Fairchild Semiconductor 74LVQ138SJX, 74LVQ138SJ, 74LVQ138SCX, 74LVQ138SC Datasheet
74LVQ138
Low Voltage 1-of-8 Decoder/Demultiplexer
74LVQ138 Low Voltage 1-of-8 Decoder/Demultiplexer
May 1998
General Description
The LVQ138 is a high-speed 1-of-8 decoder/demultiplexer.
This device is ideally suited for high-speed bipolar memory
chip select address decoding. The multiple input enables allow parallel expansion to a 1-of-24 decoder using just three
LVQ138devices or a 1-of-32 decoder using four LVQ138 devices and one inverter.
Features
n Ideal for low power/low noise 3.3V applications
n Guaranteed simultaneous switching noise level and
dynamic threshold performance
n Improved latch-up immunity
n Guaranteed incident wave switching into 75Ω
n 4 kV minimum ESD immunity
n Demultiplexing capability
n Multiple input enable for each expansion
n Active LOW mutually exclusive outputs
Ordering Code:
Order Number Package Number Package Description
74LVQ138SC M16A 16-Lead (0.150" Wide) Small Outline Integrated Circuit, SOIC JEDEC
74LVQ138SJ M16D 16-Lead Molded Small Outline Package, SOIC EIAJ
Devices also available in Tape and Reel. Specify by appending suffix letter “X” to the ordering code.
Logic Symbols Connection Diagram
Pin Assignment
for SOIC JEDEC and EIAJ
DS011350-1
IEEE/IEC
DS011350-2
Pin Descriptions
Pin Names Description
Address Inputs
Enable Inputs
Enable Input
Outputs
DS011350-4
A
E
E
O
0–A2
1–E2
3
0–O7
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Functional Description
The LVQ138 high-speed 1-of-8 decoder/demultiplexer accepts three binary weighted inputs (A
enabled, provides eight mutually exclusive active-LOW outputs (O
active-LOW (E1,E2) and one active-HIGH (E3). All outputs
). The LVQ138features three Enable inputs, two
0–O7
will be HIGH unless E1and E2are LOW and E3is HIGH.
This multiple enable function allows easy parallel expansion
0,A1,A2
) and, when
Truth Table
Inputs Outputs
E2E3A0A1A2O0O1O2O3O4O5O6O
E
1
HXXXXXHHHHHHHH
XHXXXXHHHHHHHH
XXLXXXHHHHHHHH
LLHLLLLHHHHHHH
LLHHLLHLHHHHHH
LLHLHLHHLHHHHH
LLHHHLHHHLHHHH
LLHLLHHHHHLHHH
LLHHLHHHHHHLHH
LLHLHHHHHHHHLH
LLHHHHHHHHHHHL
H=HIGH Voltage Level
L=LOW Voltage Level
X=Immaterial
of the device to a 1-of-32 (5 lines to 32 lines) decoder with
just four LVQ138 devices and one inverter (see
Figure 1
The LVQ138 can be used as an 8-output demultiplexer by
using one of the active LOW Enable inputs as the data input
and the other Enable inputs as strobes. The Enable inputs
which are not used must be permanently tied to their appropriate active-HIGH or active-LOW state.
7
).
Logic Diagram
Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.
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DS011350-5
Logic Diagram
DS011350-6
FIGURE 1. Expansion to 1-of-32 Decoding
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