22
2487D–MICRO–6/08
AT89S51
Notes: 1. Under steady state (non-transient) conditions, I
OL
must be externally limited as follows:
Maximum I
OL
per port pin: 10 mA
Maximum I
OL
per 8-bit port:
Port 0: 26 mA Ports 1, 2, 3: 15 mA
Maximum total I
OL
for all output pins: 71 mA
If I
OL
exceeds the test condition, V
OL
may exceed the related specification. Pins are not guaranteed to sink current greater
than the listed test conditions.
2. Minimum V
CC
for Power-down is 2V.
23. DC Characteristics
The values shown in this table are valid for T
A
= -40°C to 85°C and V
CC
= 4.0V to 5.5V, unless otherwise noted.
Symbol Parameter Condition Min Max Units
V
IL
Input Low Voltage (Except EA) -0.5 0.2 V
CC
-0.1 V
V
IL1
Input Low Voltage (EA) -0.5 0.2 V
CC
-0.3 V
V
IH
Input High Voltage (Except XTAL1, RST) 0.2 V
CC
+0.9 V
CC
+0.5 V
V
IH1
Input High Voltage (XTAL1, RST) 0.7 V
CC
V
CC
+0.5 V
V
OL
Output Low Voltage
(1)
(Ports 1,2,3) I
OL
= 1.6 mA 0.45 V
V
OL1
Output Low Voltage
(1)
(Port 0, ALE, PSEN
)
I
OL
= 3.2 mA 0.45 V
V
OH
Output High Voltage
(Ports 1,2,3, ALE, PSEN)
I
OH
= -60 µA, V
CC
= 5V ± 10% 2.4 V
I
OH
= -25 µA 0.75 V
CC
V
I
OH
= -10 µA 0.9 V
CC
V
V
OH1
Output High Voltage
(Port 0 in External Bus Mode)
I
OH
= -800 µA, V
CC
= 5V ± 10% 2.4 V
I
OH
= -300 µA 0.75 V
CC
V
I
OH
= -80 µA 0.9 V
CC
V
I
IL
Logical 0 Input Current (Ports 1,2,3) V
IN
= 0.45V -50 µA
I
TL
Logical 1 to 0 Transition Current
(Ports 1,2,3)
V
IN
= 2V, V
CC
= 5V ± 10% -300 µA
I
LI
Input Leakage Current (Port 0, EA)0.45 < V
IN
< V
CC
±10 µA
RRST Reset Pulldown Resistor 50 300 KΩ
C
IO
Pin Capacitance Test Freq. = 1 MHz, T
A
= 25°C 10 pF
I
CC
Power Supply Current
Active Mode, 12 MHz 25 mA
Idle Mode, 12 MHz 6.5 mA
Power-down Mode
(2)
V
CC
= 5.5V 50 µA