View ADV7120KN30_79207.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

a
FEATURES 80 MHz Pipelined Operation Triple 8-Bit D/A Converters RS-343A/RS-170 Compatible Outputs TTL Compatible Inputs +5 V CMOS Monolithic Construction 40-Pin DIP or 44-Pin PLCC and 48-Lead TQFP APPLICATIONS High Resolution Color Graphics CAE/CAD/CAM Applications Image Processing Instrumentation Video Signal Reconstruction Desktop Publishing Direct Digital Synthesis (DDS) and I/Q Modulation SPEED GRADES* 80 MHz 50 MHz 30 MHz
CMOS 80 MHz, Triple 8-Bit Video DAC ADV7120
FUNCTIONAL BLOCK DIAGRAM
VAA FS ADJUST VREF REFERENCE AMPLIFIER COMP
ADV7120
CLOCK R0 R7 PIXEL INPUT PORT RED 8 REGISTER
8
DAC
IOR
G0 G7
8
GREEN REGISTER
8 DAC IOG
B0 B7
8
BLUE REGISTER
8 DAC IOB
REF WHITE BLANK SYNC
CONTROL REGISTER
SYNC CONTROL
ISYNC
GND
GENERAL DESCRIPTION
The ADV7120 (ADV(R)) is a digital to analog video converter on a single monolithic chip. The part is specifically designed for high resolution color graphics and video systems. It is also ideal for any high speed communications type applications requiring low cost, high speed DACs. It consists of three, high speed, 8-bit, video D/A converters (RGB); a standard TTL input interface and high impedance, analog output, current sources. The ADV7120 has three separate, 8-bit, pixel input ports, one each for red, green and blue video data. Additional video input controls on the part include composite sync, blank and reference white. A single +5 V supply, an external 1.23 V reference and pixel clock input are all that are required to make the part operational. The ADV7120 is capable of generating RGB video output signals, which are compatible with RS-343A and RS-170 video standards, without requiring external buffering. The ADV7120 is fabricated in a +5 V CMOS process. Its monolithic CMOS construction ensures greater functionality with low power dissipation. The part is packaged in both a 0.6", 40-pin plastic DIP and a 44-pin plastic leaded (J-lead) chip carrier, PLCC. The ADV7120 is also available in a very small 48lead Thin Quad Flatpack (TQFP).
ADV is a registered trademark of Analog Devices, Inc. *Speed grades up to 140 MHz are also available upon special request. Please contact Analog Devices or its representatives for further details.
PRODUCT HIGHLIGHTS
1. Fast video refresh rate, 80 MHz. 2. Compatible with a wide variety of high resolution color graphics video systems. 3. Guaranteed monotonic with a maximum differential nonlinearity of 0.5 LSB. Integral nonlinearity is guaranteed to be a maximum of 1 LSB.
REV. B
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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703
ADV7120-SPECIFICATIONS I
Parameter STATIC PERFORMANCE Resolution (Each DAC) Accuracy (Each DAC) Integral Nonlinearity, INL Differential Nonlinearity, DNL Gray Scale Error Coding DIGITAL INPUTS Input High Voltage, V INH Input Low Voltage, VINL Input Current, IIN Input Capacitance, CIN2 ANALOG OUTPUTS Gray Scale Current Range Output Current White Level Relative to Blank White Level Relative to Black Black Level Relative to Blank Blank Level on IOR, IOB Blank Level on IOG Sync Level on IOG LSB Size DAC to DAC Matching Output Compliance, VOC Output Impedance, ROUT2 Output Capacitance, COUT2 VOLTAGE REFERENCE Voltage Reference Range, V REF Input Current, IVREF POWER REQUIREMENTS VAA IAA Power Supply Rejection Ratio Power Dissipation DYNAMIC PERFORMANCE Glitch Impulse2, 3 DAC Noise2, 3, 4 Analog Output Skew All Versions 8 1 0.5 5 Binary 2 0.8 1 10 15 22 17.69 20.40 16.74 18.50 0.95 1.90 0 50 6.29 9.5 0 50 69.1 5 -1 +1.4 100 30 1.14/1.26 -5 5 125 100 0.5 625 500 50 200 2
(VAA = +5 V 5%; VREF = +1.235 V; RL = 37.5 , CL = 10 pF; RSET = 560 . 1 SYNC connected to I0G. All Specifications TMIN to TMAX unless otherwise noted.)
