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19-0548; Rev 0; 5/06
HDTV Continuously Variable Anti-Aliasing Filters
General Description
The MAX7469/MAX7470 triple-channel, anti-aliasing filters and buffers are ideal for high-definition (HD) and standard-definition (SD) television (TV) applications. Compatible with 1080i, 720p, 720i, 480p, and 480i scanning system standards and computer format signals, the MAX7469/MAX7470 support component video (Y Pb Pr, GsBR, and RGBHV), as well as composite (CVBS) and S-video (Y/C). The MAX7469/MAX7470 limit the input bandwidth for anti-aliasing and out-of-band noise reduction prior to digital conversion by an ADC or video decoder. The MAX7469/MAX7470 frequency response can be continuously varied in 256 linear steps through an I2C* interface from below SD resolution to beyond HD resolution. The output buffers of the MAX7469/MAX7470 drive a 2VP-P video signal into a standard 150 load. The inputs are AC-coupled, and the outputs can be either DC- or AC-coupled. The MAX7469 has a gain of 0dB, and the MAX7470 has a gain of +6dB. Both devices are available in a 20-pin TQFN package and are fully specified over the 0C to +85C upper-commercial temperature range.
Features
o Continuously Variable Anti-Aliasing Filter 5MHz to 34MHz in 256 Steps o Supports All Standard Video and Computer Input Formats 480i, 480p, 720i, 720p, 1080i QVGA, VGA, SVGA, XGA, SXGA, UXGA Y Pb Pr, GsBR, RGBHV, Y/C, CVBS o Accepts Any Input Sync Format Sync on Y, Sync on G, External Sync (Positive or Negative) Sync on All Channels o Buffered Outputs Drive Standard 150 Video Load 0dB (MAX7469) +6dB (MAX7470) o DC- or AC-Coupled Outputs o Single +5V Analog and +3.3V Digital Supplies o 5mW Power-Down Mode o 20-Pin TQFN Lead-Free Package
MAX7469/MAX7470
Applications
HDTV (LCD, PDP, DLP, CRT) Set-Top Boxes Personal Video Recorders Home Theaters
Pin Configuration
GND A1 AVDD GND
TOP VIEW
*Purchase of I2C components from Maxim Integrated Products, Inc., or one of its sublicensed Associate Companies, conveys a license under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification defined by Philips.
15
14
13
12
A0
11
Ordering Information
IN1 16 GND 17 IN2 18 GND 19 IN3 20 10 9 OUT1
PART
AVDD OUT2 AVDD OUT3 8 7 *EP 6
PIN-PACKAGE 20 TQFN-EP* 20 TQFN-EP*
BUFFER GAIN (dB) 0 +6
PKG CODE T2055-4 T2055-4
MAX7469UTP+ MAX7470UTP+**
MAX7469 MAX7470
+
1 DGND 2 EXTSYNC 3 SCL 4 SDA
5 DVDD
Note: All devices are specified over the 0C to +85C operating temperature range. + Indicates lead-free packaging. *EP = Exposed pad. **Future product--contact factory for availability.
TQFN (5mm x 5mm)
*EXPOSED PAD. SEE PIN DESCRIPTION FOR CONNECTION.
Typical Operating Circuit appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
ABSOLUTE MAXIMUM RATINGS
AVDD to GND............................................................-0.3V to +6V DVDD to DGND.........................................................-0.3V to +4V IN_, EXTSYNC to GND ................................................................. ..................................-0.3V to the lower of (AVDD + 3V) and +6V OUT_ to GND ............................................................................... ..................................-0.3V to the lower of (AVDD + 3V) and +6V A_ to GND .................................................................................... ..................................-0.3V to the lower of (AVDD + 3V) and +6V SCL, SDA to DGND ..................................................-0.3V to +6V Continuous Power Dissipation (TA = +70C) 20-Pin TQFN (derate 33.3mW/C above +70C) ...2666.7mW Maximum Current into IN_, A_, GND, SCL, SDA, and EXTSYNC............................................50mA Operating Temperature Range...............................0C to +85C Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(AVDD = +5V 5%, DVDD = 2.7V to 3.6V, RLOAD = 150 to GND, CIN = 0.1F, TA = 0C to +85C, unless otherwise noted. Typical values are at AVDD = 5V, DVDD = 3.3V, TA = +25C.)
