TMS3705
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11-07-22-003 SCBS881B JANUARY 2010REVISED APRIL 2010
TRANSPONDER BASE STATION IC
Check for Samples: TMS3705
1FEATURES
Base Station IC for TI-RFid™ RF Identification Short-Circuit Protection
Systems Diagnosis
Drives Antenna Sleep-Mode Supply Current: 0.2 mA
Sends Modulated Data to Antenna Designed for Automotive Requirements
Detects and Demodulates Transponder 16-Pin SOIC (D) Package
Response (FSK)
DESCRIPTION
The transponder base station IC is used to drive the antenna of a TI-RFid™ transponder system, to send data
modulated on the antenna signal, and to detect and demodulate the response of the transponder. The response
of the transponder is a FSK signal (frequency shift keyed). The high or low bits are coded in two different
high-frequency signals (134.2 kHz for low bits and 123 kHz for high bits, nominal). The transponder induces
these signals in the antenna coil according an internally stored code. The energy the transponder needs to send
out the data is stored in a charge capacitor in the transponder. The antenna field charges this capacitor in a
preceding charge phase. The IC has an interface to an external microcontroller.
There are two configurations for the clock supply to both the microcontroller and the base station IC:
1. Microcontroller and base station IC are supplied with a clock signal derived from only one resonator: The
resonator is attached to the microcontroller. The base station IC is supplied with a clock signal driven by the
digital clock output of the microcontroller. The clock frequency is either 4 MHz or 2 MHz depending on the
selected microcontroller type.
2. Both the microcontroller and the base station have their own resonator.
The base station IC has a PLL on-chip that generates a clock frequency of 16 MHz for internal clock supply only.
The TMS3705BDRG4 is optimized for higher communication data rates and therefore works without frequency
measurement during the write phase.
ORDERING INFORMATION(1)
TAPACKAGE(2) ORDERABLE PART NUMBER TOP-SIDE MARKING
TMS3705A1DRG4 TMS3705AG4
–40°C to 85°C SOIC D Reel of 2500 TMS3705BDRG4 TMS3705BG4
(1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI
web site at www.ti.com.
(2) Package drawings, thermal data, and symbolization are available at www.ti.com/packaging.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date. Copyright © 2010, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
1
2
3
413
14
15
16
NC
SCIO
F_SEL
TXCT
A_TST
D_TST
SFB
SENSE
D PACKAGE
(TOP VIEW)
5
6
710
11
12
OSC2
OSC1
VSS/VSSB
ANT2
VSSA
ANT1
89VDDVDDA
NC Noconnection
TMS3705
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TERMINAL FUNCTIONS
TERMINAL TYPE DESCRIPTION
NO. NAME
1 SENSE Analog input Input of the RF amplifier
2 SFB Analog output Output of the RF amplifier
3 D_TST Digital output Test output for digital signals
4 A_TST Analog output Test output for analog signals
5 ANT1 Driver output Antenna output 1
6 VSSA Supply input Ground for the full bridge drivers
7 ANT2 Driver output Antenna output 2
8 VDDA Supply input Voltage supply for the full bridge drivers
9 VDD Supply input Voltage supply for non-power blocks
10 OSC2 Analog output Oscillator output
11 OSC1 Analog input Oscillator input
12 VSS/VSSB Supply input Ground for non-power blocks and PLL
13 NC Not connected
14 SCIO Digital output Data output to the microcontroller
15 F_SEL Digital input Control input for frequency selection (default value is high)
16 TXCT Digital input Control input from the microcontroller (default value is high)
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Vref
RF Amplifier
10k
A_TST
SFB
SENSE
VDDA
ANT1
ANT2
VSSA
VSS
VDD
SCIO
TXCT
D_TST
F_SEL
OSC2
OSC1
VSSB
Control Logic
With
Mode Control Register
Controlled
Frequency Divider
Digital Demodulator
Transponder
Resonance-Frequency
Measurement
SCI
Encoder
Power-On
Reset
PLL
Predrivers
Full Bridge
Bandpass
Limiter Diagnosis
TMS3705
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FUNCTIONAL BLOCK DIAGRAM
Power Supply
The device is supplied with 5 V by an external voltage regulator via two supply pins, one for providing the driver
current for the antenna and for supplying the analog part in front of the digital demodulator and one for supplying
the other blocks.
