Datasheet

164
4337K–USB–04/08
AT89C5130A/31A-M
27.4 AC Parameters
27.4.1 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:T
AVLL
= Time for Address Valid to ALE Low.
T
LLPL
= Time for ALE Low to PSEN Low.
T
A
= -40°C to +85°C; V
SS
= 0V; V
CC
= 3.3V ±10%; F = 0 to 48 MHz.
T
A
= -40°C to +85°C; V
SS
= 0V; V
CC
= 3.3V ± 10%.
(Load Capacitance for port 0, ALE and PSEN = 60 pF; Load Capacitance for all other outputs =
60 pF.)
Table 27-2, Table 27-5 and Table 27-8 give the description of each AC symbols.
Table 27-3, Table 27-7 and Table 27-9 give for each range the AC parameter.
Table 27-4, Table 27-7 and Table 27-10 give the frequency derating formula of the AC parame-
ter for each speed range description. To calculate each AC symbols. take the x value and use
this value in the formula.
Example: T
LLIV
and 20 MHz, Standard clock.
x = 30 ns
T = 50 ns
T
CCIV
= 4T - x = 170 ns
Symbol Parameter Min Typ Max Unit
V
REF
USB Reference Voltage 3.0 3.6 V
V
IH
Input High Voltage for D+ and D- (Driven) 2.0 4.0 V
V
IHZ
Input High Voltage for D+ and D- (Floating) 2.7 3.6 V
V
IL
Input Low Voltage for D+ and D- 0.8 V
V
OH
Output High Voltage for D+ and D- 2.8 3.6 V
V
OL
Output Low Voltage for D+ and D- 0.0 0.3 V