MSM7524 データシートの表示（PDF） - Oki Electric Industry

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MSM7524

DTMF Transceiver

Oki Electric Industry 

¡ Semiconductor

MSM7524

PIN DESCRIPTION

Pin No.

1

2

3

Name

GS1

PBI–

PBI+

4

SG

5

CPAO

6

CPA–

7

CPTO

I/O

Description

O Output and two input pins of the on-chip operational amplifier (1).

I

These pins are used to implement the pre-amplifier for DTMF tone

I

receiving. Refer to Fig. 1.

C1 PBI+/CPI+

IN

PBI-/CPI-

R1

R2

R3

+

–

GS1/GS2-

SG

R2

C1 PBI-/CPI-

IN R3 PBI+/CPI+

GS1/GS2

–

+

SG

(A)

(B)

• R1, R2, R3 ≥ 50 kW, C1 = 2.2 µF

• Voltage Gain; 1 + R2/R3.........(A)

R2/R3...............(B)

Figure 1 Receive Gain Adjustment

Voltage gain should be less than 10(20 dB).

DTMF receiver's detect and non-detect amplitude are specified as

the receive signal level at GS1.

On-chip signal ground.

O

The potential is approximately half of VDD.

O Output and inverting input pins of the on-chip operational amplifier

(II). The non-inverting input is internally connected to SG. When

I

not using this amplifier, these pins should be wired to each other.

Call progress tone (CPT) output. Tone amplitude is approximately

0 dBm on CPTO, but the transmit signal level can be adjusted by

using the on-chip operational amplifier (II). Refer to Fig. 2.

Make/Break of CPT transmitting is controlled through the

processor interface.

PBTO/CPTO

GENERATOR

R4

O

PBA/CPA

–

R5

PBAO/CPAO

OUT

+

SG

• R4, R5, ≥ 20 kW

• Voltage Gain; R5/R4 £ 10(20 dB)

Figure 2 Transmit Gain Adjustment

4/21

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