SAA5500PS Philips Semiconductors, SAA5500PS Datasheet - Page 73

• Manufacturer Part Number: SAA5500PS
• Description: Standard TV Microcontrollers with On-Screen Display(OSD)
• Manufacturer: Philips Semiconductors

Philips Semiconductors
25 ELECTROMAGNETIC COMPATIBILITY (EMC)
Optimization of circuit return paths and minimisation of
common mode emission will be assisted by using a double
sided Printed-Circuit Board (PCB) with low inductance
ground plane.
On a single sided printed-circuit board a local ground plane
under the whole Integrated Circuit (IC) should be present
as shown in Fig.30. This should be connected by the
widest possible connection back to the printed-circuit
board ground connection, and bulk electrolytic decoupling
capacitor. It should preferably not connect to other
grounds on the way, and no wire links should be present in
this connect. The use of wire links increases ground
bounce by introducing inductance into the ground.
The supply pins can be decoupled at the pin to the ground
plane under the IC. This is easily accomplished using
surface mount capacitors, which are more effective than
leaded components at high frequency.
1999 Oct 27
handbook, full pagewidth
Standard TV microcontrollers with
On-Screen Display (OSD)
GUIDELINES
under-IC GND plane
GND connection
note: no wire links
other
GND
connections
Fig.30 Power supply connections for EMC.
GND
3.3 V
electrolytic decoupling capacitor (2 F)
V SSC
73
Using a device socket will unfortunately add to the area
and inductance of the external bypass loop.
A ferrite bead or inductor with resistive characteristics at
high frequencies may be utilised in the supply line close to
the decoupling capacitor to provide a high impedance.
To prevent pollution by conduction onto the signal lines
(which may then radiate) signals connected to the V
supply via a pull-up resistor should not be connected to
the IC side of this ferrite component.
OSCGND should be connected only to the crystal load
capacitors and not to the local or circuit ground.
Physical connection distances to associated active
devices should be short.
Output traces should be routed with close proximity to
mutually coupled ground return paths.
V SSA
ferrite beads
SM decoupling capacitors (10 to 100 nF)
IC
under-IC GND plane
Preliminary specification
MBK979
SAA55xx
DD