PARAMETER SYMBOL CONDITIONS HD: f = 100kHz to 30MHz, relative to 100kHz (Note 1) Filter Passband Response APB SD: f = 100kHz to 5.75MHz, relative to 100kHz (Note 2) HD: f = 74MHz (Note 1) SD: f = 27MHz (Note 2) HD: 100kHz to 30MHz, relative to 100kHz (Note 1) SD: 100kHz to 5.75MHz, relative to 100kHz (Note 2) HD: channel to channel, 100kHz to 2MHz, (Note 1) Group Delay Matching tG(MATCH) SD: channel to channel, 100kHz to 500kHz, (Note 2) -3dB, bypass mode, independent of filter setting dG d SNR HDIST VDIST Five-step modulated staircase (Note 2) Five-step modulated staircase (Note 2) Output signal (2VP-P) to RMS noise (100kHz to 30MHz), f = 30MHz Deviations in a line with an 18s, 100 IRE bar; 1 line = 63.5s (Note 2) Deviations in 130 lines with 18s, 100 IRE bars (Note 2) 45 52 MIN -3 TYP -0.6 0.1 57 63 20 ns 15 5 ns 1.5 100 0.25 0.25 69 0.3 0.3 MHz % Degrees dB % % MAX +1 dB 1.0 dB UNITS
Filter Stopband Attenuation
ASB
Group Delay Deviation
tG
Bypass Frequency Response SD Differential Gain SD Differential Phase Signal-to-Noise Ratio SD Line-Time Distortion SD Field-Time Distortion
2
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
ELECTRICAL CHARACTERISTICS (continued)
(AVDD = +5V 5%, DVDD = 2.7V to 3.6V, RLOAD = 150 to GND, CIN = 0.1F, TA = 0C to +85C, unless otherwise noted. Typical values are at AVDD = 5V, DVDD = 3.3V, TA = +25C.)
PARAMETER Clamp Settling Time Minimum Functional Input Sync Amplitude Low-Frequency Gain (Note 1) Low-Frequency Gain Matching Maximum Output Voltage Amplitude Maximum Input Voltage Amplitude Channel-to-Channel Isolation Output Clamping Level Variation Power-Supply Rejection Ratio DIGITAL INPUTS (EXTSYNC, A1, A0) Input Logic-High Voltage Input Logic-Low Voltage Input Leakage Current Input Capacitance DIGITAL INPUTS (SDA, SCL) Input Logic-High Voltage Input Logic-Low Voltage Input Hysteresis Input Leakage Current Input Capacitance DIGITAL OUTPUT (SDA) Output Logic-Low Voltage Tri-State Leakage Current Tri-State Output Capacitance POWER REQUIREMENTS Analog Supply Voltage Range Digital Supply Voltage Range Analog Supply Current Digital Supply Current AVDD DVDD IAVDD IDVDD Normal operation, no load Power-down mode, no load fSCL = 400kHz 4.75 2.7 5 3.3 180 1 25 5.25 3.6 200 1.5 V V mA A VOL IL COUT ISINK = 3mA VIN = 0 to DVDD 0.1 6 0.4 10 V A pF VIH VIL VHYST IIN CIN VIN = 0 to DVDD 0.05 x DVDD 0.1 6 10 0.7 x DVDD 0.3 x DVDD V V V A pF VIH VIL IIN CIN VIN = 0 to DVDD 1 6 2.0 0.8 10 V V A pF PSRR (Notes 1, 4) DC 50 MAX7469 MAX7470 100kHz DC to 30MHz MAX7469 MAX7470 SYMBOL CONDITIONS To 1% with 100 IRE step (Note 4) Positive Negative 125 -0.5 5.5 0 6 0.05 2.4 2.4 1.2 62 100 +0.5 6.5 MIN TYP 350 650 MAX UNITS H mV dB dB VP-P VP-P dB mV dB
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
TIMING CHARACTERISTICS
(AVDD = +5V 5%, DVDD = 2.7V to 3.6V, RLOAD = 150 to GND, CIN = 0.1F, TA = 0C to +85C, unless otherwise noted. Typical values are at AVDD = 5V, DVDD = 3.3V, TA = +25C.)
PARAMETER Serial-Clock Frequency Bus Free Time Between STOP (P) and START (S) Condition Hold Time (Repeated) START (Sr) Condition SCL Pulse-Width Low SCL Pulse-Width High Setup Time for a Repeated START (Sr) Condition Data Hold Time Data Setup Time Rise Time of Both SDA and SCL Signals, Receiving Fall Time of Both SDA and SCL Signals, Receiving Fall Time of SDA Signal, Transmitting Setup Time for STOP (P) Condition Capacitive Load for Each Bus Line Pulse Width of Spikes that Are Suppressed by the Input Filter SYMBOL fSCL tBUF tHD;STA tLOW tHIGH tSU;STA tHD;DAT tSU;DAT tr tf tf tSU;STO Cb tSP (Note 7) 0 (Note 6) (Note 5) After this period, the first clock pulse is generated CONDITIONS MIN 0 1.3 0.6 1.3 0.6 0.6 0.0 100 0 0 20 + 0.1Cb 0.6 400 50 300 300 250 0.9 TYP MAX 400 UNITS kHz s s s s s s ns ns ns ns s pF ns
Note 1: The filter passband edge is set to code 255. Note 2: The filter passband edge is set to code 40. Note 3: 1H is the total line period, depending on the video standard. For NTSC, this is 63.5s; for HDTV, the line period is 29.64s. Note 4: The clamp level is at the sync tip for signals with sync pulses, and at the blanking level otherwise. Note 5: A master device must provide a hold time of at least 300ns for the SDA signal (referred to VIL of the SCL signal) to bridge the undefined region of SCL's falling edge. Note 6: Cb = total capacitance of one bus line in pF. tR and tF measured between 0.3VDD and 0.7VDD. Note 7: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
SDA
tf SCL
tLOW
tr
tSU;DAT
tf
tHD;STA
tSP
tr
tSP
tHD;STA tHD;DAT S tHIGH
tSU;STA Sr
tSU;STO P S
Figure 1. 2-Wire, Serial-Interface Timing Diagram
Typical Operating Characteristics
(AVDD = +5V, DVDD = 3.3V, RLOAD = 150 to GND, CLOAD = 0 to 20pF to GND, CIN = 0.1F, TA = +25C, unless otherwise noted.)
