abled, and the bus mode is set for 1:1 mode operation. This mode is intended for factory use only.
Note: The AC timing specifications given in the document do not apply in PLL-bypass mode.
4. In Clock - off mode, no clocking occurs inside the PPC740 or PPC750 regardless of the SYSCLK input.
5. This limit is 83.3MHz as specified in Section 3.1.2.1, “Clock AC Specifications“.
Table 17 provides sam ple core-to-L2 frequ en cies.
1
Table 17. Sample Core-to-L2 Frequencies
Core
Frequency
in MHz
÷1
÷1.5
÷2
÷2.5
÷3
200
225
233
250
266
—
—
—
—
—
133.3
100
80
—
—
—
—
—
112.5
116.5
125
90
—
93.2
100
—
83.3
88.6
133
106.4
Note:
1. Although the PPC750 is designed for L2 bus ratios of 1:1, 1.5:1, 2:1, 2.5:1 and 3:1, this specification
supports the L2 frequency range specified in Section 3.1.2.4, “L2 Clock AC Specifications“. For higher
L2 frequencies not supported in this document, please contact your IBM marketing representative.
8.2 PLL Power Supply Filtering
Th e AVdd an d L2AVdd power sign als are provided on th e PPC740 an d PPC750 to pro-
vide power to th e clock gen eration ph ase-locked loop an d L2 cach e delay-locked loop
respectively. To en su re stability of th e in tern al clock, th e power su pplied to th e AVdd
in pu t sign al sh ou ld be filtered u sin g a circu it sim ilar to th e on e sh own in Figu re 17 .
Th e circu it sh ou ld be placed as close as possible to th e AVdd pin to en su re it filters ou t
as m u ch n oise as possible. An iden tical bu t separate circu it sh ou ld be placed as close
as possible to th e L2AVdd pin .
10 Ω
V
AV (or L2AVdd)
DD
DD
10 µF
0.1 µF
GND
Figure 17. PLL Power Supply Filter Circuit
8.3 Decoupling Recommendations
Du e to th e PPC740’s an d PPC750’s dyn am ic power m an agem en t featu re, large address
an d data bu ses, an d h igh operatin g frequ en cies, th e PPC740 an d PPC750 can gen erate
tran sien t power su rges an d h igh frequ en cy n oise in its power su pply, especially wh ile
drivin g large capacitive loads. Th is n oise m u st be preven ted from reach in g oth er com -
pon en ts in th e PPC740 an d PPC750 system s, an d th e processor itself requ ires a clean ,
33 of 44
PPC740 and PPC750 Hardware Specifications
Preliminary and subject to change without notice
IBM [ IBM ]
