The TFE–2 is a radio transceiver unit for the GSM network. It is a GSM power
class 4 transceiver providing 15 power levels with a maximum output power of
2 W.
The transceiver consists of a Radio module (WT9) and assembly parts
WT9 is the baseband/RF module TFE–2 cellular transceiver. The WT9 module
carries out all the system and RF functions of the transceiver. The system mod-
ule WT9 is designed for a WLL terminal, that operate in the GSM system.
The small–size SIM (Subscriber Identity Module) card is located inside the
phone.
All functional blocks of the system module are mounted on a single multi layer
printed circuit board. The chassis of the radio unit has separating walls for
baseband and RF. The connections to accessories are taken through the sys-
tem connector of the radio unit. There is no physical connector between the RF
and baseband sections.
Technical Documentation
Block Diagram of External Connections
Landline
telephone
2
ANTENNA1
1
RADIO MODULE
ANTENNA2
1
Fax(G3)
2
WT9
Service
handset
3
20
SYSTEM
CONNECTOR
5
SIM
Page 3–4
2
POWER
SUPPLY
2
Optional
Battery
2
SUPPLY
POWER
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Technical Documentation
Modes of Operation
There are three different operation modes
– idle mode
– active mode
– local mode
In the idle mode transmitter is in OFF–stage.
In the active mode all the circuits are supplied with power although some parts
might be in the idle state part of the time.
The local mode is used for alignment and testing.
Circuit Description
The transceiver electronics consists of one integrated Radio Module (RF + Sys-
tem blocks + LA block). System blocks, RF blocks and LA–block are intercon-
nected with PCB wiring. Accessories are connected to the transceiver via a
system connector or 2 RJ–11 connectors.
System Module
The System blocks provide the MCU and DSP environments, Logic control IC,
memories, audio processing, RF control hardware (RFI2) and 2 to 4 wire inter-
face for the landline telephone. On board power supply circuitry delivers operat-
ing voltages for both System and RF blocks. An on–board LA power unit gener-
ates feeding voltage and ringing voltage for the landline telephone.
The general purpose microcontroller, Hitachi H3001, communicates with the
DSP, memories, and Logic control IC with an 16–bit data bus.
The RF block is designed for a WLL–terminal which operates in the GSM sys-
tem. The purpose of the RF block is to receive and demodulate the radio fre-
quency signal from the base station and to transmit a modulated RF signal to
the base station.
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System Module
Block Diagram
ANT2
BPF
ANT1
RX
RX
DUPLEX
FilterER
RF BLOCK
SYNTE
SYNTE
TX
TX
IF 13 M
Clk 13 M
AFC
TXC
TXI,TXQ
RF CONTROL
SIM
RFI2
Clk
13 M
SYSTEM BLOCK
SYSTEM
ASIC
Technical Documentation
FBUS
MCU
Clk
13 M
Clk 512 k, Clk 8 k
Clk
13 M
DSP
PCM
LA CONTROL
C
O
Tx
D
E
Rx
C
M2BUS
2TO4
WIRE
INTER–
FACE
DBUS
2W
2W
Power Distribution
The power supply is based on the ASIC circuit PSCLD. The chip consists of
regulators and control circuits providing functions like automatic power up, re-
set and watchdog functions. External buffering is required to provide more cur-
rent.
Automatic power up is needed because there is no ‘power on‘ –button on the
terminal so whenever power supply is connected to the terminal it will start au-
tomatically the power up procedure. If the input voltage is too high or too low,
the terminal will automatically shut off, and when the voltage is in the correct
window, it will automatically start power–up procedure.
Charging control is not supported.
The detailed power distribution diagrams are given in Baseband blocks and RF
blocks documents.
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Technical Documentation
External Connections
The system module has two connectors, an external system connector, and
SIM connector.