FREQUENCY RESPONSE (MAX7469)
0 -10 RESPONSE (dB) -20 -30 -40 -50 -60 -70 -80 0.1 1 10 100 1000 FREQUENCY (MHz) CODE 90 CODE 255 CODE 40 CODE 220 RESPONSE (dB)
MAX7469 toc01
PASSBAND FLATNESS (MAX7469)
MAX7469 toc02
FREQUENCY RESPONSE (MAX7470)
0 -10 RESPONSE (dB) CODE 40 -20 -30 -40 -50 -60 -70 0.1 1 10 100 1000 CODE 90 CODE 220 CODE 255
MAX7469 toc03
10
1.0 0.5 0 -0.5 -1.0 CODE 90 -1.5 -2.0 -2.5 -3.0 0.1 1 10 CODE 220 CODE 255 CODE 40
10
100
FREQUENCY (MHz)
FREQUENCY (MHz)
PASSBAND FLATNESS (MAX7470)
MAX7469 toc04
GROUP DELAY
80 70 60 DELAY (ns) 50 40 30 HD SD
MAX7469 toc05
2T RESPONSE (1 IRE = 7.14mV)
MAX7469 toc06
7.0 6.5 6.0 RESPONSE (dB) 5.5 5.0 4.5 4.0 3.5 3.0 0.1 1 10 CODE 220 CODE 255 CODE 40 CODE 90
90
300mV/div
300mV/div
20 10 0 100 0.1 1 10 100 200ns/div
FREQUENCY (MHz)
FREQUENCY (MHz)
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
Typical Operating Characteristics (continued)
(AVDD = +5V, DVDD = 3.3V, RLOAD = 150 to GND, CLOAD = 0 to 20pF to GND, CIN = 0.1F, TA = +25C, unless otherwise noted.)
MODULATED 12.5T RESPONSE (1 IRE = 7.14mV)
DIFFERENTIAL GAIN (%)
MAX7469 toc07
DIFFERENTIAL GAIN
MEASURED -3dB FREQUENCY (MHz) 0.1 0 -0.1 -0.2 1 0.2 0.1 0 -0.1 -0.2 1 2 3 4 5 6 7 0 0 51 2 3 4 5 6 7
MAX7469 toc08
-3dB FREQUENCY vs. CONTROL CODE
MAX7469 toc09
0.2
36 30 24 18 12 6
300mV/div
300mV/div
DIFFERENTIAL PHASE (deg)
DIFFERENTIAL PHASE
400ns/div
102 CODE
153
204
255
BYPASS-MODE FREQUENCY RESPONSE
MAX7469 toc10
BYPASS-MODE GROUP DELAY
MAX7469 toc11
10 5 0 RESPONSE (dB) -5 -10 -15 -20 -25 -30 -35 -40 0.1 1 10 100 MAX7470 MAX7469
20
16 DELAY (ns)
12
8
4
0 1000 0.1 1 10 100 FREQUENCY (MHz) FREQUENCY (MHz)
6
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HDTV Continuously Variable Anti-Aliasing Filters
Pin Description
PIN 1 2 3 4 5 6 7, 9, 11 8 10 12 13 14, 15, 17, 19 16 18 20 -- NAME DGND EXTSYNC SCL SDA DVDD OUT3 AVDD OUT2 OUT1 A0 A1 GND IN1 IN2 IN3 EP FUNCTION Digital Ground. See the Power-Supply Bypassing and Layout Considerations section. External Sync Input. EXTSYNC has an internal 3M resistor to ground. Connect to ground if not used. I2C-Compatible Serial-Clock Input I2C-Compatible Serial-Data Input/Output Digital Power Supply. Bypass to DGND with a 0.1F capacitor. See the Power-Supply Bypassing and Layout Considerations section. Video Output 3. OUT3 can be either DC- or AC-coupled. Analog Power Supply. Bypass to GND with a 0.1F capacitor. See the Power-Supply Bypassing and Layout Considerations section. Video Output 2. OUT2 can be either DC- or AC-coupled. Video Output 1. OUT1 can be either DC- or AC-coupled. I2C Device Address Bit 0 I2C Device Address Bit 1 Ground. Connect all GND pins to the ground plane. See the Power-Supply Bypassing and Layout Considerations section. Video Input 1. AC-couple IN1 with a series 0.1F capacitor. Video Input 2. AC-couple IN2 with a series 0.1F capacitor. Video Input 3. AC-couple IN3 with a series 0.1F capacitor. Exposed Pad. Internally connected to GND. Do not route any PC board traces under package. Connect EP to the ground plane. See the Power-Supply Bypassing and Layout Considerations section.
