltage = 0 V, differential I/O mode, unless
otherwise noted.
0.15
20
18
0.10
16
0.05
VOUT, DIFF (V)
GAIN (dB)
14
12
10
8
0
–0.05
6
4
–0.10
1
10
100
1000
FREQUENCY (MHz)
–0.15
06608-019
0
0
2
4
6
8
10
12
14
16
18
20
TIME (ns)
Figure 20. Small Signal Frequency Response, 200 mV p-p
06608-032
2
Figure 23. Small Signal Pulse Response, 200 mV p-p
18
1.5
16
1.0
14
0.5
VOUT, DIFF (V)
GAIN (dB)
12
10
8
6
4
2
0
–0.5
–1.0
10
100
1000
FREQUENCY (MHz)
–1.5
0
18
10
12
14
16
18
20
1.2
VOUT
10
0.9
VIN
OUTPUT ERROR (%)
5
14
GAIN (dB)
8
15
0pF
16
6
Figure 24. Large Signal Pulse Response, 2 V p-p
10pF
5pF
2pF
20
4
TIME (ns)
Figure 21. Large Signal Frequency Response, 2 V p-p
22
2
12
10
8
6
0.6
0
0.3
ERROR
–5
0
–10
–0.3
–15
–0.6
–20
–0.9
VOUT, DIFF (V)
1
06608-020
–2
06608-033
0
0
1
10
100
1000
FREQUENCY (MHz)
06608-031
2
–25
0
1
2
3
4
5
TIME (ns)
Figure 25. Settling Time
Figure 22. Small Signal Frequency Response with Capacitive Loads
Rev. 0 | Page 21 of 40
6
7
8
–1.2
06608-034
4
5
0
4
–10
3
–20
2
–30
CROSSTALK (dB)
1
0
–1
–2
–3
–40
–50
–60
–70
–100
0
1
2
3
4
5
6
7
8
TIME (ns)
1
0
4000
–1
3000
1650V/µs PEAK
–2
2000
–3
1000
–4
0
3
4
5
6
7
8
9
1000
–40
–60
–80
–100
–1000
10
–120
06608-036
2
1000
–20
FEEDTHROUGH (dB)
5000
0
SLEW RATE (V/µs)
1
TIME (ns)
1
10
100
FREQUENCY (MHz)
Figure 27. Large Signal Rising Edge Slew Rate
Figure 30. Crosstalk, Off Isolation
0
0
–10
–10
–20
–20
CMR (dB)
–30
–40
–30
CMENC HIGH
–40
–50
–50
–60
CMENC LOW
–60
–70
–80
1
10
100
FREQUENCY (MHz)
1000
06608-037
CROSSTALK (dB)
VOUT, DIFF (V)
6000
1
1000
Figure 29. Crosstalk, All Hostile
2
0
100
FREQUENCY (MHz)
Figure 26. Settling Time, 1% Zoom
–5
10
06608-038
–90
–5
06608-035
–4
06608-039
–80
06608-040
OUTPUT ERROR (%)
AD8178
Figure 28. Crosstalk, All Hostile, Single-Ended
–70
1
10
100
FREQUENCY (MHz)
Figure 31. Common-Mode Rejection
Rev. 0 | Page 22 of 40
AD8178
10000
600
|IPOS| AND |INEG |
(BROADCAST)
400
IMPEDANCE (Ω)
|IPOS| AND |INEG | (mA)
500
300
|IPOS| AND |INEG |
(ALL OUTPUTS DISABLED)
200
1000
1
10
100
1000
06608-044
TEMPERATURE (°C)
100
1000
06608-045
10 20 30 40 50 60 70 80 90 100
06608-041
0
–50 –40 –30 –20 –10 0
1000
06608-046
100
FREQUENCY (MHz)
Figure 32. Quiescent Supply Currents vs. Temperature
Figure 35. Input Impedance
3000
10000
2000
IMPEDANCE (Ω)
IMPEDANCE (Ω)
2500
1500
1000
1000
500
1
10
100
1000
FREQUENCY (MHz)
100
06608-042
0
1
10
100
FREQUENCY (MHz)
Figure 33. Output Impedance, Disabled
Figure 36. Input Impedance, Single-Ended
100
0
90
–10
80
–20
BALANCE ERROR (dB)
60
50
40
30
20
0
–30
–40
–50
–60
–70
10
1
10
100
FREQUENCY (MHz)
1000
06608-043
IMPEDANCE (Ω)
70
Figure 34. Output Impedance, Enabled
–80
1
10
100
FREQUENCY (MHz)
Figure 37. Output Balance Error
Rev. 0 | Page 23 of 40
AD8178
1.0
RED
1200
GREEN
0.5
15
BLUE
1000
10
5
–0.5
COUNT
0
VOUT (V)
VOUT, COMMON MODE (V)
1400
20
VSYNC
HSYNC
800
600
400
0
–1.0
0
100
200
300
400
500
600
700
800
900
–5
1000
0
–70 –60 –50 –40 –30 –20 –10
06608-047
–1.5
TIME (ns)
0
10
20
30
40
50
60
70
06608-050
200
VOS (mV)
Figure 41. VOS Distribution
Figure 38. Common-Mode Pulse Response
5
0
4
–10
3
2
–30
VOS (mV)
FEEDTHROUGH (dB)
–20
–40
–50
1
0
58µV/°C
–1
–2
–60
–3
–70
100
1000
FREQUENCY (MHz)
–5
–40
–20
40
60
80
100
60
80
100
Figure 42. VOS Drift, RTO
1.5
200
1.0
VOS COMMON MODE (mV)
160
120
80
40
0.5
–16µV/°C
0
–0.5
–1.0
0
10
20
30
40
50
60
70
FREQUENCY (MHz)
80
90
100
06608-049
NOISE SPECTRAL DENSITY (nV/√Hz)
20
TEMPERATURE (°C)
Figure 39. Common-Mode Isolation, CMENC Low
0
0
06608-051
10
06608-052
1
06608-048
–80
–4
–1.5
–40
–20
0
20
40
TEMPERATURE (°C)
Figure 43. VOS Drift, Common Mode, RTO
Figure 40. Noise Spectral Density
Rev. 0 | Page 24 of 40
AD8178
0.75
2
0.50
1
0.25
0
0
–1
0
20
40
60
–0.25
80 100 120 140 160 180 200 220 240 260 280
TIME (ns)
0.010
0.005
32ppm/°C
0
–0.005
–0.010
–0.015
Figure 44. Enable Time
–0.020
–40
–20
0
20
40
60
80
TEMPERATURE (°C)
Figure 45. Normalized DC Gain vs. Temperature
Rev. 0 | Page 25 of 40
100
06608-054
3
NORMALIZED DC GAIN (dB)
UPDATE
0.015
1.00
VOUT, SINGLE-ENDED (V)
VOUT
06608-053
4
UPDATE (V)
0.020
1.25
5
AD8178
THEORY OF OPERATION
The AD8178 is a nonblocking crosspoint with 16 RGB input
channels and 5 RGB output channels. Architecturally, the
AD8178 is a differential-in, differential-out crosspoint suited
for middle-of-Cat-5-run applications. Furthermore, its
differential-in, differential-out gain of +4 and its decoded H and
V sync outputs make it the ideal solution for driving a monitor
directly. The ability to set the output common-mode (CM) and
black level through external pins offers additional flexibility.
