Omnidirectional Microphone with

Bottom Port and Digital Output

Data Sheet

ADMP421

Rev. D

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FEATURES

Small and thin 3 mm × 4 mm × 1 mm surface-mount package

High SNR of 61 dBA

High sensitivity of −26 dBFS

Flat frequency response from 100 Hz to 15 kHz

Low current consumption: <650 µA

Sleep mode for extended battery life

High PSR of 80 dBFS

Fourth-order Σ-Δ modulator

Digital PDM output

Compatible with Sn/Pb and Pb-free solder processes

RoHS/WEEE compliant

APPLICATIONS

Smartphones and feature phones

Teleconferencing systems

Digital video cameras

Bluetooth headsets

Video phones

Tablets

GENERAL DESCRIPTION

The ADMP421 is a high performance, low power, digital output

bottom-ported omnidirectional MEMS microphone. The

ADMP421 consists of a MEMS microphone element and an

impedance converter amplifier followed by a fourth-order Σ-Δ

modulator. The digital interface allows for the pulse density

modulated (PDM) output of two microphones to be time-

multiplexed on a single data line using a single clock.

The ADMP421 has a high SNR and high sensitivity, making it

an excellent choice for far field applications. The ADMP421 has

a flat wideband frequency response, resulting in natural sound

with high intelligibility. Low current consumption and a sleep

mode enable long battery life for portable applications. A built-

in particle filter provides high reliability. The ADMP421 complies

with the TIA-920 Telecommunications Telephone Terminal

Equipment Transmission Requirements for Wideband Digital

Wireline Telephones standard.

The ADMP421 is available in a thin 3 mm × 4 mm × 1 mm

surface-mount package. It is reflow solder compatible with no

sensitivity degradation. The ADMP421 is halide free.

FUNCTIONAL BLOCK DIAGRAM

ADMP421

ADC

POWER

MANAGEMENT

CLK

DATA

PDM

MODULATOR

CHANNEL

SELECT

Figure 1.