MAX7469/MAX7470
Detailed Description
The MAX7469/MAX7470 are complete video anti-aliasing solutions, ideal for fixed-pixel HDTV display technologies, such as plasma and LCD, which digitize the input video signal and then scale the resolution to match the native pixel format of the display. With a software-selectable corner frequency ranging from 5MHz to 34MHz, the MAX7469/MAX7470 support both SD and HD video signals, including 1080i, 720p, 720i, 480p, and 480i. Higher bandwidth computer resolution signals are also supported. Integrated lowpass filters limit the analog video input bandwidth for anti-aliasing and out-of-band noise reduction prior to sampling by an ADC or video decoder. By allowing the corner frequency to be adjusted from below SD resolution to beyond HD resolutions in 256 linear steps, the filter's corner frequency can be optimized dynamically for a specific input video signal and the sampling frequency of the ADC or video decoder. For applications requiring a passband greater than the maximum frequency setting, a filter bypass mode is also provided.
An I2C interface allows a microcontroller (C) to configure the MAX7469/MAX7470s' performance and functionality, including the clamp voltage, the filter corner frequency, the sync source (internal/external), filter bypassing, etc. The Typical Operating Circuit shows the MAX7469/ MAX7470 block diagram and typical external connections.
Sync Detector and Clamp Settings
The MAX7469/MAX7470 use a video clamp circuit to establish a DC offset for the incoming video signal after the AC-coupling capacitor. This video clamp sets the DC bias level of the circuit at the optimum operating point. The MAX7469/MAX7470 support both internal and external sync detection. Selection of internal vs. external detection is achieved by programming the command byte (see Table 3). After extracting the sync information from channel 1 (or an external sync: SYNCA, SYNCB, or SYNC), the MAX7469/MAX7470 clamp the video signal during the sync tip portion of the video. Select one of two possible clamp levels according to the input signal format. Use the low level when the input signal contains sync information, such as a Y (luma) or CVBS signal.
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
Table 1. Clamp Levels
INPUT SIGNAL FORMAT Y Pb Pr GSBR CVBS Y C Y Pb Pr (sync on all signals) RGBHV CLAMP LEVEL CHANNEL 1 CHANNEL 2 CHANNEL 3 Low Low Low Low High High High Low Low High High High High Low High
data word that corresponds to the desired frequency. See the Frequency Register section for more details. The frequency set by the MAX7469/MAX7470 is the -3dB point. Set the frequency according to the desired flat passband response.
Use the high level for bipolar signals, such as C (chroma) or Pb/Pr. See Table 1 for more details.
Component/Composite Selection The MAX7469/MAX7470 accept component or composite inputs. When configured for composite video inputs, the color-burst filter is enabled; if configured for component video inputs, the color-burst filter is disabled. This filter is separate from the main filter and not in the direct signal path so that it has no effect on the overall frequency response. With normal video signals and levels, the use of this color-burst filter has a negligible effect on the sync detection. It has a more significant effect under conditions of low-signal amplitude coupled with higher relative amplitude color burst. External Sync Detection (EXTSYNC) When filtering a video signal without embedded sync information, such as computer formats (RGBHV) with separate sync signals, use the external sync mode (see Table 3) and apply the horizontal sync source to the EXTSYNC pin. The sync detector determines when the clamp circuit is turned on. The MAX7469/MAX7470 are able to detect positive or negative polarity external syncs with TTL logic levels. Use the I2C interface to program the polarity of the external sync signal.
Optimizing the Frequency Response Select the frequency response according to the resolution of the video-signal format. High-definition signals require higher bandwidth, while standard-definition signals require less bandwidth. The actual bandwidth contained in the video signal is a function of the visual resolution of the signal. This bandwidth is typically less than what is indicated by the format resolution (1080i, 720p, etc.). For more information, see Maxim Application Note 750: Bandwidth Versus Video Resolution, which is available on www.maxim-ic.com. The frequency response can be optimized to improve the overall performance. It is important, at a minimum, to meet the Nyquist criterion. Beyond this, the frequency response can be further optimized. In oversampled systems, the sample rate is significantly more than the desired passband response. The extra frequency span between the passband and the sample rate contains noise and other undesirable interferers that can be eliminated by setting the corner frequency of the filter to just pass the desired bandwidth. This results in a higher signal-to-noise ratio of the overall system. Filter Bypass The MAX7469/MAX7470 offer selectable filter bypassing that allows the input video signals to bypass the internal filters and reach the output buffers unfiltered. Write the appropriate command byte to enable (0Eh) or disable (0Fh) filter-bypass mode as shown Table 3.
Output Buffer
Each output buffer can drive a 2VP-P signal into a 150 video load. The MAX7469/MAX7470 can drive a DC- or AC-coupled load. Output AC-coupling capacitors can be eliminated when driving a cable, thereby eliminating the normal adverse effects caused by these large capacitors, such as line, and field-time distortion, also known as droop. The output DC level is controlled to limit the DC voltage on the cable so that the blanking level of the video signal is always less than 1V, meeting digital TV specification. See the Output Considerations section for more information.
