22

ATSAM3303

6091A–DRMSD–07/04

Recommended Board

Layout

Like all HCMOS high integration ICs, the following simple rules of board layout are man-

datory for reliable operation:

•

GND, VC33, VC18 Distribution and Decouplings

All GND, VC33, VC18 pins should be connected. A GND plane is strongly recom-

mended. The board GND + VC33 distribution should be in grid form.

Recommended VC18 decoupling is 0.1 µF at each corner of the IC with an additional 10

µF decoupling close to the crystal. VC33 requires a single 0.1µF decoupling.

•

Crystal, LFT

The paths between the crystal, the crystal compensation capacitors, the LFT filter R-C-

R and the ATSAM3033 should be short and shielded. The ground return from the com-

pensation capacitors and LFT filter should be the GND plane from ATSAM3033.

•

Buses

Parallel layout between D0 - D7 and WA0 - WA21/WD0 - WD15 should be avoided. The

D0 - D7 bus is an asynchronous type bus. Even on short distances, it can induce pulses

on WA0 - WA21/WD0 - WD15 that can corrupt address and/or data on these buses.

A ground plane should be implemented below the D0 - D7 bus, which is connected to

the host and to the ATSAM3033 GND.

A ground plane should be implemented below the WA0 - WA21/WD0 - WD15 bus,

which is connected to the ROM/Flash grounds and to the ATSAM3033.

•

Analog Section

A specific AGND ground plane should be provided, which is connected to the GND

ground by a single trace. No digital signals should cross the AGND plane.

Refer to the Codec vendor recommended layout for correct implementation of the ana-

log section.