FEDL 2213-01

1Semiconductor

ML2213

22/26

9.

Low Pass Filter

ML2213’s analog output goes through the built-in Low Pass Filter. The Figure 9.1 below shows Frequency

Characteristics and Table 9.1 shows Cut-off Frequency of the LPF.

No analog output passing through the LPF is available on this chip.

Figure 9.1 LPF Frequency Characteristics (f

Table 9.1 LPF Cut-off Frequency

Sampling Frequency (kHz)

(f

Cut-off Frequency (kHz)

(f

4.0

1.2

5.3

1.6

6.4

2.0

8.0

2.5

10.6

3.2

12.8

4.0

16.0

5.0

10. AOUT Connecting Circuit

It is recommended to connect a capacitor of 0.01 to 0.033

µF to the AOUT pin.

The circuit diaram is as shown below.

The capacitor is used for improving a voice quality. Check the voice quality before determining the capacitor

value. If the voice quality is excellent without connecting a capacitor, no capacitor is required.

[dB] 20

10

0

–10

–20

–30

–40

–50

–60

–70

–80

10

100

1 k

10 k

[Hz]

AOUT

0.01 to 0.033

µF