Filter
The internal video filter delivers an optimized response with a steep transition band to achieve a wide passband along with excellent stopband rejection. In addition, the filter is optimized to provide an excellent time domain response with low overshoot.
Setting the Filter Frequency Use the I2C interface to vary the frequency response (-3dB cutoff frequency) of the filter in the MAX7469/ MAX7470 from less than the SD passband to beyond the HD passband in 256 linear steps. Write command byte 12h to access the frequency register, followed by an 8-bit
8
Gain Options The MAX7469 features an overall gain of 0dB, while the MAX7470 features an overall gain of +6dB. Use the MAX7470 when driving a back-matched cable and the
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HDTV Continuously Variable Anti-Aliasing Filters
MAX7469 when driving an ADC or video decoder with an input range the same as the input to the MAX7469. For added flexibility, the MAX7469 accepts input signals with twice the standard video-signal range, which can be used for driving an ADC or video decoder with an input signal range that accepts a larger signal swing. The MAX7470 can also be used to drive an ADC or video decoder when a gain of two is desired.
Power-On Reset (POR)
The MAX7469/MAX7470 include a POR circuit that resets the internal registers and I2C interface to their default conditions (see Tables 4, 5, and 6).
MAX7469/MAX7470
Serial Interface
The MAX7469/MAX7470 feature an I2C-compatible, 2-wire serial interface consisting of a bidirectional serial-data line (SDA) and a serial-clock line (SCL). SDA and SCL facilitate bidirectional communication between the MAX7469/ MAX7470 and the master at rates up to 400kHz. The MAX7469/MAX7470 have a command interpreter that is accessed by writing a valid command byte. Once a command byte is written to the MAX7469/ MAX7470, the command interpreter updates the control/status register accordingly. See the Control/Status Register section for more information. The command interpreter also controls access to the frequency register through a command byte (see the Command Byte (Write Cycle) section). The MAX7469/MAX7470 are transmit/receive slave-only devices, relying upon a master to generate a clock signal. The master (typically a C) initiates data transfer on the bus and generates SCL. A master device communicates to the MAX7469/ MAX7470 by transmitting the proper address (see the Slave Address section) followed by a command and/or data words. Each transmit sequence is framed with a START (S) or REPEATED START (Sr) condition and a STOP (P) condition. The SDA driver is an open-drain output, requiring a pullup resistor (2.4k or greater) to generate a logichigh voltage. Optional resistors (24) in series with SDA and SCL protect the device inputs from high-voltage spikes on the bus lines. Series resistors also minimize crosstalk and undershoot of the bus signals.
Output Clamp Level The MAX7469/MAX7470 output can be DC- or ACcoupled. The nominal output clamp level in the DC-coupled case depends on the clamp voltage setting and can be determined according to Table 2.
Table 2. Output Clamp Level
CLAMP SETTING Low High OUTPUT CLAMP LEVEL (V) 1.0 (typ) 1.6 (typ)
As shown in the Sync Detector and Clamp Settings section, the low clamp level is used for signals with sync information and determines the voltage level of the sync tip, while the high clamp level is used for signals without sync information and sets the blanking level. The absolute voltage level of the output signal is relative to the output clamp level. A video signal containing sync information (i.e., CVBS or Y) is unipolar above the clamp level and conversely, a video signal without sync (i.e., Pb Pr or C) is bipolar around the clamp level.
Power-Down Mode
The MAX7469/MAX7470 include a power-down mode that reduces the supply current from 180mA (typ) to 1mA (typ) by powering down the analog circuitry. The I2C interface remains active, allowing the device to return to full-power operation. The clamp settling time (see the Electrical Characteristics section) limits the wake-up time of the MAX7469/MAX7470. After exiting the power-down mode, the MAX7469/MAX7470 resume normal operation using the settings stored prior to power-down. The power-down and wake-up modes are controlled through the command byte (see Table 3). A software reset sets the control/status register to its default conditions, but the frequency register is not affected.
Bit Transfer Each SCL rising edge transfers 1 data bit. Nine clock cycles are required to transfer the data into or out of the MAX7469/MAX7470. The data on SDA must remain stable during the high period of the SCL clock pulse. Changes in SDA while SCL is high are read as control signals (see the START and STOP Conditions section). When the serial interface is inactive, SDA and SCL idle high.
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
START and STOP Conditions A master device initiates communication by issuing a START condition, a high-to-low transition on SDA with SCL high (Figure 2). The master terminates transmission by a STOP condition (see the Acknowledge Bit (ACK) and NotAcknowledge Bit (NACK) section). A STOP condition is a low-to-high transition on SDA while SCL is high (Figure 2). The STOP condition frees the bus. If a repeated START condition is generated instead of a STOP condition, the bus remains active. When a STOP condition or incorrect address is detected, the MAX7469/ MAX7470 then ignore all communication on the I2C bus until the next START or REPEATED START condition, minimizing digital noise and feedthrough. Early STOP Conditions The MAX7469/MAX7470 recognize a STOP condition at any point during transmission except when a STOP
condition occurs in the same high pulse as a START condition (Figure 3). This condition is not a legal I2C format; at least one clock pulse must separate any START and STOP conditions. The MAX7469/MAX7470 discard any data received during a data transfer aborted by an early STOP condition.
