CS4270_06 CIRRUS [Cirrus Logic], CS4270_06 Datasheet - Page 29

• Manufacturer Part Number: CS4270_06
• Description: 24-Bit, 192 kHz Stereo Audio CODEC
• Manufacturer: CIRRUS [Cirrus Logic]

DS686PP1
Attenuation: The required attenuation factor depends on the magnitude of the input signal. For
VA = 5 V, the full-scale input voltage equals 1 Vrms. The full-scale input voltage scales with VA as indi-
cated on pages 13 and 14. The user should select values for R1 and R2 such that the magnitude of the
incoming signal multiplied by the attenuation factor is less than or equal to the full-scale input voltage of
the device.
Input Impedance: Input impedance is the impedance from the signal source to the ADC analog input
pins.
Figure 18
will attenuate a typical line level voltage, 2 Vrms, to the full-scale input of the ADC, 1 Vrms when VA = 5
V and is the maximum source impedance for the ADC specifications listed in this Data Sheet.
Table 6
illustrates an example configuration using two 2 kΩ resistors in place of R1 and R2. This circuit
shows the input parameters and the associated design equations.
Figure 17. A/D Dynamic Range vrs. Input Source Resistance
Source Impedance
Attenuation Factor
Table 6. Analog Input Design Parameters
Input Impedance
(
------------------------ -
------------------------ -
(
(
R1 R2
R1
R1
R1
(
R2
×
+
+
+
R2
R2
R2
)
)
)
)
CS4270
29