System Connector X120
System Module
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TFE–2
PAMS
System Module
Accessory Connector
Pin:Name:Description:
1
RS_RXSerial RX (Receive data for serial communication)
2RS_TXSerial TX (Transmit data for serial communication)
3SCK_RTSSerial Clock (Serial Clock for synchronous communica-
4WDDIS• ”0”; min/max 0...0.6 V Watchdog disable, Flash mode
5PCMDCLKAudio Clock (512 kHz) clock for audio data
Technical Documentation
• ”0”; min/max 0...0.6 V
• ”1”; min/max 2.4...3.2 V
• ”0”; min/max 0...0.6 V
• ”1”; min/max 2.4...3.2 V
tion / RS_RTS)
• ”0”; min/max 0...0.6 V
• ”1”; min/max 2.4...3.2 V
• ”1”; min/max 2.4...7.15 V, Normal mode
• ”0”; min/max 0...0.6 V
• ”1”; min/max 2.4...3.2 V
6MBUSSerial control bus (General Purpose Control and Test
Control Bus)
• ”0”; min/max 0...0.5 V
• ”1”; min/max 2.4...3.2 V
7VPPProgramming Voltage (Programming voltage is applied
before entering the programming state)
• active; min/max 11.6...12.6 V
• inactive; min/max 0...3.2 V
8DBUS_RXDDBUS Interface (Receive data for DAI)
• ”0”; min/max 0...0.6 V
• ”1”; min/max 2.4...3.2 V
9DBUS_TXDDBUS Interface (Transmit data for DAI)
• ”0”; min/max 0...0.6 V
• ”1”; min/max 2.4...3.2 V
10PCMSCLKAudio Clock (8 kHz slot clock for audio data)
• ”0”; min/max 0...0.6 V
• ”1”; min/max 2.4...3.2 V
11VLLogic Supply Voltage (3 V Logic voltage)
• typical; 3.2 V
12FBUS_TXFBUS TX (FBUS transmit)
• ”0”; min/max 0...0.5 V
• ”1”; min/max 2.4...3.2 V
Page 3–8
13FBUS_RXFBUS RX
• FBUS receive ”0”; min/max 0...0.6 V
• Pull–up on base band ”1”; min/max 2.4...3.2 V
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Technical Documentation
VBATTBattery supply voltage
14
15DGNDDigital ground
16RS_CTSRS232 (Handshake signal for RS–232 serial interface)
17HOOK_DTRAccessory detection
18AGNDAnalog ground
19XMIC_IDExternal Microphone Input (Audio in e.g. service hand-
20XEAR_DSRExternal Speaker (Audio out e.g. service handset)
SIM Connector X300
Pin:Name:Description:
System Module
• min/max 6.45...7.15 V
• active; min/max 0...0.5 V
• inactive; min/max 2.4...3.2 V
set)
• typical 200 mV
1VSIMSIM voltage supply • min/typ/max:
4.8...4.9...5.0 V
2SRESReset for SIM
3CLKClock for SIM data (clock frequency minimum 1
MHz if clock stopping not allowed)
4GNDGround for SIM
6SDATASerial data for SIM
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System Module
Baseband Block
Introduction
The WT9 module is used in TFE–2 products. The baseband is built around one
DSP, System ASIC and the MCU. The DSP performs all speech and GSM/PCN
related signal processing tasks. The baseband power supply is 3V, except for
the A/D and D/A converters that are the interface to the RF section, and to the
comparators in the LAPWRU.
The audio codec is a separate device which is connected to both the DSP and
the MCU. The audio codec supports the internal audio from line adapter and
external audio from the service handset.
The baseband clock reference is derived from the RF section, and the reference frequency is 13 MHz. A low level sinusoidal wave form is fed to the ASIC
which acts as the clock distribution circuit. The DSP is running at 39 MHz using
an internal PLL. The clock frequency supplied to the DSP is 13 MHz. The MCU
bus frequency is the same as the input frequency. The system ASIC provides
both 13 MHz and 6.5 MHz as alternative frequencies. The MCU clock frequency is programmable by the MCU. The baseband uses 13 MHz as the MCU operating frequency. The RF A/D, D/A converters are operated using the 13 MHz
clock supplied from the system ASIC
Technical Documentation
The power supply IC contains three different regulators. The output voltage
from each regulator is 3.15V nominal. One of the regulators uses an external
transistor as the boost transistor.
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Technical Documentation
Modes of Operation
The baseband can operate only in the active mode in WLL terminal.
Circuit Description
Power Supply
+6.6 V
5,21,44,39,37
VBAT
N300
43
35
40
V300
System Module
VBATT
+6.6 V
VL +3.2V
VA +3.2 V
VSL +3.2 V
DGND
4,20,38
6,32
AGND
The baseband has one power supply circuit N300 delivering power to the different parts in the baseband. There are two logic power supplies and one analog
power supply. The analog power supply VA is used for analog circuits such as
audio codec. Due to the current consumption and the baseband architecture
the digital supply is divided into to parts.