The power supply supplies a power-on reset that brings the control logic into idle mode as soon as the supply
voltage drops under a certain value.
In sleep mode the sum of both supply currents is reduced to 0.2 mA. The base station device falls into sleep
mode 100 ms after TXCT has changed to high. When TXCT changes to low or is low, the base station IC
immediately goes into and remains in normal operation.
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Oscillator
The oscillator generates the clock of the base station IC of which all timing signals are derived. Between its input
and output a crystal or ceramic resonator is connected that oscillates at a typical frequency of 4 MHz. If a digital
clock signal with a frequency of 4 MHz or 2 MHz is supplied to pin OSC1, the signal can be used to generate the
internal operation frequency of 16 MHz.
The oscillator block contains a PLL that generates the internal clock frequency of 16 MHz from the input clock
signal. The PLL multiplies the input clock frequency depending on the logic state of the input pin F_SEL by a
factor of 4 (F_SEL is high) or by a factor of 8 (F_SEL is low).
In sleep mode the oscillator is switched off.
Predrivers
The predrivers generate the signals for the four power transistors of the full bridge using the carrier frequency
generated by the frequency divider. The gate signals of the p-channel power transistors (active low) have the
same width 1 cycle of the 16 MHz clock), the delay between one p-channel MOSFET being switched off and
the other one being switched on is defined to be 12 cycles of the 16 MHz clock. In write mode the first activation
of a gate signal after a bit pause is synchronized to the received transponder signal by a phase shift of 18°.
Full Bridge
The full bridge drives the antenna current at the carrier frequency during the charge phase and the active time of
the write phase. The minimal load resistance the full bridge sees between its outputs in normal operation at the
resonance frequency of the antenna is 43.3 . When the full bridge is not active, the two driver outputs are
switched to ground.
Both outputs of the full bridge are protected independently against short-circuits to ground.
In case of an occurring short-circuit, the full bridge is switched off in less than 10 µs in order to avoid a drop of
the supply voltage. After a delay time of less than 10 ms the full bridge is switched on again to test if the
short-circuit is still there. An overcurrent due to a resistive short to ground that is higher than the maximum
current in normal operation but lower than the current threshold for overcurrent protection does not need to be
considered.
RF Amplifier
The RF amplifier is an operational amplifier with a fixed internal voltage reference and a voltage gain of 5 defined
by external resistors. It has a high gain-bandwidth product of at least 2 MHz in order to show a phase shift of less
than 16° for the desired signal and to give the possibility to use it as a low-pass filter by adapting additional
external components.
The input signal of the RF amplifier is DC coupled to the antenna. The amplitude of the output signal of the RF
amplifier is higher than 5 mV peak-to-peak.
Band-Pass Filter and Limiter
The band-pass filter provides amplification and filtering without external components. The lower cut-off frequency
is about a factor of 2 lower than the average signal frequency of 130 kHz, the higher cut-off frequency is about a
factor of 2 higher than 130 kHz.
The limiter converts the analog sine-wave signal to a digital signal. It provides a hysteresis depending on the
minimal amplitude of its input signal. The duty cycle of its digital output signal is between 40% and 60%. The
band-pass filter and the limiter together have a high gain of at least 1000.
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Diagnosis
The diagnosis is carried out during the charge phase to detect whether the full bridge and the antenna are
working. When the full bridge drives the antenna, the voltage across the coil exceeds the supply voltage so that
the voltage at the input of the RF amplifier is clamped by the ESD-protection diodes. For diagnosis, the SENSE
pin is loaded on-chip with a switchable resistor to ground so that the internal switchable resistor and the external
SENSE resistor form a voltage divider, while the internal resistor is switched off in read mode. When the voltage
drop across the internal resistor exceeds a certain value, the diagnosis block passes the frequency of its input
signal to the digital demodulator. The frequency of the diagnosis signal is accepted, if eight subsequent time can
be detected, all with their counter state within the range of 112 to 125, during the diagnosis time (at most 0.1
ms). The output signal is used during the charge phase only else it is ignored.