Test Conditions/Comments
Units Bits LSB max LSB max % Gray Scale max
Guaranteed Monotonic Max Gray Scale Current: IOG = (VREF* 12,082/RSET) mA IOR, IOB = (VREF* 8,627/RSET) mA
V min V max A max pF max mA min mA max mA min mA max mA min mA max mA min mA max A min A max mA min mA max A min A max A typ % max V min V max k typ pF max V min/V max mA typ V nom mA max mA max %/% max mW max mW max pV secs typ pV secs typ ns max
VIN = 0.4 V or 2.4 V
Typically 19.05 mA Typically 17.62 mA Typically 1.44 mA Typically 5 A Typically 7.62 mA Typically 5 A
Typically 2%
IOUT = 0 mA VREF = 1.235 V for Specified Performance
Typically 80 mA: 80 MHz Parts Typically 70 mA: 50 MHz & 35 MHz Parts Typically 0.12%/%: f = 1 kHz, COMP = 0.1 F Typically 400 mW: 80 MHz Parts Typically 350 mW: 50 MHz & 30 MHz Parts
Typically 1 ns
NOTES 1 Temperature range (T MIN to TMIN); 0C to +70C. 2 Sample tested at +25C to ensure compliance. 3 TTL input values are 0 to 3 volts, with input rise/fall times 3 ns, measured between the 10% and 90% points. Timing reference points at 50% for inputs and outputs. See timing notes in Figure 1. 4 This includes effects due to clock and data feedthrough as well as RGB analog crosstalk. Specifications subject to change without notice.
-2-
REV. B
ADV7120 TIMING CHARACTERISTICS1
Parameter fMAX tl t2 t3 t4 t5 t6 t7 t 83 80 MHz Version 80 3 2 12.5 4 4 30 20 3 12 50 6 2 20 7 7 30 20 3 15
(VAA = +5 V 5%; VREF = +1.235 V; RL = 37.5 , CL = 10 pF; RSET = 560 . ISYNC connected to IOG. All Specifications TMIN to TMAX2 unless otherwise noted.)
30 MHz Version 30 8 2 33.3 9 9 30 20 3 15 Units MHz max ns min ns min ns min ns min ns min ns max ns typ ns max ns typ Conditions/Comments Clock Rate Data & Control Setup Time Data & Control Hold Time Clock Cycle Time Clock Pulse Width High Time Clock Pulse Width Low Time Analog Output Delay Analog Output Rise/Fall Time Analog Output Transition Time
50 MHz Version
NOTES 1 TTL input values are 0 to 3 volts, with input rise/fall times 3 ns, measured between the 10% and 90% points. Timing reference points at 50% for inputs and outputs. See timing notes in Figure 1. 2 Temperature range (T MIN to TMAX): 0C to +70C 3 Sample tested at +25C to ensure compliance. Specifications subject to change without notice.
t4 t5
CLOCK
t3
DIGITAL INPUTS (R0-R7, G0-G7, B0-B7; SYNC, BLANK, REF WHITE)
t1
DATA
t2
t6
ANALOG OUTPUTS (IOR, IOG, IOB, I SYNC )
t8
t7
NOTES 1. OUTPUT DELAY (t ) MEASURED FROM THE 50% POINT OF THE RISING EDGE OF 6 CLOCK TO THE 50% POINT OF FULL-SCALE TRANSITION. 2. TRANSITION TIME (t ) MEASURED FROM THE 50% POINT OF FULL-SCALE 8 TRANSITION TO WITHIN 2% OF THE FINAL OUTPUT VALUE. 3. OUTPUT RISE/FALL TIME (t ) MEASURED BETWEEN THE 10% AND 90% POINTS 7 OF FULL TRANSITION.
