MAX14579E Datasheet, PDF (7/11 Pages) Maxim Integrated Products – Low-Power Headset Detectors with SEND/END Button Support Low-Power Microphone Mode

Low-Power Headset Detectors
with SEND/END Button Support
Functional Diagram
MODE
SWD
DET
VCC
MAX14579E
MAX14579AE
LOW-NOISE
2.2V LDO
CONTROL
DEBOUNCE
DEBOUNCE
VBIAS
CAP
0.22V_BIAS
VCC
LM
0.5VCC
RES
MIC
DETIN
Detailed Description
The MAX14579E/MAX14579AE manage headsets by
integrating 3.5mm jack insertion detection, microphone
bias generation, and SEND/END button press detection.
These devices feature a low-power microphone mode
to reduce the high bias current required for microphone
operation while it is not in use. The devices require only
a single MODE input to select between call mode and
low-power mode. See the Jack Insertion Detection sec-
tion for details about the differences among the devices.
Internal LDO Regulator
The devices feature an internal low-noise, low-dropout
regulator (LDO) for biasing the microphone connected to
MIC. The LDO’s output voltage is set at 2.2V. The LDO
is enabled and enters low-noise mode when the MODE
input is logic-high and a jack is detected. Pull the MODE
input low to put the LDO in low-power shutdown mode.
Microphone Operation and
Bias Voltage Generation
An externally preamplified microphone is connected to
MIC. Connect MIC to RES through an external 2.2kI
resistor to bias the microphone.
All the devices generate a bias voltage (VBIAS) at RES.
VBIAS is generated either by the internal 2.2V (typ) LDO
when the MODE input is logic-high or by VCC when the
MODE input is logic-low.
Microphone Low-Power Mode (MPLP)
A microphone draws a large amount of current due to the
required bias resistor when it is connected. This current
is dissipated even while the microphone is not in use.
The ICs feature internal circuitry to reduce this current
while simultaneously detecting SEND/END button press
events.
_______________________________________________________________________________________   7