87C51 Intel Corporation, 87C51 Datasheet - Page 16

• Manufacturer Part Number: 87C51
• Description: CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER
• Manufacturer: Intel Corporation

87C51 80C51BH 80C31BH
SERIAL PORT TIMING SHIFT REGISTER MODE
SHIFT REGISTER MODE TIMING WAVEFORMS
AC TESTING INPUT OUTPUT WAVEFORMS
16
Symbol
TXLXL
TQVXH
TXHQX
TXHDX
TXHDV
AC inputs during testing are driven at V
and 0 45V for a Logic ‘‘0 ’’ Timing measurements are made at V
min for a Logic ‘‘1’’ and V
Serial Port Clock
Cycle Time
Output Data Setup
to Clock Rising Edge
Output Data Hold
After Clock
Rising Edge
Input Data Hold
After Clock
Rising Edge
Clock Rising Edge
to Input Data Valid
87C51 BH
87C51-24 BH-24
Parameter
IL
max for a Logic ‘‘0’’
CC
b
Min
700
1 0
50
Oscillator
0 5 for a Logic ‘‘1’’
0
12 MHz
272335– 19
Max
700
IH
0 500
Min
284
34
Oscillator
0
24 MHz
FLOAT WAVEFORMS
For timing purposes a 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
I
OL
Max
283
I
OH
e
10TCLCL
g
2TCLCL
2TCLCL
20 mA
12TCLCL
Min
Variable Oscillator
0
b
b
b
117
133
34
10TCLCL
Max
OH
V
b
OL
133
272335 –18
272335 –20
level occurs
Units
ns
ns
ns
ns
s