Datasheet

104
A/T89C51AC2
4127H–8051–02/08
DC Parameters for A/D Converter
Notes: 1. Typicals are based on a limited number of samples and are not guaranteed.
2. With ADC enabled.
AC Parameters
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: 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
= 5V ±10%; F = 0 to 40 MHz.
T A = -40°C to +85°C; V
SS
= 0V; V
CC
= 5V ± 10%.
(Load Capacitance for port 0, ALE and PSEN = 60 pF; Load Capacitance for all other
outputs = 60 pF.)
Table 78, Table 81 and Table 84 give the description of each AC symbols.
Table 79, Table 83 and Table 85 give for each range the AC parameter.
Table 80, Table 83 and Table 86 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
Table 77. DC Parameters for AD Converter in Precision Conversion
Symbol Parameter Min Typ
(1)
Max Unit Test Conditions
AVin Analog input voltage Vss- 0.2 Vref + 0.2 V
Rref
(2)
Resistance between Vref and Vss 12 16 24 k Ω
Vref Reference voltage 2.40 3.00 V
Cai Analog input Capacitance 60 pF During sampling
Rai Analog input Resistor 400 Ω During sampling
INL Integral non linearity 1 2 lsb
DNL Differential non linearity 0.5 1 lsb
OE Offset error -2 2 lsb