– 5-10 –
AD6525
MIC
Speaker
A,B,C Serial Port
Receiver
VOUTNOR P/N
Phone
Jack
VINAUXP/N
VOUTLOUDP/N
AIN1P/1N
AOUT1P/1N
AOUT3P/3N
AOUT2P/2N
AIN2P/2N
VOUTAUXP
PJ_FUNC_SEL
Voice
Data
Analog
Switch
VINNOR P/N
TX/RX
Figure 5.9. Audio system block diagram
AD6537 is a complete mixed-signal baseband processor that combines all of the data converters and power supply regulator
required for a GSM 900/GSM 850/DCS 1800/PCS 1900 mobile on a single device, including HSCSD and GPRS.
The AD6537 auxiliary section provides a voltage reference, an automatic frequency control DAC, an auxiliary ADC, and light
controllers. It has two differential output port, two differential input ports, and a buzzer output. Voiceband normal output is used in
normal receiver mode. Voiceband auxiliary output is used in earpiece receiver mode.
Buzzer output signal via a meledy IC is used in loud-speak mode.
About input, voiceband normal input is used to microphone and the auxiliary input is design for earpiece microphone.
5.3.1. Voiceband Baseband Codec
Chipset
ADI AD6537
Package
148-Ball LFBGA
Feature
■
Baseband Transmit Section
GMSK Modulator
I-channel & Q-channel Transmit DACs and Filters
Power Ramping DAC
■
Baseband Receive Section
I-channel and Q-channel Receive ADCs and Filters
■
Auxiliary Section
Voltage Reference
Automatic Frequency Control DAC
Auxiliary ADC
Light Controllers
■
Audio Section
8 kHz & 16 kHz Voiceband Codec
48 kHz Monophonic DAC
Power Amplifiers
■
Power Management Section
Voltage Regulators
Battery Charger
Battery Protection
■
Digital Processor Interface
Control,Baseband, and Audio Serial Ports
Interrupt Logic
5.3. Audio System
AD6537