TIRIS RF-Module IC for Automotive
RI-RFM-006A
Reference Guide
December 1996
SCBU036
TIRIS RF-Module IC for Automotive
RI-RFM-006A
Reference Guide
Literature Number: SCBU036
December 1996
Contents
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Overview ....................................................................................................................
Features .....................................................................................................................
TIRIS™ System Configuration (Schematic Diagram)........................................................
Internal Block Diagram and Pin Assignment ..................................................................
Description of Pins ......................................................................................................
Function and Operation ...............................................................................................
4
4
4
5
6
6
6.1
General ............................................................................................................ 6
6.2
Sending Mode .................................................................................................... 7
6.3
Receiving Mode .................................................................................................. 7
Electrical Specifications............................................................................................... 9
7.1
Absolute Maximum Rating ...................................................................................... 9
7.2
Recommended Operating Conditions........................................................................ 10
Input-Output Specifications ........................................................................................ 10
8.1
Transmitter Signal I/O Timing ................................................................................. 10
8.2
Receiver Signal I/O Timing .................................................................................... 11
Dimensional Outline Drawing – 16-pin SOP ..................................................................
Applied Circuit Configuration – Example ......................................................................
Typical Transmitter Circuit Configuration .....................................................................
Typical Receiver Circuit Configuration .........................................................................
Typical Antenna Circuit Configuration .........................................................................
Precautions for Mounting and Actual Use ....................................................................
12
12
13
14
15
16
.............................................................................................
16
14.1
Power Supply Line
14.2
Wiring for Antenna Circuit ..................................................................................... 17
Package ................................................................................................................... 18
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Table of Contents
3
Reference Guide
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TIRIS RF-Module IC for Automotive
1
Overview
RI-RFM-006A is a CMOS-technology based RF-module IC which integrates all transmitter-receiver
functions required for constructing a TIRIS Read-Write System into one single chip.
RI-RFM-006A consists of a transmitter signal control logic which generates signals for transmission and
for sending the data you wrote to a remote TIRIS transponder, and a receiver amplifies and demodulates
frequency shift keyed (FSK) signals received from this transponder.
Therefore, RI-RFM-006A is beneficially usable for constructing, in particular, a compact TIRIS Read- Write
System at a reduced cost. Furthermore, demodulation of the FSK signals received in its receiver from a
remote transponder is entirely digitized; this completely eliminates the need of regulations and lessens the
number of required external parts, thus enhancing the operational reliability of the system.
2
Features
The TIRIS RF-Module IC for Automotive Application, RI-RFM-006A, provides the following features
amongst others:
• It incorporates a transmitter circuit with power selector and an open drain transmission power
predriver.
• Also incorporated are a receiver signal amplifier and a digitized FSK signal demodulator.
• I/O specifications: Conform to TIRIS standard RF-module specifications, with available signals of
TXCT–, RXDT– (1) and RXCK only.
• Operating supply voltage: 4.5 V to 5.5 V
• Operating temperature range: –40°C to 85°C
• Package: 16-pin SO package
• Structure: CMOS process
(1)
3
For RXDT– signals, this RF-module has a reverse polarity in relation to TIRIS standard RF-modules. See the section “Description of
Pins” for more information.
TIRIS™ System Configuration (Schematic Diagram)
TIRIS Read-Write System
TIRIS RF-module
Controller
TIRIS RF-Module IC for Automotive
TIRIS transponder
ASK
Serial
transmission
RI45538NS
4
Transmitter-receiver
Antenna
FSK
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Internal Block Diagram and Pin Assignment
4
Internal Block Diagram and Pin Assignment
A3OP 1
A3IN
MOS INVERTER
16 RXCK
DIGITAL
2
15 RXDT-
DEMODULATOR
A2OP 3
A2IN
MOS INVERTER
14 TXCTCONTROL
4
13 TPC
LOGIC
A1OP 5
A1IN
Name
8
12 VCC
TRANSMITTER
6
TXLO 7
TXHI
MOS INVERTER
11 GND
NCH OPEN DRAIN
PCH OPEN DRAIN
I/O Function
10 OSCO
OSCILLATOR
Name
9 OSCI
I/O Function
A3OP
CMOS INVERTER-3/FSK SIGNAL OUTPUT
OSCI
OSCILLATOR INPUT(17.1776MHz typ.)