Processing of CM voltage levels is achieved by placing the AD8178
in either of its two operation modes. In the first operation mode
(CMENC low), the input CM of each RGB differential pair
(possibly present in the form of either sync-on CM signaling or
noise) is removed through the switch, and the output CM is set
to a global reference voltage via the VOCM_CMENCOFF analog
input. In this mode, the AD8178 behaves as a traditional
differential-in, differential-out switch. If sync-on CM signaling
is present at the differential RGB inputs, then the H and V
outputs represent decoded syncs. In the second operation mode
(CMENC high), input sync-on CM signaling is propagated
through the switch with unity gain. In this mode, the overall
output CM is set to a global reference voltage via the
VOCM_CMENCON analog input. Note that in both operation
modes, the overall input CM is blocked through the switch.
Input Pin VBLK defines the black level of the positive output
phase. The combination of VBLK and VOCM_CMENCOFF
allows the user to position the positive and negative output
phases anywhere in the allowable output voltage range, thus
maximizing output headroom usage.
The switch is organized into five 16:1 RBG multiplexers, with
each being responsible for connecting an RGB input channel to
its respective RGB output channel. Decoding logic selects a single
input (or none) in each multiplexer and connects it to its respective
output. Feedback around each multiplexer realizes a closed-loop
differential-in, differential-out gain of +2 in the core.
Each differential RGB input channel is buffered by a differential
receiver that is capable of accepting input CM voltages extending
all the way to either supply rail. Excess closed-loop receiver
bandwidth reduces the effect of the receiver on the overall device
bandwidth. Feedback around each differential receiver realizes
a gain of +2 yielding an overall differential-in, differential-out
crosspoint gain of +4. A separate loop realizes a closed-loop
common-mode gain of +1.
The outputs of the AD8178 can be disabled to minimize on-chip
power dissipation. When disabled, there is only a commonmode feedback network of 2.7 kΩ between the differential outputs.
This high impedance allows multiple ICs to be bussed together
without additional buffering. Care must be taken to reduce
output capacitance, which can result in overshoot and frequencydomain peaking. A series of internal amplifiers drive internal
nodes such that wideband high impedance is presented at the
disabled output, even while the output bus experiences fast signal
swings. When the outputs are disabled and driven externally, the
voltage applied to them should not exceed the valid output swing
range for the AD8178 to keep these internal amplifiers in their
linear range of operation. Applying excessive differential voltages
to the disabled outputs can cause damage to the AD8178 and
should be avoided (see the Absolute Maximum Ratings section
for guidelines).
The connectivity of the AD8178 is controlled by a flexible TTLcompatible logic interface. Either parallel or serial loading into
a first rank of latches preprograms each output. A global update
signal moves the programming data into the second rank of latches,
simultaneously updating all outputs. In serial mode, a serial-out
pin allows devices to be daisy-chained together for a single-pin
programming of multiple ICs. A power-on reset pin is available
to avoid bus conflicts by disabling all outputs. This power-on
reset clears the second rank of latches but does not clear the first
rank of latches. In serial mode, preprogramming individual inputs
is not possible and the entire shift register needs to be flushed. A
global chip-select pin gates the input clock and the global update
signal to the second rank of buffers.
The AD8178 can operate on a single 5 V supply, powering both
the signal path (with the VPOS/VNEG supply pins) and the control
logic interface (with the VDD/DGND supply pins). Split supply
operation is possible with ±2.5 V supplies that easily interface to
ground-referenced video signals. In this case, a flexible logic
interface allows the control logic supplies (VDD/DGND) to be
run off 5 V/0 V to 3.3 V/0 V while the analog core remains on
split supplies. Additional flexibility in the analog output commonmode level (VOCM_CMENCOFF) and output black level (VBLK)
facilitates operation with unequally split supplies. If +3 V/−2 V
supplies to +2 V/−3 V supplies are desired, the output CM can
still be set to 0 V for ground-referenced video signals.
The output stage is designed for fast slew rate and settling time,
while driving a series-terminated Cat-5 cable. Unlike competing
multiplexer designs, the small signal bandwidth closely approaches
the large signal bandwidth.
Rev. 0 | Page 26 of 40
AD8178
APPLICATIONS INFORMATION
Figure 47 shows the voltage levels and CM handling for a single
input channel connected to a single output channel in a middleof-Cat-5-run application with CM encoding turned on.
OPERATING MODES
Depending on the state of the CMENC logic input, the AD8178
can be set in either of two differential-in, differential-out operating modes. In addition, monitors can be driven directly by tapping
the outputs single-ended and making use of the decoded H and
V sync outputs.
DIFF. R
DIFF. B
CMR
INPUT
OVERALL
CM
In this application, the AD8178 is placed somewhere in the middle
of a Cat-5 run. By tying CMENC low, the CM of each RGB differential pair is removed through the device (or turned off), and
the overall CM at the output is defined by the reference value
VOCM_CMENCOFF. In this mode of operation, CM noise is
removed, while the intended differential RGB signals are buffered
and passed to the outputs. The AD8178 is placed in this operation
mode when used in a sync-on color scheme. Figure 46 shows
the voltage levels and CM handling for a single input channel
connected to a single output channel in a middle-of-Cat-5-run
application with CM encoding turned off.
AD8178
OUTPUT
OVERALL
CM
DIFF. G
DIFF. G
06608-022
CMG
CMENC
VOCM_CMENCON
Figure 47. AD8178 in Middle-of-Cat-5-Run Application, CM Encoding On
(Note that in this application, the H and V outputs, though asserted, are not used.)
In this operation mode, the difference Δdiff = 2 × (VBLK −
VOCM_CMENCOFF) still adds an output differential voltage,
as described in the Middle-of-Cat-5-Run Application, CM
Encoding Turned Off section.
End-of-Cat-5-Run Application, CM Encoding Turned Off—
Driving a Monitor Directly
DIFF. B
CMB
DIFF. R
CMG
CMB
CMG
DIFF. R
INPUT
OVERALL
CM
DIFF. B
CMR
Middle-of-Cat-5-Run Application, CM Encoding Turned Off
CMR
DIFF. R
CMB
AD8178
DIFF. G
CMR
CMG
DIFF. B
CMB
OUTPUT
OVERALL
CM
DIFF. G
06608-021
CMENC
VOCM_CMENCOFF
Figure 46. AD8178 in a Middle-of-Cat-5-Run Application, CM Encoding Off
(Note that in this application, the H and V outputs, though asserted, are not used.)
Input VBLK and Input VOCM_CMENCOFF allow the user
complete flexibility in defining the output CM level and the
amount of overlap between the positive and negative phases,
thus maximizing output headroom usage. Whenever VBLK
differs from VOCM_CMENCOFF by more than ±100 mV,
a differential voltage, Δdiff, is added at the outputs according
to the expression Δdiff = 2 × (VBLK − VOCM_CMENCOFF.)
Conversely, whenever the difference between VBLK and
VOCM_CMENCOFF is less than ±100 mV, no differential
voltage is added at the outputs.
