AT87C5111-ICSIL datasheet(77/86 Pages) ATMEL

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AT8xC5111

4190A–8051–11/02

AC Parameters

Explanat ion of the AC

Symbols

Each timing symbol has 5 characters. The first character is always a “t” (that stands for

Time). The other characters, depending on their positions, stand for the name of a sig-

nal or the logical stat us of that signal. The following is a list of all the characters and

what they stand for.

Example:TXHDV = Time from clock rising edge to input dat a valid.

TA = -40

°C to +85°C (industrial temperat ure range); V

SS = 0V; 2.7V < VCC < 5.5V ; -L

range.

Table 61. gives the maximum applicable load capacitance for Port 1, 3 and 4. Timings

will be guaranteed if these capacitances are respected. Higher capacitance values can

be used, but timings will then be degraded.

Table 4. Load Capacitance Versus Speed Range, in pF

Table 63 gives the description of each AC symbols.

Table 64. gives for each range the AC parameter.

Table 65. gives the frequency derat ing formula of the AC parameter. To calculat e each

AC symbols, take the x value corresponding to the speed grade you need ( -L) and

replace this value in the formula. Values of the frequency must be limited to the corre-

sponding speed grade:

Table 5. Max frequency for Derat ing Formula Regarding the Speed Grade

Example:

XHDV in X2 mode for a -L part at 20 MHz (T = 1/20

E6 = 50 ns):

x = 133 (Table 65)

T = 50 ns

XHDV = 5T - x = 5 x 50 - 133 = 117 ns

-L

Port 1, 3 & 4

-L X1 Mode, VCC = 5V -L X2 Mode, VCC = 5V -L X1 Mode, VCC = 3V -L X2 Mode, VCC = 3V

Freq (MHz)

T (ns)

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