Rainbow Electronics W78C58 - Manual (Page 14)

W78C58
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AC CHARACTERISTICS
The AC specifications are a function of the particular process used to manufacture the part, the
ratings of the I/O buffers, the capacitive load, and the internal routing capacitance. Most of the
specifications can be expressed in terms of multiple input clock periods (T
CP ), and actual parts will
usually experience less than a ±20 nS variation. The numbers below represent the performance
expected from a 0.8 micron CMOS process when using 2 and 4 mA output buffers.
Clock Input Waveform
T
T
XTAL1
F
CH
CL
OP, T CP
PARAMETER SYMBOL MIN. TYP. MAX. UNIT NOTES
Operating Speed F OP 0 - 40 MHz 1
Clock Period T CP 25 - - nS 2
Clock High T CH 10 - - nS 3
Clock Low T CL 10 - - nS 3
Notes:
1. The clock may be stopped indefinitely in either state.
2. The T CP specification is used as a reference in other specifications.
3. There are no duty cycle requirements on the XTAL1 input.
Program Fetch Cycle
External Program Memory Fetch Cycle (see Figure 6)
PARAMETER SYMBOL MIN. TYP. MAX. UINT NOTES
Address Valid to ALE Low T AAS 1T CP -
∆ - - nS
Address Hold After ALE Low T AAH 1T CP - ∆ - - nS 1
ALE Low to PSEN Low
T APL 1T CP - ∆ 1T CP 1T CP + ∆ nS
PSEN Low to Data Valid
T PDA - - 2T CP nS 2
Data Hold After PSEN High
T PDH 0 - 1T CP nS 3
Data Float After PSEN High
T PDZ 0 - 1T CP nS
ALE Pulse Width T ALW 2T CP - ∆ 2T CP 2T CP + ∆ nS 4
PSEN Pulse Width
T PSW 3T CP - ∆ 3T CP 3T CP + ∆ nS 4