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4.0 Device Specifications
4.1 PIN DESCRIPTIONS
The following are brief descriptions of all NS32081 FPU
pins. The descriptions reference the relevant portions of the
Functional Description, Section 3.
Dual-In-Line Package
TL/EE/5234 – 3
Top View
FIGURE 4-1. Connection Diagram
Order Number NS32081D-10 or NS32081D-15
See NS Package Number D24C
Order Number NS32081N-10 or NS32081N-15
See NS Package Number N24A
4.1.1 Supplies
Power (V
CC
):
a
5V positive supply. Section 3.1.
Logic Ground (GNDL):
Ground reference for on-chip logic.
Section 3.1.
Buffer Ground (GNDB):
Ground reference for on-chip driv-
ers connected to output pins. Section 3.1.
4.1.2 Input Signals
Clock (CLK):
TTL-level clock signal.
Reset (RST):
Active low. Initiates a Reset, Section 3.3.
Status (ST0, ST1):
Input from CPU. ST0 is the least signifi-
cant bit. Section 3.4 encodings are:
00Ð(Reserved)
01ÐTransferring Operation Word or Operand
10ÐReading Status Word
11ÐBroadcasting Slave ID
4.1.3 Input/Output Signals
Slave Processor Control (SPC):
Active low. Driven by the
CPU as the data strobe for bus transfers to and from the
NS32081 FPU, Section 3.4. Driven by the FPU to signal
completion of an operation, Section 3.5.1. Must be held high
with an external pull-up resistor while floating.
Data Bus (D0 – D15):
16-bit bus for data transfer. D0 is the
least significant bit. Section 3.4.
4.2 ABSOLUTE MAXIMUM RATINGS
Temperature Under Bias
0
§
C to
a
70
§
C
Storage Temperature
b
65
§
C to
a
150
§
C
All Input or Output Voltages
with Respect to GND
b
0.5V to
a
7.0V
Power Dissipation
1.5W
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Note:
Absolute maximum ratings indicate limits beyond
which permanent damage may occur. Continuous operation
at these limits is not intended; operation should be limited to
those conditions specified under Electrical Characteristics.
4.3 ELECTRICAL CHARACTERISTICS
T
A
e
0
§
C to 70
§
C, V
CC
e
5V
g
5%, GND
e
0V
Symbol
Parameter
Conditions
Min
Typ
Max
Units
V
IH
HIGH Level Input Voltage
2.0
V
CC
a
0.5
V
V
IL
LOW Level Input Voltage
b
0.5
0.8
V
V
OH
HIGH Level Output Voltage
I
OH
e b
400
m
A
2.4
V
V
OL
LOW Level Output Voltage
I
OL
e
4 mA
0.45
V
I
I
Input Load Current
0
s
V
IN
s
V
CC
b
10.0
10.0
m
A
I
L
Leakage Current
0.45
s
V
IN
s
2.4V
Output and I/O Pins in
b
20.0
20.0
m
A
TRI-STATE/Input Mode
I
CC
Active Supply Current
I
OUT
e
0, T
A
e
25
§
C
200
300
mA
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