SAF7115
General Description
The SAF7115 is a video capture device that, due to its improved comb filter performance and 10-bit video output capabilities, is suitable for various applications such as In-car video reception, In-car entertainment or In-car navigation.
The SAF7115 is a combination of a two channel analog preprocessing circuit and a high performance scaler.
The two channel analog preprocessing circuit includes source-selection, an anti-aliasing filter and Analog-to-Digital Converter (ADC) per channel, an automatic clamp and gain control, two Clock Generation Circuits (CGC1 and CGC2) and a digital multi standard decoder that contains two-dimensional chrominance/luminance separation utilizing an improved adaptive comb filter.
The high performance scaler has variable horizontal and vertical up and down scaling and a brightness/contrast/saturation control circuit.
The decoder is based on the principle of line-locked clock decoding and is able to decode the color of PAL, SECAM and NTSC signals into ITU-601 compatible color component values. The SAF7115 accepts CVBS or S-video (Y/C) from TV or VCR sources as analog inputs, including weak and distorted signals.
The expansion port (X-port) for digital video (bi-directional half duplex, D1 compatible) can be used to either output unscaled video using 10-bit or 8-bit dithered resolution or to connect to other external digital video sources for reuse of the SAF7115 scaler features.
The enhanced image port (I-port) of the SAF7115 supports 8-bit and 16-bit wide output data with auxiliary reference data for interfacing, e.g. with VGA controller applications. It is also possible to output video in square pixel formats accompanied by a square pixel clock of the appropriate frequency.
The SAF7115 also incorporates provisions for capturing the serially coded data in the Vertical Blanking Interval (VBI-data) of several standards in parallel. Three basic options are available to transfer the VBI data to other devices:
- Capturing raw video samples, after interpolation to the required output data rate, using the scaler and transferring the data to a device connected to the I-port
- Slicing the VBI data using the built-in VBI data slicer (data recovery unit) and transferring the data to a device connected to the I-port
- Slicing the VBI data using the built-in VBI data slicer and reading out the sliced data through the I²C-bus (for several slow VBI data type standards only)
The SAF7115 incorporates a frame locked audio clock generation. This function ensures that there is always the same number of audio samples associated with a frame, or a set of fields. This prevents the loss of synchronization between video and audio, during capture or playback. Furthermore, there is an option to use a second analog onboard PLL to enhance this audio clock to a low jitter frame locked audio clock.
The SAF7115 is controlled through the I²C-bus with full write/read capability for all programming registers and a bit-rate of up to 400 kbit/s. See Ref. 1 for a detailed register description, pin strapping and applications.
Key Features
Video acquisition
- Six analog inputs, internal analog source selectors, e.g. (6 x CVBS) or (2 x Y/C and 2 x CVBS) or (1 x Y/C and 4 x CVBS)
- Two differential (bi-phase) video inputs as an alternative
- Two built-in analog anti-alias filters
- Two improved 9-bit CMOS ADCs in differential CMOS style at two-fold ITU-656 oversampling (27 MHz)
- Fully programmable static gain or Automatic Gain Control (AGC) for the selected CVBS or Y/C channel
- Automatic Clamp Control (ACC) for CVBS, Y and C
- Switchable white peak control. Two 9-bit video CMOS ADCs, digitized CVBS or Y/C
- Signals are available on the expansion port (X-port)
- Requires only one crystal (32.11 MHz or 24.576 MHz) for all standards
- Independent gain and offset adjustments for raw data path
Comb filter video decoder
- Digital PLL for synchronization and clock generation from all standard and non-standard video sources e.g. consumer grade Video Tape Recorders (VTR)
- Automatic detection of 50 Hz and 60 Hz field frequencies
- Automatic recognition of all common broadcast standards
- Enhanced horizontal and vertical sync detection
- Luminance and chrominance signal processing for:
- PAL BGDHIN
- Combination-PAL N
- PAL M
- NTSC M
- NTSC-Japan
- NTSC 4.43
- SECAM (50 Hz/60 Hz)
- PAL delay line for correcting PAL phase errors
- Improved 2/4-line comb filter for two dimensional chrominance/luminance-separation operating with adaptive comb filter parameters.
- Increased luminance and chrominance bandwidth for all PAL and NTSC-standards
- Reduced cross color and cross luminance artefacts
- Independent Brightness Contrast Saturation (BCS) – adjustment for decoder part
- User programmable sharpness control
- Detection of copy protected input signals:
- According to Macrovision standard
- Indicating the level of protection
- Automatic TV/VCR detection
- 10-bit wide video output at comb filter video decoder
- X-port video output either as:
- Noise shaped 8-bit ITU-656 video or
- Full 10-bit ITU-656 interface (DC-performance 9-bit)
Video scaler
- Horizontal and vertical down-scaling and up-scaling to randomly sized windows
- Horizontal and vertical scaling range: variable zoom to 1/64 (icon) (note: H and V zoom are restricted by the transfer data rates)
- Vertical scaling with linear phase interpolation and accumulating filter for anti-aliasing (6-bit phase accuracy)
- Conversion to square pixel format
- Generation of a video output stream with improved synchronization grid at the I-port
- Two independent programming sets for scaler part, to define two regions (e.g. for different scaling for VBI and active picture) per field or sequences over frames
- Fieldwise switching between decoder part and expansion port (X-port) input
- Brightness, contrast and saturation controls for scaled outputs
VBI data slicer
- Versatile VBI-data decoder, slicer, clock regeneration and byte synchronization, e.g.:
- WST525/WST625 (CCST)
- VPS
- US/European Close Caption (CC)
- WSS525 (CGMS), WSS625
- US NABTS
- VITC 525/VITC 625
- Gemstar 1x
- Gemstar 2x
- Moji
- I²C-bus read-back of the following decoded data types:
- US Close Caption (CC)
- European Close Caption (CC)
- WSS525 (CGMS)
- WSS625 (CGMS)
- Gemstar 1x
- Gemstar 2x
Clock generation
- On-chip line locked clock generation according ITU-601
- Generation of a frame locked audio master clock to support a constant number of audio clocks per video field
- Second onboard analog Phase-Locked Loop (PLL) to be used for:
- On-chip line locked square pixel clock generation for PAL and NTSC square pixel video output or
- The generation of a low jitter frame locked audio clock from the audio master clock through reuse of the analog square pixel PLL. The audio clock frequencies supported are 256 x fs, 384 x fs and 512 x fs (fs = 32 kHz, 44.1 kHz or 48 kHz)
General features
- CMOS 3.3 V device with 5 V tolerant digital inputs and I/O ports
- Programming through serial I²C-bus, full read-back ability by an external controller, bit-rate up to 400 kbit/s
- Software controlled power saving stand-by modes
- Boundary Scan Test circuit complies to the IEEE Std. 1149.b1-1994
Block Diagram
