LM1973M/NOPB National Semiconductor, LM1973M/NOPB Datasheet - Page 6

• Manufacturer Part Number: LM1973M/NOPB
• Description: IC AUDIO ATTENUATR W/MUTE 20SOIC
• Manufacturer: National Semiconductor
• Type: Audio Attenuatorr

Specifications of LM1973M/NOPB

• Applications: Consoles, MIDI
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)
• Pin Count: 20
• Screening Level: Commercial
• Package Type: SOIC W
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM1973M; *LM1973M/NOPB; LM1973M

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Application Information
ATTENUATION STEP SCHEME
The fundamental attenuation step scheme for the LM1973
µPot is shown in Figure 3. This attenuation step scheme,
however, can be changed through programming techniques
to fit different application requirements. One such example
would be a constant logarithmic attenuation scheme of 2dB
steps for a panning function as shown in Figure 5. The only
restriction to the customization of attenuation schemes are
the given attenuation levels and their corresponding data
bits shown in Table 1. The device will change attenuation
levels only when a channel address is recognized. When
recognized, the attenuation level will be changed corre-
sponding to the data bits shown in Table 1. As shown in
Figure 6, an LM1973 can be configured with a mono audio
signal level control and with a panning control which sepa-
rates the mono signal into left and right channels. This circuit
may utilize the fundamental attenuation scheme of the
LM1973 for the level control, but also possess a constant
2dB panning control for the left and right channels as stated
earlier.
FIGURE 3. LM1973 Attenuation Step Scheme
LM1973 Channel Attenuation
vs Digital Step Value
01195807
6
FIGURE 5. LM1973 2.0dB Attenuation Step Scheme
FIGURE 4. LM1973 1.0dB and 2.0dB
LM1973 Channel Attenuation
LM1973 Channel Attenuation
(Programmed 1.0dB Steps)
(Programmed 2.0dB Steps)
Attenuation Step Scheme
vs Digital Step Value
vs Digital Step Value
01195814
01195815