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 Fig-

ure 6, an LM1973 can be configured with a mono audio sig-

nal level control and with a panning control which separates

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 pan-

ning control for the left and right channels as stated earlier.

THD+Nvs Amplitude

f = 20 Hz, V

V

DS011958-25

THD+Nvs Amplitude

f = 1 kHz, V

V

DS011958-26

THD+Nvs Amplitude

f = 20 kHz, V

V

DS011958-27

LM1973 Channel Attenuation

vs Digital Step Value

DS011958-7

FIGURE 3. LM1973 Attenuation Step Scheme

LM1973 Channel Attenuation

vs Digital Step Value

(Programmed 1.0dB Steps)

DS011958-14

FIGURE 4. LM1973 1.0dB and 2.0dB

Attenuation Step Scheme

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