When the short-circuit protection switches off one of the full-bridge drivers, the diagnosis also indicates an
improper operation of the antenna by sending the same diagnostic byte to the microcontroller as for the other
failure mode.
During diagnosis, the antenna drivers are active. In synchronous mode the antenna drivers remain active up to 1
ms after the diagnosis is performed, without any respect to the logic state of the signal at TXCT (thus enabling
the microcontroller to clock out the diagnosis byte).
Power-On Reset
The power-on reset generates an internal reset signal to allow the control logic to start up in the defined way.
Frequency Divider
The frequency divider is a programmable divider that generates the carrier frequency for the full-bridge antenna
drivers. The default value for the division factor is the value 119 needed to provide the nominal carrier frequency
of 134.45 kHz generated from 16 MHz. The resolution for programming the division factor is one divider step that
corresponds to a frequency shift of about 1.1 kHz. The different division factors needed to cover the range of
frequencies for meeting the resonance frequency of the transponder are 114 to 124.
Digital Demodulator
The input signal of the digital demodulator comes from the limiter and is frequency-coded according to the high-
and low-bit sequence of the transmitted transponder code. The frequency of the input signal is measured by
counting the oscillation clock for the time period of the input signal. As the high-bit and low-bit frequencies are
specified with wide tolerances, the demodulator is designed to distinguish the high-bit and the low-bit frequency
by the shift between the two frequencies and not by the absolute values. The threshold between the high-bit and
the low-bit frequency is defined to be 6.5 kHz lower than the measured low-bit frequency and has a hysteresis of
±0.55 kHz.
The demodulator is controlled by the control logic. After the charge phase (that is during read or write phase) it
measures the time period of its input signal and waits for the transponder resonance-frequency measurement to
determine the counter state for the threshold between high-bit and low-bit frequency. Then the demodulator waits
for the occurrence of the start bit. For that purpose, the results of the comparisons between the measured time
periods and the threshold are shifted in a 12-bit shift register. The detection of the start bit comes into effect
when the contents of the shift register matches a specific pattern, indicating 8 subsequent periods below the
threshold immediately followed by 4 subsequent periods above the threshold. A 2-period digital filter is inserted in
front of the 12-bit shift register to make a start bit detection possible in case of a non-monotonous progression of
the time periods during a transition from low- to high-bit frequency.
The bit stream detected by the input stage of the digital demodulator passes a digital filter before being
evaluated. After demodulation, the serial bit flow received from the transponder is buffered byte-wise before
being sent to the microcontroller by SCI encoding.
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Transponder Resonance-Frequency Measurement
During the pre-bit reception phase, the bits the transponder transmits show the low-bit frequency, which is the
resonance frequency of the transponder. The time periods of the pre-bits are evaluated by the demodulator
counter. Based on the counter states, an algorithm is implemented that guarantees a correct measurement of the
transponder’s resonance frequency:
1. A time period of the low-bit frequency has a counter state between 112 and 125.
2. The measurement of the low-bit frequency (the average of eight subsequent counter states) is accepted
during the write mode, when the eight time periods have counter states in the defined range. The
measurement during write mode is started with the falling edge at TXCT using the fixed delay time at which
end the full bridge is switched on again.
3. The counter state of the measured low-bit frequency results in the average counter state of an accepted
measurement and can be used to update the register of the programmable frequency divider.
4. The measurement of the low-bit frequency (the average of eight subsequent counter states) is accepted
during the read mode, when the eight time periods have counter states in the defined range. The start of the
measurement during read mode is delayed in order to use a stable input signal for the measurement.
