PCA84C646 Philips Semiconductors, PCA84C646 Datasheet - Page 17

• Manufacturer Part Number: PCA84C646
• Description: Microcontrollers for TV tuning control and OSD applications
• Manufacturer: Philips Semiconductors

Philips Semiconductors
9.4.1
To achieve good OSD performance, take the following
precautions for the microcontroller mounting:
1995 Jun 15
handbook, full pagewidth
Apply the recommended R, C
values as shown in Fig.12 and place them as close as
possible to pin C (41).
To guarantee stable PLL operation, apply a noise-free
HSYNC signal (pin 6).
Avoid heavy loading of the output pins.
The supply voltage (V
Connect decoupling capacitors as close as possible to
the V
Microcontrollers for TV tuning
control and OSD applications
(1) R = 10 to 47 k ; typ. 15 k .
(2) Example:
HSYNC
f 1
C
C
For mounting see Section 9.4.1 “Mounting precautions”.
If f
and the output of the Programmable 7-bit counter is 15.750 kHz.
DD
s
p
1
M
= 100 to 470 nF; typ. 220 nF.
=
= 15.750 kHz and (decimal value of 7-bit counter) = 32 then f
and V
1
OUNTING PRECAUTIONS
10
C
DETECTOR
s
.
ACTIVE
SS
LEVEL
pins.
DD
) must be correctly decoupled.
s
f 2
and C
(2)
p
PROGRAMMABLE
FREQUENCY
7-BIT COUNTER
DETECTOR
(PLL loop filter)
PHASE/
Fig.12 On-chip OSD oscillator.
STANDBY
divided by N
VCO
17
= 8.064 MHz
CHARGE PUMP
LOOP FILTER
Position microcontroller optimal and away from
components bearing high voltage and/or strong current.
PLL loop filter ground of capacitors C
directly connected to the V
loop and separate the ground from other digital signals
ground.
The connection between V
ground/switching power supply secondary ground must
be as short as possible.
16
AND
OSD disable
f VCO
PCA84C646; PCA84C846
CONTROLLED
OSCILLATOR
VOLTAGE
SS
SS
pin (21) and +5 V regulator
pin (21). Avoid a ground
C
Preliminary specification
C s
R
s
and C
(OSD clock)
f OSD
MED196
C p
p
(1)
must be