Repeated START (Sr) Conditions An Sr condition is used to indicate a change in direction of data flow (see the Read Cycle section). Sr can also be used when the bus master is writing to several I2C devices and does not want to relinquish control of the bus. The MAX7469/MAX7470 serial interface supports continuous write operations with (or without) an Sr condition separating them.
S
Sr
P
SCL
SDA
Figure 2. START/STOP Conditions
LEGAL STOP CONDITION SCL SCL ILLEGAL STOP CONDITION
SDA
SDA
STOP
START
START
ILLEGAL STOP
Figure 3. Early STOP Conditions
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HDTV Continuously Variable Anti-Aliasing Filters
Acknowledge Bit (ACK) and Not-Acknowledge Bit (NACK) Successful data transfers are acknowledged with an acknowledge bit (ACK) or a not-acknowledge bit (NACK). Both the master and the MAX7469/MAX7470 (slave) generate acknowledge bits. To generate an acknowledge, the receiving device must pull SDA low before the rising edge of the acknowledge-related clock pulse (ninth pulse) and keep it low during the high period of the clock pulse (Figure 4). To generate a NACK, the receiver allows SDA to be pulled high before the rising edge of the acknowledge-related clock pulse (ninth pulse) and leaves it high during the high period of the clock pulse. Monitoring the acknowledge bits allows for detection of unsuccessful data transfers. An unsuccessful data transfer happens if a receiving device is busy or if a system fault has occurred. In the event of an unsuccessful data transfer, the master should reattempt communication at a later time. The MAX7469/MAX7470 generate an acknowledge bit when receiving an address or data by pulling SDA low during the ninth clock pulse. When transmitting data during a read, the MAX7469/MAX7470 do not drive SDA during the ninth clock pulse (i.e., the external pullups define the bus as a logic-high) so that the receiver of the data can pull SDA low to acknowledge receipt of data.
S
Slave Address A bus master initiates communication with a slave device by issuing a START condition, followed by the 7-bit slave address (Figure 5). When idle, the MAX7469/MAX7470 wait for a START condition, followed by their slave address. The serial interface compares each address bit by bit, allowing the interface to power down and disconnect from SCL immediately if an incorrect address is detected. After recognizing a START condition followed by the correct address, the MAX7469/MAX7470 are ready to accept or send data. The least significant bit (LSB) of the address byte (R/W) determines whether the master is writing to or reading from the MAX7469/MAX7470 (R/W = 0 selects a write condition, R/W = 1 selects a read condition). After receiving the proper address, the MAX7469/MAX7470 (slave) issue an ACK by pulling SDA low for one clock cycle. The MAX7469/MAX7470 slave address consists of 5 fixed bits, A6-A2 (set to 10010), followed by 2 pin-programmable bits, A1 and A0. The most significant address bit (A6) is transmitted first, followed by the remaining bits. Addresses A1 and A0 can also be driven dynamically if required, but the values must be stable when they are expected in the address sequence.
MAX7469/MAX7470
NOT ACKNOWLEDGE
SDA ACKNOWLEDGE SCL 1 8 9
Figure 4. Acknowledge and Not-Acknowledge Bits
. SDA 1 MSB SCL 0 0 1 0 A1 A0 LSB R/W ACK
Figure 5. Slave-Address Byte Definition
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
Command Byte (Write Cycle) A write cycle begins with the bus master issuing a START condition followed by 7 address bits (Figure 5) and 1 write bit (R/W = 0). After successfully receiving its address, the MAX7469/MAX7470 (slave) issue an ACK. The slave recognizes the next byte after a successfully received address as the command byte (Table 3).
Use the command byte to configure the MAX7469/ MAX7470. While most of the commands listed in Table 3 modify the functionality of the MAX7469/MAX7470, some commands prepare the device for further data transfers (see the Control/Status Register and Frequency Register sections). If the write cycle is prematurely aborted, the register is not updated, and the
Table 3. Command Byte Definition
COMMAND BYTE: INDIVIDUAL BIT DEFINITIONS C7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 C6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 C5 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 C4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 C3 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 C2 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 C1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 C0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 Enters power-down mode. Wake-up; resumes normal operation using the frequency/status previously stored (unless power has been cycled). Sets IN1 clamp voltage level to low. Sets IN1 clamp voltage level to high. Sets IN2 clamp voltage level to low. Sets IN2 clamp voltage level to high. Sets IN3 clamp voltage level to low. Sets IN3 clamp voltage level to high. Selects component input, color-burst filter disabled. Selects composite input, color-burst filter enabled. Selects internal sync. Selects external sync. Selects positive polarity external sync. Selects negative polarity external sync. Enables filters. Disables filters, enters bypass mode. Resets the control/status register to the default values as described in the Control/ Status Register section. This command does not affect the frequency register. Requests a control/status register read. The interface expects an Sr condition to follow with address and read/write set to read so data can be driven onto the bus. Loads the frequency register with the data byte following the command byte. Requests a frequency register read. The interface expects an Sr condition to follow with address and read/write set to read so data can be driven onto the bus. DESCRIPTION
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HDTV Continuously Variable Anti-Aliasing Filters
write sequence must be repeated. Figures 6 and 7 show examples of write sequences.
