The data output functions may be enabled or disabled by various signals at the OE and DIR inputs. Data input functions are always enabled; i.e.,
data at the bus pins will be stored on every LOW-to-HIGH transition of the appropriate clock inputs. Also applies to data I/O (A and B: 8-15) and #2 control
pins.
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2
74LVT16646 • 74LVTH16646
Functional Description
In the transceiver mode, data present at the HIGH imped-
ance port may be stored in either the A or B register or
both. The select (SAB
n
, SBA
n
) controls can multiplex
stored and real-time. The examples shown below demon-
strate the four fundamental bus-management functions
that can be performed.
The direction control (DIR
n
) determines which bus will
receive data when OE
n
is LOW. In the isolation mode (OE
n
HIGH), A data may be stored in one register and/or B data
may be stored in the other register. When an output func-
tion is disabled, the input function is still enabled and may
be used to store and transmit data. Only one of the two
busses, A or B, may be driven at a time.
Real-Time Transfer
Bus B to Bus A
Real-Time Transfer
Bus A to Bus B
OE DIR CPAB CPBA SAB SBA
L
L
X
X
X
L
OE DIR CPAB CPBA SAB SBA
L
H
X
X
L
X
Transfer Storage
Data to A or B
Storage
OE DIR CPAB CPBA SAB SBA
OE DIR CPAB CPBA SAB SBA
L
L
L
H
X
H or L
H or L
X
X
H
H
X
L
L
H
H
H
L
X
X
X
X
L
X
X
X
X
L
X
X
X
X
3
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74LVT16646 • 74LVTH16646
Logic Diagrams
Please note that these diagrams are provided only for the understanding of logic operations and should not be used to estimate propagation delays.
1. Introduction
Electronic scales are gradually replacing traditional measuring tools like springs and balances in everyday life, such as electronic price computing scales and electronic weigh...[详细]
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