8 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

8.1 Application Information

The CD326x device is a highly efficient, small, and flexible wired headset signaling transmitter compatible with

systems including a specially enabled audio interface. The design includes support for systems with and without

a microphone while being compatible with up to four unique buttons.

8.2 Typical Application

VSHUNT

MIC

TONE

MICPWR

GND

REM

CD326x

R1

6.81k

RTONE

20k

CTONE

200pF

S0

RVSHUNT

1.0k

CVSHUNT

0.1µF

S1

R2

2.61k

S2

S3

S4

Microphone

module

VMIC

Phone host

audio interface

INT

MICBIAS

GND

R3

3.57k

R4

6.81k

Figure 8-1. Typical Application

8.2.1 Design Requirements

Table 8-1. Typical Component Values

PARAMETER

VALUE UNIT

CMIC

MIC capacitor

10

µF

CVSHUNT

VSHUNT capacitor

0.1

CTONE

TONE capacitor

200

pF

RMIC

MIC resistor

1.0

kΩ

RVSHUNT

VSHUNT resistor

1.0

RTONE

TONE resistor

20.0

R1

S1 switch resistor

6.81

R2

S2 switch resistor

2.61

R3

S3 switch resistor

3.57

R4

S4 switch resistor

6.81

CD3268A, CD3269A

SCHS463 – MAY 2025

www.ti.com

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