A3IN
CMOS INVERTER-3/FSK SIGNAL INPUT
OSCO
OSCILLATOR OUTPUT
A2OP
CMOS INVERTER-2 OUTPUT
GND
GND(POWER SUPPLY)
A2IN
CMOS INVERTER-2 INPUT
VCC
VCC(POWER SUPPLY)
A1OP
CMOS INVERTER-1 OUTPUT
TPC
TX-POWER Hi/Lo SELECT SIG. INPUT
A1IN
CMOS INVERTER-1 INPUT
TXCT–
TX-OUTPUT CONTROL SIGNAL INPUT
TXLO
TX-OUTPUT(NCH OPEN DRAIN OUTPUT)
RXDT–
RX-DATA("L"="1","H"="0") OUTPUT
TXHI
TX-OUTPUT(PCH OPEN DRAIN OUTPUT)
RXCK
RX-DATA CLOCK OUTPUT
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Description of Pins
5
Description of Pins
Pin #
Signal
I/O
Description
1
A3OP
O
Signal output from CMOS inverter-3 amplifier; this pin is connected to the internal FSK
signal digital demodulator.
2
A3IN
I
Signal input to CMOS inverter-3 amplifier; if an external circuit is used to amplify FSK
signals, the amplified signals are input through this pin.
3
A2OP
O
Signal output from CMOS inverter-2 amplifier.
4
A2IN
I
Signal input to CMOS inverter-2 amplifier.
5
A1OP
O
Signal output from CMOS inverter-1 amplifier.
I 16. Signal input to CMOS inverter-1 amplifier.
6
A1IN
I
7
TXLO
Negative
open drain
output
8
TXHI
9
OSCI
I
Signal input to 17.1776 MHz master clock oscillator.
10
OSCO
O
Signal output from 17.1776 MHz master clock oscillator.
11
GND
–
Negative power supply.
12
VCC
–
Positive power supply.
13
TPC
I, w/pull-up
resistor
Input of transmission power selection signals (High-Low). A Low level signal input
through this pin substantially lowers the power during transmission
14
TXCT–
I, w/pull-up
resistor
Input of transmission output control signals (Transmit-Receive Mode Selector). A Low
level signal input through this pin outputs a transmission signal to either “TXLO/TXHI”
pin while a High level signal input turns the mode to Receive and activates the internal
FSK signal digital demodulator.
15
RXDT–
O
Serial output of demodulated FSK signal bit data. Negative level output when the bit
data received from the remote transponder is “1”, and positive level output when it is
“0”.
Note: The RI-RFM-006A has a reverse polarity in relation to TIRIS standard
RF-modules.
16
RXCK
O
Synchronous clock output of demodulated FSK signal data; a clock signal synchronized
with the “RXDT-“ signal is output.
Negative level output of transmission signals; this output drives the n-channel MOSFET
used as antenna driver.
Positive open Positive level output of transmission signals; this output drives the p-channel MOSFET
drain output used as antenna driver.
6
Function and Operation
6.1
General
This RF-module IC counts on two operating modes:
Sending Mode – This mode is active when the “TXCT–“ pin is set to L-level. A remote TIRIS
transponder can be charged up and ID code can be sent to that transponder in this mode.
Receiving Mode – This mode is active when the “TXCT–“ pin is set to H-level. FSK signals sent from a
remote TIRIS transponder are received and demodulated in this mode.
Therefore, by switching over these modes using an external controller, data communications with a TIRIS
transponder can be made.
Note that this RF-module IC is exclusively designed to provide the user with a simple signal
modulator-demodulator (modem) function for data communications with a remote TIRIS transponder,
based on the appropriate data modulation-demodulation specifications. And therefore, it does not
incorporate error detection, data allotment nor other similar data processing functions in terms of protocol
and data formats.
6
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Function and Operation
(*) In both transmit and receive modes, this RF-module IC modulates and demodulates signals by logical
operation based on the incorporated master clock. This means that the modulating-demodulating
performance characteristics of this IC are directly affected by the frequency accuracy and variation of its
master clock (normal frequency is 17.1776 MHz). Therefore, the user is requested to select an oscillating
element or an external clock which is compatible with the remote TIRIS transponder to be used (see the
section describing the specifications “fexc”, “fL” and “fH”).
