LM1972N/NOPB National Semiconductor, LM1972N/NOPB Datasheet - Page 3

• Manufacturer Part Number: LM1972N/NOPB
• Manufacturer: National Semiconductor

Specifications of LM1972N/NOPB

• Attenuator Step Size: 0.5/1dB
• Number Of Bits: 16
• Number Of Channels: 2
• Power Dissipation: 150mW
• Supply Current: 4mA
• Operating Temperature (min): 0C
• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Lead Free Status / Rohs Status: Compliant

Timing Diagram
Pin Descriptions
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):
V
Voltage Supply (7, 18): Negative voltage supply pins, V
and V
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, allowing 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-
Typical Performance Characteristics
DD1
and V
SS2
. To be tied to ground in a single supply configuration.
DD2
.
Positive voltage supply pins,
FIGURE 2. Timing Diagram
SS1
3
controller that will be latched and decoded to change a
channel'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 registers.
Connection Diagram
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