Figure 1. Video Input/Output Timing
REV. B
-3-
ADV7120
RECOMMENDED OPERATING CONDITIONS Parameter Power Supply Ambient Operating Temperature Output Load Reference Voltage Symbol VAA TA RL VREF Min 4.75 0 1.14 37.5 1.235 Typ 5.00 Max 5.25 +70 1.26 Units Volts C Volts ORDERING GUIDE
Model ADV7120KN80 ADV7120KN50 ADV7120KN30 ADV7120KP80 ADV7120KP50 ADV7120KP30 ADV7120KST50 ADV7120KST30
Speed 80 MHz 50 MHz 30 MHz 80 MHz 50 MHz 30 MHz 50 MHz 30 MHz
Temperature Range1 0C to +70C 0C to +70C 0C to +70C 0C to +70C 0C to +70C 0C to +70C 0C to +70C 0C to +70C
Package Option2 N-40A N-40A N-40A P-44A P-44A P-44A ST-48 ST-48
ABSOLUTE MAXIMUM RATINGS 1
VAA to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V Voltage on Any Digital Pin . . . . . GND -0.5 V to VAA +0.5 V Ambient Operating Temperature (TA) . . . . . . . . 0C to +70C Storage Temperature (TS) . . . . . . . . . . . . . . -65C to +150C Junction Temperature (TJ) . . . . . . . . . . . . . . . . . . . . +150C Soldering Temperature (10 secs) . . . . . . . . . . . . . . . . . . 300C Vapor Phase Soldering (1 minute) . . . . . . . . . . . . . . . . . 220C IOR, IOB, IOG, ISYNC to GND2 . . . . . . . . . . . . . . 0 V to VAA
NOTES 1 Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2 Analog Output Short Circuit to any Power Supply or Common can be of an indefinite duration.
NOTES 1 Industrial temperature range (-40C to +85C) version available to special request. Please consult your local Analog Device representative. 2 N = Plastic DIP; P = Plastic Leaded Chip Carrier.
CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADV7120 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. PIN CONFIGURATIONS DIP
R4 R5 R6 R7 G0 G1 G2 G3 G4 G5 1 2 3 4 5 6 7 8 9 10 40 R3
WARNING!
ESD SENSITIVE DEVICE
PLCC
FS ADJUST
TQFP
GND GND GND
COMP
R5
R6
R3
R7
R4
R6
R5
R4
R3
R2
R7
R1
R0
39 R2 38 R1 37 R0 36 FS ADJUST 35 VREF 34 COMP 33 IOR 32 IOG
VREF
48 47 46 45 44 43 42 41 40 39 38 37 GND 1 36 FS ADJUST 35 VREF 34 COMP 33 IOR
6 G0 G1 G2 7 8 9
5
4
3
2
1
44 43 42 41 40 39 IOR 38 IOG
G0 2 G1 3 G2 4 G3 5 G4 6 G5 7 G6 8 G7 9 BLANK 10 SYNC 11 VAA 12 13 14 15 16 17 18 19 20 21 22 23 24
37 ISYNC 36 VAA
G3 10 G4 11 G5 12 G6 13 G7 14 BLANK 15 SYNC 16 VAA 17 18 19 20 21 22 23 24 25 26 27 28
REF WHITE CLOCK GND B1 B2 B3 B4 B5 B0 B6 B7
R2
R1
R0
NC
32 IOG 31 VAA 30 VAA 29 IOB 28 GND 27 GND 26 CLOCK 25 NC
31 ISYNC TOP VIEW G6 11 (Not to Scale) 30 VAA G7 12 29 IOB
ADV7120
ADV7120
TOP VIEW (Not to Scale)
35 VAA 34 VAA 33 IOB 32 GND 31 GND 30 GND 29 GND
ADV7120
TOP VIEW (Not to Scale)
BLANK SYNC VAA
13 14 15
28 GND 27 GND 26 GND 25 24 23 22 CLOCK REF WHITE B7 B6
B0 16 B1 17 B2 18 B3 19 B4 20
GND
B0
B1
B2
B3
B4
B5
B6
NC
GND
21 B5
NC = NO CONNECT
NOTE For the ADV7120 in TQFP package: The REF WHITE pin is not available. The ISYNC pin is not available and is internally connected to the IOG pin.
