User Manual
Table Of Contents
- 1. Introduction
- 2. GR47/GR48 Radio Devices
- 3. Abbreviations
- 4. Mechanical Description
- 5. System Connector Interface
- 5.1 Overview
- 5.2 General Electrical and Logical Characteristics
- 5.3 Grounds
- 5.4 VCC - Regulated Power Supply Input
- 5.5 Battery Charging Input (CHG_IN)
- 5.6 Turning the Radio Device ON/OFF and the External Power Signal
- 5.7 Analogue Audio
- 5.8 PCM Digital Audio
- 5.9 Serial Data Interfaces
- 5.10 SIM Card Related Signals
- 5.11 Service/Programming
- 5.12 Buzzer
- 5.13 LED
- 5.14 General Purpose Digital I/O Ports
- 5.15 Extended I/O capabilities
- 5.16 General Purpose Analogue I/O Ports
- 5.17 External I 2C Serial Control Bus
- 5.18 TX_ON - Burst Transmission
- 5.19 Real Time Clock
- 6. Antenna Connector
- 7. Keyboard Interface
- 8. Hints for Integrating the Radio Device
- 9. Embedded Applications
- 10. TCP/IP Stack
- 11. Technical Data
- 12. Declaration of Conformity
- 13. Introduction to the Developer’s Kit
- 14. Using the Developer’s Kit
5. SYSTEM CONNECTOR INTERFACE
31
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
1k
1k
GR47
MICN
68nF
68nF
2 - 2.5V
@ 1mA
CODEC
AGND