5. The threshold to distinguish between high-bit and low-bit frequency is calculated to be by a value of 5 or 7
(see hysteresis in threshold) higher than the counter state of the measured low-bit frequency.
SCI Encoder
An SCI encoder performs the data transmission to the microcontroller. As the transmission rate of the
transponder is lower than the SCI transmission rate, the serial bit flow received from the transponder is buffered
after demodulation and before SCI encoding.
The SCI encoder uses an 8-bit shift register to send the received data byte-wise (least significant bit first) to the
microcontroller with a transmission rate of 15.625 kbaud 1.5 %), one start bit (high) and one stop bit (low), but
no parity bit (asynchronous mode indicated by the SYNC bit of the mode control register permanently low). The
data bits at the SCIO output are inverted with respect to the corresponding bits sent by the transponder.
The transmission starts after the reception of the start bit. The start byte detection is initialized with the first rising
edge. Typical values for the start byte are 81_H or 01_H (at SCIO). The start byte is the first byte to be sent to
the microcontroller. The transmission stops and the base station returns to idle state when TXCT becomes low or
20 ms after the beginning of the read phase. TXCT remains low for at least 128 µs to stop the read phase and
less than 900 µs to avoid starting the next transmission cycle.
The SCI encoder also sends the diagnostic byte 2 ms after beginning of the charge phase. In case of a normal
operation of the antenna, the diagnostic byte AF_H is sent. If no antenna oscillation can be measured or if at
least one of the full-bridge drivers is switched off due to a detected short-circuit, the diagnostic byte FF_H is sent
to indicate the failure mode.
The SCI encoder can be switched into a synchronous data transmission mode by setting the mode control
register bit SYNC to high. In this mode, the output SCIO indicates by a high state that a new byte is ready to be
transmitted. The microcontroller can receive the eight bits at SCIO when sending the eight clock signals (falling
edge means active) for the synchronous data transmission via pin TXCT to the SCI encoder.
Control Logic
The control logic is the core of the TMS3705 circuit. It contains a sequencer or a state machine that controls the
global operations of the base station (see Figure 1). This block has a default mode configuration but can also be
controlled by the microcontroller via the TXCT serial input pin to change the configuration and to control the
programmable frequency divider. For that purpose a mode control register is implemented in this module that can
be written by the microcontroller.
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(3)
Power-
On SLEEP
IDLE
after approx. 2 ms
Approx. 2 ms after
TXCT goes low(4)
after approx. 100 ms
TXCT is low
TXCT goes high
before 96ms
T XCT goes high
(1) In SCI synchronous mode, this transition always occurs approx. 3 ms after leaving Idle state (diag. byte trans mission
should be completed before).
0.9 ms after TX CT goes low (2)
or approx. 4 ms after start of R eceive
phase if no start bit is detected
or otherwise approx. 20 ms after
start of R eceive phase
(2) A falling edge on T XCT inter rupts the R eceive phase after a delay of 0.9 ms. T XCT must remain low for at least 128 ms.
If TXCT is still low after the 0.9 ms delay, the basestation will go to Idle and directly to the D iagnosis phase one clock
cycle later (D otted line( 3)).No MCR can be wr itten, only default mode is fully supported in this case.
Otherwise, if TXCT returns to high and remains high during the delay, the basestation w ill s tay in Idle and wait for T XC T
to go low (this will start properly a new MCR programming) or wait for 100 m s to go to Sleep.
Notes :
MCR Programming:
W rite bits into
Mode C ontrol R egister
DIAGNOSIS Phase:
Start of Charge Phase
Perform diagnosis
S end diag. byte approx.
2 ms after leaving Idle state
MCR bits received
CHARGE Phase:
Charge phase continues
Diag. byte sent
(1)
WRITE Phase :
(6)
Start of write phase
F requency me as urem ent
Program phase
RECEIVE Phase:
F requency me as urem ent
Tra nsponder signal
dem odulation
Data output to mC afte r
reception of start byte
TXCT remains high for 1.6 ms
(4) A falling edge on T XCT interrupts the Sleep state. Only default mode is fully supported when starting an oper ation
from Sleep with only one falling edge on TXCT (because of the 2 m s delay). F or a proper M CR programming, T XCT has
to return to high and remain high during this delay.
