AD6423 查看數據表（PDF） - Analog Devices
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AD6423 Datasheet PDF : 8 Pages
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AD20msp415
POWER DISSIPATION CONSIDERATIONS
In mobile applications, minimizing the power consumption of
all devices is critical to achieve longer standby and talk times. In
a GSM handset the baseband subsystem dominates the current
consumption of the phone in standby. The design of the GSMP
and VBC includes extensive features to reduce power consump-
tion and give standby times of up to 100 hours.
Both devices are specifically designed to operate from 2.7 V to
3.3 V, to enable three or four cell battery designs.
The GSMP incorporates intelligent power management, permit-
ting automatic control of power consumption in the Channel
Codec part of the GSMP and the peripheral circuitry. Data
processing modules are switched on only when they process
data, otherwise they are powered down. Additional control
signals are provided that enable the Layer 1 software to control
the external subsystems, such as the VBC, the radio and
memory components, so that their power is intelligently switched
by the GSMP.
In the VBC, the power-down functions are split separately
among receive, transmit and auxiliary circuits. This provides
optimal analog power performance when operating in different
modes.
INTERFACES
The chipset has eleven external interfaces (see Figure 5) that
have to be considered in the design of the complete mobile
radio.
• Analog Voice Interface to VBC
• Radio Interface to VBC and GSMP
• Digital SIM Card Interface to GSMP
• Digital Interface to the Keypad
• Digital Bus Interface from GSMP to Memory and Display
• Digital Audio Interface (DAI)
• Digital Interface to GSMP for Data Services
• Digital Interface from the GSMP to the EEPROM
• Digital Interface from GSMP to Accessories
• Digital Test Interface
• Digital Interface from GSMP to Optional EFR Coprocessor
Analog Voice Interface to VBC
The analog voice interface to the VBC is specified in the AD6421
data sheet. Several design examples are given for single-ended
or differential inputs or outputs. A voltage reference for biasing
the microphone signal is provided on the VBC. The analog
output of the VBC is capable of directly driving an earpiece with
an impedance of 32 Ω. For optional use of a separate external
microphone and power amplifier, a set of auxiliary input/output
signals are provided on the VBC.
Radio Interface to VBC and GSMP
The analog interface between the VBC and the radio subsystem
is specified in detail in the AD6421 data sheet. The digital inter-
face between the GSMP and the radio subsystem is specified in
detail in the AD6422 data sheet.
Digital SIM Card Interface to GSMP
The GSMP is designed to interface directly to the SIM. How-
ever, interface logic may be necessary to connect the 3 V chipset
to a 5 V SIM.
Digital Interface to Keypad
Keypad interface logic for up to 30 keys is provided on the
GSMP. This interface provides keyboard scan for six rows
and four columns. Additionally, an extra column can be imple-
mented by using the “ghost column” method.
Digital Bus Interface to Memory and Display
External RAM and ROM, as well as the display controller,
interface directly to the 21-bit address bus and 16-bit data bus
of the GSMP.
Interface to FLASH Memory
The large FLASH memory can contain all programs for the
embedded Control Processor of the GSMP. This includes the
complete GSM protocol software as well as the User Interface
Software. A total size of 8 Mbits is suggested, assuming a typical
size of User Interface and a GSM Phase 2 Software. Enhanced
features requiring larger memories are easily supported by the
large address space of the embedded Control Processor.
To support FLASH memory, the GSMP provides embedded
code to download the software into the FLASH memory via its
standard serial port.
Interface to SRAM
In addition to the FLASH memory, the Control Processor also
supports static RAM to store user-defined variables, typically
those used by the Protocol Stack or Application Layer. Standard
SRAMs interface directly to the address and data bus of the
GSMP.
Interface to Display Controller
This interface is achieved through the address and data buses
and associated read and write strobes, as well as a specific en-
able signal. One backlight pin with PWM control is provided by
the GSMP to control brightness of backlight.
Digital Audio Interface (DAI)
As required by the GSM specifications, a digital audio interface
is provided to allow certain tests of the audio section during type
approval. This interface is activated in one of the test modes. A
fully functional “DAI box” needed for the FTA process may be
obtained from Analog Devices upon request.
Digital Interface to GSMP for Data Services
The chipset uses a serial interface that is connected to an exter-
nal data terminal adapter as described in the AD6422 data
sheet.
Digital Interface from the GSMP to the EEPROM
The GSMP provides separate pins to interface directly to an
external serial EEPROM via a serial bus. This EEPROM is
typically used for storage of calibration or user variable param-
eters like:
• Handset Identifier (IMEI)
• Language
• Keypad Lock
• DTMF ON/OFF
• Radio Calibration Parameters
A typical size of the EEPROM is 2K × 8 bits, but this depends
on the individual design of the handset.
REV. 0
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