Read Cycle In read mode (R/W = 1), the MAX7469/MAX7470 write the contents of the control/status or frequency registers to the bus. When the command byte indicates a read operation of either the control/status or the frequency register, the serial interface expects an Sr condition to
SCL
follow the command byte. After sending an Sr, the master sends the MAX7469/MAX7470 slave address byte followed by a R/W bit (set to 1 to indicate a read). The slave device (MAX7469/MAX7470) generates an ACK for the second address word and immediately after the ACK clock pulse, the direction of data flow reverses. The slave (MAX7469/MAX7470) then transmits 1 byte of data containing the value of the register that was
MAX7469/MAX7470
SDA
1
0
0
1
0
A1
A0
R/W
ACK
0 C7
0 C6
0 C5
1 C4 IN
0 C3
0 C2
1 C1
0 C0
ACK
SDA DIRECTION
IN TO MAX7469/MAX7470
OUT
OUT
START
SCL (CONT) SDA (CONT) SDA DIRECTION COMMAND BYTE C7-C0 IS 0010010. STOP F7 F6 F5 F4 F3 F2 F1 F0 ACK
IN
OUT
IN
Figure 6. Write Sequence to Update the Frequency Register
SCL
SDA
1
0
0
1
0
A1
A0
R/W
ACK
0 C7
0 C6
0 C5
0 C4 IN
0 C3
0 C2
0 C1
0 C0
ACK
SDA DIRECTION
IN TO MAX7469/MAX7470
OUT
OUT
IN
START
THE COMMAND BYTE IS FOR POWER-DOWN.
STOP
Figure 7. Write Sequence for a Command Byte
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
SCL
SDA
1
0
0
1
0
A1
A0
R/W
ACK
0 C7
0 C6
0 C5
1 C4 IN
0 C3
0 C2
1/0 C1
1 C0
ACK
SDA DIRECTION
IN TO MAX7469/MAX7470
OUT
OUT
START SCL (CONT) SDA (CONT) SDA DIRECTION Sr 1 0 0 1 0 A1 A0 R/W ACK D7 D6 D5 D4 D3 D2 D1 D0 ACK
IN
OUT
IN
STOP
Figure 8. Basic Read Sequence
selected in the command byte. Figure 8 shows a basic read sequence. Note: The master has to write a command byte, requesting to read the control/status or frequency register, to the slave (MAX7469/MAX7470) before the master can read the contents of the selected register.
Table 5. Control/Status Register Bit Description
BIT S7 S6 S5 S4 S3 S2 S1 S0 DESCRIPTION 0 = component input signal selected (default). 1 = composite input signal selected. 0 = internal sync enabled (default). 1 = external sync enabled. 0 = external sync: positive polarity (default). 1 = external sync: negative polarity. 0 = normal operation mode (default). 1 = power-down mode. 0 = filters enabled (default). 1 = bypass mode--no filtering. 0 = clamp voltage for IN1 set to low (default). 1 = clamp voltage for IN1 set to high. 0 = clamp voltage for IN2 set to low. 1 = clamp voltage for IN2 set to high (default). 0 = clamp voltage for IN3 set to low. 1 = clamp voltage for IN3 set to high (default).
Control/Status Register The MAX7469/MAX7470 store their status in an 8-bit register that can be read back by the master. The individual bits of the control/status register are summarized in Tables 4 and 5. The power-on default value of this register is 03h. Frequency Register The frequency response (-3dB passband edge) of the MAX7469/MAX7470 can be continuously varied in 256 linear steps by changing the codes in the frequency register (Table 6). See the Command Byte (Write Cycle) section for a write sequence to update the frequency register.
Table 4. Control/Status Register
CONTROL/STATUS REGISTER S7 S6 S5 S4 S3 S2 S1 S0
Table 6. Frequency Register Setting for Different Video-Signal Formats
VIDEO-SIGNAL FORMAT Standard Definition (Interlaced) Standard Definition (Progressive) High-Definition Low Bandwidth High-Definition High Bandwidth F7 0 0 1 1 F6 0 1 1 1 F5 1 0 0 1 F4 0 1 1 1 F3 1 1 1 1 F2 0 0 1 1 F1 0 1 0 1 F0 0 0 0 1 CODE NO. 40 90 220 255 APPROXIMATE FREQUENCY (-3dB) MHz 10 15 30 34 (default)
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HDTV Continuously Variable Anti-Aliasing Filters
I2C Compatibility The MAX7469/MAX7470 are compatible with existing I2C systems supporting standard I2C 8-bit communications. The general call address is ignored, and CBUS formats are not supported. The device's address is compatible with 7-bit I2C addressing protocol only; 10bit address formats are not supported.
