DG528 Datasheet, PDF (9/10 Pages) Vishay Siliconix – Latchable Single 8-Ch/Differential 4-Ch Analog Multiplexers

DG528/529
Vishay Siliconix
APPLICATION HINTS^a
V+ Positive Supply Volt-
age
(V)
V– Negative Supply
Voltage
(V)
V_IN Logic Input Voltage
V_INH(min)/V_INL(max)
(V)
20
–20
15^b
–15
8^c
–8 (min)
2.4/0.8
2.4/0.8
2.4/0.8
Notes:
a. Application Hints are for DESIGN AID ONLY, not guaranteed and not subject to production testing.
b. Electrical Parameter Chart based on V+ = 15 V, V_L = 5 V, V_R = GND.
c. Operation below "8 V is not recommended.
V_S or V_D Analog Voltage
Range
(V)
"20
"15
"8
The DG528/DG529 minimize the amount of interface
hardware between a microprocessor system bus and the
analog system being controlled or measured. The internal TTL
compatible latches give these multiplexers write-only memory,
that is, they can be programmed to stay in a particular switch
state (e.g., switch 1 on) until the microprocessor determines it
is necessary to turn different switches on or turn all switches off
(see Figure 9).
The input latches become transparent when WR is held low;
therefore, these multiplexers operate by direct command of the
coded switch state on A₂, A₁, A₀. In this mode the DG528 is
identical to the popular DG508A. The same is true of the
DG529 versus the popular DG509A.
During system power-up, RS would be low, maintaining all
eight switches in the off state. After RS returned high the
DG528 maintains all switches in the off state. When the system
program performs a write operation to the address assigned to
the DG528, the address decoder provides a CS active low
signal which is gated with the WRITE (WR) control signal. At
this time the data on the DATA BUS (that will determine which
switch to close) is stabilizing. When the WR signal returns to
the high state, (positive edge) the input latches of the DG528
save the data from the DATA BUS. The coded information in
the A₀, A₁, A₂ and EN latches is decoded and the appropriate
switch is turned on.
The EN latch allows all switches to be turned off under program
control. This becomes useful when two or more DG528s are
cascaded to build 16-line and larger multiplexers.
Document Number: 70068
P-32167—Rev. C, 15-Nov-93
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