Both digital power supply VSL and VL from the N300 PSCLD are used to distribute the power dissipation inside N300 PSCLD. The main logic power supply
VL has an external power transistor, V300 to handle the power dissipation.
D400, ASIC, and the MCU SRAM D440 are connected to the same logic supply
voltage. All other digital circuits are connected to the main digital supply. The
analog voltage supply is connected to the audio codec.
N350
VCC
+5.0 V
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System Module
Power Supply Regulator PSCLD, N300
The power supply regulators are integrated into the same circuit N300. The
power supply IC contains three different regulators. The main digital power supply regulator is implemented using an external power transistor V300. The other two regulators are completely integrated into N300.
PSCLD, N300 External Components
N300 performs the required power–on timing. The PSCLD N300 internal power on and reset timing is defined by the external capacitor C318. This capacitor
determines the internal reset delay, which is applied when the PSCLD N300 is
initially powered by applying the power supply. The baseband power–on delay
is determined by C315. With a value of 10 nF, the power–on delay after a power–on request has been active is in the range of 50–150 ms. C311 determines
the PSCLD N300 internal oscillator frequency, and the minimum power–off
time when power is switched off.
The sleep control signal from the ASIC D400 is connected via PSCLD N300.
During normal operation, the baseband sleep function is controlled by the ASIC
D400, but since the ASIC is not powered up during the startup phase, the sleep
signal is controlled by PSCLD N300 as long as the PURX signal is active. This
arrangement ensures that the 13 MHz clock provided from RF to the ASIC
D400 is started and stable before the PURX signal is released, and the baseband exits reset. When PURX is inactive high, the sleep control signal is controlled by the ASIC D400.
Technical Documentation
N300 requires capacitors on the input power supply as well as on the output
from each regulator to keep each regulator stable during different load and temperature conditions. Due to EMC precautions, a Filterer using C301, L302 and
L303 has been inserted into the supply rail. This Filterer reduces the high frequency components present at the VBAT from exiting the baseband into the
power supply. The regulator outputs also have Filterer capacitors for power
supply Filterering and regulator stability. A set of different capacitors are used
to achieve a high bandwidth in the suppression Filterer.
PSCLD, N300 Control Bus
The PSCLD N300 is connected to the baseband common serial control bus.
This bus is a serial control bus from the ASIC D400 to several devices on the
baseband. This bus is used by the MCU to control the operation of N300 and
other devices connected to the bus. N300 has two internal 8 bit registers and
the PWM register used for charging control. The registers contain information
for controlling reset levels, charging HW limits, watchdog timer length, and
watchdog acknowledgement.
The control bus includes three wires: clock, serial data, and chip select for each
device on the bus. From the PSCLD N300 point of view, the bus can be used
for writing only. It is not possible to read data from PSCLD N300 using this bus.
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Technical Documentation
The MCU can program the HW reset levels when the baseband exits/enters reset. The programmed values are retained until PSCLD N300 is powered off,
i.e. the power supply is cut off. At initial power–on, when PSCLD is powered–
on, the default reset level is used. The default value is 5.1 V, with the default
hysteresis of 400 mV. This means that reset is exit at 5.5 V when the PSCLD
N300 is powered for the first time.
The watchdog timer length can be programmed by the MCU using the serial
control bus. The default watchdog time is 32 s with a 50 % tolerance. The complete baseband is reset if the watchdog is not acknowledged within the specified time. The watchdog is running while PSCLD N300 is powering–up the system but PURX is active. This arrangement ensures that if for any reason the
supply voltage doesn’t increase above the reset level within the watchdog time
the system is reset by the watchdog. As the time PURX is active is not exactly
known, and depends upon startup conditions, the watchdog is internally acknowledged in PSCLD when PURX is released. This allows the MCU always
the same time to respond to the first watchdog acknowledgement.
The PSCLD N300 also contains a switch for connecting and the supply voltage
to the baseband A/D converters. The switch state can be changed by the MCU
via the serial control bus. When PURX is active, the switch is open to prevent
the supply voltage from being applied to the baseband measurement circuitry,
which is powered off. Before any measurement can be performed, the switch
must be closed by MCU.
System Module
SIM Interface and Regulator in N300
The SIM card regulator and interface circuit is integrated into PSCLD N300.
