User Guide

PAMS Technical Documentation System Module & UI
NHM-8NX
Issue 1 05/02 ãNokia Corporation Page 57
This word contains information regarding the external SRAM if one is used for the base-
band. The information specifies the size of the SRAM and the number of WAIT states to
be used when accessing it. External SRAM is not supported by NHM-8NX.
EMC Strategy
The NHM-8NX phone complies with the given CE and SPR requirements concerning EMC
and ESD. Attention has been paid to obtaining immunity in the PWB layout itself, and
the implementation of filters in the circuit design.
Requirements for EMC and ESD:
CE requirements for EMC and ESD according to ETS 300 342-1
Internal requirements for EMC and ESD are according to SPR4
PWB strategy
PWB construction
The pwb in NHM-8NX is a 6-layer board with RCCu-foil, 17u cu and FR4 dielectric.
Via types are through hole, laser via and buried via.
The pwb layers has been defined to be:
Layer 1: Component placement
Layer 2: BB+RF
Layer 3: RF
Layer 4: Ground
Layer 5: BB+RF
Layer 6: Ground
PWB immunity
The pwb has been designed to shield all tracks from the bottom connector and all lines
susceptible for radiation. Sensitive PWB tracks have been drawn with respect to shield-
ing by having groundplane over and under the tracks, and ground close to the tracks at
the same layer.
The edge of the pwb has been designed to control the direction of the ESD pulse by
implementing a low impedance path for ESD. This is done by an open gold layer of
0,7mm at both sides of the pwb.
Keyboard