Middle-of-Cat-5-Run Application, CM Encoding Turned On
In this application, the AD8178 is also placed somewhere in the
middle of a Cat-5 run, although the common-mode handling is
different. By tying CMENC high, the CM of each RGB input is
passed through the part with a gain of +1, while at the same time,
the overall output CM is stripped and set equal to the voltage
applied at the VOCM_CMENCON pin. The AD8178 is placed in
this operation mode when used with a sync-on CM scheme.
Although asserted, the H and V outputs are not used in this
application.
In this application, the AD8178 is placed at the end of a Cat-5
run to drive a monitor directly: the differential outputs are
tapped single-ended to drive the monitor inputs, CMENC is
tied to logic low to remove sync-on-CM information at the
output of the part, and the decoded H and V sync outputs are
tied to the sync inputs of the monitor.
The differential-in, differential-out gain of +4 provides a
differential-in, single-ended out gain of +2 at the output pins of
the AD8178. This yields the correct differential-in, single-ended
out gain of +1 at the input of the monitor.
The relationship between the incoming sync-on CM signaling
and the H and V syncs is defined according to Table 16.
Table 16. H and V Sync Truth Table (VPOS/VNEG = ±2.5 V)
CMR
0.5
0
−0.5
0
CMG
0
0.5
0.5
−0.5
CMB
0
−0.5
0
0.5
H
Low
Low
High
High
V
High
Low
Low
High
The following two statements are equivalent to the truth table
(Table 16) in producing H and V for all allowable CM inputs:
•
H sync is high when the CM of Blue is larger than the CM
of Red.
•
V sync is high when the combined CM of Red and Blue is
larger than the CM of Green.
Rev. 0 | Page 27 of 40
AD8178
For a practical example, refer to Figure 48. Note that the output
pulses have been shifted slightly with respect to each other for
clarity.
VOCM_CMENCOFF = 0.7V
NEGATIVE
1.4V PHASE
0V
POSITIVE
PHASE
06608-023
VBLK = 0V
Figure 48. Output at the AD8178 Pins for 0 V to 0.7 V Input Differential Pulse,
VBLK = 0 V, VOCM_CMENCOFF = 0.7 V
The input to the AD8178 is a differential pulse with a low level
of 0 V and a high level of 0.7 V. VBLK is set to 0 V, and VOCM_
CMENCOFF is set to 0.7 V. With this choice of values, the positive
and negative output phases are overlapped, with the positive phase
ranging from 0 V to 1.4 V, and the negative phase ranging from
1.4 V to 0 V, respectively. The supplies are set to +3 V/−2 V to be in
compliance with output headroom requirements.
The voltage on the positive output phase for a 0 V differential
input is equal to the voltage on VBLK, for all cases when VBLK
and VOCM_CMENCOFF differ by more than ±100 mV.
PROGRAMMING
The AD8178 has two options for changing the programming of
the crosspoint matrix. In the first option, a serial word of 45 bits
can be provided that updates the entire matrix each time. The
second option allows for changing the programming of a single
output using a parallel interface. The serial option requires
fewer signals, but more time (clock cycles), for changing the
programming; the parallel programming technique requires more
signals, but it allows for changing a single output at a time,
therefore requiring fewer clock cycles.
Serial Programming Description
The serial programming mode uses the device pins CS, CLK,
SERIN, UPDATE, and SER/PAR. The first step is to enable the
CLK on by pulling CS low. Next, SER/PAR is pulled low to
enable the serial programming mode. The parallel clock WE
should be held high during the entire serial programming
operation.
The UPDATE signal should be high during the time that data
is shifted into the serial port of the device. Although the data still
shifts in when UPDATE is low, the transparent, asynchronous
latches allow the shifting data to reach the matrix. This causes
the matrix to try to update to every intermediate state as
defined by the shifting data.
The data at SERIN is clocked in at every falling edge of CLK.
A total of 45 bits must be shifted in to complete the programming.
A total of five bits must be supplied for each of the five RGB
output channels: an output enable bit (D4) and four bits (D3
to D0) that determine the input channel.
If D4 is low (output disabled), the four associated bits (D3 to
D0) do not matter because no input is switched to that output.
A sequence of five bits at Logic 0 must be supplied in between
each D4 to D0 group of bits for padding purposes. There is a total
of four such sequences of zeros.
The most significant output address data is shifted in first, with
the enable bit (D4) shifted in first, followed by the input address
(D3 to D0) entered sequentially with D3 first and D0 last. The first
sequence of five bits at Logic 0 is shifted in next. Each remaining
output is programmed sequentially in a similar fashion, until
the least significant output address data is shifted in. Note that
the last D4 to D0 group is not followed by a corresponding group
of five zeros. At this point, UPDATE can be taken low, which
causes the programming of the device according to the data that
was just shifted in. The UPDATE latches are asynchronous; and
when UPDATE is low, they are transparent.
If more than one AD8178 device is to be serially programmed
in a system, the SEROUT signal from one device can be connected
to the SERIN of the next device to form a serial chain. All of the
CLK, UPDATE, and SER/PAR pins should be connected in parallel
and operated as described previously. The serial data is input to
the SERIN pin of the first device of the chain, and it ripples
through to the last. Therefore, the data for the last device in the
chain should come at the beginning of the programming sequence.
The length of the programming sequence is 45 bits times the
number of devices in the chain. CS gates the CLK and UPDATE
signals, so that when CS is held high, both CLK and UPDATE are
held in their inactive high state. When CS is held low, both CLK
and UPDATE function normally.
Parallel Programming Description
When using the parallel programming mode, it is not necessary
to reprogram the entire device when making changes to the matrix.
In fact, parallel programming allows the modification of a single
output or more at a time. Because this modification takes only
one WE/UPDATE cycle, significant time savings can be realized
by using parallel programming.
One important consideration in using parallel programming is
that the RST signal does not reset all registers in the AD8178.
When taken low, the RST signal only sets each output to the
disabled state. This is helpful during power-up to ensure that
two parallel outputs are not active at the same time.
After initial power-up, the internal registers in the device generally
have random data, even though the RST signal is asserted. If
parallel programming is used to program one output, then that
output is properly programmed, but the rest of the device has
a random program state, depending on the internal register content
at power-up. Therefore, when using parallel programming, it is
essential that all outputs be programmed to a desired state after
power-up. This ensures that the programming matrix is always
in a known state. From then on, parallel programming can be
used to modify a single output or more at a time.
Rev. 0 | Page 28 of 40
AD8178
In similar fashion, if UPDATE is taken low after initial power-up,
the random power-up data in the shift register is programmed into
the matrix. Therefore, to prevent the crosspoint from being
programmed into an unknown state, do not apply a logic level
to UPDATE after power is initially applied. Programming the
device into a known state after reset or power-up is a one-time
event that is accomplished by the following two steps:
The RST pin has a 20 kΩ pull-up resistor to VDD that can be
used to create a simple power-up reset circuit. A capacitor from
RST to ground holds RST low for some time, while the rest of the
device stabilizes. The low condition causes all the outputs to be
disabled. The capacitor then charges through the pull-up resistor
to the high state, thus allowing full programming capability of
the device.
