Fairchild Semiconductor DM74AS640WMX, DM74AS640WM, DM74AS640N Datasheet
© 2000 Fairchild Semiconductor Corporation DS006708 www.fairchildsemi.com
October 1986
Revised March 2000
DM74AS640 3-STATE Octal Bus Transceiver
DM74AS640
3-STATE Octal Bus Transceiver
General Description
This advanced Schottky device contains 8 pairs of 3STATE logic elements confi gured as octa l bus transce iver.
This circuit is designed for us e in memory, microprocessor
systems and in asynchronous bidirectional data buses.
This device transmits data from the A bus to the B b us, or
vice versa, depending upon the l ogic level of th e direction
control input (DIR). T he enable input (G
) can be used to
disable the devices, effecting isolation of buses A and B.
The 3-STATE circuitry also contains a prote ction feature
that prevents these transceivers from glitching the bus during power-up or power-down.
Features
■ Switching specifications at 50 pF
■ Switching specifications guaranteed over full tempera-
ture and V
CC
range
■ Advanced oxide-isolated, ion-implanted Schottky TTL
process
■ Functionally and pin for pin compatible with Schottky,
low power Schottky, and advanced low power Schottky
TTL counterpart
■ Improved AC performance over Schottky, low power
Schottky, and advanced low power Schottky counterparts
■ 3-STATE outputs independent ly controlled on A and B
buses
■ Low output impedance driv e to drive terminated transmission lines to 133Ω
■ Specified to interface with CMOS at V
OH
= VCC − 2V
Ordering Code:
Devices also availab le in Tape and Reel. Specify by appending th e s uffix let t er “X” to the ordering code.
Connection Diagram
Top View
Function Table
H = HIGH Logic Level
L = LOW Logic Level
X = Immaterial
Logic Diagram
Order Number Package Number Package Description
DM74AS640WM M20B 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
DM74AS640N N20A 20-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Control Inputs
Operation
G
DIR
LLB
Data to A Bus
LHA
Data to B Bus
HX Isolation
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DM74AS640
Absolute Maximum Ratings(Note 1)
Note 1: The “Absolute Maximum Ratings” are those values beyond which
the safety of the dev ice cannot be guaranteed. T he device sh ould not be
operated at these limits. The parametric values defined in the Electrical
Characteristics tables are not guaranteed at the absolute maximum ratings.
The “Recommend ed O peratin g Cond itions” t able w ill defin e the co ndition s
for actual device operation.
Recommended Operating Conditions
Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted)
Note 2: All typicals are at VCC = 5.0V, TA = 25°C.
Note 3: For I/O ports, the parameters I
IH
and IIL include the OFF-Stat e output current, I
OZH
and I
OZL
.
Supply Voltage 7V
Input Voltage
Control Inputs 7V
I/O Ports 5.5V
Operating Free Air Temperature Range 0°C to +70°C
Storage Temperature Range −65°C to +150°C
Typical θ
JA
N Package 51.5°C
M Package 69.0°C
Symbol Parameter Min Typ Max Units
V
CC
Supply Voltage 4.5 5 5.5 V
V
IH
HIGH Level Input Voltage 2 V
V
IL
LOW Level Input Voltage 0.8 V
I
OH
HIGH Level Output Current −15 mA
I
OL
LOW Level Output Current 64 mA
T
A
Free Air Operating Temperature 0 70 °C
Symbol Parameter Conditions
Min Typ Max
Units
(Note 2)
V
I
Input Clamp Voltage VCC = Min, II = −18 mA −1.2 V
V
OH
HIGH Level VCC = 4.5V to 5.5V, IOH = −2 mA VCC − 2V
Output Voltage VCC = 4.5V, IOH = −3 mA 2.4 V
VCC = 4.5V, IOH = Max 2.4 V
V
OL
LOW Level Output Voltage VCC = Min, IOL = Max 0.35 0.55 V
I
I
Input Current at Max VCC = Max, VI = 7V,
0.1 mA
Input Voltage (VI = 5.5V for A or B Ports)
I
IH
HIGH Level VCC = Max Control Inputs 20
µA
Input Current VI = 2.7V (Note 3) A or B Ports 70
I
IL
LOW Level VCC = Max, Control Inputs −0.5
mA
Input Current VI = 0.4V (Note 3) A or B Ports −0.75
I
O
Output Drive Current VCC = Max, VO = 2.25V −50 −150 mA
I
CCH
Supply Current with Outputs HIGH VCC = Max 37 58 mA
I
CCL
Supply Current with Outputs LOW 78 123 mA
I
CCZ
Supply Current with Outputs
51 80 mA
in 3-STATE
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