User's Manual

Shenzhen Neoway Technology Co., Ltd. Page 24 of 32

6.7 Audio Interface

Table7 Audio Interface

Signal

I/O

Function

Note

MICP

MIC+ input

Vpp ≤ 200mV

MICN

MIC- input

Vpp ≤ 200mV

EAR-L

Earpiece output L

Can drive a 16Ω/32Ω earpiece directly

EAR-R

Earpiece output R

Can drive a 16Ω/32Ω earpiece directly

For reference audio interface see Figure 18. The peak-peak voltage routed to MIC+/MIC- should not

exceed 200mV. AGC circuit is integrated inside the module. Electret microphone is suited.

Figure 18 Reference design of microphone interface

A bias voltage for microphone is provided through MICP and MICN, as shown in Figure 19. But if

an amplifier is used between the microphone and module, capacitors like C1 and C2, should be

placed between the outputs of amplifier and module, to block the bias voltage.

For a peak-peak voltage greater than 200mV, an attenuation circuit comprised of R1-R4 should be

used.