-4-
NC
B7
REV. B
ADV7120
PIN FUNCTION DESCRIPTION
Pin Mnemonic BLANK
Function Composite blank control input (TTL compatible). A logic zero on this control input drives the analog outputs, IOR, IOB and IOG, to the blanking level. The BLANK signal is latched on the rising edge of CLOCK. While BLANK is a logical zero, the R0-R7, G0-G7, R0-R7 and REF WHITE pixel and control inputs are ignored. Composite sync control input (TTL compatible). A logical zero on the SYNC input switches off a 40 IRE current source on the ISYNC output. SYNC does not override any other control or data input; therefore, it should only be asserted during the blanking interval. SYNC is latched on the rising edge of CLOCK. Clock input (TTL compatible). The rising edge of CLOCK latches the R0-R7, G0-G7, B0-B7, SYNC, BLANK and REF WHITE pixel and control inputs. It is typically the pixel clock rate of the video system. CLOCK should be driven by a dedicated TTL buffer. Reference white control input (TTL compatible). A logical one on this input forces the IOR, IOG and IOB outputs to the white level, regardless of the pixel input data (R0-R7, G0-G7 and B0-B7). REF WHITE is latched on the rising edge of clock. Red, green and blue pixel data inputs (TTL compatible). Pixel data is latched on the rising edge of CLOCK. R0, G0 and B0 are the least significant data bits. Unused pixel data inputs should be connected to either the regular PCB power or ground plane. Red, green, and blue current outputs. These high impedance current sources are capable of directly driving a doubly terminated 75 coaxial cable. All three current outputs should have similar output loads whether or not they are all being used. Sync current output. This high impedance current source can be directly connected to the IOG output. This allows sync information to be encoded onto the green channel. ISYNC does not output any current while SYNC is at logical zero. The amount of current output at ISYNC while SYNC is at logical one is given by: ISYNC (mA) = 3,455 x VREF (V)/ RSET () If sync information is not required on the green channel, ISYNC should be connected to AGND.
SYNC
CLOCK
REF WHITE
R0-R7, G0-G7, B0-B7 IOR, IOG, IOB
ISYNC
FS ADJUST
Full-scale adjust control. A resistor (RSET) connected between this pin and GND, controls the magnitude of the full-scale video signal. Note that the IRE relationships are maintained, regardless of the full-scale output current. The relationship between RSET and the full-scale output current on IOG (assuming ISYNC is connected to IOG) is given by: RSET () = 12,082 x VREF (V)/IOG (mA) The relationship between RSET and the full-scale output current on IOR and IOB is given by: IOR, IOB (mA) = 8,628 x VREF (V)/ RSET () Compensation pin. This is a compensation pin for the internal reference amplifier. A 0.1 F ceramic capacitor must be connected between COMP and VAA. Voltage reference input. An external 1.2 V voltage reference must be connected to this pin. The use of an external resistor divider network is not recommended. A 0.1 F decoupling ceramic capacitor should be connected between VREF and VAA. Analog power supply (5 V 5%). All VAA pins on the ADV7120 must be connected. Ground. All GND pins must be connected.
COMP VREF
VAA GND
REV. B
-5-
ADV7120
TERMINOLOGY Blanking Level Raster Scan
The level separating the SYNC portion from the video portion of the waveform. Usually referred to as the front porch or back porch. At 0 IRE units, it is the level which will shut off the picture tube, resulting in the blackest possible picture.
Color Video (RGB)
The most basic method of sweeping a CRT one line at a time to generate and display images.
Reference Black Level
The maximum negative polarity amplitude of the video signal.
Reference White Level
This usually refers to the technique of combining the three primary colors of red, green and blue to produce color pictures within the usual spectrum. In RGB monitors, three DACs are required, one for each color.
Sync Signal (SYNC)
The maximum positive polarity amplitude of the video signal.
Sync Level
The peak level of the SYNC signal.
Video Signal
The position of the composite video signal which synchronizes the scanning process.
Gray Scale
That portion of the composite video signal which varies in gray scale levels between reference white and reference black. Also referred to as the picture signal, this is the portion which may be visually observed.
The discrete levels of video signal between reference black and reference white levels. An 8-bit DAC contains 256 different levels while a 6-bit DAC contains 64.
CIRCUIT DESCRIPTION AND OPERATION
The ADV7120 contains three 8-bit D/A converters, with three input channels each containing an 8-bit register. Also integrated on board the part is a reference amplifier and CRT control functions BLANK, SYNC and REF WHITE.
Digital Inputs
The REF WHITE control input drives the RGB video outputs to the white level. This function could be used to overlay a cursor or crosshair onto the RGB video output. Table I details the resultant effect on the analog outputs of BLANK, SYNC and REF WHITE. All these digital inputs are specified to accept TTL logic levels.
Clock Input
24-bits of pixel data (color information) R0-R7, G0-G7 and B0-B7 are latched into the device on the rising edge of each clock cycle. This data is presented to the three 8-bit DACs and is then converted to three analog (RGB) output waveforms. (See Figure 2.) Three other digital control signals are latched to the analog video outputs in a similar fashion. BLANK, SYNC and REF WHITE are each latched on the rising edge of CLOCK to maintain synchronization with the pixel data stream. The BLANK and SYNC functions allow for the encoding of these video synchronization signals onto the RGB video output. This is done by adding appropriately weighted current sources to the analog outputs, as determined by the logic levels on the BLANK and SYNC digital inputs. Figure 3 shows the analog output, RGB video waveform of the ADV7120. The influence of SYNC and BLANK on the analog video waveform is illustrated.
