TS3A225E_17 Datasheet, PDF (14/37 Pages) Texas Instruments – AUTONOMOUS AUDIO HEADSET SWITCH

TS3A225E
SCDS329A – AUGUST 2012 – REVISED MAY 2013
DESCRIPTION OF OPERATION
www.ti.com
GENERAL OPERATION
The TS3A225E is an audio headset switch device that detects the existence and polarity of a microphone
connected to a headset. Upon detection of a microphone the TS3A225E automatically connects a system analog
microphone pin to the appropriate audio jack connection. The device also routes the system microphone GND to
the proper jack connection.
The detection sequence is initiated via I²C command or the external trigger detection (DET_TRIGGER) pin. The
automatic routing feature can be disabled by I²C command. Additionally, all the switches of TS3A225E can be
manually controlled by I²C register. See the I²C register usage section for details.
EXTERNAL PIN CONNECTION
(1) HARDWARE MODE
The TS3A225E can be used in a non- I2C system in which the controls are performed via external pins. The
following table summarizes how the external pins should be connected in a non- I²C system:
PIN
CONNECT TO
SCL/SDA
V_DD
I2C_ADDR_SEL V_DD or GND
/MIC_Present
None
DET_TRIGGER
Rising edge initiates
detection
DETAILED DESCRIPTION
In a non- I²C system, these two pins should be tied directly to V_DD to emulate the default state
in an I²C commutation protocol.
In a non- I²C system this pin has no use and should be grounded.
This is an output pin and can be read to check whether microphone is detected. This pin will
be driven low upon microphone detection.
In a non- I²C system, this pin needs to be manually asserted to initiate a headset detection
sequence. A rising edge on this pin triggers the detection.
(2) I²C Mode
In an I²C system, the external pins should be connected as follows:
PIN
SCL/SDA
I2C_ADDR_SEL
CONNECT TO
I²C buses
V_DD or GND
NOTE
SCL/SDA pins should be connected to the corresponding I2C buses in an I2C system
This pin is used to modify the device I2C address in an I2C system to avoid address conflict. The
address can be changed as follows:
/MIC_Present
DET_TRIGGER
None
Rising edge
initiates detection
I2C_ADDR_SEL
Pin
Address
Read/Write
0*
8’h76
Write
8’h77
Read
1
8’h78
Write
8’h79
Read
*This is the factory programmed value
By default, this is an output pin. This pin will be driven low upon microphone detection and will
remain low until another detection event. In an I²S system, this pin can also serve as interrupt for
I2C register update. See the I²C register usage section for more details.
In an I²C system, detection sequence can be initiated via the I2C DET_TRIGGER register or this
DET_TRIGGER external pin. A rising edge on this pin triggers the detection.
MICROPHONE PRESENT INDICATOR
The TS3A225E detects whether or not a microphone is present on an inserted audio stereo jack. If a microphone
is detected, the TS3A225E pulls the /MIC_PRESENT pin low and also indicates the presence of the microphone
in an I²C register. The /MIC_PRESENT connection is an open-drain output with a maximum on resistance of 25
Ω. This makes the /MIC_PRESENT pin compatible with HDA standards (if /MIC_PRESENT is asserted low when
connected to an external 5.1 kΩ pull-up resistor, the effective series resistance of the MIC_PRESENT transistor
+ pull-up resistor will be changed by less than 0.5%).
14
Submit Documentation Feedback
Product Folder Links: TS3A225E
Copyright © 2012–2013, Texas Instruments Incorporated