Integrator's Manual GR47/GR48

5. SYSTEM CONNECTOR INTERFACE

LZT 123 7589 R1A

5.7.3 Microphone Signals

MICP and MICN are balanced differential microphone input pins. These

inputs are compatible with an electret microphone. The microphone

contains an FET buffer with an open drain output, which is supplied with

at least +2 V relative to ground by the radio device as shown below.

Figure 5.5 Microphone connections to the radio device

Output Capacitance 2.2 µF ±10 %

Levels (THD < 5 %)

Drive capability into 5 kΩ

(0.3 - 3.5 kHz)

> 2.4 V

p-p

Drive capability into 1.5 k

Ω

(0.3 - 3.5 kHz)

> 2.2 V

p-p

Drive capability into 150 Ω

(at 1 kHz)

> 1.3 V

p-p

Parameter Limit

Pin Speaker signals Dir Function

53 MICP I Microphone positive input

54 MICN I Microphone negative input

MICP

GR47

MICN

68nF

2 - 2.5V

@ 1mA

CODEC

AGND