6.2
Sending Mode
In the Sending Mode, the frequency of the IC master clock (normal value: 17.1776 MHz) is divided by 128.
The resulting clock signal then has a frequency of 134.2 kHz (normal value). This resulting signal is output
as a composite signal for “TXHI” and “TXLO” terminals (pins) to drive the MOSFET which is incorporated
as an antenna resonance circuit driver, as illustrated below.
RI45538NS
Master clock frequency divided by 128
(Ref. frequency, resulting: 134.2 kHz)
MOSFET(PCH)
TXLO
TXHI
7
8
"A"
MOSFET(NCH)
When the IC is in the Receiving Mode, its “TXHI” terminal is fixed at positive level and the “TXLO” at high
impedance. As a result, the output terminal “A” of the MOSFET used as an antenna resonance circuit
driver is fixed at negative level.
Note that when the IC is in the Sending Mode, its “RXDT–“ terminal is always fixed at positive level and as
a consequence, the IC’s FSK signal demodulator remains deactivated although data clock signals, which
are transmitted at a frequency resulting from division of the “A3IN” terminal signal frequency by 16, are
output to the “RXCK”.
6.3
Receiving Mode
In the Receiving Mode, the frequency-shift-keyed data signals are sequentially digitized to discriminate
their frequencies by binary notation (high-low) and demodulate them into bit strings consisting of bit data
“1” and “0”.
For binary discrimination of signal frequencies between high and low, the frequency level of each
FS-keyed signal is measured from its leading edge at the “A3OP” terminal through to the next leading
edge by count of the internal master clock, as shown below. The threshold for this counted value (x in the
diagram below) is fixed at 132; when the clock count is over 132, it results in a negative level output at the
“RXDT–“ terminal (bit data ”1”), and when the clock count does not reach 132, a positive level output at
the same terminal (bit data “0”), respectively.
Internal master clock
Signals discriminated
at A3OP terminal
Clock counts
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1
2
3
4
5
6
X-1 X
1
2
3
4
5
6
7
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Function and Operation
As the normal frequency of the internal master clock is 17.1776 MHz, one clock count is equivalent to
130.133... kHz (17.1776 MHz divided by 132 = 130.133... kHz). Accordingly, a signal is identified as bit
data “1” with the resulting negative level output at the “RXDT–“ terminal when the signal frequency at the
“A3OP” terminal is 130.133... kHz or less, and it is identified as bit data “0” with the resulting positive level
output at the “RXDT–“ terminal when the signal frequency at the “A3OP” terminal is over 130.133... kHz.
An additional feature is included to maximize the stability of the above-mentioned FSK signal
demodulating system based on binary notation: the system incorporates a circuit which disables definition
of an “RXDT–“ signal unless more than four consecutive FS-keyed signal waves are identified within the
same frequency band during binary discrimination. This protects the once defined “RXDT–“ signal in the
bit data form from being affected by sporadic events. For instance, even when its discrimination result is
sporadically inverted due to some noise effects, it is not affected if only three or less consecutive FSkeyed
signal waves are identified at the “A3OP” terminal. (See the diagram below.)
Signal discriminated
at A3OP terminal
Internal frequency
discriminating signals
RXDT- terminal
DATA VALID
DATA VALID
output signals
Note: For the timing between “A3OP” and “RXDT–“ signals, refer to the section describing “Input-Output
Specifications”.
The signals demodulated through the above-mentioned process are sequentially output from the “RXDT–“
terminal in bit strings (“1” or “0”). To delimit these continuous bit strings, clock signals are output from the
“RXCK” terminal in synchronization with each bit data.
In normal operating conditions (when data communication can be properly performed between the
RI-RFM-006A and a TIRIS transponder), each bit data group sent from the remote transponder is
composed of sixteen consecutive signal waves belonging to the same frequency band (consisting of two
wave groups, 134.2-kHz high and 123.2-kHz low in terms of normal values). Therefore, clock signals at a
frequency resulting from a simple division of the “A3OP” terminal signal frequency by 16, are output from
the “RXCK” terminal. Then, each “RXCK” clock signal is controlled for output so that its first transition falls
after four consecutive “A3OP” signal waves from the “RXDT–“ signal change point. This enables an
external controller to obtain the relevant bit data without fail provided that each “RXDT–“ signal is fetched
well timed with the first transition of each “RXCK” signal. (See the diagram below.)
