Datasheet
IBM PowerPC 750GX RISC Microprocessor
DD1.X
3.3 Clock AC Specifications
Table 3-7 provides the clock AC timing specifications as defined in Figure 3-1.
Table 3-7. Clock AC Timing Specifications
See Table 3-2 on page 15 for recommended operating conditions.1, 3, 6
Figure 3-1
Value
Timing
Reference
Characteristic
Unit
Notes
Min.
500
25
Max.
1000
200
40
Processor frequency
SYSCLK frequency
SYSCLK cycle time
SYSCLK slew rate
MHz
MHz
ns
1
2, 3
4
5.0
1.0
25
4.0
V/ns
%
2
SYSCLK duty cycle measured at 0.65 V
SYSCLK cycle-to-cycle jitter
Internal PLL relock time
75
—
150
100
ps
4
5
—
µs
Notes:
1. Caution: The SYSCLK frequency and the PLL_CFG[0:4] settings must be chosen such that the resulting SYSCLK (bus)
frequency, CPU (core) frequency, and PLL frequency do not exceed their respective maximum or minimum operating frequencies.
Refer to the PLL_CFG[0:4] signal description in Table 5-2, 750GX Microprocessor PLL Configuration, on page 48 for valid
PLL_CFG[0:4] settings.
2. Slew rate for the SYSCLK inputs is measured from 0.4 to 1.0 V.
3. Timing is guaranteed by design and characterization, and is not tested.
4. See Section 3.4, Spread Spectrum Clock Generator, on page 19 for long-term jitter.
5. Relock timing is guaranteed by design and characterization, and is not tested. PLL-relock time is the maximum amount of time
required for PLL lock after a stable V and SYSCLK are reached during the power-on reset sequence. This specification also
DD
applies when the PLL has been disabled and subsequently re-enabled during sleep mode. Also note that hard reset (HRESET)
must be held asserted for a minimum of 255 bus clocks after the PLL-relock time during the power-on reset sequence.
6. Lower voltage and frequency operation will be available based on characterization results. See the IBM PowerPC 750GX RISC
Microprocessor Supplement for more information.
Figure 3-1. SYSCLK Input Timing Diagram
1
2
3
4
4
CVIH
V
M
SYSCLK
CVIL
V
: 0.65 V
M-SYSCLK
Electrical and Thermal Characteristics
Page 18 of 73
750GX_ds_body.fm SA14-2765-02
September 2, 2005
IBM [ IBM ]
