Philips SAA7102 Datasheet page 70

Philips Semiconductors
Digital video encoder
12.1 Analog output voltages
The analog output voltages are dependent on the total
load (typical value 37.5 Ω), the digital gain parameters and
2
the I C-bus settings of the DAC reference currents (analog
settings).
The digital output signals in front of the DACs under
nominal (nominal here stands for the settings given in
Tables 54 to 61 for example a standard PAL or NTSC
signal) conditions occupy different conversion ranges, as
indicated in Table 113 for a
Table 113 Digital output signals conversion range
SET/OUT CVBS, SYNC TIP-TO-WHITE VBS, SYNC TIP-TO-WHITE
Digital settings
Digital output
Analog settings
Analog output
12.2 Suggestions for a board layout
Use separate ground planes for analog and digital ground.
Connect these planes only at one point directly under the
device, by using a 0 Ω resistor directly at the supply stage.
Use separate supply lines for the analog and digital supply.
Place the supply decoupling capacitors close to the supply
pins.
Use L (ferrite coil) in each digital supply line close to
bead
the decoupling capacitors to minimize radiation energy
(EMC).
2004 Mar 01
handbook, halfpage
C10
390 pF
FIN
Fig.16 FLTR0, FLTR1 and FLTR2 of Fig.15.
⁄
100
colour bar signal.
100
see Tables 54 to 61
1014
e.g. B DAC = 1FH
1.23 V (p-p)
C16
120 pF
L2 L3
2.7 µH 2.7 µH
C13
560 pF
AGND
JP11 JP12
FILTER 1
= byp.
ll act.
By setting the reference currents of the DACs as shown in
Table 113, standard compliant amplitudes can be
achieved for all signal combinations; it is assumed that in
subaddress 16H, parameter DACF = 0000b, that means
the fine adjustment for all DACs in common is set to 0%.
If S-video output is desired, the adjustment for the C
(chrominance subcarrier) output should be identical to the
one for VBS (luminance plus sync) output.
see Tables 54 to 61
881
e.g. G DAC = 1BH
1.00 V (p-p)
Place the analog coupling (clamp) capacitors close to the
analog input pins. Place the analog termination resistors
close to the coupling capacitors.
Be careful of hidden layout capacitors around the crystal
application.
Use serial resistors in clock, sync and data lines, to avoid
clock or data reflection effects and to soften data energy.
70
Product specification
SAA7102; SAA7103
FOUT
MHB912
RGB, BLACK-TO-WHITE
see Table 49
876
e.g. R DAC = G DAC = B DAC = 0BH
0.70 V (p-p)