1 Features

• Compatible with specially enabled audio interfaces

(iPhone® and iPad®)

• Low quiescent current

– Button mode (microphone not in use): 3μA

– Tone mode (microphone in use): 110μA

• Miniature DSBGA (YZP) package

• ESD performance

– Human body model: 2000V

– Charged device model: 500V

2 Applications

• Wired headset signaling transmitter compatible

with systems including a specially enabled audio

interface

• See Chapter 54: Headset Remote and Microphone

Transmitter in Accessory Design Guidelines for

Apple Devices from the Apple Development Page

3 Description

The CD326x supports two operating modes; button

mode and tone mode. Button mode offers no

microphone support. Button mode passes the DC

voltage from an external switch-resistor network (tied

to the REM pin) to the MIC pin to measure the

voltage externally. Tone mode offers microphone

support and senses button presses based on an

external switch-resistor network (tied to the REM

pin). Tone mode generates corresponding ultrasonic

signals that are superimposed (via a driver output on

the TONE pin) on the system MICBIAS line. These

signals control audio functions when connected to

a specially enabled audio interface. The input DC

bias level provided on the MIC pin controls button or

tone mode selection. During tone mode, the CD326x

also provides functionality to control or bias an

external MEMS (micro-electrical-mechanical systems)

technology microphone module.