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Rev. C - 06 March, 2001
TS80C51RA2/RD2
TS83C51RB2/RC2/RD2
TS87C51RB2/RC2/RD2
10.5. AC Parameters
10.5.1. Explanation of the AC Symbols
Each timing symbol has 5 characters. The first character is always a “T” (stands for time). The other characters,
depending on their positions, stand for the name of a signal or the logical status of that signal. The following is
a list of all the characters and what they stand for.
Example:TAVLL = Time for Address Valid to ALE Low.
TLLPL = Time for ALE Low to PSEN Low.
TA =0to+70
°C (commercial temperature range); V
SS =0V;VCC =5V ± 10%; -M and -V ranges.
TA = -40
°Cto+85°C (industrial temperature range); V
SS =0V;
VCC =5V ± 10%; -M and -V ranges.
TA =0to+70
°C (commercial temperature range); V
SS =0V;2.7V<VCC < 5.5 V; -L range.
TA = -40
°Cto+85°C (industrial temperature range); V
SS =0V;2.7V<VCC < 5.5 V; -L range.
Table 34. gives the maximum applicable load capacitance for Port 0, Port 1, 2 and 3, and ALE and PSEN signals.
Timings will be guaranteed if these capacitances are respected. Higher capacitance values can be used, but timings
will then be degraded.
Table 34. Load Capacitance versus speed range, in pF
AC symbols, take the x value corresponding to the speed grade you need (-M, -V or -L) and replace this value
in the formula. Values of the frequency must be limited to the corresponding speed grade:
Table 35. Max frequency for derating formula regarding the speed grade
Example:
TLLIV in X2 mode for a -V part at 20 MHz (T = 1/20
E6 = 50 ns):
T= 50ns
TLLIV=2T-x=2x50-22= 78ns
-M
-V
-L
Port 0
100
50
100
Port 1, 2, 3
80
50
80
ALE / PSEN
100
30
100
-M X1 mode
-M X2 mode
-V X1 mode
-V X2 mode
-L X1 mode
-L X2 mode
Freq (MHz)
40
20
40
30
20
T (ns)
25
50
25
33.3
50