(3) T his transition only occurs in a special case (see note(2))
FAIL
(5 )
(5) Idle mode is the next state in cas e of undefined sataes ('fail safe state machine')
Frequency measurement only available for TMS3705A1DRG4
(6)
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Figure 1. Operational State Diagram for the Control Logic
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The default mode is a read-only mode that uses the default frequency as the carrier frequency for the full bridge.
Therefore the mode control register does not need to be written (it is filled with low states), and the
communication sequence between microcontroller and base station starts with TXCT being low for a fixed time to
initiate the charge phase. When TXCT becomes high again, the module enters the read phase and the data
transmission via the SCIO pin to the microcontroller starts.
There is another read-only mode that differs from the default mode only in the writing of the mode control register
before the start of the charge phase. The way that the mode control register is filled and the meaning of its
contents is described below.
The write-read mode starts with the programming of the mode control register. Then the charge phase starts with
TXCT being low for a fixed time. When TXCT becomes high again, the write phase begins in which the data are
transmitted from the microcontroller to the transponder via the TXCT pin, the control logic, the predrivers, and the
full bridge by amplitude modulation of 100% with a fixed delay time. After the write phase TXCT goes low again
to start another charge or program phase. When TXCT becomes high again, the read phase begins.
The contents of the mode control register define the mode and the way that the carrier frequency generated by
the frequency divider is selected in order to meet the transponder resonance frequency as good as possible.
Table 1. Mode Control Register (7-Bit Register)
BIT RESET DESCRIPTION
VALUE
NAME NO.
START_BIT Bit 0 0 START_BIT = 0 The start bit is always low and does not need to be stored.
DATA_BIT[4:1] = 0000 Microcontroller selects division factor 119
DATA_BIT1 Bit 1 0 DATA_BIT[4:1] = 1111 Division factor is adapted automatically(1)
DATA_BIT[4:1] = 0001 Microcontroller selects division factor 114
DATA_BIT2 Bit 2 0 DATA_BIT[4:1] = 0010 Microcontroller selects division factor 115
... ...
DATA_BIT3 Bit 3 0 DATA_BIT[4:1] = 0110 Microcontroller selects division factor 119
... ...
DATA_BIT4 Bit 4 0 DATA_BIT[4:1] = 1011 Microcontroller selects division factor 124
SCI_SYNC = 0 Asynchronous data transmission to the microcontroller
SCI_SYNC Bit 5 0 SCI_SYNC = 1 Synchronous data transmission to the microcontroller
RX_AFC = 0 Demodulator threshold is adapted automatically
RX_AFC Bit 6 0 RX_AFC = 1 Demodulator threshold is defined by DATA_BIT[4:1]
TEST_BIT = 0 No further test bytes
TEST_BIT Bit 7 0 TEST_BIT = 1 Further test byte follows for special test modes
(1) Only available for TMS3705A1DRG4
The TMS3705A1DRG4 can adjust the carrier frequency to the transponder resonance frequency automatically by
giving the counter state of the transponder resonance-frequency measurement directly to the frequency divider
by setting the first four bits in high state. This setting is not available for TMS3705BDRG4. The other
combinations of the first four bits allow the microcontroller to select the default carrier frequency or to use
another frequency. The division factor can be selected to be between 114 and 124.
Some bits for testability reasons can be added. The default value of these test bits for normal operation is low.
Especially the bit 7 called TEST_BIT is Low for normal operation; otherwise the base station may enter one of
the test modes.
The control logic also controls the demodulator, the SCI encoder, the diagnosis, and especially the transmission
of the diagnosis byte during the charge phase.
The state diagram in Figure 1 shows the general behavior of the state machine (note that the state blocks drawn
can contain more than one state). All given times are measured from the moment when the state is entered if not
specified otherwise.
