Noise Reduction
6-41
18524C/0—Nov1996
AMD-K5 Processor Technical Reference Manual
6.7
Noise Reduction
Circuit noise can be minimized by the following design rules:
■
Clock Signal
•
Place the processor as close as possible to the clock
source.
•
Route the CPUCLK signal on a single PCB layer. Do not
use vias.
•
Guard-band the CPUCLK signal with twice the minimum
pitch width to minimize unwanted cross talk.
■
Capacitors
•
Place all capacitors as near as possible to the processor.
•
Connect the positive sides of all capacitors through vias
directly to the processor power plane.
•
Connect the negative sides of all capacitors through vias
to the ground plane.
•
Use tantalum 47
µ
F and 1
µ
F capacitors.
•
Use ceramic capacitors with low equivalent series resis-
tance (ESR) ratings at high frequencies and a minimum
voltage rating of 6 V for all other capacitor values.
•
Place some capacitors very near to the processor, prefer-
ably on the inside perimeter of the processor socket.
•
Connect bypass capacitors on the top side of the PCB di-
rectly to the processor’s power pins.
■
Multilayer Printed-Circuit Boards
•
Use a minimum of four layers—one split power plane,
one ground plane, two routing planes.
■
Regulator Circuit
•
Use surface-mounted components placed as near as pos-
sible to the processor.
•
Use at least three vias to the +5-V power plane for the in-
put power connection.
•
Use at least three vias to the +3-V processor power plane
for the output power connection.
AMD recommends using a split power plane to isolate the pro-
cessor from the rest of the motherboard. This approach
Summary of Contents for AMD-K5
Page 1: ...AMD K5 Processor Technical Reference Manual TM...
Page 10: ...x AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 24: ...1 4 Overview AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 54: ...2 30 Internal Architecture AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 116: ...4 26 Performance AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 356: ...6 44 System Design AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 380: ...7 24 Test and Debug AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 396: ...A 16 AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 406: ...I 10 Index AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...