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.