参数资料
型号: TVP7002PZPR
厂商: TEXAS INSTRUMENTS INC
元件分类: 消费家电
英文描述: SPECIALTY CONSUMER CIRCUIT, PQFP100
封装: GREEN, PLASTIC, HTQFP-100
文件页数: 8/57页
文件大小: 517K
代理商: TVP7002PZPR
SLES206B
– MAY 2007 – REVISED MAY 2011
Sync Slicer
TVP7002 includes a circuit that compares the input signal on Green channel to a level 150 mV (typical value)
above the clamped level (sync tip). The slicing level is programmable by I2C register subaddress at 10h. The
digital output of the composite sync slicer is available on the SOGOUT pin.
Noise Immunity
In general, noise on a slowly varying input signal (i.e., sync falling edge) may cause a voltage comparator to
false trigger as the input passes through the linear range of the comparator. To improve the overall performance
of the TVP7002 sync slicer in the presence of noise on the SOG input, the voltage comparator includes
hysteresis. Maintaining a 50% slice level using the I2C programmable slice level control can further improve the
noise immunity of the Sync slicer. The slice level is programmable in 11.2-mV increments over a 350-mV range
as follows.
slice_level = (350 mV)
× (NTH/31)
where 0
≤ NTH ≤ 31, default: 11
0
≤ slice_level ≤ 350 mV
Glitch Immunity
During white-to-black transitions, the input video waveform may undershoot below the sync slicer threshold. To
help attenuate the amplitude of such glitches, a single-pole low-pass filter with three selectable cutoff frequencies
(2.5, 10, and 33 MHz) is provided at the input of the SOG voltage comparator circuit. This filter is bypassed in the
default mode.
NOTE
Although the low-pass filter may attenuate the amplitude of glitches present on the SOG
input, it also makes the sync falling edge less sharp.
Sync Separator
The sync separator automatically extracts VSYNC and HSYNC from the sliced composite sync input supplied at
the SOG input. The G or Y input containing the composite sync must be ac coupled to the SOG input pin using a
1-nF capacitor. Support for PC graphics, SDTV, EDTV, and HDTV up to 1080p is provided. The internal sync
separator provides support for formats having field rates (VSYNC frequencies) at or above 40 Hz. An external
sync separator or separated VSYNC must be used for field rates less than 40 Hz.
Sync Activity Detection
The TVP7002 provides activity detection on the sync inputs (VSYNC, HSYNC) to enable the host processor to
determine whether the PC graphics source is configured as a 3-wire, 4-wire, or 5-wire interface as defined here:
5 wire (G, B, R, HSYNC, VSYNC)
4 wire (G, B, R, CSYNC)
3 wire (G, B, R with SOG)
If activity is detected on the VSYNC input, the host processor should assume that the PC graphics input is a
standard 5-wire interface. In this case, the HSYNC input of the TVP7002 should be configured as an HSYNC
input. If AHSO and AVSO are set for automatic selection in I2C Reg 0Eh, the TVP7002 will automatically use the
HSYNC and VSYNC inputs, provided signals are present at both inputs.
If activity is detected on the HSYNC input but not on the VSYNC input, the host processor should assume that
the PC graphics input is a standard 4-wire interface. In this case, the HSYNC input of the TVP7002 should be
used as a digital CSYNC input. If AHSO and AVSO are set for automatic selection, VSYNC will be properly
decoded from the CSYNC input, provided no signal is present at the VSYNC input pin. Some test sources output
CSYNC on both the HSYNC pin and the VSYNC pin. In this case, the active VSYNC source (AVSS) must be
manually set to Sync separated VSYNC in Reg 0Eh.
16
Copyright
2007–2011, Texas Instruments Incorporated
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