MIPS R10000 Microprocessor User's Manual - SGI TechPubs Library

218 Chapter 12.
Decoupling Capacitance
Errata
In order to regulate the transient current requirements of a R10000-based system,
it is suggested that explicit decoupling capacitors be used. The R10000 package
allows for the following capacitors:
• eight Vcc-Vss
• five VccQSC-Vss
• four VccQSys-Vss
The package also provides six connections for the PLL power supplies and loop
capacitors.
VccPa (VccPd) is connected to VssPa (VssPd) through three decoupling
capacitors, as shown in Figures 12-1 and 12-2. The 0.1µF and 1 nF low-inductance
capacitors are placed in parallel with the 10 µF capacitor, as close to the R10000
package as possible. †
Vcc
Vss
Figure 12-1 Decoupling VccPa and VssPa
Vcc
Vss
Figure 12-2 Decoupling VccPd and VssPd
10 ohm VccPa
10 ohm
10 µF 0.1 µF 1 nF
VssPa
2 ohm VccPd
2 ohm
10 µF 0.1 µF 1 nF
VssPd
† Decoupling between VccPa and VssPa is far more important than decoupling
between VccPd and VssPd, if both are not possible.
Version 2.0 of January 29, 1997 MIPS R10000 Microprocessor User's Manual