CS7620
The output of the compander is available at the pins
DOUT<9:0> and it makes transitions either at the
falling or rising edges of the pixel rate clock CL-
KO, controlled by a register bit. The Falling edge
option is shown in Figure 14.
Two options exist for outputting data. The first op-
tion will output the pixel rate clock on the CLKO
pin. The polarity of the pixel clock out of the pin is
programmable so that the user may choose the ap-
propriate clock edge to latch in the data. Based on
the RD_OUT and HSYNC signals, the user will be
able to determine when he is over active pixels. The
second option will output a data_valid signal on the
CLKO pin that is synchronous with the input clock
(Figure 15). The data_valid signal will only toggle
over active pixels. The user may then latch the data
during this valid time. Note: DATA_VALID mode
cannot be used if the system clock runs at the pixel
rate.
3.4 Timing Generator
There are three timing options available with the
CS7620. The chip may produce all the vertical and
horizontal timing for the imager, only the horizon-
tal timing, or the chip may be used in a complete
slave mode and not produce any of the CCD timing
at all. Each will be discussed in detail in this sec-
tion.
3.4.1 Vertical and Horizontal Timing
Mode
To select this option, the user must tie the
BYPASS_PLL pin low and select the proper inter-
nal timing mode in the timing mode register. The
CS7620 is the master of the clocking. It will pro-
vide vertical outputs and horizontal outputs. In this
mode, the user must control two signals. The first is
the master PWR_DN signal. When this signal is
high, all of the CS7620 powers down except for the
CODE_OUT
OFFSET4
OFFSET3
1023
OFFSET2
(x1,y1)
(x3,y3)
(x2,y2)
SLOPE3
SLOPE2
SLOPE4
OFFSET1
SLOPE1
64 X1
X2
X3
Figure 13. 13-to-10 bit compander
8191 CODE_IN
CLKO
DOUT<9:0>
Figure 14. CS7620 output data and clocks
DS301PP2
15