1.
DIFFERENTIAL AND SINGLE-ENDED OPERATION
CLR is held at logic low thereafter.
To change the programming of an output via parallel programming, CS should be taken low, and SER/PAR and UPDATE
should be taken high. The serial programming clock, CLK,
should be left high during parallel programming. The parallel
clock, WE, should start in the high state. The 3-bit address of
the output to be programmed should be put on A2 to A0. Data
Bit D3 to Data Bit D0 should contain the information that identifies
the input that gets programmed to the output that is addressed.
Data Bit D4 determines the enabled state of the output. If D4 is low
(output disabled), the data on D3 to D0 does not matter.
After the desired address and data signals have been established,
they can be latched into the shift register by a high-to-low transition of the WE signal. The matrix is not programmed, however,
until the UPDATE signal is taken low. It is thus possible to latch
in new data for several or all of the outputs first via successive
negative transitions of WE while UPDATE is held high, and then
have all the new data take effect when UPDATE goes low. This
is the technique that should be used to program the device for the
first time after power-up when using parallel programming.
Programming the device to a known state can be accomplished
in serial programming mode by clocking in the entire 45-bit
sequence immediately after reset or power-up.
Reset
Although the AD8178 has fully differential inputs and outputs,
it can also be operated in 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 AD8178 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 each
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 application
with sync-on CM signaling coupling into all three pairs in an RGB
channel are rejected at the output of the AD8178, while 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, Inc. 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 49.
RF
When powering up the AD8178, it is usually desirable to have
the outputs come up in the disabled state. The RST pin, when
taken low, causes all outputs to be in the disabled state. However,
the RST signal does not reset all registers in the AD8178. This is
important when operating in the parallel programming mode.
See the Parallel Programming Description section for
information about programming internal registers after powerup. Serial programming programs the entire matrix each time,
so no special considerations apply.
Because the data in the shift register is random after power-up,
it should not be used to program the matrix, or the matrix can
enter unknown states. To prevent this, do not apply a logic low
signal to UPDATE initially after power-up. The shift register
should first be loaded with the desired data, and only then can
the UPDATE be taken low to program the device.
RG
IN+
OUT–
RCM
RCVR
IN–
TO SWITCH MATRIX
OUT+
RG
RF
06608-024
2.
Output 4 to Output 0 are programmed to the off state
while holding the CLR input at a logic high.
Each output (Output 4 to Output 0) is programmed to its
desired state while holding the CLR input at a logic low.
Figure 49. 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 AD8178 appears in parallel
with the internal gain-setting resistors, such that there may be
a gain error for some values of source resistance.
Rev. 0 | Page 29 of 40
AD8178
The AD8178 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
AD8178 input receiver can be calculated as
G DM =
5.05 kΩ
2.5 kΩ + R S
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 AD8178 receiver. For the AD8178
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 AD8178 is linear for ±0.5 V of differential input voltage difference (this limitation is primarily due to
the ability of the output to swing close to the rails because the
differential gain through the part is +4). 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 longterm reliability of the input stage. The limits in the Absolute
Maximum Ratings section should be observed to avoid degrading
device performance permanently.
AC Coupling of Inputs
It is possible to ac-couple the inputs of the AD8178 receiver
so that bias current does not need to be supplied externally.
A capacitor in series with the inputs to the AD8178 creates
a high-pass filter with the input impedance of the device. This
capacitor needs to be large enough that the corner frequency
includes all frequencies of interest.
Single-Ended Input
The AD8178 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
R IN =
1−
RG
RF
2 × (RG + R F )
with RG and RF, as shown in Figure 49.
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
resistance (RCM, also shown in Figure 49) is present across the
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 signalfrequency current flows at the undriven input, such input
should be treated as a signal line in the board design.
For example, to achieve best dynamic performance, the undriven
input should be terminated with an impedance matching that seen
by the part at the driven input.
Differential Output
Benefits of Differential Operation
The AD8178 has a fully differential switch core with differential
outputs. The two output voltages move in opposite directions,
with a differential feedback loop maintaining a fixed output
stage differential gain of +2 through the core. This differential
output stage provides improved crosstalk cancellation due to
parasitic coupling from one output to another being equal and
out of phase. Additionally, if the output of the device is utilized
in a differential design, then noise, crosstalk, and offset voltages
generated on-chip that are coupled equally into both outputs
are cancelled by the common-mode rejection ratio of the next
device in the signal chain. By utilizing the AD8178 outputs in
a differential application, the best possible noise and offset
specifications can be realized.
Differential Gain
The specified signal path gain of the AD8178 refers to its
differential gain. For the AD8178, the gain of +4 means that the
difference in voltage between the two output terminals is equal
to four times the difference between the two input terminals.
Common-Mode Gain
The common-mode, or average voltage pairs of output signals
is set by the voltage on the VOCM_CMENCOFF pin when
common-mode encoding is off (CMENC is a logic low), or by
the voltage on the VOCM_CMENCON pin when common-mode
encoding is on (CMENC is a logic high). Note that in the latter
case, VCOM_CMENCON sets the overall common mode of
RGB triplets of differential outputs, and the individual common
mode of each RGB output is free to change. VCOM_CMENCON
and VCOM_CMENCOFF are typically set to midsupply (often
ground) but can be moved approximately ±0.5 V to accommodate
cases where the desired output common-mode voltage may not
be midsupply (as in the case of unequal split supplies). Adjusting
the output common-mode voltage beyond ±0.5 V can limit differential swing internally below the specifications on the data sheet.
The overall common mode of the output voltages follow the
voltage applied to VOCM_CMENCON or VCOM_CMENCOFF,
implying a gain of +1. Likewise, sync-on common-mode signaling
is carried through the AD8178 (CMENC must be in its high
state), implying a gain of +1 for this path as well.
The common-mode reference pins are analog signal inputs,
common to all output stages on the device. They require only
Rev. 0 | Page 30 of 40
AD8178
small amounts of bias current, but noise appearing on these
pins is buffered to all the output stages. As such, they should
be connected to low noise, low impedance voltage references
to avoid being sources of noise, offset, and crosstalk in the
signal path.
ended output sums half the differential offset voltage and all
of the common-mode offset voltage for a net increase in
observed offset.
Single-Ended Gain
Termination at the load end is recommended to shorten settling
time and provide for best signal integrity. In differential signal
paths, it is often desirable to series-terminate the outputs, with a
resistor in series with each output. A side effect of termination
is an attenuation of the output signal by a factor of two. In this
case, gain is usually necessary somewhere else in the signal path
to restore the signal level.
The AD8178 operates as a closed-loop differential amplifier.
The primary control loop forces the difference between the
output terminals to be a ratio of the difference between the
input terminals. One output increases in voltage, while the
other decreases an equal amount to make the total output
voltage difference correct. The average of these output voltages
is forced to the voltage on the common-mode reference terminal
(VOCM_CMENCOFF or VOCM_CMENCON) by a second
control loop. If only one output terminal is observed with respect
to the common-mode reference terminal, only half of the difference voltage is observed. This implies that when using only one
output of the device, half of the differential gain is observed.
An AD8178 taken with single-ended output appears to have
a gain of +2.