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
2
3
A3OP terminal signal
One bit data group (16 waves)
RXDT- terminal output
DATA VALID
4 waves
8 waves
4 waves
RXCK terminal output
8
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Electrical Specifications
Sometimes at starting or during data receiving, some bit data group (composed of sixteen consecutive
signal waves belonging to the same frequency band) may be affected by interference noise, this causing
the number of its waves to vary and the consequent synchronous discrepancy between “RXDT–“ and
“RXCK” signals. To correct this discrepancy, the sixteenth dividing counter of frequency incorporated in
this RF-module IC for “RXCK” clock signal generation are always reset at the moment at which any
internal demodulated bit data changes from “0” to “1” so that “RXCK” terminal signals are forcibly output at
L-level with the timing shown below. This correction is made automatically regardless of whether or not
receiving signals are properly input. (The frequency dividing counter is not reset at bit data change from
“1” to “0”.)
13
14
15
16
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
1
A3OP terminal signal
RXDT- terminal output
DATA="1"
DATA="0"
Timing is controlled so that these durations are uniform
(each duration is equivalent to four A3OP terminal
RXCK terminal output
Note: For details about timing among these signals, refer to the section describing “Input- Output
Specifications”.
7
Electrical Specifications
7.1
Absolute Maximum Rating
Supply voltage
(VCC)
–0.5 to 7.0V
Input voltage range
(VI)
–0.5 to 7.0V
Output voltage range
(Vo)
–0.5 to 7.0V
Input clamping current
(Iik)
±20 mA
Output clamping current
(Vok)
±20 mA
Output current
(Iout(Vout=0 to VCC))
±25 mA
Operating temperature
(TA)
–40 to +85°C
Storage temperature
(Tstg)
–65 to +150°C
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Input-Output Specifications
7.2
Recommended Operating Conditions
7.2.1
Recommended Operating Conditions
Supply voltage, VCC
High-level input voltage, VIH
MIN
MAX
3.5
5.5
0.7 VCC
Low-level input voltage, VIL
Operating free-air temperature, TA
7.2.2
–40
UNIT
V
V
0.2 VCC
V
85
°C
Electrical Characteristics (VCC=5.0V, TA=25°C)
PARAMETER
Vth
Hysteresis voltage
IOH
High-level output current
CONDITIONS
TYP
MAX
1.7
VOH=3.7V
(TXHI)
(A2OP,A3OP)
(A1OP)
IOL
MIN
Low-level output current
VOH=0.5V
(TXLO)
(A2OP,A3OP)
(A1OP)
UNIT
V
6.8
mA
20
mA
73
µA
144
µA
–6.8
mA
–20
mA
–72
µA
µA
–144
Ci
Input capacitance
7.4
pF
ICC
Supply current
35
mA
Note: Unless otherwise specified, all the voltage values indicated above are those measured versus the
“GND” pin of this RF-module IC.
8
Input-Output Specifications
8.1
Transmitter Signal I/O Timing
TXCT-
tc(TX)
twh(TX)
tdl(TX)
twl(TX)
tdh(TX)
TX=
TXHI+TXLO
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Input-Output Specifications
ITEM
SIGNAL
MIN
TYP
MAX
UNIT
Delay time between TXCT– and TX trailing edges
tdl(TX)
64Tc(OSC)
nS
Delay time between TXCT– and TX leading edges
tdh(TX)
1Tc(OSC)
nS
TX cycle time
tc(TX)
128Tc(OSC)
nS
TX low level pulse duration
twl(TX)
64Tc(OSC)
nS
TX high level pulse duration
twh(TX)
64Tc(OSC)
nS
Note: “Tc(osc)" denotes the master clock cycle of this RF-module IC and its normal value is specified at
56.3 ns (1/0.0171776). The same applies hereinafter. “TX” is defined as a composite signal of “TXLO” and
“TXHI” signals.
