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DA7212

Ultra-low power stereo codec

Company confidential

Datasheet

Revision 3c

24-Nov-2015

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13.3 Microphone inputs

The DA7212 includes two pairs of analogue microphone inputs that can be connected in three ways:

● fully differential mode for improved common mode noise rejection

● single ended or pseudo-differential mode by connecting MIC1_N or MIC2_N to GND

(see Figure 7). The microphone source is specified using MIC_1_AMP_IN_SEL and

MIC_2_AMP_IN_SEL

● single ended or pseudo-differential mode by connecting MIC1_P or MIC2_P to GND

(see Figure 7). The microphone source is specified using MIC_1_AMP_IN_SEL and

MIC_2_AMP_IN_SEL

The microphone PGAs are enabled by the MIC_1_AMP_EN / MIC_2_AMP_EN controls and can be

muted via MIC_1_AMP_MUTE_EN / MIC_2_AMP_MUTE_EN. For maximum flexibility, each

microphone channel includes an individual gain setting (MIC_1_AMP_GAIN / MIC_2_AMP_GAIN

controls) that has a range of -6 dB to +36 dB in 6 dB steps. The currently active gain setting of each

microphone is stored in MIC_1_GAIN_STATUS and MIC_2_GAIN_STATUS.

A maximum analogue gain from microphone to ADC input of +54 dB with a resolution of 1.5 dB can

be selected.

MICBIAS2

MIC1_N

MICBIAS1

MIC1_P

MICBIAS1

MIC1_P

MIC1_N

(b) Pseudo-differential

MICBIAS1

MIC1_P

MIC1_N

(a) Differential

Figure 7: Typical microphone application for MIC1 (MIC2 is similar)

Standard electret microphones can be supplied from an embedded microphone bias regulator,

enabled using the MICBIAS2_EN control bit. Two separate outputs are available on either the

MICBIAS1 pin or the MICBIAS2 pin. These are enabled using the MICBIAS2_EN and MICBIAS1_EN

controls. The voltage on the MICBIAS pins is set to 1.6 V, 2.2 V, 2.5 V or 3.0 V by the

MICBIAS2_LEVEL and MICBIAS1_LEVEL controls. The microphone bias generates an ultra-

low-noise voltage to feed several electret microphones with up to 2 mA.

13.4 Digital microphones

DA7212 implements a digital microphone interface via a clock output (shared pin with MIC1_P) and a

serial data input (shared pin with MIC1_N). The serial data is a sigma delta sampled bitstream.

Modulators up to 3rd Order are supported.

MICBIAS1 can be used to power the digital microphone, but it must be enabled because it is

MICBIAS1 that supplies the digital microphone pins.

The clock and data pins are shared with two analogue microphone inputs. This allows DA7212 to

record from single or dual channel digital microphones, or from conventional mono/stereo analogue

microphones.

The clock frequency can be selected to be either 1.5 MHz or 3 MHz by using DMIC_CLK_RATE

control.

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