User's Manual

GM29 INTEGRATOR’S MANUAL

LZT 123 7361 R1A

Audio signal descriptions are listed below:

MICP and MICN are balanced differential microphone input signals.

These inputs are compatible with an electret microphone.

BEARP and BEARN are the speaker output signals. These are

differential-mode outputs. The electrical characteristics are given in the

table below.

The following table shows the ear piece impedances that can be

connected to BEARP and BEARN.

Pin Signal Dir Description

1 MICN I Microphone negative input

2 BEARN O Earpiece negative output

3 BEARP O Earpiece positive output

4 MICP I Microphone positive input

Parameter Limit

Output level (differential) ≥4.0V

Output level (dynamic load = 32Ω) ≥2.8V

Distortion at 1kHz and maximum output level ≤5%

Offset, BEARP to BEARN ±30mV

Ear-piece mute-switch attenuation ≥40dB

Ear piece model Impedance Tolerance

Dynamic ear piece [32Ω + 800µH] // 100pF ±20%

Dynamic ear piece [150Ω + 800µH] // 100pF ±20%

Piezo ear piece 1kΩ + 60nF ±20%