8.2
Receiver Signal I/O Timing
A3OP
td(RXDT)
twh(A3OP)
tc(A3OP)
tdl(RXCK)
tdh(RXCK)
th(RXDT)
twh(RXCK)
ts(RXDT)
RXCK
tc(RXCK)
tw(RXDT)
RXDTDATA VALID
ITEM
A3OP cycle time for normal FSK signal demodulation
A3OP positive level pulse duration for normal FSK signal
demodulation
SIGNAL
MIN
tc(A3OP)
2Tc(OSC)
TYP
MAX
UNIT
nS
twh(A3OP)
1Tc(OSC)
nS
132Tc(OSC)
nS
A3OP cycle time for negative level output of RXDT–
signal (bit data “1”)
tc(A3OP)
Delay time between A3OP and RXCK leading edges
tdh(RXCK)
1Tc(OSC)
nS
Delay time between A3OP leading edge and RXCK
trailing edge
tdl(RXCK)
1Tc(OSC)
nS
RXCK cycle time
tc(RXCK)
16Tc(A3)
twh(RXCK)
8Tc(A3)
RXCK positive level pulse duration
Delay time from consecutive A3OP identical signal
waves to definition of an RXDT– signal
td(RXDT)
RXDT– positive/negative level duration, definite
tw(RXDT)
RXDT– signal setup time in relation to RXCK signal
ts(RXDT)
nS
nS
16Tc(A3)+1Tc(OSC)
16Tc(A3)
4Tc(A3)—1Tc(OSC
nS
nS
nS
)
RXDT– signal hold time in relation to RXCK signal
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th(RXDT)
4Tc(A3)–1Tc(OSC)
TIRIS RF-Module IC for Automotive
nS
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Dimensional Outline Drawing – 16-pin SOP
Note: “Tc(A3)” denotes the signal cycle at the “A3OP” terminal and the above values are based on the
condition that a bit data group composed of sixteen consecutive signal waves belonging to the same
frequency band (sent from a remote TIRIS transponder in normal operating conditions) has been
previously input; otherwise, the values shown in the table below shall apply.
ITEM
RXCK cycle time (except for normal signal receiving)
9
SIGNAL
MIN
TYP
MAX
UNIT
tc(RXCK)
9Tc(A3)
nS
RXCK positive level pulse duration (except for normal signal receiving)
twh(RXCK)
1Tc(A3)
nS
RXDT– positive/negative level duration, definite (except for normal
signal receiving)
tw(RXDT)
9Tc(A3)
nS
Dimensional Outline Drawing – 16-pin SOP
9.90~10.50
–’PˆÊ‚Í‚ ‚
16
9
(Dimensions in mm)
S57780
MA
RI45538NS
5.00~5.60 7.40~8.20
YMLLLLJ
1
8
0.81(MAX)
0.35~0.51
0.25
1.27(TYP)
0.15(TYP)
2.00(MAX)
0 - 10
0.10
10
0.55~1.05
0.05(MIN)
Applied Circuit Configuration – Example
Shown below is an example of applied circuit configuration for constructing a TIRIS Transmit-Receive
RF-module using the RI-RFM-006A. This example illustrates a simplified amplifier circuit for received
signals by eliminating a frequency band rejection filter which effectively eliminates external noises and
signals out of the frequency band of the response signals from the remote TIRIS transponder. In this
configuration, therefore, it is assumed that the available data communication distance of the system could
be easily affected by environmental conditions.
Note that this is only one of various possible applications. For more information of applied circuit
configurations, refer to the Application Handbook issued by our TIRIS Operation Dept.
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Typical Transmitter Circuit Configuration
VCC
GND
(*)
0.1uF
TXCT
RXDT
RXCK
(*)
100uF
17.1776MHz
ANTENNA
(L=48uH)
NC
16
15
14
13
12
11
10
9
2SJ182
TMS57780NS
RI45538NS
120
1
2
3
4
5
6
7
8
2SK974
1S1588
1M
68pF
120pF
1M
68pF
120pF
10K
68pF
100
1200pF
1S1588
0.01uF 0.01uF 0.01uF
* When configuring an applied circuit, take the following into account:
• Choose the capacity of a resonance capacitor for clock generator oscillator in accordance with the
oscillator characteristics.
• Define the frequency accuracy and variation of the clock generator oscillator by conversion based on
the specifications for the TIRIS transponder to be used together so that it can be within the range of
17.17248 MHz to 17.18272 MHz (standard frequency: 17.1776 MHz).
• Select the values at resonance points around 134.2 kHz for L and C of the antenna circuit,
respectively. (In the example illustrated above, the following combination is used: antenna: 48 µH;
capacitor: 0.03 µF = 0.01 µF × 3 units)
• It is desirable to use a MOSFET having a low on-state resistance for antenna driver
11
Typical Transmitter Circuit Configuration
This RF-module IC is provided with “TXHI” and “TXLO” terminals which can drive external MOSFETs for
driving the LC serial resonance antenna circuit. This resonance antenna circuit is to send 134.2-kHz
signals to the remote TIRIS transponder. Use these terminals as illustrated below.
