
Electrical Characteristics
(Note 1) (Note 2) (Continued)
Pin Description
Signal Ground (3, 19):
Each input has its own independent
ground, GND1 and GND2.
Signal Input (4, 20):
There are 2 independent signal inputs,
IN1 and IN2.
Signal Output (2, 17):
There are 2 independent signal out-
puts, OUT1 and OUT2.
Voltage Supply (13, 15):
Positive voltage supply pins, V
DD1
and V
DD2
.
Voltage Supply (7, 18):
Negative voltage supply pins, V
and V
SS2
. To be tied to ground in a single supply configura-
tion.
AC Ground (1, 5, 6, 14, 16):
These five pins are not physi-
cally connected to the die in any way (i.e., No bondwires).
These pins must be AC grounded to prevent signal coupling
between any of the pins nearby. Pin 14 should be connected
to pins 13 and 15 for ease of wiring and the best isolation, as
an example.
Logic Ground (8):
Digital signal ground for the interface
lines; CLOCK, LOAD/SHIFT, DATA-IN and DATA-OUT.
Clock (9):
The clock input accepts a TTL or CMOS level sig-
nal. The clock input is used to load data into the internal shift
register on the rising edge of the input clock waveform.
Load/Shift (10):
The load/shift input accepts a TTL or
CMOS level signal. This is the enable pin of the device, al-
lowing data to be clocked in while this input is low (0V).
Data-In (11):
The data-in input accepts a TTL or CMOS level
signal. This pin is used to accept serial data from a micro-
controller that will be latched and decoded to change a chan-
nel’s attenuation level.
Data-Out (12):
This pin is used in daisy-chain mode where
more than one μPot is controlled via the same data line. As
the data is clocked into the chain from the μC, the preceding
data in the shift register is shifted out the DATA-OUT pin to
the next μPot in the chain or to ground if it is the last μPot in
the chain. The LOAD/SHIFT line goes high once all of the
new data has been shifted into each of its respective regis-
ters.
Connection Diagram
DS011978-3
FIGURE 2. Timing Diagram
DS011978-4
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