CHRONTEL
CH7317B
8 201-0000-097 Rev. 1.7, 11/26/2012
2.0 Functional Description
2.1 Input Interface
2.1.1 Overview
One pair of differential clock signal and three differential pairs of data signals (R/G/B) form one channel data. The input
data are 10-bit serialized data. Input data run at 1Gbits/s~2Gbits/s, being a 10x multiple of the clock rate
(SDVOB_CLK+/-). The CH7317B de-serializes the input into 10-bit parallel data with synchronization and alignment.
Then the 10-bit characters are mapped into 8-bit color data or control data (HSYNC, VSYNC, DE).
2.1.2 Interface Voltage Levels
All differential SDVO pairs are AC coupled differential signals. Therefore, there is not a specified DC signal level for
the signals to operate at. The differential p-p input voltage has a min of 175mV, and a max of 1.2V. The differential p-p
output voltage has a min of 0.8V, with a max of 1.2V.
2.1.3 Input Clock and Data Timing
A data character is transmitted least significant bit first. The beginning of a character is noted by the falling edge of the
SDVOB_CLK+ edge. The skew among input lanes is required to be no larger than 2ns.
The clock rate runs at 100MHz~200MHz. The pixel rate can be 25MP/s~165MP/s. The pixel rate and the clock rate do
not always equal. The clock rate can be a multiple of the pixel rate (1x, 2x, 4x depending on the pixel rate) so that the
clock rate will be stay in the 100MHz~200MHz range. In the condition that the clock rate is running at a multiple of the
pixel rate, there isn’t enough pixel data to fill the data channels. Dummy fill characters (‘0001111010’) are used to stuff
the data stream. The CH7317B supports the following clock rate multipliers and fill patterns shown in Table 2.
Table 2: CH7317B supported Pixel Rates, Clock Rates, Data Transfer Rates and Fill Patterns
Pixel Rate Clock Rate – Multiplier Stuffing Format Data Transfer Rate - Multiplier
25~50 MP/s 100~200 MHz – 4xPixel Rate Data, Fill, Fill, Fill 1.00~2.00Gbits/s – 10xClock Rate
50~100 MP/s 100~200 MHz – 2xPixel Rate Data, Fill 1.00~2.00Gbits/s – 10xClock Rate
100~200 MP/s 100~200 MHz – 1xPixel Rate Data 1.00~2.00Gbits/s – 10xClock Rate
2.1.4 Synchronization
Synchronization and channel-to-channel de-skewing is facilitated by the transmission of special characters during the
blank period. The CH7317B synchronizes during the initialization period and subsequently uses the blank periods to re-
synch to the data stream.
2.2 VGA Output Operation
The CH7317B can operate in VGA RGB Bypass mode. In VGA RGB Bypass mode, data from the graphics device, after
proper decoding, are bypassed directly to the video DACs to implement a second RGB DAC function. Sync signals,
after proper decoding, are buffered internally, and can be output to drive the VGA Monitor. The CH7317B can support a
pixel rate of 200MHz. This operating mode uses 8-bits of three of the DAC’s 10-bit range, and provides a nominal
signal swing of 0.661V (or 0.7V depending on DAC Gain setting in control registers) when driving a 75Ω doubly
terminated load. No scaling, scan conversion or flicker filtering is applied in VGA RGB Bypass modes.
Table 3 lists some of the VGA resolutions.