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Typical Receiver Circuit Configuration
RI45538NS
GND
VCC
LC resonance circuit
L1
134.2KHz
T1
8
7
TXLO
TXHI
R1
Antenna
T2
C1
To receiving circuit
In this circuit configuration, by selecting a value for R1 within a range of several hundred ohms and in
accordance with the characteristics of MOSFETs (T1 and T2) and introducing the selected value, the
through current which is consumed by the MOSFETs themselves during transmission can be reduced. If
the value for R1 is too high, the on-state resistances of T1 and T2 become very high and they will have
difficulty in driving the LC resonance circuit, leading to a possible reduction of available data
communication distance. Therefore, it is recommended that the value for R1 be defined after careful
evaluation of the characteristics of T1 and T2.
L1 and C1 in the LC resonance circuit may be mutually exchanged in position without giving significant
adverse effects to the operating performance of the circuit. However, the connection as is as illustrated
above is most preferable since it reduces potential influence of high-voltage transmission signals produced
at C1 on T1 and T2, thus a higher efficiency is gained.
12
Typical Receiver Circuit Configuration
Three simple CMOS inverter type amplifiers are integrated in this RF-module IC in order to amplify the
FSK signals received from a remote TIRIS transponder up to a satisfactory logic level. The IC is designed
so as to permit their amplification factor and frequency characteristics to be selected within a certain range
by the use of appropriate external parts and/or circuits. A typical applied receiver circuit is illustrated
below.
14
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Typical Antenna Circuit Configuration
To FSK signal demodulator
2
1
A3OP
R1
3
A3IN
C2
From Antenna
RI45538NS
5
4
A2OP
R2
A2IN
C4
6
A1OP
R3
A1IN
R4
D2
C6
C1
C3
C5
D1
In general, the FSK signals sent from a remote TIRIS transponder are found within a band of 120 kHz to
140 kHz, mainly due to dispersion of workmanship during manufacture and ambient temperature
fluctuation during transmitting operation. Therefore, by damping signals that fall out of the above band
range as much as possible, noise suppression performance can be improved. In the illustrated circuit
configuration, amplifier input coupling capacitors C2, C4 and C6 are used to reduce extremely
low-frequency noise signals, and amplifier output load capacitors C1, C3 and C5 to reduce high-frequency
noises. If you desire to enhance the noise resistance of the circuit still more, it is necessary to install a
required number of external wide band amplifiers with high amplification factor and add an active band
pass filter, LC resonance circuit, etc.
D1, D2 and R4 for input into the first amplifier (A1) form a circuit to prevent high-voltage signals for power
transmission and similar signals from entering the IC, thereby keeping from occurrence of latch-up or
other adverse situations. This circuit or otherwise, an equivalent protector, must be inserted without fail.
13
Typical Antenna Circuit Configuration
The antenna circuit consisting of L and C illustrated earlier in this manual (see the section describing
“Applied Circuit Configuration – Example”) is designed to work as an LC serial resonance circuit in which
impedance drops in the presence of resonance frequencies during sending operation, and as an LC
parallel resonance circuit in which impedance increases in the presence of resonance frequencies during
receiving operation. The relationship between L and C incorporated in the resonance circuit can be
defined according to the following expression. Each value is calculated using this expression:
f (134. 2 KHz ) =
1
2 π LC
The higher the Q value (quality factor) is, the higher transmission power the antenna L obtains and also
the higher the receiving gain becomes, thus allowing the system to have a greater available data
communication distance. If, however, at switch-over from power transmission mode to the receiving mode,
damping of the power transmission signal would not be completed before the remote TIRIS transponder
sends its ID code back to the IC, the signals sent from the transponder could not be received properly.
And the higher the Q value is, the longer the decay time of this power transmission signal will be. It has
been revealed by experimental testing that an antenna with its maximum Q value of around 30 is usable in
the circuit as is as illustrated in the “Applied Circuit Configuration – Example” section. If it is desired to use
an antenna having a higher Q value, some measures must be devised and added to this circuit.