Whenever a differential output is used single-ended, it is desirable
to terminate the used single-ended output with a series resistor,
as well as to place a resistor on the unused output to match the
load seen by the used output.
It is important to note that all considerations that apply to the
used output phase regarding output voltage headroom apply
unchanged to the complement output phase, even if this is not
actually used.
When disabled, the outputs float to midsupply. A small current
is required to drive the outputs away from their midsupply state.
This current is easily provided by an AD8178 output (in its
enabled state) bussed together with the disabled output.
Exceeding the allowed output voltage range may saturate
internal nodes in the disabled output, and consequently,
an increase in disabled output current may be observed.
Termination
Termination
The AD8178 is designed to drive 100 Ω terminated to ground
on each output (or an effective 200 Ω differential) while
meeting data sheet specifications over the specified operating
temperature range, if care is taken to observe the maximum
power derating curves.
Single-Ended Output
Usage
The AD8178 output pairs can be used single-ended, taking only
one output and not using the second. This is often desired to
reduce the routing complexity in the design or because a singleended load is being driven directly. This mode of operation
produces good results but has some shortcomings when compared
to taking the output differentially. When observing the singleended output, noise that is common to both outputs appears in
the output signal.
When observing the output single-ended, the distribution of offset
voltages appears greater. In the differential case, the difference
between the outputs, when the difference between the inputs is
zero, is a small differential offset. This offset is created from
mismatches in devices in the signal path. In the single-ended
case, this differential offset is still observed, but an additional
offset component is also relevant. This additional component
is the common-mode offset, which is the difference between the
average of the outputs and the output common-mode reference.
This offset is created by mismatches that affect the signal path
in a common-mode manner. A differential receiver rejects this
common-mode offset voltage, but in the single-ended case, this
offset is observed with respect to the signal ground. The single-
When operating the AD8178 with a single-ended output, the
preferred output termination scheme is to refer the load to the
output common mode. A series termination can be used, at an
additional cost of one half the signal gain.
In single-ended output operation, the complementary phase of
the output is not used and may or may not be terminated locally.
Although the unused output can be floated to reduce power dissipation, there are several reasons for terminating the unused output
with a load resistance matched to the load on the signal output.
One component of crosstalk is magnetic coupling by mutual
inductance between output package traces and bond wires that
carry load current. In a differential design, there is coupling from
one pair of outputs to other adjacent pairs of outputs. The differential nature of the output signal simultaneously drives the
coupling field in one direction for one phase of the output and
in an opposite direction for the other phase of the output. These
magnetic fields do not couple equally into adjacent output pairs,
due to different proximities; but they do destructively cancel the
crosstalk to some extent. If the load current in each output is equal,
this cancellation is greater and less adjacent crosstalk is observed
(regardless of whether the second output is actually being used).
A second benefit of balancing the output loads in a differential
pair is to reduce fluctuations in current requirements from the
power supply. In single-ended loads, the load currents alternate
from the positive supply to the negative supply. This creates a
parasitic signal voltage in the supply pins due to the finite
resistance and inductance of the supplies. This supply fluctuation
appears as crosstalk in all outputs, attenuated by the power
supply rejection ratio (PSRR) of the device.
Rev. 0 | Page 31 of 40
AD8178
10
TJ = 150°C
9
8
7
6
5
4
3
15
The signal path compensation capacitors in the AD8178 are
connected to the VNEG supply. At high frequencies, this limits
the power supply rejection ratio (PSRR) from the VNEG supply
to a lower value than that from the VPOS supply. If given a
choice, an application board should be designed such that the
VNEG power is supplied from a low inductance plane, subject
to a least amount of noise.
VOCM_CMENCON and VOCM_CMENCOFF are high speed
common-mode control loops of all output drivers. In the singleended output sense, there is no rejection from noise on these
inputs to the outputs. For this reason, care must be taken to
produce low noise sources over the entire range of frequencies
of interest. This is important not only to single-ended operation,
but to differential operation, because there is a common-modeto-differential gain conversion that becomes greater at higher
frequencies.
35
45
55
65
AMBIENT TEMPERATURE (°C)
75
85
Figure 50. Maximum Die Power Dissipation vs. Ambient Temperature
The curve in Figure 50 was calculated from
Decoupling
The signal path of the AD8178 is based on high open-loop gain
amplifiers with negative feedback. Dominant-pole compensation
is used on-chip to stabilize these amplifiers over the range of
expected applied swing and load conditions. To guarantee this
designed stability, proper supply decoupling is necessary with
respect to both the differential control loops and the commonmode control loops of the signal path. Signal-generated currents
must return to their sources through low impedance paths at all
frequencies in which there is still loop gain (up to 700 MHz at
a minimum).
25
06608-025
A third benefit of driving balanced loads is that the output pulse
response changes as the load changes. The differential signal
control loop in the AD8178 forces the difference of the outputs
to be a fixed ratio to the difference of the inputs. If the two
output responses are different due to loading, this creates a
difference that the control loop sees as signal response error, and
it attempts to correct this error. This distorts the output signal
from the ideal response compared to the case when the two
outputs are balanced.
Power Dissipation
Calculation of Power Dissipation
MAXIMUM DIE POWER (W)
At low frequencies, this is a negligible component of crosstalk,
but PSRR falls off as frequency increases. With differential,
balanced loads, as one output draws current from the positive
supply, the other output draws current from the negative supply.
When the phase alternates, the first output draws current from
the negative supply and the second draws from the positive
supply. The effect is that a more constant current is drawn from
each supply, such that the crosstalk-inducing supply fluctuation
is minimized.
PD , MAX =
TJUNCTION , MAX − TAMBIENT
θ JA
(1)
As an example, if the AD8178 is enclosed in an environment at
45°C (TA), the total on-chip dissipation under all load and supply
conditions must not be allowed to exceed 7.0 W.
When calculating on-chip power dissipation, it is necessary to
include the power dissipated in the output devices due to current
flowing in the loads. For a sinusoidal output about ground and
symmetrical split supplies, the on-chip power dissipation due to
the load can be approximated by
PD,OUTPUT = (VPOS − VOUTPUT,RMS) × IOUTPUT,RMS
(2)
For nonsinusoidal output, the power dissipation should be
calculated by integrating the on-chip voltage drop across the
output devices multiplied by the load current over one period.
The user can subtract the quiescent current for the Class AB
output stage when calculating the loaded power dissipation. For
each output stage driving a load, subtract a quiescent power,
according to
PDQ,OUTPUT = (VPOS − VNEG) × IOUTPUT,QUIESCENT
(3)
where IOUTPUT, QUIESCENT = 1.65 mA for each single-ended output
pin of the AD8178.
For each disabled RGB output channel, the quiescent power supply
current in VPOS and VNEG drops by approximately 34 mA.
VOCM_CMENCON and VOCM_CMENCOFF are internally
buffered to prevent transients flowing into or out of these inputs
from acting on the source impedance and becoming sources of
crosstalk.
Rev. 0 | Page 32 of 40
AD8178
VPOS
loads driven by the H and V outputs are high and because the
voltage at these outputs typically sits close to either rail, the
correction to the on-chip power estimate is small. Furthermore,
the H and V outputs are active only briefly during sync
generation and returned to digital ground thereafter.