The CLOCK input of the ADV7120 is typically the pixel clock rate of the system. It is also known as the dot rate. The dot rate, and hence the required CLOCK frequency, will be determined by the on-screen resolution, according to the following equation: Dot Rate = (Horiz: Res) x (Vert Res) x (Refresh Rate)/ (Retrace Factor) Horiz Res Vert Res Refresh Rate = = = Number of pixels/line Number of lines/frame Horizontal scan rate. This is the rate at which the screen must be refreshed, typically 60 Hz for a noninterlaced system or 30 Hz for an interlaced system. Total blank time factor. This takes into account that the display is blanked for a certain fraction of the total duration of each frame (e.g., 0.8).
Retrace Factor
=
CLOCK
DIGITAL INPUTS (R0-R7, G0-G7, B0-B7; SYNC, BLANK, REF WHITE)
DATA
ANALOG OUTPUTS (IOR, IOG, IOB, I SYNC )
Figure 2. Video Data Input/Output
-6-
REV. B
ADV7120
If we, therefore, have a graphics system with a 1024 x 1024 resolution, a noninterlaced 60 Hz refresh rate and a retrace factor of 0.8, then: Dot Rate = 1024 x 1024 x 60/0.8 = 78.6 MHz
RED, BLUE mA 19.05 V 0.714 GREEN mA 26.67 V 1.000
WHITE LEVEL
The required CLOCK frequency is thus 78.6 MHz. All video data and control inputs are latched into the ADV7120 on the rising edge of CLOCK, as previously described in the "Digital Inputs" section. It is recommended that the CLOCK input to the ADV7120 be driven by a TTL buffer (e.g., 74F244).
92.5 IRE
1.44 0
0.054 0
9.05 7.62
0.340
7.5 IRE
BLACK LEVEL BLANK LEVEL 40 IRE
0.286
0
0
SYNC LEVEL
NOTES 1. OUTPUTS CONNECTED TO A DOUBLY TERMINATED 75 LOAD. 2. V REF = 1.235V, RSET = 560, I SYNC CONNECTED TO IOG. 3. RS-343A LEVELS AND TOLERANCES ASSUMED ON ALL LEVELS.
Figure 3. RGB Video Output Waveform
Table I. Video Output Truth Table
Description WHITE LEVEL WHITE LEVEL VIDEO VIDEO to BLANK BLACK LEVEL BLACK to BLANK BLANK LEVEL SYNC LEVEL
IOG (mA)l 26.67 26.67 video + 9.05 video + 1.44 9.05 1.44 7.62 0
IOR, IOB (mA) 19.05 19.05 video + 1.44 video + 1.44 1.44 1.44 0 0
REF WHITE 1 0 0 0 0 0 0 0
SYNC 1 1 1 0 1 0 1 0
BLANK 1 1 1 1 1 1 0 0
DAC Input Data xxH FFH data data 00H 00H xxH xxH
NOTE Typical with full-scale IOG = 26.67 mA. VREF = 1.235 V, RSET = 560 , ISYNC connected to IOG.
Video Synchronization and Control
Reference Input
The ADV7120 has a single composite video sync (SYNC) input control. Many graphics processors and CRT controllers have the ability of generating horizontal sync (HSYNC), vertical sync (VSYNC) and composite SYNC. In a graphics system which does not automatically generate a composite SYNC signal, the inclusion of some additional logic circuitry will enable the generation of a composite SYNC signal. The ISYNC current output is typically connected directly to the IOG output, thus encoding video synchronization information onto the green video channel. If it is not required to encode sync information onto the ADV7120's analog outputs, the SYNC input should be tied to logic low and the ISYNC should be connected to analog ground.
An external 1.23 V voltage reference is required to drive the ADV7120. The AD589 from Analog Devices is an ideal choice of reference. It is a two-terminal, low cost, temperature compensated bandgap voltage reference which provides a fixed 1.23 V output voltage for input currents between 50 A and 5 mA. Figure 4 shows a typical reference circuit connection diagram. The voltage reference gets its current drive from the ADV7120's VAA through an onboard 1 k resistor to the VREF pin. A 0.1 F ceramic capacitor is required between the COMP pin and VAA. This is necessary so as to provide compensation for the internal reference amplifier.
