PCA8516 Datasheet, PDF (48/64 Pages) NXP Semiconductors – Stand-alone OSD

Philips Semiconductors
Stand-alone OSD
12.3 Maximum number of rows per frame
The number of rows per frame is a function of the number
of active lines per display field and the number of vertical
dots in the character matrix (which is 18). The number of
rows per frame (N) is calculated as shown below.
N = ^{n----u---m-----b----e---r----o---f---a----c---t-i-1-v--8-e-----l-i-n----e---s-----p---e---r----f--i-e----l-d--}
The four examples shown below illustrate how the
maximum number of rows per frame is obtained for each
TV scanning standard.
12.3.1 NTSC 525LPF/60 HZ
The number of active lines per field for this standard is
between 241.5 and 249H (see Fig.41). If the value of 241
is used then the maximum number of rows per frame is 13.
12.3.2 PAL 625LPF/50 HZ
The number of active lines per field for this standard is 280.
Therefore, the maximum number of rows per frame is 15.
12.3.3 NTSC 1050LPF/60 HZ
For this standard the number of active lines per frame is
double that of the NTSC 525LPF/60 Hz standard.
However, as HSYNC is divided by two internally, the
maximum number of rows per frame is also 13.
12.3.4 PAL 1250LPF/100 HZ
With this standard it is not necessary to divide HSYNC by
two as both the horizontal and vertical frequency are
doubled. The maximum number of rows per frame is 15.
Preliminary specification
PCA8516
1995 Mar 30
48