參數(shù)資料
型號： PCA8514P
廠商： NXP Semiconductors N.V.
英文描述： Stand-alone OSD
中文描述： 單機OSD
文件頁數(shù)： 47/64頁
文件大?。?/td> 322K
代理商： PCA8514P
1995 Nov 27
47
Philips Semiconductors
Product specification
Stand-alone OSD
PCA8514
12 OSD CLOCK SELECTION FOR DIFFERENT TV
STANDARDS
12.1
OSD frequency
The PCA8514 supports four different TV scanning
standards. To obtain the best quality character display,
each TV standard requires a different OSD frequency. To
cater for this requirement the PCA8514 provides a
programmable OSD clock that generates frequencies in
the range 4 to 14 MHz. The three examples given below
illustrate the OSD clock requirements for different TV
scanning standards.
12.1.1
NTSC 525LPF/60 Hz and PAL 625LPF/50 Hz
The OSD clock is applied directly to the OSD circuitry and
can take any value within the 4 to 14 MHz frequency
range. The NTSC 525LPF/60 Hz standard when used with
a 19 inch screen and an OSD clock of 8 MHz, produces a
character dot width of 13.2 mm.
12.1.2
NTSC 1050LPF/60 Hz
With this standard, in order to obtain the same character
dot width as in the NTSC 525LPF/60 Hz standard that
uses an OSD clock of 7 MHz; the OSD clock must be
doubled to 14 MHz because the horizontal frequency is
doubled.
To keep the same character height as that in the
NTSC 525LPF/60 Hz standard, HSYNC is also divided by
two, internally.
12.1.3
PAL 1250LPF/100 Hz
With this standard, in order to obtain the same character
dot width as in the PAL 625LPF/50 Hz standard; the OSD
clock must be doubled.
HSYNC is applied directly to the OSD circuitry without
being divided by two as both the horizontal frequency
(1250 Hz) and the vertical frequency (100 Hz) are
doubled.
12.2
Maximum number of characters per row
The number of characters per row is a function of the OSD
clock frequency and the TV standard used.
With reference to Fig.40 the active video signal period of a
horizontal line is 53.5
μ
s. However, in order to reduce
jittering at the screen edge, overscan is normally applied
by the TV manufacturer and this reduces the visible video
signal period to 48.15
μ
s. The examples given below show
how the number of characters per row and the character
width may be obtained for the NTSC 525LPF/60 Hz
TV standard using different OSD clock frequencies.
12.2.1
NTSC 525LPF/60 Hz; f
OSD
= 6 MHz
As f
OSD
= 6 MHz: t
OSD
= 0.1666
μ
s.
The number of visible dots on one horizontal line is 290
(48.15
μ
s/0.1666
μ
s). However, as the starting position
of the first character dot is approximately 45 dots after
HSYNC, the actual visible number of dots per line is 245.
Each character is composed of a 12
×
18 dot matrix;
therefore the maximum number of characters on one
line is 20 (245/12).
If a 19 inch TV screen is used, the width of a horizontal
line is approximately 370 mm and this gives a character
width of 18.5 mm.
12.2.2
NTSC 525LPF/60 Hz; f
OSD
= 10 MHz
As f
OSD
= 10 MHz: t
OSD
= 0.1
μ
s.
The number of visible dots on one horizontal line is 481
(48.15
μ
s/0.1
μ
s). Allowing for the initial starting position
of 45 dots, the actual number of visible dots per line is
436.
Each character is composed of a 12
×
18 dot matrix;
therefore the maximum number of characters on one
line is 36.
With a 19 inch TV screen, the width of a horizontal line
is approximately 370 mm and the character width is
10.3 mm.
相關PDF資料
PDF描述
PCA8514T Stand-alone OSD
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相關代理商/技術參數(shù)
參數(shù)描述
PCA8514T 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Stand-alone OSD
PCA8515 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Stand-alone OSD
PCA8515P 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Stand-alone OSD
PCA8515T 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Stand-alone OSD
PCA8515T/009 制造商:NXP Semiconductors 功能描述:ON-SCREEN DISPLAY IC, PDSO24
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