IO, QUIESCENT
QNPN
VOUTPUT
QPNP
Short-Circuit Output Conditions
IOUTPUT
VNEG
06608-026
IO, QUIESCENT
Figure 51. Simplified Output Stage
Example
With an ambient temperature of 85°C, all nine RGB output
channels driving 1 Vrms into 100 Ω loads, and power supplies at
±2.5 V, follow these steps:
1.
Calculate the power dissipation of the AD8178 using data
sheet quiescent currents, neglecting the VDD current because
it is insignificant.
PD,QUIESCENT = (VPOS × IVPOS) + (VNEG × IVNEG)
(4)
PD,QUIESCENT = (2.5 V × 460 mA) + (2.5 V × 460 mA) = 2.3 W
2.
Calculate power dissipation from loads. For a differential
output and ground-referenced load, the output power is
symmetrical in each output phase.
PD,OUTPUT = (VPOS − VOUTPUT,RMS) × IOUTPUT,RMS
(5)
There are 15 output pairs, or 30 output currents.
nPD,OUTPUT = 30 × 15 mW = 0.45 W
Subtract quiescent output stage current for the number of
loads (30 in this example). The output stage is either standing
or driving a load, but the current needs to be counted only
once (valid for output voltages > 0.5 V).
PDQ,OUTPUT = (VPOS − VNEG) × IOUTPUT,QUIESCENT
(6)
PDQ,OUTPUT = (2.5 V − (−2.5 V)) × 1.65 mA = 8.25 mW
There are 15 output pairs, or 30 output currents.
nPD,OUTPUT = 30 × 8.25 mW = 0.25 W
4.
Verify that the power dissipation does not exceed the
maximum allowed value.
PD,ON-CHIP = PD,QUIESCENT + nPD,OUTPUT − nPDQ,OUTPUT
Crosstalk
Many systems (such as KVM switches) that handle numerous
analog signal channels have strict requirements for keeping the
various signals from influencing any of the other signals in the
system. Crosstalk is the term used to describe the coupling of
the signals of other nearby channels to a given channel.
When there are many signals in close proximity in a system,
as is undoubtedly the case in a system that uses the AD8178,
the crosstalk issues can be quite complex. A good understanding
of the nature of crosstalk and some definition of terms is required
to specify a system that uses one or more crosspoint devices.
Types of Crosstalk
Crosstalk can be propagated by means of any of three methods.
These fall into the categories of electric field, magnetic field, and the
sharing of common impedances. This section explains these effects.
PD,OUTPUT = (2.5 V − 1 V) × (1 V/100 Ω) = 15 mW
3.
Although there is short-circuit current protection on the AD8178
outputs, the output current can reach values of 80 mA into
a grounded output. Any sustained operation with too many
shorted outputs can exceed the maximum die temperature
and can result in device failure (see the Absolute Maximum
Ratings section).
(7)
PD,ON-CHIP = 2.3 W + 0.45 W − 0.25 W = 2.5 W
From Figure 50 or Equation 1, this power dissipation is below
the maximum allowed dissipation for all ambient temperatures
up to and including 85°C.
In a general case, the power delivered by the digital supply and
dissipated into the digital output devices has to be taken into
account following a similar derivation. However, because the
Every conductor can be both a radiator of electric fields and
a receiver of electric fields. The electric field crosstalk mechanism
occurs when the electric field created by the transmitter propagates
across a stray capacitance (for example, free space) and couples
with the receiver and induces a voltage. This voltage is an unwanted
crosstalk signal in any channel that receives it.
Currents flowing in conductors create magnetic fields that circulate
around the currents. These magnetic fields then generate voltages
in any other conductors whose paths they link. The undesired
induced voltages in these other channels are crosstalk signals.
The channels that crosstalk can be said to have a mutual inductance
that couples signals from one channel to another.
The power supplies, grounds, and other signal return paths
of a multichannel system are generally shared by the various
channels. When a current from one channel flows in one of these
paths, a voltage that is developed across the impedance becomes
an input crosstalk signal for other channels that share the common
impedance.
All these sources of crosstalk are vector quantities, so the magnitudes cannot simply be added together to obtain the total crosstalk.
In fact, there are conditions where driving additional circuits in
parallel in a given configuration can actually reduce the crosstalk.
The fact that the AD8178 is a fully differential design means that
Rev. 0 | Page 33 of 40
AD8178
many sources of crosstalk either destructively cancel, or are
common mode to, the signal and can be rejected by a differential
receiver.
Areas of Crosstalk
A practical AD8178 circuit must be mounted to an actual circuit
board to connect it to power supplies and measurement equipment.
Great care has been taken to create an evaluation board (available
upon request) that adds minimum crosstalk to the intrinsic device.
This, however, raises the issue that system crosstalk is a combination of the intrinsic crosstalk of the devices, in addition to the
circuit board to which they are mounted. It is important to try
to separate these two areas when attempting to minimize the
effect of crosstalk.
In addition, crosstalk can occur among the inputs to a crosspoint
and among the outputs. It can also occur from input to output.
In the following sections, techniques are discussed for diagnosing
which part of a system is contributing to crosstalk.
Measuring Crosstalk
Crosstalk is measured by applying a signal to one or more channels
and measuring the relative strength of that signal on a desired
selected channel. The measurement is usually expressed as decibels
(dB) down from the magnitude of the test signal. The crosstalk
is expressed by
⎛ A (s ) ⎞
⎟
XT = 20 log 10 ⎜ SEL
⎟
⎜A
⎝ TEST (s) ⎠
(8)
three at a time; and so on, until, finally, there is only one way to
drive a test signal into all 15 other input channels in parallel.
Each of these cases is legitimately different from the others and
can yield a unique value, depending on the resolution of the
measurement system, but it is hardly practical to measure all
these terms and then specify them. In addition, this measurement
describes the crosstalk matrix for just one input channel. A similar
crosstalk matrix can be proposed for every other input. In addition,
if the possible combinations and permutations for connecting
inputs to the other outputs (not used for measurement) are taken
into consideration, the numbers rather quickly grow to astronomical proportions. If a larger crosspoint array of multiple
AD8178 devices is constructed, the numbers grow larger still.
Obviously, some subset of all these cases must be selected to be
used as a guide for a practical measure of crosstalk. One common
method is to measure all hostile crosstalk; this means that the
crosstalk to the selected channel is measured while all other system
channels are driven in parallel. In general, this yields the worst
crosstalk number; but this is not always the case, due to the vector
nature of the crosstalk signal.
Other useful crosstalk measurements are those created by one
nearest neighbor or by the two nearest neighbors on either side.
These crosstalk measurements are generally higher than those
of more distant channels, so they can serve as a worst-case
measure for any other one-channel or two-channel crosstalk
measurements.
Input and Output Crosstalk
where:
s = jω is the Laplace transform variable.
ASEL(s) is the amplitude of the crosstalk induced signal in the
selected channel.
ATEST(s) is the amplitude of the test signal.
It can be seen that crosstalk is a function of frequency but not
a function of the magnitude of the test signal (to first order).
