saa6713ah NXP Semiconductors, saa6713ah Datasheet - Page 40

• Manufacturer Part Number: saa6713ah
• Description: Xga Analog Input Flat Panel Controller
• Manufacturer: NXP Semiconductors

Philips Semiconductors
7.4.1
7.4.1.1
The system clock is applied to pin CLK and is used to drive
the internal control structures and block configuration, and
serves as input for the panel clock PLL. The maximum
clock rate is 50 MHz.
The system clock is directly taken from pin CLK if clk_div4
is set to logic 0; otherwise the system clock is derived from
the clock signal at pin CLK additionally divided by 4 as
shown in Table 18.
Table 18 System clock switching modes
7.4.1.2
The back-end clock is the pixel clock used in data
processing behind the decoupling FIFO. Possible clock
rates lie between 5 and 100 MHz in case of single pixel
panel output, but it is identical with the panel clock; if using
double pixel mode it equals twice the panel clock.
The clock signal is generated by the panel clock PLL
based on the system clock if bclk_in_en is set to logic 0;
otherwise the signal applied externally to pin CLK is used
as system clock (see Table 19).
Table 19 Back-end clock switching modes
7.4.1.3
The front-end clock is the pixel clock of the input section
and is generated by the line PLL for the analog RGB input.
The front-end clock rate can be up to 110 MHz.
Pin VCLK is switched as output for the used clock signal.
2004 Apr 05
bclk_in_en
XGA analog input flat panel controller
clk_div4
0
1
1
0
C
LOCK SIGNALS
System clock
Back-end clock
Front-end clock
BACK-END
PLL clock
SYSTEM
CLOCK
CLOCK
1
CLK
CLK
4
CLK
direct input
divided by 4
external clock
internal clock generation
DESCRIPTION
DESCRIPTION
40
An externally generated clock signal can also be
connected to pin VCLK if vclk_in_en is set to logic 1.
Alternatively, the back-end clock can be selected as
front-end clock, which is particularly needed if the picture
generator is used without an external clock source.
Front-end clock modes are shown in Table 20.
Table 20 Front-end clock switching modes; note 1
Note
1. X = don’t care.
7.4.1.4
The internal configuration clock is driving the configuration
parameters section of all modules. It is usually running at
half the back-end clock frequency. If somehow the
back-end clock is not usable for the configuration, the
system clock could be used to drive the configuration clock
instead. The selection of the configuration clock source
could either be done automatically monitoring the
back-end clock or forced manually if this is desired. For
power saving issues the configuration clock is
powered-down during inactive periods when no data is
received or requested via the I
See Table 21 for configuration clock switching options.
Table 21 Configuration clock switching modes
frontend_
cfgclk_select
bclk
1
0
0
0
1
Configuration clock
vclk_in_en
half back-end clock
CLK
X
1
0
CONFIGURATION
CLOCK
FRONT-END
back-end
clock
VCLK
line PLL
clock
CLOCK
2
C-bus interface.
SAA6713AH
Product specification
application
(stable back-end
clock)
initialization
DESCRIPTION
DESCRIPTION
initialization
external clock
generation
internal clock
generation