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Test Pins
The IC has an analog test pin A_TST for the analog part of the receiver. The digital output pin D_TST is used for
testing the internal logic. Both pins need not be connected in the application.
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ABSOLUTE MAXIMUM RATINGS(1)
over operating free-air temperature range (unless otherwise noted)
VDD Supply voltage range VDD, VSS/VSSB, VDDA, VSSA –0.3 V to 7 V
VOSC Voltage range OSC1, OSC2 –0.3 V to (VDD + 0.3) V
Vinout Voltage range SCIO, TXCT, F_SEL, D_TST –0.3 V to (VDD + 0.3) V
Iinout Overload clamping current SCIO, TXCT, F_SEL, D_TST –5 mA to 5 mA
VANT Output voltage ANT1, ANT2 –0.3 V to (VDD + 0.3) V
IANT Output peak current ANT1, ANT2 –1.1 A to 1.1 A
Vanalog Voltage range SENSE, SFB, A_TST –0.3 V to (VDD + 0.3) V
ISENSE SENSE input current SENSE, SFB, A_TST –5 mA to 5 mA
ISFB Input current in case of overvoltage SFB –5 mA to 5 mA
TAOperating ambient temperature –40°C to 85°C
Tstg Storage temperature range –55°C to 150°C
RqJA Thermal resistance, junction to free air 130°C/W
PDTotal power dissipation at TA= 85°C 0.5 W
VESD ESD protection (MIL STD 883) –2000 V to 2000 V
(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS MIN NOM MAX UNIT
VDD Supply voltage VDD, VSS/VSSB, VDDA, VSSA 4.5 5 5.5 V
fosc Oscillator frequency OSC1, OSC2 4 MHz
VIH High-level input voltage F_SEL, TXCT, OSC1 0.7 VDD V
TXCT, OSC1 0.3 VDD
VIL Low-level input voltage V
F_SEL 0.2 VDD
IOH High-level output current SCIO, D_TST –1 mA
IOL Low-level output current SCIO, D_TST 1 mA
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ELECTRICAL CHARACTERISTICS
VDD = 4.5 V to 5.5 V, fosc = 4 MHz, F_SEL = high, over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Power Supply (VDD, VSS/VSSB, VDDA, VSSA)Sum of supply currents in charge phase,
IDD Supply current 8 20 mA
without antenna load
Sum of supply currents in sleep mode, without mA
ISLEEP Supply current, sleep mode 0.015 0.2
I/O currents
Oscillator (OSC1, OSC2)
gosc Transconductance fosc = 4 MHz, 0.5 Vpp at OSC1 0.5 2 5 mA/V
Cin Input capacitance at OSC1(1) 10 pF
Cout Output capacitance at OSC2(1) 10 pF
Logic Inputs (TXCT, F_SEL, OSC1) TXCT 120 500
Rpullup Pullup resistance k
F_SEL 10 500
Logic Outputs (SCIO, D_TST)
VOH High-level output voltage 0.8 VDD V
VOL Low-level output voltage 0.2 VDD V
Full-Bridge Outputs (ANT1, ANT2) Full bridge n-channel and p-channel MOSFETs
ΣRds_on Sum of drain-source resistances 7 14
at driver current Iant = 50 mA
Duty cycle p-channel MOSFETs of full bridge 38 40 42 %
Symmetry of pulse widths for the
ton1/ton2 96 104.5 %
p-channel MOSFETs of full bridge
Threshold for overcurrent
Ioc 220 1100 mA
protection
Switch-off time of overcurrent
toc Short to ground with 3 0.25 10 µs
protection
Delay for switching on the full
tdoc 2 2.05 2.1 ms
bridge after an overcurrent
Ileak Leakage current 1 µA
Analog Module (SENSE, SFB, A_TST)
ISENSE Input current SENSE, In charge phase –2 2 mA
VDCREF/ DC reference voltage of RF 9.25 10 11 %
VDD amplifier, related to VDD At 500 kHz with external components to
Gain-bandwidth product of RF
GBW achieve a voltage gain of minimum 4-mVpp and 2 MHz
amplifier 5-mVpp input signal
At 134 kHz with external components to
fOPhase shift of RF amplifier achieve a voltage gain of 5-mVpp and 20-mVpp 16 °
input signal
Peak-to-peak input voltage of band At 134 kHz (corresponds to a minimal total gain
Vsfb pass at which the limiter 5 mV
of 1000)
comparator should toggle(2)
Lower cut-off frequency of
flow 24 60 100 kHz
band-pass filter(3)
Higher cut-off frequency of
fhigh 160 270 500 kHz
band-pass filter(3)
A_TST pin used as input, D_TST pin as output,
ΔVhys Hysteresis of limiter 25 50 135 mV
Offset level determined by bandpass stage
(1) Specified by design
(2) Specified by design; functional test done for input voltage of 90 mVpp.