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Precautions for Mounting and Actual Use
Additionally, the characteristics and efficiency of the resonance circuit used here greatly depend not only
on the antenna L but also on the capacitor C and the MOSFETs which drive them. Therefore, the
application of the lowest possible impedance at the frequency f(134.2 kHz) to them will permit a higher
transmission power, and as a result, it will allow the system to have a greater available data
communication distance with the remote transponder.
14
Precautions for Mounting and Actual Use
Described in this section are the precautions to be taken at mounting and actual use of the RI-RFM-006A
while designing and manufacturing a TIRIS Read-Write System using this IC, especially, critical issues as
may affect the operating performance of the IC and, in particular, the system communication performance
with a remote TIRIS transponder.
14.1 Power Supply Line
When the signals returned from a remote TIRIS transponder are amplified by sequentially using the three
CMOS inverter type amplifiers incorporated in this RF-module IC, an undesirable feedback loop is formed
from the third amplifier toward the first one through parasitic L, R and C whose formation is not avoidable
because of the structure of this IC and its internal power supply line (see the diagram below) as CMOS
devices are inevitably bi-directional. If this feedback loop is left as is, it normally leads to an oscillation;
particularly, when the frequency band of each amplifier is limited so that it matches that of the transponder
return signals, oscillation occurs at a frequency within this band which counts on high gains from the very
nature of things, in consequence, adversely affecting the demodulating performance of the received FSK
signals.
Positive power supply (Vcc) line
16
15
Bypass capacitor
14
13
12
11
Internal power supply line
Feedback loop
Amplifier 3
1
2
Amplifier 1
Amplifier 2
3
4
5
6
From Antenna
Equivalent circuit for internal power supply line feedback loop
This situation does not a little occur when a multiple number of high-gain amplifiers are integrated in a
CMOS device. Formation of this undesirable feedback loop in the amplifier band can be avoided by
minimizing the impedance of the power supply line through optimization of the printed circuit boards and
using a suitable bypass capacitor. It is extremely difficult to obtain true values for these parasitic L, R and
C forming the internal power supply line feedback loop, but it can be said from the empirical viewpoint that
it is possible to inhibit the said oscillation using a bypass capacitor with a capacity of 1 µF and having a
sufficiently low impedance within the said amplifier frequency band provided that appropriate wiring
patterns are defined for the power supply line on the printed circuit boards and in the peripheries of
external parts for the amplifiers.
16
TIRIS RF-Module IC for Automotive
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Precautions for Mounting and Actual Use
14.2 Wiring for Antenna Circuit
As previously described, the FSK signals sent from a remote TIRIS transponder are normally found within
a band of 120 kHz to 140 kHz. Therefore, the signal receiving circuit of this TIRIS Transmitter- Receiver
System is designed so that the signal amplification factor is necessarily highest within this band. Because
of this, all signals and noises which are produced by other devices and whose frequencies fall within this
band greatly affect the system performance, especially, its available data communication distance with the
remote TIRIS transponder among others.
In the same way, they have quite the undesirable effect not only upon the environment in which the proper
antenna for the system is found, but also upon the wire used to connect it with the IC’s “A1IN” pin which
works as the first-phase amplifier for received signals. Furthermore, if there are wires for square or pulse
wave logic signals containing high-frequency components (even though their fundamental frequencies are
low) very close to this antenna connection wire, the system’s available data communication distance with
the remote TIRIS transponder is further shortened due to the adverse effects of such wires. For all that, if
there is no other alternative than to use a long wiring between the IC and its external antenna, it is
suggested that a shielded wire be used for antenna wiring in either way as illustrated below. With this, the
antenna wiring will be less susceptible to the aforementioned adverse effects.
RI45538NS
Antenna
TXLO
TXHI
7
8
Shielded wire
Antenna resonance capacitor
To receiver amplifier
a. When the antenna is driven first.
RI45538NS
Antenna
TXLO
TXHI
7
8
Antenna resonance capacitor
Shielded wire
To receiver amplifier
b. When the capacitor is driven first.
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Package
15
Package
50 pcs./tube
Silica gel
Antistatic finish poly bag
1,000 pcs. (20 tubes/bag)
Bar code label
Aluminum laminated case
Heat-sealed
Corrugated fiberboard case
Texas Instruments
18
TIRIS RF-Module IC for Automotive
Destination label
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