AT89C51IC2_08 Datasheet, PDF (138/147 Pages) ATMEL Corporation – 8-bit Flash Microcontroller with 2-wire Interface

Shift Register Timing
Waveforms
INSTRUCTION
ALE
CLOCK
OUTPUT DATA
WRITE to SBUF
INPUT DATA
CLEAR RI
0
1
2
3
T_XLXL
T_QVXH
T_XHQX
0
1
2
T_XHDV
VALID
T_XHDX
VALID
VALID
4
3
VALID
5
4
VALID
6
5
VALID
7
8
6
7
SET TI
VALID
VALID
SET RI
External Clock Drive
Waveforms
AC Testing Input/Output
Waveforms
Float Waveforms
Clock Waveforms
V_CC-0.5V
0.45V
0.7V_CC
0.2V_CC-0.1
T_CHCL
T_CLCX
T_CLCL
T_CHCX
T_CLCH
INPUT/OUTPUT
V_CC -0.5V
0.45 V
0.2 V_CC + 0.9
0.2 V_CC - 0.1
AC inputs during testing are driven at V_CC - 0.5 for a logic “1” and 0.45V for a logic “0”.
Timing measurement are made at V_IH min for a logic “1” and V_IL max for a logic “0”.
FLOAT
V_OH - 0.1 V
V_OL + 0.1 V
V_LOAD
V_LOAD + 0.1 V
V_LOAD - 0.1 V
For timing purposes as port pin is no longer floating when a 100 mV change from load
voltage occurs and begins to float when a 100 mV change from the loaded V_OH/V_OL level
occurs. I_OL/I_OH ≥ ± 20mA.
Valid in normal clock mode. In X2 mode XTAL2 must be changed to XTAL2/2.
138 AT89C51IC2
4301D–8051–02/08