(3) BP filter tested at three different frequencies: fmid =134 kHz and gain > 30 db; flow = 24 kHz, fhigh = 500 kHz and attenuation < –3 dB
(reference = measured gain at fmid = 134 kHz).
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ELECTRICAL CHARACTERISTICS (continued)
VDD = 4.5 V to 5.5 V, fosc = 4 MHz, F_SEL = high, over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
Diagnosis (SENSE)
Current threshold for operating
Idiag 80 240 µA
antenna(4)
Phase-Locked Loop (D_TST)
fpll PLL frequency 15.984 16 16.0166 MHz
Δf/fpll Jitter of the PLL frequency 6 %
Power-On Reset (POR)
Vpor_r POR threshold voltage, rising VDD rising with low slope 1.9 3.5 V
Vpor_f POR threshold voltage, falling VDD falling with low slope 1.3 2.6 V
(4) Internal resistance switched on and much lower than external SENSE resistance.
SWITCHING CHARACTERISTICS
VDD = 4.5 V to 5.5 V, fosc = 4 MHz, F_SEL = high, over operating free-air temperature range (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
From start of the oscillator after
power-on or waking up until reaching
tinit min Time for TXCT high to initialize a new transmission 2 2.05 2.2 ms
the idle mode (see Figure 2,Figure 3,
Figure 4)
Delay between leaving idle mode and start of Normal operation (see Figure 2,
tdiag 2 2.12 2.2 ms
diagnosis byte at SCIO Figure 3,Figure 4)
Delay between end of charge or end of program and
tRSee Figure 2,Figure 3,Figure 4) 3 ms
start of transponder data transmit on SCIO
toff Write pulse pause See Figure 6 0.1 ms
tdwrite Signal delay on TXCT for controlling the full bridge Write mode 73 79 85 µs
tmcr NRZ bit duration for mode control register See Figure 5 121 128 135 µs
tsci NRZ bit duration on SCIO Asynchronous mode (see Figure 7) 63 64 65 µs
tdstop Low signal delay on TXCT to stop Synchronous mode 128 800 µs
tt_sync Total TXCT time for reading data on SCIO Synchronous mode (see Figure 8) 900 µs
tsync TXCT period for shifting data on SCIO Synchronous mode (seeFigure 8) 4 64 100 µs
tL_sync Low phase on TXCT Synchronous mode (see Figure 8) 2 32 tsync 2 µs
tready Data ready for output after SCIO goes high Synchronous mode (see Figure 8) 1 127 µs
12 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated
Start
byte
Diag
byte
tinit tR
tch
TxCT
tdiag
CHARGE RESPONSE
data bytes
PHASE
SCIO
Init. transmission
M.C.W.
Start
byte
Diag
byte
tinit tR
tch
TxCT
tdiag
CHARGE RESPONSE
data bytes
PHASE
SCIO
Init. transmission
M.C.W.
