M65845AFP 查看數據表（PDF） - Renesas Electronics

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M65845AFP

Digital Echo with Microphone Mixing Circuit

Renesas Electronics 

M65845AFP

2. Auto mute function

The IC carries out auto mute function at the time of powering up and switching on MIC SW in order to suppress

shock noise that the digital delay may produce.

• At power up

Reset Time

• At switching on MIC SW

Mute time

(400 ms)

MIC SW OFF

Mute time

(400 ms)

Switching on MIC SW

3. Input and output LPF

Signal through frequency fsig is also determined by LPF of digital echo cut off frequency.

2 degree LPF of digital echo is formed by external resistance and capacitor. (refer to next figure)

So, cut off frequency is determined by next formula.

1

fsig =

2π R8 • R9 • C13 • C14

LPF1

REF

LPF2

REF

+

–

12

13

C14

R8

24 kΩ

R7

24 kΩ

C13

R9

24 kΩ

+

–

23

24

C14

R8

24 kΩ

R7

24 kΩ

C13

R9

24 kΩ

REJ03F0170-0201 Rev.2.01 Jan 25, 2008

Page 10 of 13

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