In addition, the crosstalk signal has a phase relative to the test
signal associated with it.
A network analyzer is most commonly used to measure crosstalk
over a frequency range of interest. It can provide both magnitude
and phase information about the crosstalk signal.
As a crosspoint system or device grows larger, the number of
theoretical crosstalk combinations and permutations can become
extremely large. For example, in the case of the triple 16 × 5 matrix
of the AD8178, note the number of crosstalk terms that can be
considered for a single channel, for example, Input Channel
INPUT0. INPUT0 is programmed to connect to one of the
AD8178 outputs where the measurement can be made.
First, the crosstalk terms associated with driving a test signal into
each of the other 15 input channels can be measured one at a time,
while applying no signal to INPUT0. Next, the crosstalk terms
associated with driving a parallel test signal into all 15 other inputs
can be measured two at a time in all possible combinations; then
Capacitive coupling is voltage-driven (dV/dt), but it is generally
a constant ratio. Capacitive crosstalk is proportional to input or
output voltage, but this ratio is not reduced by simply reducing
signal swings. Attenuation factors must be changed by changing
impedances (lowering mutual capacitance), or destructive
canceling must be utilized by summing equal and out-of-phase
components. For high input impedance devices such as the
AD8178, capacitances generally dominate input-generated
crosstalk.
Inductive coupling is proportional to current (dI/dt) and often
scales as a constant ratio with signal voltage, but it also shows
a dependence on impedances (load current). Inductive coupling
can also be reduced by constructive canceling of equal and outof-phase fields. In the case of driving low impedance video loads,
output inductances contribute highly to output crosstalk.
The flexible programming capability of the AD8178 can be used
to diagnose whether crosstalk is occurring more on the input
side or the output side. Some examples are illustrative. A given
input channel (INPUT7 roughly in the middle for this example)
can be programmed to drive OUTPUT2 (exactly in the middle).
The inputs to INPUT7 are just terminated to ground (via 50 Ω
or 75 Ω), and no signal is applied.
All the other inputs are driven in parallel with the same test signal
(practically provided by a distribution amplifier), with all other
outputs except OUTPUT2 disabled. Because grounded INPUT7
Rev. 0 | Page 34 of 40
AD8178
is programmed to drive OUTPUT2, no signal should be present.
Any signal that is present can be attributed to the other 15 hostile
input signals because no other outputs are driven (they are all
disabled). Thus, this method measures the all hostile input
contribution to crosstalk into INPUT7. Of course, the method
can be used for other input channels and combinations of
hostile inputs.
For output crosstalk measurement, a single input channel is
driven (INPUT0, for example) and all outputs other than
a given output (OUTPUT2 in the middle) are programmed to
connect to INPUT0. OUTPUT2 is programmed to connect to
INPUT15 (far away from INPUT0), which is terminated to
ground. Thus, OUTPUT2 should not have a signal present because
it is listening to a quiet input. Any signal measured at OUTPUT2
can be attributed to the output crosstalk of the other eight hostile
outputs. Again, this method can be modified to measure other
channels and other crosspoint matrix combinations.
Effect of Impedances on Crosstalk
The input side crosstalk can be influenced by the output
impedance of the sources that drive the inputs. The lower the
impedance of the drive source, the lower the magnitude of the
crosstalk. The dominant crosstalk mechanism on the input side
is capacitive coupling. The high impedance inputs do not have
significant current flow to create magnetically induced crosstalk.
However, significant current can flow through the input termination resistors and the loops that drive them. Thus, the PC board
on the input side can contribute to magnetically coupled crosstalk.
From a circuit standpoint, the input crosstalk mechanism looks
like a capacitor coupling to a resistive load. For low frequencies,
the magnitude of the crosstalk is given by
XT = 20 log 10 [(RS C M ) × s ]
(9)
where:
RS is the source resistance.
CM is the mutual capacitance between the test signal circuit and
the selected circuit.
s is the Laplace transform variable.
Equation 9 illustrates that this crosstalk mechanism has a high-pass
nature; it can also be minimized by reducing the coupling capacitance of the input circuits and lowering the output impedance
of the drivers. If the input is driven from a 75 Ω terminated cable,
the input crosstalk can be reduced by buffering this signal with
a low output impedance buffer.
On the output side, the crosstalk can be reduced by driving
a lighter load. Although the AD8178 is specified with excellent
settling time when driving a properly terminated Cat-5, the
crosstalk is higher than the minimum obtainable due to the
high output currents. These currents induce crosstalk via the
mutual inductance of the output pins and the bond wires of
the AD8178.
From a circuit standpoint, this output crosstalk mechanism
looks like a transformer with a mutual inductance between the
windings that drives a load resistor. For low frequencies, the
magnitude of the crosstalk is given by
⎛
s
XT = 20 log 10 ⎜ M XY ×
⎜
RL
⎝
⎞
⎟
⎟
⎠
(10)
where:
MXY is the mutual inductance of output X to output Y.
RL is the load resistance on the measured output.
This crosstalk mechanism can be minimized by keeping the
mutual inductance low and increasing RL. The mutual
inductance can be kept low by increasing the spacing of the
conductors and minimizing their parallel length.
PCB Layout
Extreme care must be exercised to minimize additional crosstalk
generated by the system circuit board(s). The areas that must be
carefully detailed are grounding, shielding, signal routing, and
supply bypassing.
The packaging of the AD8178 is designed to help keep crosstalk
to a minimum. On the BGA substrate, each pair is carefully routed
to predominately couple to each other, with shielding traces separating adjacent signal pairs. The ball grid array is arranged such
that similar board routing can be achieved. Input and output differential pairs are grouped by channel rather than by color to allow
for easy, convenient board routing.
The input and output signals have minimum crosstalk if they
are located between ground planes on layers above and below,
and are separated by ground in between. Vias should be located
as close to the IC as possible to carry the inputs and outputs to
the inner layer. The input and output signals surface at the input
termination resistors and the output series back-termination
resistors. To the extent possible, these signals should also be
separated as soon as they emerge from the IC package.
PCB Termination Layout
As frequencies of operation increase, the importance of proper
transmission line signal routing becomes more important. The
bandwidth of the AD8178 is large enough that using high impedance routing does not provide a flat in-band frequency response
for practical signal trace lengths. It is necessary for the user to
choose a characteristic impedance suitable for the application and
properly terminate the input and output signals of the AD8178.
Traditionally, video applications have used 75 Ω single-ended
environments. RF applications are generally 50 Ω single-ended
(and board manufacturers have the most experience with this
application). Cat-5 cabling is usually driven as differential pairs
of 100 Ω differential impedance.
For flexibility, the AD8178 does not contain on-chip termination resistors. This flexibility in application comes with some
board layout challenges. The distance between the termination
of the input transmission line and the AD8178 die is a high
impedance stub and causes reflections of the input signal. With
some simplification, it can be shown that these reflections cause
peaking of the input at regular intervals in frequency, dependent
Rev. 0 | Page 35 of 40
AD8178
on the propagation speed (VP) of the signal in the chosen board
material and the distance (d) between the termination resistor
and the AD8178. If the distance is great enough, these peaks can
occur in-band. In fact, practical experience shows that these
peaks are not high Q and should be pushed out to three or four
times the desired bandwidth to not have an effect on the signal.