Power-Supply Bypassing and Layout Considerations
The MAX7469/MAX7470 operate from a single +5V analog supply and a +3.3V digital supply. Bypass AVDD to GND with a 0.1F capacitor and an additional 1F capacitor in parallel for additional low-frequency decoupling. Determine the proper power-supply bypassing necessary by taking into account the desired disturbance level tolerable on the output, the power-supply rejection of the MAX7469/MAX7470, and the amplitude and frequency of the disturbance signals present in the vicinity of the MAX7469/MAX7470. Use an extensive ground plane to ensure optimum performance. The three AVDD pins (pins 7, 9, and 11) that supply the individual channels can be connected together and bypassed as one, provided the components are close to the pins. Bypass DV DD to DGND with a 0.1F capacitor. All ground pins (GND) must be connected to a low impedance ground plane as close as possible to the device. Place the input termination resistors as close as possible to the device. Alternatively, the terminations can be placed further from the device if the PC board traces are designed to be a controlled impedance of 75. Minimize parasitic capacitance as much as possible to avoid performance degradation in the upper frequency range possible with the MAX7469/MAX7470. Refer to the MAX7469/MAX7470 evaluation kit for a proven PC board layout.
MAX7469/MAX7470
Applications Information
Input Considerations
Use 0.1F ceramic capacitors to AC-couple the inputs. The inputs cannot be DC-coupled. The internal clamp circuit stores a DC voltage across the input capacitors to obtain the appropriate output DC voltage level. Increasing the value of these capacitors to improve linetime distortion is not necessary due to the extremely low input leakage current yielding a very low line-time distortion performance. The MAX7469/MAX7470 provide a high input impedance to allow a nonzero source impedance to be used, such as when the input is connected directly to a backmatched video cable, ensuring the external resistance determines the termination impedance.
Output Considerations
The MAX7469/MAX7470 outputs can be DC- or ACcoupled. The MAX7470, with its +6dB gain, is typically connected to a 75 series back-match resistor followed by the video cable. Because of the inherent divide-by-two of this configuration, the blanking level of the video signal is always less than 1V, which complies with digital TV requirements. The MAX7469, with its 0dB gain, is typically connected to an ADC or video decoder. This can be a DC or AC connection. If a DC connection is used, ensure that the DC input requirements of the ADC or video decoder are compatible. If an AC connection is used, choose an AC-coupling capacitor value that ensures that the lowest frequency content in the video signal is passed and the line-time distortion is kept within desired limits. The selection of this value is a function of the input impedance and, more importantly, the input leakage of the circuit being driven. Use a video clamp to reestablish the DC level, if not already included in the subsequent circuit. The outputs of the MAX7469/MAX7470 are fully protected against a short-circuit condition either to ground or the positive supply of the device.
Exposed Pad and Heat Dissipation
The MAX7469/MAX7470 TQFN package has an exposed pad on its bottom. This pad is electrically connected, internal to the device, to GND. Do not route any PC board traces under the package. The MAX7469/MAX7470 typically dissipate 900mW of power, therefore, pay careful attention to heat dispersion. The use of at least a two-layer board with a good ground plane is recommended. To maximize heat dispersion, place copper directly under the MAX7469/ MAX7470 package so that it matches the outline of the plastic encapsulated area. Do the same thing on the bottom ground plane layer and then place as many vias as possible connecting the top and bottom layers to thermally connect it to the ground plane. Maxim has evaluated a four-layer board using FR-4 material and 1oz copper with equal areas of metal on the top and bottom side coincident with the plastic encapsulated area of the 20-pin TQFN package. The two middle layers are used as power and ground
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HDTV Continuously Variable Anti-Aliasing Filters MAX7469/MAX7470
planes. The board has 21, 15-mil, plated-through via holes between the top, bottom, and ground plane layers. Thermocouple measurements confirm device temperatures to be safely within maximum limits.
Chip Information
PROCESS: BiCMOS
Typical Operating Circuit
EXT SYNC AVDD
SYNC DETECTOR
MAX7469 MAX7470
0dB (+6dB) OUT1
DECODER
Y/G 0.1F 75
IN1
CLAMP/ BIAS
5MHz TO 34MHz PROGRAMMABLE PASSBAND LOWPASS FILTER
A/D 0.1F
Pb/B 0.1F 75
IN2
0dB (+6dB) CLAMP/ BIAS 5MHz TO 34MHz PROGRAMMABLE PASSBAND LOWPASS FILTER
OUT2 A/D 0.1F
Pr/R 0.1F 75
IN3
0dB (+6dB) CLAMP/ BIAS 5MHz TO 34MHz PROGRAMMABLE PASSBAND LOWPASS FILTER FREQUENCY SELECT I2C INTERFACE EXT SYNC ENABLE
OUT3 A/D 0.1F
BYPASS CLAMP LEVEL
( ) FOR MAX7470
GND SCL SDA DGND DVDD A1 A0
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HDTV Continuously Variable Anti-Aliasing Filters
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)
QFN THIN.EPS
MAX7469/MAX7470
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 17
(c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
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