The benefit from this is that the interface circuits are operating from the same
supply voltage as the card, avoiding the voltage drop caused by the external
switch used in previous designs. The PSCLD N300 SIM interface also acts as
voltage level shifting between the SIM interface in the ASIC D400 operating at
3V and the card operating at 5V. Interface control in PSCLD is direct from
ASIC, D400 SIM interface. The MCU can select the power supply voltage for
the SIM using the serial control bus. The default value is 3V which needs to be
changed to 5V before power–up of the SIM interface in ASIC D400. The regulator enable and disable is controlled by the ASIC via SIMI(2).
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TFE–2
PAMS
System Module
Power–Up Sequence
PSCLD
N300
VBAT
Watchdog
disable
C351
R346
5,21,37
39,44
25
22
28
30
C311
VL VSLVA
42
40
35
26
16,18,19
17130
14
13
CRFCONT
N601
Purx
Serial Bus
VCXO Enable
CHARGAlarm
1415
SRAM, FLASH
D440 D430
120
129
22
VCXO
Address Bus
13 MHz
ASIC
D400
Watchdog
Register
Technical Documentation
32 kHz
125 126
Data Bus
83
84
82
81
MCU Clock
MCU Reset
4851
DSP Reset
DSP Clock
MCU
D420
Power–On Reset Operation
The system power–up reset is generated by the regulator IC N300. The reset
is connected to the ASIC D400 that is reset whenever the reset signal PURX is
low. The ASIC D400 then resets the DSP D360, the MCU D420, and the digital parts in N450. When reset is removed, the clock supplied to the ASIC D400
is enabled inside the ASIC. At this point, the 32 kHz oscillator signal is not enabled inside the ASIC, since the oscillator is still in the startup phase. To start
up the block requiring 32 kHz clock, the MCU must enable the 32 kHz clock.
The MCU reset counter is now started and the MCU reset is still kept active
low. A 6.5 MHz clock is started to MCU in order to put the MCU D420 into reset. The MCU is a synchronous reset device, and needs a clock to reset. The
reset to MCU is set inactive after 128 MCU clock cycles, and MCU is started.
DSP D360 and N450 reset is kept active when the clock inside the ASIC D400
is started. A13 MHz clock is started to DSP D360 and puts it into reset. D360
is a synchronous reset device, and requires a clock to enter reset. The N450
digital parts are reset asynchronously and do not need a clock to be supported
to enter reset.
As both the MCU D420 and DSP D360 are synchronous reset devices, all interface signals connected between these devices and ASIC D400 which are
used as I/O are set into input mode on the ASIC D400 side during reset. This
avoids bus conflicts occurring before the MCU D420 and the DSP D360 are
actually reset.
Page 3–14
The DSP D360 and N450 reset signal remains active after the MCU has exited
reset. The MCU writes to the ASIC register to disable the DSP reset. This arrangement allows the MCU to reset the DSP D360 and N450 whenever needed. The MCU can put DSP into reset by writing the reset active in the ASIC
D400 register
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Technical Documentation
MCU
The baseband uses a Hitachi H3001 type of MCU. This is a 16–bit internal
MCU with 8–bit external data bus. The MCU is capable of addressing up to 16
MByte of memory space linearly, depending upon the mode of operation. The
MCU has a non multiplexed address/data bus which means that memory access can be done using less clock cycles thus improving the performance but
also tightening up memory access requirements. The MCU is used in mode 3
which means 8–bit external data bus and 16 Mbyte of address space. The
MCU operating frequency is equal to the supplied clock frequency. The MCU
has 512 bytes of internal SRAM. The MCU has one serial channel, USART that
can operate in synchronous and asynchronous mode. The USART is used in
the MBUS implementation. The clock required for the USART is generated by
the internal baud rate generator. The MCU has 5 internal timers that can be
used for timing generation. Timer TIOCA0 input pin 71 is used for generation of
the netfree signal from the MBUS receive signal which is connected to the MCU
USART receiver input on pin 2.
The MCU contains 4 10–bit A/D converters channels that are used for baseband monitoring.
System Module
The MCU, D420 has several programmable I/O ports which can be configured
by SW. In this case, the data bus lines D0–D7 are used for baseband control
functions. It is not used as part of the data bus.
