AT87C54X2-3CSUL View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT87C54X2-3CSUL

8-bit CMOS Microcontroller 16/32 Kbytes ROM/OTP

Atmel Corporation 

AT/TS8xC54/8X2

19.5 AC Parameters

19.5.1

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 sta-

tus 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 = 0 to +70°C (commercial temperature range); VSS = 0 V; VCC = 5 V ± 10%; -M and -V ranges.

TA = -40°C to +85°C (industrial temperature range); VSS = 0 V; VCC = 5 V ± 10%; -M and -V

ranges.

TA = 0 to +70°C (commercial temperature range); VSS = 0 V; 2.7 V < VCC < 5.5 V; -L range.

TA = -40°C to +85°C (industrial temperature range); VSS = 0 V; 2.7 V < VCC < 5.5 V; -L range.

Table 19-3. 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 19-3. Load Capacitance versus speed range, in pF

-M

-V

-L

Port 0

100

50

100

Port 1, 2, 3

80

50

80

ALE / PSEN

100

30

100

Table 19-5., Table 19-8. and Table 19-11. give the description of each AC symbols.

Table 19-6., Table 19-9. and Table 19-12. give for each range the AC parameter.

Table 19-7., Table 19-10. and Table 19-13. give the frequency derating formula of the AC

parameter. To calculate each 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 19-4. Max frequency for derating formula regarding the speed grade

Freq (MHz)

T (ns)

-M X1 mode

40

25

-M X2 mode

20

50

-V X1 mode

40

25

-V X2 mode

30

33.3

-L X1 mode

30

33.3

-L X2 mode

20

50

Example:

TLLIV in X2 mode for a -V part at 20 MHz (T = 1/20E6 = 50 ns):

x= 22 (Table 19-7.)

T= 50ns

TLLIV= 2T - x = 2 x 50 - 22 = 78ns

47

4431E–8051–04/06

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