TMS3705
www.ti.com
11-07-22-003 SCBS881B JANUARY 2010REVISED APRIL 2010
TIMING DIAGRAMS
Figure 2. Default Mode (Read Only, No Writing Into Mode Control Register)
Figure 3. Read-Only Mode (Writing Into Mode Control Register)
Copyright © 2010, Texas Instruments Incorporated Submit Documentation Feedback 13
Start
byte
Diag
byte
tinit tR
tch
TxCT
tdiag
CHARGE WRITE RESPONSE
data bytes
PHASE
SCIO
Init. transmission
M.C.W. PROG.
tprog
tinit
TxCT
tmcr
PHASE
Init. transmission
Low
Start Bit
Bit1 Bit3 Bit4Bit2
tmcr
Test Bit
CHARGE
End transmission
Bit5 Bit6 Bit7
TXCT
PHASE
TMS3705
11-07-22-003 SCBS881B JANUARY 2010REVISED APRIL 2010
www.ti.com
TIMING DIAGRAMS (continued)
NOTE: M.C.W.: Mode control write (to write into the mode control register)
PROG.: Program phase of transponder
Figure 4. Write/Read Mode (Writing Into Mode Control Register)
Figure 5. Mode Control Write Protocol (NRZ Coding)
Figure 6. Transponder Write Protocol
14 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated
Stop
“bit”
SCIO
Byte
ready
tsync
LSB 1 2 3 4 5 6 MSB
TxCT
tready
shift data mC
reads data
tL_sync
tsync
tt_sync
TMS3705
www.ti.com
11-07-22-003 SCBS881B JANUARY 2010REVISED APRIL 2010
TIMING DIAGRAMS (continued)
Figure 7. Transmission on SCIO in Asynchronous Mode (NRZ Coding)
Figure 8. Transmission on SCIO in Synchronous Mode (NRZ Coding)
(For Diagnosis Byte and Data Bytes)
Copyright © 2010, Texas Instruments Incorporated Submit Documentation Feedback 15
TMS3705
SENSE
SFB
D_TST
A_TST
ANT1
VSSA
ANT2
VDDA VDD
OSC2
OSC1
VSS
NC
SCIO
F_SEL
TXCT
9
10
11
12
13
14
15
16
8
7
6
5
4
3
2
1
C3
C2
Q1
4 MHz
C1
C4
TXCT Input
SCIO Output
5 V
Ground
Antenna
L1
R2
R1
TMS3705
11-07-22-003 SCBS881B JANUARY 2010REVISED APRIL 2010
www.ti.com
APPLICATION INFORMATION
Application Diagram
Figure 9. Application Diagram
16 Submit Documentation Feedback Copyright © 2010, Texas Instruments Incorporated
TMS3705
www.ti.com
11-07-22-003 SCBS881B JANUARY 2010REVISED APRIL 2010
REVISION HISTORY
Revision Comments
SCBS881 Initial release
SCBS881A Add parameter values for "Full-Bridge Outputs (ANT1, ANT2)" section in Electrical Characteristics (page 10)
Add TMS3705BDRG4 orderable part number (page 1)
SCBS881B Add information specific to TMS3705B (page 7 and 8)
Copyright © 2010, Texas Instruments Incorporated Submit Documentation Feedback 17
PACKAGE OPTION ADDENDUM
www.ti.com 3-Mar-2012
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status (1) Package Type Package
Drawing Pins Package Qty Eco Plan (2) Lead/
Ball Finish MSL Peak Temp (3) Samples
(Requires Login)
TMS3705A1DRG4 NRND SOIC D 16 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-3-260C-168 HR
TMS3705BDRG4 ACTIVE SOIC D 16 2500 Green (RoHS
& no Sb/Br) CU NIPDAU Level-3-260C-168 HR
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
(3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
TMS3705A1DRG4 SOIC D 16 2500 330.0 16.4 6.5 10.3 2.1 8.0 16.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 14-Jul-2012
Pack Materials-Page 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
TMS3705A1DRG4 SOIC D 16 2500 367.0 367.0 38.0
PACKAGE MATERIALS INFORMATION
www.ti.com 14-Jul-2012
Pack Materials-Page 2
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