MCU Access and Wait State Generation
The MCU can access external devices in 2 state access or 3 state access. In
two state access the MCU uses two clock cycles to access data from the external device In 3 state access the MCU uses 3 clock cycles to access the external device or more if wait states are enabled. The wait state controller can operate in different modes. In this case, the programmable wait mode is used.
This means that the programmed amount of wait states in the wait control register are inserted when an access is performed to a device located in that area.
The complete address space is divided into 8 areas each area covering 2
MByte of address space. The access type for each area can be set by bits in
the access state control register. Furthermore, the wait state function can be
enabled separately for each area by the wait state controller enable register.
This means that in 3 state access, two types of access can be performed with a
fixed setting:
– 3 state access without wait states
– 3 state access with the amount of wait states inserted determined by the
If the wait state controller is not enabled for a 3 state access area, no wait
states are inserted when accessing that area even if the wait control register
contains a value that differs from 0 states.
Original 02/98
wait control register
Page 3–15
TFE–2
PAMS
System Module
MCU Flash Loading
The flash loading equipment is connected to the baseband by means of the
service adapter. The power supply for the baseband is supplied via the adapter
and controlled by the flash programming equipment. The baseband module is
powered up when the power is connected to the power supply connector.
Five signals are required for the flash programming, with the addition of the
power supply. The baseband MCU will automatically wait for flash down–loading to be performed if one of the two following criteria are met.
– The flash is found to be empty when tested by the MCU
– The serial clock line at the baseband MCU is forced low when the MCU is
exiting reset
The second alternative is used for reprogramming as the flash is not empty in
this case. To allow the serial clock line to be forced low during MCU initial boot
there is a requirement that the flash prommer can control the power on of the
baseband module. This is done by controlling the switching of the power supply. This arrangement allows the baseband module to operate in normal mode
even if the flash prommer is connected but not active. The flash prommer also
disables the power supply watchdog during flash programming to prevent unwanted reset of the baseband. The programming voltage to the flash is applied
when the flash prommer has detected that the baseband module is powered.
This detection is performed by monitoring the serial interface RS_RX line from
the baseband. The RS_RX line is pulled high by a pull–up resistor in idle. The
VPP voltage is set to 5V as it is not known at this point what type of device is
used.
Technical Documentation
The following diagram shows the block diagram for the baseband flash programming circuitry.
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Technical Documentation
X120
VPP
RS_RX
RS_TX
SCK_RTS
WDDis
GND
VBAT
5...22
PSCLD
N301
7
1
2
3
4
15
WDDIS Flash Prommer
26
42
40
FLASH pin11 Vpp
PSCLD pin 22 WDDis
GND
Programming Voltage Vpp
ASIC pin 120
PurX
VL,VSL
ASIC pin 130 PwrDown
VLC
R436
11
FLASH
D430
ASIC pin 51 CSelX
2,71
1
3
MCU pin 55 RdX
MCU
D420
Internal
RAM
38(9)37(24)9(24)12(10)
MCU pin 56 WrX
PSCLD pin 26 PurX
Master Reset
56
55
MCUResX
5182
MCUClk
MCUAddress
MCUData
WrX
RdX
SRAM
D440
System Module
120
55
ASIC
56
D400
8148
BOOT
ROM
49
RAMCSelX
30
5
32
MCU pin 56 WrX
MCU pin 55 RdX
The interface lines between the flash prommer and the baseband are in low
state when power is not connected by the flash prommer. The data transfer between the flash programming equipment and the base band is synchronous,
and the clock is generated by the flash prommer. The same MCU USART that
is used for MBUS communication is used for the serial synchronous communication. The PSCLD watchdog is disabled when the service adapter and flash
prommer are connected.
After the service adapter has been connected to the board the power to the
baseband module can be connected by the flash prommer or the test equipment. All interface lines are kept low, except for the data transmit from the
baseband that is in reception mode on the flash prommer side, this signal is
called RS_TX. The MCU boots from ASIC and investigates the status of the
synchronous clock line. If the clock input line from the flash prommer is low or
no valid SW is located in the flash, MCU forces the initially high RS_TX line low
acknowledging to the flash prommer that it is ready to accept data.