REV. B
-7-
ADV7120
A resistance RSET connected between FS ADJUST and GND determines the amplitude of the output video level according to the following equations: IOG (mA) = 12,082 x VREF (V)/RSET () (1) IOR, IOB (mA) = 8,628 x VREF (V)/RSET () (2) If SYNC is not being encoded onto the green channel, then Equation 1 will be similar to Equation 2. Using a variable value of RSET, as shown in Figure 4, allows for accurate adjustment of the analog output video levels. Use of a fixed 560 RSET resistor yields the analog output levels as quoted in the specification page. These values also correspond to the RS-343A video waveform values as shown in Figure 3.
ANALOG POWER PLANE 0.1F COMP VAA IREF 4mA VREF FS ADJUST +5V
as a doubly terminated 75 coaxial cable. Figure 5a shows the required configuration for each of the three RGB outputs connected into a doubly terminated 75 load. This arrangement will develop RS-343A video output voltage levels across a 75 monitor.
IOR, IOG, IOB DACs (CABLE) ZS = 75 (SOURCE TERMINATION) ZL = 75 (MONITOR) ZO = 75
TERMINATION REPEATED THREE TIMES FOR RED, GREEN AND BLUE DACs
Figure 5a. Analog Output Termination for RS-343A
1k TO DACs
One suggested method of driving RS-170 video levels into a 75 monitor is shown in Figure 5b. The output current levels of the DACs remain unchanged but the source termination resistance, ZS, on each of the three DACs is increased from 75 to 150 .
AD589
IOR, IOG, IOB DACs (CABLE)
(1.235V VOLTAGE REFERENCE)
ZO = 75
500 RSET 560 GND 100
ADV7120*
ZS = 150 (SOURCE TERMINATION)
ZL = 75 (MONITOR)
*ADDITIONAL CIRCUITRY, INCLUDING DECOUPLING COMPONENTS, EXCLUDED FOR CLARITY
TERMINATION REPEATED THREE TIMES FOR RED, GREEN AND BLUE DACs
Figure 4. Reference Circuit
D/A Converters
Figure 5b. Analog Output Termination for RS-170
The ADV7120 contains three matched 8-bit D/A converters. The DACs are designed using an advanced, high speed, segmented architecture. The bit currents corresponding to each digital input are routed to either the analog output (bit = "1") or GND (bit = "0") by a sophisticated decoding scheme. As all this circuitry is on one monolithic device, matching between the three DACs is optimized. As well as matching, the use of identical current sources in a monolithic design guarantees monotonicity and low glitch. The onboard operational amplifier stabilizes the full-scale output current against temperature and power supply variations.
Analog Outputs
More detailed information regarding load terminations for various output configurations, including RS-343A and RS-170, is available in an application note entitled "Video Formats & Required Load Terminations" available from Analog Devices, publication number E1228-15-1/89. Figure 3 shows the video waveforms associated with the three RGB outputs driving the doubly terminated 75 load of Figure 5a. As well as the gray scale levels, black level to white level, the diagram also shows the contributions of SYNC and BLANK. These control inputs add appropriately weighted currents to the analog outputs, producing the specific output level requirements for video applications. Table I details how the SYNC and BLANK inputs modify the output levels.
Gray Scale Operation
The ADV7120 has three analog outputs, corresponding to the red, green and blue video signals. A fourth analog output (ISYNC) can be used if it is required to encode video synchronization information onto the green signal. In this case, ISYNC is connected to IOG . (See "Video Synchronization and Control" section.) The red, green and blue analog outputs of the ADV7102 are high impedance current sources. Each one of these three RGB current outputs is capable of directly driving a 37.5 load, such
The ADV7120 can be used for stand-alone, gray scale (monochrome) or composite video applications (i.e., only one channel used for video information). Any one of the three channels, red, green or blue, can be used to input the digital video data. The two unused video data channels should be tied to logical zero.
-8-
REV. B
ADV7120
The unused analog outputs should be terminated with the same load as that for the used channel. In other words, if the red channel is used and IOR is terminated with a doubly terminated 75 load (37.5 ), IOB and IOG should be terminated with 37.5 resistors. (See Figure 6.)
