NS486SXL Datasheet, PDF (21/26 Pages) National Semiconductor (TI) – Optimized 32-Bit 486-Class Controller with On-Chip Peripherals for Embedded Systems

ISA-like Bus Cycles Timing Specification (Continued)
TABLE 19. No Command Delay ISA-like Bus Specifications (Continued)
Symbol
Parameter
Formula
Min
Max
t_RCDH
t_WCDH
t_WCVD
t_WCS
Read CMD Data Hold Time
Write CMD Data Hold Time
Write CMD to Valid Data
Write Command Setup Time
1.0T +
0.5T +
0
−25
5
−20
Note 12: The value of (Wait) in the above formulae, is the number of programmed wait states associated with that access cycle (default value is 7, but may be pro-
grammed to 0–7).
TABLE 20. One Programmed Command Delay ISA-like Bus Specifications
Symbol
Parameter
Formula
Min
Max
t_AHCD
t_ASCD
t_CDPW
t_CHCD
t_CSCD
t_DOFF
t_RCAT
t_RCDH
t_WCDH
t_WCVD
t_WCS
Address Hold Time from CMD
Address Setup Time to CMD
Command Pulse Width
Chip Select Hold Time from CMD
Chip Select Setup Time to CMD
Read Data TRI-STATE
Read CMD Data Access Time
Read CMD Data Hold Time
Write CMD Data Hold Time
Write Valid Data to CMD (Note 14)
Write Command Setup Time
1.0T +
−20
2.0T +
−20
1.0T + (Wait)T +
−10
1.0T +
−25
2.0T +
−40
1.0T +
−25
1.0T + (Wait)T +
−30
0
1.0T +
−25
1.0T +
−5
0.5T +
−20
Note 13: The value of (Wait) in the above formulae, is the number of programmed wait states associated with that access cycle (default value is 7, but may be pro-
grammed to 0–7).
Note 14: For this case Valid Write Data Sets-up to the leading edge of the Command Strobe.
Ready Feedback Timing Specifications
FIGURE 10. Ready Feedback Timing Diagram
DS100121-15
TABLE 21. Ready Signal Timing Specifications
Symbol
Parameter
Formula
Min
Max
t_RACD
t_RDYH
t_RDYL
RDY Active to CMD Rising
RDY Hold Time from CMD
CMD to RDY Inactive Feedback
(E_RDY)T +
0
0
1.0T + (Wait)T +
−30
Note 15: The value of (Wait) in the above formulae, is the number of programmed wait states associated with that access cycle (default value is 7, but may be pro-
grammed to 0–7). The value of (E_RDY) in the above formulae, is the number of programmed extended ready states associated with every access cycle (default
number is 2, but may be programmed to 0–2).
21
www.national.com