m65845afp Renesas Electronics Corporation., m65845afp Datasheet - Page 6

• Manufacturer Part Number: m65845afp
• Description: Digital Echo With Microphone Mixing Circuit
• Manufacturer: Renesas Electronics Corporation.

M65845AFP
Function Description
Microphone Amplifier
The gain (G
Assuming G
<Attention point when M65845FP is replaced with M65845AFP>
REJ03F0170-0201 Rev.2.01 Jan 25, 2008
Page 6 of 13
R3 and C4 are required for the M65845FP, not for the M65845AFP. As mentioned above, the gain of microphone
amplifier can set it up with R1.
G
G
R1 = 0 Ω, C1 = 2.2 μF
R1 = 3.3 kΩ, C1 = 2.2 μF
V
V
= 20log
(max) = 47 dB, fcl = 50 Hz
V
V
) and low cut-off frequency (fcl) of microphone amplifier are expressed as follows.
= 37 dB, fcl = 15 Hz, for instance, the constants take the following values.
R1 + 1.5 k + 334 k
R1 + 1.5 k
R1 for the gain of microphone
amplifier setting in use M65845AFP.
R3 and C4 are not required for
the M65845AFP.
MIC
fcl =
2
MIC
5 k
(R1 + 1.5 k) C1
Recommended circuit in use M65845FP
1 F
1
2
R2
1.5 k
1 F
+
REF
10 k (Typ)
3
334 k
R1
C1
2
+
–
4
REF
10 k (Typ)
3
+
R1
C1
+
–
C4
R3
4