For a board designer using FR4 (VP = 144 × 106 m/sec), this
means the AD8178 should be no more than 1.5 cm after the
termination resistors and should preferably be placed even closer.
The BGA substrate routing inside the AD8178 is approximately
1 cm in length and adds to the stub length, so 1.5 cm PCB routing
equates to d = 2.5 × 10–2 m in the calculations.
f PEAK =
(2n + 1)VP
(11)
4d
where n = {0, 1, 2, 3, ...}.
In some cases, it is difficult to place the termination close to the
AD8178 due to space constraints, differential routing, and large
resistor footprints. A preferable solution in this case is to maintain
a controlled transmission line past the AD8178 inputs and terminate the end of the line. This is known as fly-by termination.
The input impedance of the AD8178 is large enough, and stub
length inside the package is small enough, that this works well
in practice. Implementation of fly-by input termination often
includes bringing the signal in on one routing layer, then passing
through a filled via under the AD8178 input ball, then back out
to termination on another signal layer. In this case, care must be
taken to tie the reference ground planes together near the signal
via if the signal layers are referenced to different ground planes.
50Ω
While the examples discussed so far are for input termination,
the theory is similar for output back-termination. Taking the
AD8178 as an ideal voltage source, any distance of routing between
the AD8178 and a back-termination resistor is an impedance
mismatch that potentially creates reflections. For this reason,
back-termination resistors should also be placed close to the
AD8178. In practice, because back-termination resistors are
series elements, they can be placed close to the AD8178
outputs.
Finally, the AD8178 pinout allows the user to bring the outputs
out as surface traces to the back-termination resistors. The
designer can avoid creating stubs and reflections by keeping the
AD8178 output signal path on the surface of the board. A stub
is created when a top-to-bottom via connection is made on the
output signal path that is perpendicular to the signal flow.
OPn
ONn
06608-027
IPn
INn
AD8178
When driving the AD8178 single-endedly, the undriven input is
often terminated with a resistance to balance the input stage.
By terminating the undriven input with a resistor of one-half
the characteristic impedance, the input stage is perfectly
balanced (25 Ω, for example, to balance the two parallel 50 Ω
terminations on the driven input). However, due to the
feedback in the input receiver, there is high speed signal current
leaving the undriven input. To terminate this high speed signal,
proper transmission line techniques should be used. One
solution is to adjust the trace width to create a transmission line
of half the characteristic impedance and terminate the far end
with this resistance (25 Ω in a 50 Ω system). This is not often
practical because trace widths become large. In most cases, the
best practical solution is to place the half-characteristic impedance
resistor as close as possible (preferably less than 1.5 cm away)
and reduce the parasitics of the stub (by removing the ground
plane under the stub, for example). In either case, the designer
must decide if the layout complexity created by a balanced,
terminated solution is preferable to simply grounding the
undriven input at the ball with no trace.
Figure 52. Fly-By Input Termination. (Grounds for the two transmission lines
shown must be tied together close to the INn pin.)
If multiple AD8178s are to be driven in parallel, a fly-by input
termination scheme is very useful, but the distance from each
AD8178 input to the driven input transmission line is a stub
that should be minimized in length and parasitics by using the
discussed guidelines.
Rev. 0 | Page 36 of 40
AD8178
VPOS
FOUR 15-PIN HD
CONNECTORS
15-PIN HD
CONNECTOR
PC
FOUR AD8147
(G = +2)
AD8003
(G = +4)
THREE 15-PIN HD
CONNECTORS
THREE RGB, HV
CHANNELS
FOUR RGB, HV
CHANNELS
OUT0 TO OUT1
IN0 TO IN3
FOUR 15-PIN HD
CONNECTORS
15-PIN HD
CONNECTOR
PC
VDD
FOUR AD8147
(G = +2)
FOUR DIFFERENTIAL
RGB WITH SYNC-ON
CM CHANNELS
FOUR RGB, HV
CHANNELS
IN0 TO IN3
IN4 TO IN7
THREE 15-PIN HD
CONNECTORS
THREE RGB, HV
CHANNELS
THREE RGB
CHANNELS
OUT0 TO OUT1
IN4 TO IN7
OUT2
OUT2
THREE HV
PAIRS
THREE RGB, HV
CHANNELS
RGB
MONITOR
RGB
MONITOR
RJ-45
CONNECTOR
AD8145 RGB, HV
(G = +2)
CHANNEL
IN8 TO IN11
15-PIN HD
CONNECTORS
DIFFERENTIAL
OFFSET
IN14 TO IN15
RJ-45
CONNECTOR
OUT4
DIFFERENTIAL
RGB WITH
SYNC-ON CM
CAT-5
OUT3
RGB
MONITOR
AD8178 DUT
CAT5
PC
OUT3
IN12 TO IN13
IN8 TO IN11
FOUR RJ-45
CONNECTORS
TWO
DIFFERENTIAL
RGB CHANNELS
AD8147 (G = +2)
EVALUATION BOARD
TWELVE SMA
CONNECTORS
SIGNAL GENERATOR/
NETWORK ANALYZER
DIFFERENTIAL
RGB, HV
CHANNEL
IN12 TO IN13
RIBBON CABLE
IN14 TO IN15
NATIONAL
INSTRUMENTS
CONTROLLER BOARD
TWO GORE
HEADERS
GORE
HEADER
OUT4
USB
AD8178
CUSTOMER
EVALUATION BOARD
GND
VNEG
TO CONTROLLER PC USB
Figure 53. Evaluation Board Schematic
Rev. 0 | Page 37 of 40
06608-029
RGB, HV
CHANNEL
AD8178
OUTLINE DIMENSIONS
27.20
27.00 SQ
26.80
A1 CORNER
INDEX AREA
26
25
24
22 20 18 16 14 12 10
8
6
4
2
23 21 19 17 15 13 11 9
5
3
7
1
A
B
C
D
E
F
G
H
J
K
L
M
N
P
R
T
U
V
W
Y
AA
AB
AC
AD
AE
AF
A1 BALL
PAD CORNER
24.20
24.00 SQ
23.80
TOP VIEW
1.00
BSC
2.43
2.32
2.15
DETAIL A
1.19
1.17
1.15
DETAIL A
0.60
0.55
0.50
0.70
0.60
0.50
BALL DIAMETER
COMPLIANT TO JEDEC STANDARDS MS-034-AAL-1
COPLANARITY
0.20 MAX
SEATING
PLANE
070207-B
0.70
0.60
0.50
Figure 54. 676-Ball Plastic Ball Grid Array [PBGA]
(B-676)
Dimensions shown in millimeters
ORDERING GUIDE
Model
AD8178ABPZ 1
AD8178-EVALZ1
1
Temperature Range
−40°C to +85°C
Package Description
676-Ball Plastic Ball Grid Array [PBGA]
Evaluation Board
Z = RoHS Compliant Part.
Rev. 0 | Page 38 of 40
Package Option
B-676
AD8178
NOTES
Rev. 0 | Page 39 of 40
AD8178
NOTES
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D06608-0-7/07(0)
Rev. 0 | Page 40 of 40