Application Information

ATTENUATION STEP SCHEME

The fundamental attenuation step scheme for the LM1972

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 1dB

steps for a panning function as shown in

Figure 4. 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 Fig-

ure 6, an LM1972 can be configured as a panning control

which separates the mono signal into left and right channels.

This circuit may utilize the fundamental attenuation scheme

of the LM1972 or be programmed to provide a constant 1dB

logarithmic attenuation scheme as shown in

Figure 4.

THD+Nvs Amplitude

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THD+Nvs Amplitude

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THD+Nvs Amplitude

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LM1972 Channel Attenuation

vs Digital Step Value

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FIGURE 3. LM1972 Attenuation Step Scheme

LM1972 Channel Attenuation

vs Digital Step Value

(Programmed 1.0dB Steps)

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FIGURE 4. LM1972 1.0dB

Attenuation Step Scheme

LM1972 Channel Attenuation

vs Digital Step Value

(Programmed 2.0dB Steps)

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FIGURE 5. LM1972 2.0dB Attenuation Step Scheme

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