M65845AFP datasheet(6/14 Pages) RENESAS

Part #	M65845AFP

Description	Digital Echo with Microphone Mixing Circuit

PDF	14 Pages

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Manufacturer	RENESAS [Renesas Technology Corp]

Direct Link	http://www.renesas.com

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6 / 14 page

M65845AFP

REJ03F0170-0201 Rev.2.01 Jan 25, 2008

Page 6 of 13

Function Description

Microphone Amplifier

The gain (GV) and low cut-off frequency (fcl) of microphone amplifier are expressed as follows.

GV = 20log •

R1 + 1.5 k + 334 k

R1 + 1.5 k

π • (R1 + 1.5 k) • C1

fcl =

GV (max) = 47 dB, fcl = 50 Hz

R1 = 0

Ω, C1 = 2.2 μF

Assuming GV = 37 dB, fcl = 15 Hz, for instance, the constants take the following values.

R1 = 3.3 k

Ω, C1 = 2.2 μF

MIC

–

5 k

10 k

Ω (Typ)

1.5 k

334 k

μF

REF

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.

Recommended circuit in use M65845FP

R3 and C4 are not required for

the M65845AFP.

R1 for the gain of microphone

amplifier setting in use M65845AFP.

MIC

–

10 k

Ω (Typ)

μF

REF

M65845AFP Datasheet(PDF) 6 Page - Renesas Technology Corp