The flash prommer sends data length, 2 bytes, on the RS_RX data line to the
baseband. The MCU acknowledges the 2 data byte reception by pulling the
RS_TX line high. The flash prommer now transmits the data on the RS_RX line
to the MCU. The MCU loads the data into the internal SRAM. After having received the transferred data correctly MCU puts the RS_TX line low and jumps
into internal SRAM and starts to execute the code. After a guard time of 1 ms
the RS_TX line is put high by the MCU. After 1 ms the RS_TX is put low indicating that the external SRAM test is going on. After a further 1 ms, the RS_TX
is put high indicating that external SRAM test has passed. The MCU performs
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TFE–2
PAMS
System Module
the flash memory identification based upon the identifiers specified in the Flash
Programming Specifications. In case of an empty device, identifier locations
shows FFH, the flash device code is read and transmitted to the Flash Prommer.
After that, the device mounted on baseband has been identified, and the Flash
Prommer down–loads the appropriate algorithm to the baseband. The programming algorithm is stored in the external SRAM on the baseband module,
and after having down–loaded the algorithm and data transfer SW, the MCU
jumps to the external SRAM and starts to execute the code.
The MCU now asks the prommer to connect the flash programming power supply. This SW loads the data to be programmed into the flash, and implements
the programming algorithm that has been down loaded.
Flash, D430
A 8 MBit Boot Block flash is used as the main program memory D430. The device is 3 V read/program with external 12V VPP for programming. The device
has a lockable boot sector. This function is not used since the complete code is
reprogrammed. The Boot sector is located at the ”bottom”, definition by Intel,
address 00000H–03FFFH. The block is unlocked by a logic high state on pin
12. This logic high level is generated from VPP. The device can be programmed by a VPP of 5V but the programming procedure takes longer. To improve programming, the programming voltage used is 12V. The speed of the
device is 150 ns. The MCU operating at 6.5 MHz will access the flash in 2 state
access, requiring 150 ns access time from the memory.
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Technical Documentation
SRAM D440
The baseband is designed to take two different size of SRAMs, 64kx8 and
128kx8, not at the same time. The required speed is 150 ns as the MCU will
operate at 6.5 MHz and the SRAM will be accessed in 2 state access. The
SRAM has no battery backup which means that the content is lost even during
short power supply disconnections. As shown in the memory map, the SRAM is
not accessible after boot until the MCU has enabled the SRAM access by writing to the ASIC register.
EEPROM D445
The baseband is designed to take an 8kx8 serial EEPROM. TFE–2 will use the
8kx8 serial device over the I2C bus. The I2C bus protocol is implemented in
SW and the physical implementation is performed on MCU Port 4.
MCU and Peripherals
MCU Port P4 Usage
System Module
MCU, D420 port 4 is used for baseband control.
Port Pin MCU pinControl Function Remark
Baseband A/D Converter Channels usage in N450 and D420
The auxiliary A/D converter channels inside RFI2 N450 are used only for measuring of the system board temperature by the MCU.
The MCU has 4 10 bit A/D channels which are used for baseband voltage monitoring. The MCU can measure supply voltage, accessory detection (ID), loop
current (IBBDET) and line apapter power supply voltage (VBBDET) by using it‘s
own converters.
Baseband N450 A/D Converter Channel Usage
Name:Usage:Input volt. range
Chan 0
Chan 1–7not used
MCU Baseband A/D Converter Channel Usage
Name: Usage: Input volt. range
Chan 0
System board temperature0...3.2 V
Supply voltage0...3.2 V
Chan 1Accessory detection0...3.2 V
Chan 2IBBDET0...3.2 V
Chan 3VBBDET0...3.2 V
Supply Voltage Measurement
The supply voltage is measured using MCU N420 A/D converter channel 0.
The supply voltage supplied to the A/D converter input is switched off when the
baseband is powered off. The supply voltage measurement voltage is supplied
by PSCLD N300, which performs switch–off, and scaling with a scaling factor
of R1(R1+R2). The measurement voltage is Filterered by a capacitor to achieve
an average value that is not depending upon the current consumption behavior
of the baseband. To be able to measure the supply voltage during transmission
pulse, the time constant must be short. The value for the Filterering capacitor is
set to 10 nF C316. The scaling factor used to scale the supply voltage must be
1:3, which means that a 9V supply voltage will give 3V A/D converter input voltage. The A/D converter value in decimal can be calculated using the following
formula:
A/D = 1023xR1xU
BAT
where K is the scaling factor. K = R1/((R1+R2)xU
/((R1+R2)xU
) = 1023xU
ref
BAT
ref).
xK
Page 3–20
Original 02/98
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