DOUBLY TERMINATED 75 LOAD
Video Output Buffers
VIDEO INPUT
R0 R7
IOR
IOG G0 G7 37.5
The ADV7120 is specified to drive transmission line loads, which is what most monitors are rated as. The analog output configurations to drive such loads are described in the Analog Interface section and illustrated in Figure 5. However, in some applications it may be required to drive long "transmission line" cable lengths. Cable lengths greater than 10 meters can attenuate and distort high frequency analog output pulses. The inclusion of output buffers will compensate for some cable distortion. Buffers with large full power bandwidths and gains between 2 and 4 will be required. These buffers will also need to be able to supply sufficient current over the complete output voltage swing. Analog Devices produces a range of suitable op amps for such applications. These include the AD84X series of monolithic op amps. In very high frequency applications (80 MHz), the AD9617 is recommended. More information on line driver buffering circuits is given in the relevant op amp data sheets. Use of buffer amplifiers also allows implementation of other video standards besides RS-343A and RS-170. Altering the gain components of the buffer circuit will result in any desired video level.
B0 B7
IOB 37.5
ADV7120
GND
Figure 6. Input and Output Connections for Stand-Alone Gray Scale or Composite Video
Z2 Z1 +VS 0.1F
2 IOR, IOG, IOB
7 75
ZO = 75 6 0.1F (CABLE) ZL = 75 (MONITOR)
AD848
3 4
DACs
ZS = 75 (SOURCE TERMINATION)
-V S
GAIN (G) = 1 +
Z1 Z2
Figure 7. AD848 As an Output Buffer
REV. B
-9-
ADV7120
PC BOARD LAYOUT CONSIDERATIONS Ground Planes
The ADV7120 is optimally designed for lowest noise performance, both radiated and conducted noise. To complement the excellent noise performance of the ADV7120, it is imperative that great care be given to the PC board layout. Figure 8 shows a recommended connection diagram for the ADV7120. The layout should be optimized for lowest noise on the ADV7120 power and ground lines. This can be achieved by shielding the digital inputs and providing good decoupling. The lead length between groups of VAA and GND pins should by minimized so as to minimize inductive ringing.
The ADV7120 and associated analog circuitry, should have a separate ground plane referred to as the analog ground plane. This ground plane should connect to the regular PCB ground plane at a single point through a ferrite bead, as illustrated in Figure 8. This bead should be located as close as possible (within 3 inches) to the ADV7120. The analog ground plane should encompass all ADV7120 ground pins, voltage reference circuitry, power supply bypass circuitry, the analog output traces and any output amplifiers. The regular PCB ground plane area should encompass all the digital signal traces, excluding the ground pins, leading up to the ADV7120.
COMP
R0 R7 VAA VIDEO DATA INPUTS G0 G7
C6 0.1F ANALOG POWER PLANE
L1 (FERRITE BEAD) C3 0.1F C4 0.1F C5 0.1F +5V (VCC )
B0 B7 VREF Z1 (AD589) C2 10F C1 33F
ADV7120
ANALOG GROUND PLANE GND RSET 560 FS ADJUST CLOCK IOR VIDEO CONTROL INPUTS REF WHITE IOG SYNC BLANK ISYNC IOB RGB VIDEO OUTPUT R1 75 R2 75 R3 75 L2 (FERRITE BEAD) GROUND
COMPONENT
C1 C2 C3, C4, C5, C6 L1, L2 R1, R2, R3 Rset SET Z1
DESCRIPTION
33F TANTALUM CAPACITOR 10F TANTALUM CAPACITOR 0.1F CERAMIC CAPACITOR FERRITE BEAD 75 1% METAL FILM RESISTOR 560 1% METAL FILM RESISTOR 1.235V VOLTAGE REFERENCE
VENDOR PART NUMBER
FAIR-RITE 274300111 OR MURATA BL01/02/03 DALE CMF-55C DALE CMF-55C ANALOG DEVICES AD589JH
Figure 8. ADV7120 Typical Connection Diagram and Component List
-10-
REV. B
ADV7120
Power Planes
The PC board layout should have two distinct power planes, one for analog circuitry and one for digital circuitry. The analog power plane should encompass the ADV7120 (VAA) and all associated analog circuitry. This power plane should be connected to the regular PCB power plane (VCC) at a single point through a ferrite bead, as illustrated in Figure 8. This bead should be located within three inches of the ADV7120. The PCB power plane should provide power to all digital logic on the PC board, and the analog power plane should provide power to all ADV7120 power pins, voltage reference circuitry and any output amplifiers. The PCB power and ground planes should not overlay portions of the analog power plane. Keeping the PCB power and ground planes from overlaying the analog power plane will contribute to a reduction in plane-to-plane noise coupling.
