SAA5X9X Datasheet, PDF (63/68 Pages) NXP Semiconductors – Economy teletext and TV microcontrollers

Philips Semiconductors
Economy teletext and TV microcontrollers
Preliminary specification
SAA5x9x family
16 EMC GUIDELINES
If possible, a ground plane under the whole IC should be
present, i.e. no signal tracks running underneath the IC as
shown in Fig.29.
The ground plane under the IC should be connected by the
widest possible connection back to the ground connection
of the PCB, and electrolytic decoupling capacitor. It should
preferably not connect to other grounds on the way and no
wire links should be present in this connection. The use of
wire links increases ground bounce by introducing
inductance into the ground, thereby reducing the
electrolytic capacitor’s decoupling efficiency.
The supply pins should be decoupled at the pin, to the
ground plane under the IC. This is easily accomplished
when using SM capacitors (which are also most effective
at high frequencies). Each supply pin should be connected
separately to the power connection of the PCB, preferably
via at least one wire link which:
1. May be replaced by a ferrite or inductor at a later point
if necessary
2. Will introduce a small amount of inductance.
Signals connected to the +5 V supply e.g. via a pull-up
resistors, should be connected to the +5 V supply before
the wire link to the IC (i.e. not the IC side). This will prevent
if from being polluted and conduct or radiate noise onto
signal lines, which may then radiate themselves.
OSCGND should connect only to the crystal load
capacitors (and not GND).
handbook, full pagewidth
other
GND
connections
under-IC GND plane
GND connection
note: no wire links
GND +5 V
electrolytic decoupling capacitor (2 µF)
wire links
VDDM
VDDD
SM decoupling capacitors (10 to 100 nF)
VDDA
under-IC GND plane
VSSD
VSSA
IC
MGL127
Fig.29 Power supply and GND connections for SOT247-1.
1997 Jul 07
63