Supply Decoupling
the main PCB. Alternatively, consideration could be given to using a three terminal voltage regulator.
Digital Signal Interconnect
The digital signal lines to the ADV7120 should be isolated as much as possible from the analog outputs and other analog circuitry. Digital signal lines should not overlay the analog power plane. Due to the high clock rates used, long clock lines to the ADV7120 should be avoided so as to minimize noise pickup. Any active pull-up termination resistors for the digital inputs should be connected to the regular PCB power plane (VCC), and not the analog power plane.
Analog Signal Interconnect
The ADV7120 should be located as close as possible to the output connectors thus minimizing noise pickup and reflections due to impedance mismatch. The video output signals should overlay the ground plane, and not the analog power plane, thereby maximizing the high frequency power supply rejection. For optimum performance, the analog outputs should each have a source termination resistance to ground of 75 (doubly terminated 75 configuration). This termination resistance should be as close as possible to the ADV7120 so as to minimize reflections. Additional information on PCB design is available in an application note entitled "Design and Layout of a Video Graphics System for Reduced EMI." This application note is available from Analog Devices, publication number E1309-15-10/89.
Noise on the analog power plane can be further reduced by the use of multiple decoupling capacitors. (See Figure 8.) Optimum performance is achieved by the use of 0.1 F ceramic capacitors. Each of the two groups of VAA should be individually decoupled to ground. This should be done by placing the capacitors as close as possible to the device with the capacitor leads as short as possible, thus minimizing lead inductance. It is important to note that while the ADV7120 contains circuitry to reject power supply noise, this rejection decreases with frequency. If a high frequency switching power supply is used, the designer should pay close attention to reducing power supply noise. A dc power supply filter (Murata BNX002) will provide EMI suppression between the switching power supply and
REV. B
-11-
ADV7120
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
44-Terminal Plastic Leaded Chip Carrier (P-44A)
C1379-24-4/90
0.045 TYP 0.045 TYP
6 7 PIN 1 IDENTIFIER 40 39
0.045 TYP
0.045 TYP
0.050 0.005 (1.27 0.13) 0.630 (16.00) 0.590 (14.99) 0.021 (0.533) 0.013 (0.331) 0.032 (0.812)
TOP VIEW
(PINS DOWN)
17 18
29 28
0.026 (0.661) 0.020 MIN
0.656 (16.662) 0.650 (16.510)
SQ
0.120 (3.04) 0.090 (2.29) 0.180 (4.57) 0.165 (4.20) R.020 MAX 3 PLCS
0.695 (17.65) SQ 0.685 (17.40)
40-Pin Plastic DIP (N-40A)
40
21 0.545 (13.843) 0.535 (13.589)
1
20 0.155 (3.937) 0.145 (3.683)
2.090 (53.0) 2.008 (51.0) 0.17 (4.32) MAX
0.630 (16.0) 0.590 (15.0)
0.012 (0.305) 0.008 (0.203) 0.021 (0.533) 0.015 (0.381) 0.105 (2.67) 0.095 (2.42) 0.052 (1.32) 0.048 (1.219) 0.175 (4.45) 0.125 (3.18) 15 0
LEAD NO. 1 IDENTIFIED BY DOT, NOTCH OR "1." LEADS ARE SOLDER PLATED KOVAR OR ALLOY 42.
0.059 +0.008 -0.004 (1.50 +0.2 -0.1) 0.02 0.008 (0.5 0.02) 0.055 0.002 (1.40 0.05)
48 1
0.354 0.008 (9.00 0.2) 0.276 0.004 (7.0 0.1)
37 36
TOP VIEW
(PINS DOWN)
0.004 0.002 (0.1 0.05) (3.5 3.5)
0 MIN
12 13
25 24
0.005 +0.002 -0.0008 (0.127 +0.05 -0.02)
0.02 0.003 0.007 0.003 -0.001 (0.50 0.08) (0.18 0.08 -0.03)
-12-
0.276 0.004 (7.0 0.1) 0.354 0.008 (9.00 0.2)
SEATING PLANE
REV. B
PRINTED IN U.S.A.
48-Lead TQFP (ST-48)

▲Up To Search▲

Price & Availability of ADV7120KN30

	To Download ADV7120KN30 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .