MC13173FTB [MOTOROLA]
INFRARED TRANSCEIVER; 红外收发器
| 型号： | MC13173FTB |
| 厂家： | 
MOTOROLA |
| 描述： | INFRARED TRANSCEIVER |
| 文件： | 总18页 (文件大小：340K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Order this document by MC13173/D
The MC13173 is a low power infrared integrated system (IRIS). It is a
unique blend of a split IF wideband FM receiver and a specialized infrared
LED transmitter. This device was designed to provide communications
between portable computers via a half duplex infrared link at data rates up to
200 kbps.
INFRARED
TRANSCEIVER
The receiver includes a mixer, IF amplifier and limiter and data slicer. The
IF amplifier is split to accommodate two low cost cascaded filters. The RSSI
output is derived by summing the output of both IF sections.
The transmitter section includes a frequency synthesizer, FSK modulator,
harmonic low pass filter and an IR LED driver.
SEMICONDUCTOR
TECHNICAL DATA
• Transmitter Operates in Two Modes:
– On/Off Pulsing for Remote Control
– FSK Modulation at 1.4 MHz for Data Communications
• Over 70 dB of RSSI Range
• Split IF for Improved Filtering and Extended RSSI Range
• Digitally controlled Via a Six Line Interface Bus
FTB SUFFIX
PLASTIC PACKAGE
CASE 873
32
1
(Thin QFP)
• Individual Circuit Blocks Can Be Powered Down When Not In Use for
ORDERING INFORMATION
Operating
Power Conservation
Temperature Range
Device
Package
MC13173FTB
T
A
= – 40° to +85°C
TQFP–32
Simplified Block Diagram
32 kHz
Ref
Ma
PLL
Tx
PLL
14 MHz
Ref
Data
In
IR LED
Driver
T
E
32
31
30
29
28
27
26
25
FSK
Modulator
LED Driver
Feedback
1
24
12 M
Harmonic
LPF
Master
VCO/PLL
V
Mode Select
V
2
3
4
5
23
Driver
EE3
EE1
R
22
21
20
19
Data Out
Data Slicer
V
RF In1
EE2
Mixer
Data
Slicer In
RF In2
V
Reg1
Mixer
Out
Demod
6
7
8
IF
Amplifier
Limiter
V
18 Quad Coil
CC1
V
Reg2
Carrier
17
IF In
Detect
9
10
11
12
13
14
15
16
IF
Dec1
IF
Dec2
IF
Out
V
Lim
In
Lim
Dec1
Lim
Dec2
RSSI
CC2
This device contains 914 active transistors.
Motorola, Inc. 1996
Rev 0
MC13173
MAXIMUM RATINGS
Rating
Symbol
V – V
CC
Value
6.0
Unit
Vdc
°C
Power Supply Voltage
Junction Temperature
Storage Temperature
EE
T
J
150
T
stg
– 55 to +150
°C
NOTE: Devices should not be operated at or outside these values. The “Recommended Operating
Conditions” table provides for actual device operation.
RECOMMENDED OPERATING CONDITIONS
Characteristic
Power Supply Voltage
Ambient Temperature Range
Symbol
– V
Value
Unit
Vdc
°C
V
2.7 to 5.5
– 40 to +85
CC
EE
T
A
DC ELECTRICAL CHARACTERISTICS (T = +25°C, V
unless otherwise noted.)
= 3.3 Vdc, f = 32.768 kHz. Measured using test circuit in Figure 1,
REF
A
CC
Characteristic
Pin
7, 12
Symbol
Min
Typ
Max
Unit
Supply Current (See Table 2)
Control Pin
Logic State
I
CC
T
R
1
0
0
0
E
Receive Mode
Communications Mode
A/V Mode
0
1
1
0
0
0
1
0
–
–
–
–
6.5
4.75
1.5
9.0
8.0
–
mA
Standby Mode
<10
–
nA
Master PLL Charge Current
DATA SLICER
31
I
–
±25
–
µA
MA
Data Slicer Threshold Voltage
Maximum Pull–Down Current
CARRIER DETECT
20
22
V
0.85
1.0
1.1
1.8
1.4
–
Vdc
mA
TH1
I
DS
Carrier Detect Threshold Voltage
Maximum Pull–Down Current
TRANSMITTER
16
17
V
I
1.0
1.1
1.15
3.0
1.3
–
Vdc
mA
TH2
CD
Maximum Pull–Up Current
Maximum Pull–Down Current
DC Output Voltage
25
25
24
30
I
5.8
–
7.0
150
200
±25
–
700
–
mA
µA
OH
I
OL
V
–
mV
µA
O
Transmit PLL Charge Current
I
–
–
TX
AC ELECTRICAL CHARACTERISTICS (T = +25°C, V
Figure 1, unless otherwise noted.)
= 3.3 Vdc, f
= 32.768 kHz. Measured using test circuit in
A
CC
REF
Characteristic
Pin
Symbol
Min
Typ
Max
Unit
TRANSMITTER
Upper Sideband Frequency (Mark)
Lower Sideband Frequency (Space)
Upper and Lower Sideband Amplitude
RECEIVER
24
24
24
f
–
–
1.427
1.317
54
–
–
MHz
MHz
HI
f
LO
V
40
70
mVrms
SB
Receiver Sensitivity – 12 dB SINAD
MIXER
4, 19
V
SIN
–
5.0
–
µV
Mixer Conversion Gain
Mixer Output Impedance
4, 5, 6
6
AV
–
–
23.5
330
–
–
dB
(Mix)
Z
Ω
O
2
MOTOROLA ANALOG IC DEVICE DATA
MC13173
AC ELECTRICAL CHARACTERISTICS (continued) (T = +25°C, V
Figure 1, unless otherwise noted.)
= 3.3 Vdc, f
= 32.768 kHz. Measured using test circuit in
REF
A
CC
Characteristic
Pin
Symbol
Min
Typ
Max
Unit
IF AMPLIFIER
IF Amplifier Gain
8, 11
16
8
–
–
–
–
–
–
–
–
54
275
330
330
20
–
–
–
–
–
–
dB
nA/dB
Ω
IF Amplifier RSSI Slope
Input Impedance
Z
IN
Output Impedance
RSSI Current Range
RSSI Dynamic Range
LIMITING AMPLIFIER
Input Impedance
11
Z
O
Ω
16
16
–
µA
–
70
dB
13
16
16
16
Z
IN
–
–
–
–
330
360
20
–
–
–
–
Ω
nA/dB
µA
Limiter RSSI Slope
RSSI Current Range
RSSI Dynamic Range
–
–
–
58
dB
Figure 1. Test Circuit
MC33202
V
CC
V
CC
10 k
127 k
0.1
0.001
100 k
µF
100 k
10 k
10 k
µ
F
200 k 100 p
V
EE
100 nF
V
CC
100 k
100 k
24.9 k
V
CC
20 p
V
– 1V
100 p
CC
V
– 1V
CC
10 nF
36 k
10 k
V
V
CC
CC
V
V
CC
CC
100 p
10 p
V
CC
V
V
CC
0.3
µH
MV209
CC
50
0.001
µ
F
0.1
µ
H
100 pF
0.1
µF
V
CC
MV209
V
2N2222A
10 k
CC
32
25
0.001
µF
1
24
100 n
V
CC
0.1
100
µ
F
V
0.1
µH
V
CC
V
CC
V
+
EE
10 k
10 k
V
EE
µF
CC
33
200
100 n
V
MC13173
EE
LPF
ATTEN
10 k
V
CC
F1
0.1
µ
F
6.81 k
150 p
V
CC
V
EE
8
17
V
CC
9
16
0.1
µF
330
Ω
50Ω
100 n
1.0 n
1.0
µH
V
CC
100 n
1.0 n
V
V
CC
CC
1.0 n
0.1
µ
F
1.0 n
0.1
µ
F
V
V
CC
CC
330
Ω
50Ω
V
V
CC
CC
3
MOTOROLA ANALOG IC DEVICE DATA
MC13173
CIRCUIT DESCRIPTION
General
The MC13173 infrared transceiver integrates a split IF
exchange of data between portable computers. In this mode
it is capable of 200 kbps half duplex FSK operation.
The transmitter can also operate in an “A/V” Mode, which
pulses the LED on and off with no carrier. (See Figure 11).
wideband FM receiver and an IR LED transmitter into a single
IC. The transmitter is comprised of an FSK modulator,
harmonic low pass filter, and IR LED driver. The receiver
consists of a mixer, IF amplifier and limiting IF, detector, and
data slicer. It includes RSSI and carrier detect functions.
The transmitter is capable of two modes of operation. It
was primarily designed for use in the Communications Mode,
which enables point–to–point data links, such as the
communication from keyboard to computer, or for the
Digital Interface Bus
The MC13173 is controlled via a six line 3.3 V digital
interface bus. That includes three control pins, data in and
out pins, and a carrier detect pin. Listed below is a brief
description of each pin and its function.
Table 1. Digital Interface Pin Descriptions
Pin
Pin Name
Transmit Enable
Symbol
I/O
Description
28
T
I
High – Transmitter is enabled
Low – Transmitter is disabled
27
3
Data In
DI
R
I
I
Data Input – 38.2 kbps
Communication Mode
Receive Enable
High – Receiver is enabled
Low – Receiver is disabled
22
17
Data Out
DO
CD
O
O
Demodulated Output Signal
Carrier Detect
High – Carrier is present
Low – Carrier is not present
26
Transmit Modulation Enable
E
I
High – Transmitter is in A/V Mode
Low – Transmitter is in
Communications Mode
This transceiver was designed for use in battery powered,
hand–held consumer products. To minimize power
consumption, the digital interface enables individual system
blocks to be powered down while not in use. The following
diagram shows the mode of the IC and the power state of
each circuit block for a given set of control levels.
Table 2. Power State Table
Control
Pins*
Circuit Block Power States
(See Figures 2 and 3)
Supply
Master
VCO
FSK
Modulator
LED
Driver
Current
(Typical)
T
0
0
0
1
1
1
1
R
0
0
1
1
1
0
0
E
0
1
X
1
0
0
1
Mode
Receiver
Off
OFF
Off
Off
On
On
On
On
Off
Off
Off
Off
Off
On
On
Off
Off
Off
Off
On
On
On
On
10 nA
70 µA
OFF
Off
Receive
Receive
On
6.5 mA
7.5 mA
9.0 mA
4.75 mA
1.5 mA
On
Transmit – Comm Mode
Transmit – Comm Mode
Transmit – A/V Mode
On
Off
Off
* With Data In Pin Low
4
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Master VCO/PLL
The master VCO provides the reference frequency for the
FSK modulator and the LO frequency for the receiver
downconverter. With a 32.768 kHz input frequency to the
master VCO on Pin 1, the LO frequency for the receiver will
be at 12.075 MHz. The reference frequency for the FSK
modulator will be at approximately 1.1 MHz. The master VCO
and FSK modulator are not used when the transmitter is used
in A/V mode, and both are powered down.
carrier detect output will go high. A large resistor may be
added externally between the comparator output and the
positive input for hysteresis.
Quadrature Detector
The demodulator is a conventional quadrature type with
an external LC tank driven through an internal 5 pF capacitor.
The output is buffered to give an output impedance of less
than 1.0 kΩ at an average DC level of around 1.1 V.
Receiver Description
Data Slicer
The single conversion receiver portion of the MC13173 is
low power and wideband, and incorporates a split IF. This
section includes a mixer, IF amplifier, limiting IF, quadrature
detector and data slicer.
The data slicer is designed to square up the data signal. It
is self centering at about 1.1 V, and clips at about 0.75 V and
1.45 V. There is a short time constant for large peak–to–peak
voltage swings or when there is a change in DC level at the
detector output. The time constant is longer for small signals
or for continuous bits of the same polarity which drift close to
the threshold voltage.
Mixer
The mixer is a double balanced four quadrant multiplier. It
can be driven either differentially or single–ended by
connecting the unused input to the positive supply rail.
The buffered output is internally loaded for an output
impedance of 330 Ω for use with a standard ceramic filter.
Transmission Description
The MC13173 uses a dual modulus PLL to frequency shift
key (FSK) modulate the baseband digital input signal,
producing the necessary logic high and low frequencies for
transmission. The transmit frequency for a logic high is
1.427 MHz, and the frequency for a low is 1.317 MHz with a
32.768 kHz reference frequency.
IF Amplifier
The first IF amplifier section is composed of three
differential stages with the second and third stages
contributing to the RSSI. This section has internal DC
feedback and external input decoupling for improved
symmetry and stability. The total gain of the IF amplifier block
is approximately 40 dB. The fixed internal input impedance is
330 Ω for use with a 10.7 MHz ceramic filter. The output of the
IF amplifier is buffered and the impedance is 330 Ω.
FSK Modulator
In the communications mode, the FSK modulator uses the
reference frequency from the Master VCO to produce the two
frequencies required for a logic high and a logic low. In the
A/V mode, the FSK modulator is not used and is powered
down.
Limiter
The limiter section is similar to the IF amplifier section,
except that four stages are used with the last three
contributing to the RSSI. This IF limiting amplifier section
drives the quadrature detector internally.
LED Driver Stage
A low pass filter following the FSK modulator removes the
undesired harmonic frequencies from the square–wave
output of the divider circuits in PLLs. The resulting sinusoidal
waveforms are fed into a unity gain difference amplifier,
which drives the base of an external transistor, modulating
the IR LED.
RSSI/Carrier Detect
The received signal strength indicator (RSSI) outputs a
current proportional to the log of the received signal
amplitude. The RSSI current output is derived by summing
the currents from the IF and limiting amplifier stages. An
external resistor sets the output voltage range.
In A/V mode, the data is input directly into the inverting
input of the op amp, and the low pass filter is not used.
The carrier detect threshold is set at approximately
1.2 Vdc. When the RSSI level exceeds that threshold, the
5
MOTOROLA ANALOG IC DEVICE DATA
MC13173
DOCUMENT CONTAINS SCANNED IMAGES WHICH
COULD NOT BE PROCESSED FOR PDF FILES. FOR
COMPLETE DOCUMENT WITH IMAGES PLEASE
ORDER FROM MFAX OR THE LITERATURE
DISTRIBUTION CENTER
6
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Figure 2. Transmitter Block Diagram
V
CC
f
R
V
CC
PFD/
Charge
Pump
PFD/
Charge
÷
2
Pump
LED Driver
Stage
f
f
M1
M2
FSK
Modulator
Harmonic
LED
Driver
Master
VCO
LPF
÷
÷
67
11
÷
÷
12
13
÷
10
f
LO
V
CC
Data In
(Comm Mode)
Data In
(A/V Mode)
f
f
= 32.768 kHz
R
67 X 11
2
=
f
R
LO
13
11 X 10
Data High: f
=
f
LO
M1
12
11 X 10
Data Low: f
=
f
LO
M2
Figure 3. Receiver Block Diagram
f
R
2
PFD/
Charge
Pump
÷
Master
VCO
Receiver
V
Reg1
f
LO
÷
11
÷ 67
Carrier
Detect
RSSI
V
V
CC
Reg2
IF
Amplifier
Limiter
Mixer
Detector
Data
Output
RF
Input
V
CC
7
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Table 3. PIN FUNCTION DESCRIPTION (T = 25°C, V
= 5.0 Vdc, f
REF
= 32.768 kHz, f
= 32.768 kHz)
MOD
A
CC
Internal Equivalent
Circuit
Pin Symbol
Description
Waveform
1
12 M
VCO for Master PLL.
V
CC
(Measured using a
low capacitance FET
probe. Standard
oscilloscope probes
can pull oscillator off
frequency. See
1
Figure 14.)
V
EE
2,
21,
23
V
EE
DC ground. Should be
connected to a
continuous ground
plane on the PCB.
3
R
Receive Enable Pin.
See Tables 1 & 2.
V
4, 5
RF In1
RF In2
RF Input to the mixer.
1.375 MHz average
carrier frequency with
± 50 kHz deviation.
CC
4
5
V
EE
6
Mixer
Out
10.7 MHz IF
V
CC
Z
O
= 330 Ω
RF In = – 20 dBm
Modulation =
32.768 kHz
6
V
EE
7,
12
V
CC
Supply voltage and
RF ground, should be
decoupled to V
.
EE
V
8
IF In
IF input impedance is
330 Ω.
CC
RF In = – 20 dBm
Modulation =
32.768 kHz
10
8
9
V
EE
8
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Table 3. PIN FUNCTION DESCRIPTION (continued) (T = 25°C, V
= 5.0 Vdc, f
REF
= 32.768 kHz, f
= 32.768 kHz)
A
CC
MOD
Internal Equivalent
Circuit
Pin Symbol
Description
Waveform
9,
10
IF Dec
IF decoupling as
shown in Figure 15.
See Circuit for Pin 8.
11
IF Out
IF Output.
V
CC
Z
O
= 330 Ω.
–20 dBm RF input
level. Output is
sinusoidal with lower
drive levels.
11
V
EE
13
Lim In
Limiter input.
V
CC
Z
In
= 330 Ω.
15
13
14
14, Lim Dec
15
External limiter
decoupling as shown
in application circuit.
V
EE
16
17
RSSI
Received Signal
Strength Indicator
Output. (See
Figure 13)
17
Carrier
Detect
Logic output of the
carrier detect
comparator.
V
EE
18
18
Quad
Coil
Quadrature tuning
circuit.
V
CC
Modulated 10.7 MHz
IF.
5 p
Measured with a low
capacitance FET
probe.
V
EE
19
Demod
Demodulated signal
output measured at
the pin (before
filtering).
V
CC
Modulation =
32.768 kHz
sine wave.
19
V
EE
9
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Table 3. PIN FUNCTION DESCRIPTION (continued) (T = 25°C, V
= 5.0 Vdc, f
REF
= 32.768 kHz, f
= 32.768 kHz)
A
CC
MOD
Internal Equivalent
Circuit
Pin Symbol
Description
Waveform
20
Data
Slicer In
Input from the
receiver demodulated
output.
22
Data
Out
Output from the
receiver data slicer.
Modulation =
32.768 kHz
sine wave.
RF input driven by
frequency generator.
See also Figure 10.
24
25
LED
Driver
Feed-
back
Feedback for the LED
driver op amp.
IR LED
Driver
Output of the unity
gain output buffer in
Communications
Mode. See Figure 11
for transmit output in
A/V mode.
V
CC
24
Modulation =
32.768 kHz
square wave.
25
25 k
.
V
EE
26
E
Transmit Modulation
Enable.
See Tables 1 & 2.
27
28
29
Data In
T
Modulation input for
transmit data.
Transmit Enable pin.
See Tables 1 & 2.
14 MHz
Ref
VCO for FSK
Modulator phase
locked loop.
V
CC
(Measured using a
low capacitance FET
probe. Standard
oscilloscope probes
can pull oscillator off
frequency. See
29
Figure 14.)
No modulation
(Data In low).
V
EE
10
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Table 3. PIN FUNCTION DESCRIPTION (continued) (T = 25°C, V
= 5.0 Vdc, f
REF
= 32.768 kHz, f
= 32.768 kHz)
A
CC
MOD
Internal Equivalent
Circuit
Pin Symbol
Description
Waveform
Phase detector output
for the FSK Modulator.
30
Tx PLL
(With loop closed and
locked.)
No modulation
(Data In low).
V
CC
30
With 32.768 kHz
square wave
modulation.
V
EE
Note: Probing the
output of the phase
detectors directly may
disturb the loop. It is
best to probe the
output of the op amp
when evaluating loop
response.
31
Ma PLL
Output of the phase
detector charge pump
for the Master PLL.
V
CC
(With loop closed and
locked.)
31
V
EE
32
32 kHz
Ref
Input to 32.768 kHz
reference. Filtered
from TTL oscillator
using application
V
CC
circuit in Figure 15.
Approximately
1.0 Vp–p triangle
wave at 32.768 kHz.
32
V
EE
11
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Typical Performance Over Temperature
(Measured using test circuit in Figure 1)
Figure 5. Normalized IF Amp Gain
versus Temperature
Figure 4. Normalized Mixer Gain
versus Temperature
1.0
0.5
1.0
0.5
0
0
–0.5
–0.5
–1.0
–1.0
– 50
0
50
100
100
100
– 50
0
50
100
100
100
T , AMBIENT TEMPERATURE (
°
C)
T , AMBIENT TEMPERATURE (°C)
A
A
Figure 6. Maximum Pull–Up Current
versus Temperature (Pin 25)
Figure 7. Maximum Pull–Down Current
versus Temperature (Pin 25)
7.0
6.5
6.0
5.5
140
130
120
110
100
90
80
70
60
– 50
0
50
– 50
0
50
T , AMBIENT TEMPERATURE (
°C)
T , AMBIENT TEMPERATURE (°C)
A
A
Figure 9. Data Slicer and Carrier Detect
Threshold Voltages versus Temperature
Figure 8. Supply Current
versus Temperature
– 4.5
– 5.0
– 5.5
– 6.0
– 6.5
–7.0
1.5
Transmit Communications Mode
1.25
1.0
Carrier Detect
Data Slicer
Receive Mode
0.75
– 50
0
50
– 50
0
50
T , AMBIENT TEMPERATURE (
°C)
T , AMBIENT TEMPERATURE (°C)
A
A
12
MOTOROLA ANALOG IC DEVICE DATA
MC13173
APPLICATIONS INFORMATION
loop. Although the FSK Modulator loop is dependent on the
The MC13173 transceiver is specially designed to operate
from a 32.768 kHz reference which is readily available in
most computer applications. The frequency synthesizer on
chip generates a receiver local oscillator frequency and the
transmit mark and space frequencies from this fixed
reference frequency, eliminating the need for additional
crystals or manual tuning.
Master VCO, the Master VCO is completely independent of
the FSK Modulator. In fact, the FSK Modulator can be
powered down (see Table 2) without affecting the Master
VCO operation. In the application circuit in Figure 15 a single
reference voltage for both op amps in the loop filters is
provided by two diodes to V . If the Master VCO is affected
CC
by the FSK Modulator loop, this generally indicates a problem
with the common reference voltage to the op amp, and may
mean the diodes are in backwards.
Once the loops are closed you should see a phase
detector output such as is shown in the Pin Function
Description in Table 3. If the VCO was on frequency when the
loop was open, the phase detector outputs should swing
around mid supply and not hit against either the positive or
Large divide ratios are needed to generate these
frequencies, however. For example, the receiver LO
frequency is 368.5 times the 32.768 kHz reference
frequency. This requires that the reference frequency be both
accurate and stable. A two percent error in the reference
frequency would pull the LO off frequency by over 240 kHz,
putting the IF frequency out of the usable bandwidth of the
filters and discriminator. For this reason, a 32.768 kHz
oscillator circuit has been included on the demonstration
board design. Although TTL crystal oscillators are available,
this oscillator circuit uses an inexpensive tuning fork crystal
and a hex inverter to generate a square wave reference
frequency, which is then filtered and level adjusted to a
1.0 Vp–p triangle wave to drive pin 32. A TTL Clock Oscillator
could also be used with the filter circuit as shown.
negative rail. Latching to V
filter circuitry is not implemented correctly.
or V
may indicate the loop
CC
EE
Due to the digital design of the phase detectors, the
transmitter can only transition between mark and space
frequencies on a clock edge. On the receive side this may be
seen as a double image on the detector output, with a
discrete time delay which does not vary with the frequency of
the data input (see Figure 10). This is a normal consequence
of using a digital phase detector and should not be confused
with jitter from the data slicer.
Frequency Synthesizer
The recommended op amp for the external loop filter is the
MC33202. For low voltage operation, (V
≤ 3.3 V) an op
CC
amp that is rail–to–rail on both the input and output is
advisable to obtain the widest possible output voltage range
without distortion. Sufficient distortion from the op amp such
as phase reversal on the output caused by overdriving the
inputs could prevent the loop from locking to the reference.
In debugging the loop filter, it is important to note that the
FSK Modulator phase locked loop will not lock until the
Master VCO is locked to the reference. If the application
circuit in Figure 15 is used, both loops should lock without the
need for any additional tweaking. Since the VCO has
±2.0 MHz of range using the MV209 varactor diode (see
Figure 11), neither precision components nor tuning should
be required. To ensure both loops are operating properly, first
evaluate each VCO with the loop open and a voltage equal to
Figure 10. Receive Data Output
(Data Transmitted from Companion MC13173)
V
/2 applied to the resistor in series with the varactor. Since
CC
there is a relatively small capacitance (<40 pF) in series with
the LC tank circuit, the VCO pin is sensitive to any parasitic
capacitance. Thus when using a standard oscilloscope probe
having 10 to 20 pF capacitance it is difficult to measure the
VCO frequency without shifting its frequency. A low
capacitance FET probe used with a frequency counter will
enable you to accurately measure the VCO frequency
without altering it in the process.
The free running frequency of the VCO should be
approximately on frequency when the loop is open and the
varactor is biased at mid–supply. The VCO for the Master
PLL should run at 12.05 MHz. The free running frequency of
the FSK Modulator should be at 13.72 MHz, midway between
the two VCO frequencies needed to generate the transmit
mark and space frequencies. The FSK Modulator loop is only
active when the transmitter is enabled and the device is in the
communications mode (see Tables 1 & 2). If either the “T”
pin is low or the “E” pin is high, the VCO will be off and
you will see no oscillation on Pin 29.
Transmitter
The light emitting diode (LED) driver in the transmitter is
capable of 6.0 to 10 mA of pull–up current. Selection of the
external transistor and biasing resistor will depend on the
LEDs used. Typical infrared LEDs require 50 to 100 mA of
current and have a forward voltage of 1.5V. Sufficient current
is needed to obtain the maximum power output without
distorting the output by overdriving the LED. Key
specifications include rise and fall time, wavelength, beam
width (generally given in half–angle), maximum power output
and efficiency. Choice of wavelengths is generally
determined by cost and power efficiency, which may vary
between vendors. The LEDs used in this application are at
880 nm and were chosen for best efficiency. However LEDs
in general are very inefficient, converting only 1 or 2 percent
of the electrical power into optical power. Multiple LEDs can
be used to increase transceiver range.
Once the loops are closed, the VCO frequencies should
track the reference frequency within the hold–in range of the
13
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Disabling the transmitter via the data bus turns off the
harmonics. In the application circuit in Figure 15, Toko filters
with a bandwidth of 330 kHz or 360 kHz are recommended to
accommodate higher data rates. If the IF filters are too
narrow, the recovered signal may have noise on the peaks
(see Figure 12).
output of the LED driver, removing the base current from the
external transistor and thereby turning off the IR LED.
Because of the high current drawn by the LED, this offers
considerable power savings when the transmitter is not in
use and can be easily controlled by a microcontroller with no
additional circuitry.
Figure 12. Receive Data Output
In the “A/V” transmit mode, the data output is on/off keyed,
with the LED on for a data high, and off for a data low. It is a
baseband signal, with no carrier present (see Figure 11).
Figure 11. LED Driver Output in A/V Mode
The RSSI has over 70 dB of dynamic range and 20 µA of
current range. The RSSI output provides the input to the
carrier detect comparator (see Figure 13) and a logarithmic
output proportional to the input signal level. It can, therefore,
be used to recover amplitude shift keyed (ASK) data.
The key specifications for the infrared detectors are
response time, sensitivity, acceptance angle, and
wavelength. Some vendors offer detectors in a black
package with a built–in daylight filter. Although the
transparent packages offer better sensitivity, the detectors
with the daylight filter offer a much better signal to noise ratio.
Response time (or maximum frequency) of the system is
generally limited by the capability of the emitters rather than
the detectors. For this application, a rise and fall time of
500 ns is sufficient.
Receiver
The receiver portion of the MC13173 is similar to the
design of Motorola’s MC13156 Wideband FM Receiver.
Instead of using the mixer to downconvert from a higher RF
frequency, this application is designed to upconvert the
1.372 MHz input to a 10.7 MHz IF. The wide deviation,
relative to the RF input frequency, requires a low Q tuned
circuit to recover this bandwidth:
f
c
Q
, where f
1.372 MHz
c
BW
3 dB
Design and Layout Considerations
By Carson’s Rule, the BW = 2(fdev + fmod). Since for
mark/space frequencies of 1.317 MHz and 1.427 MHz the
deviation is fixed at ±50 kHz, the bandwidth for a 50 kHz
square wave (100 kbps) would be 200 kHz, and the tuned
input requires a Q of less than 7. The low Q of the tank circuit
reduces both the selectivity and the sensitivity of the receiver.
For a Q of 7, the resistor required across the 56 µH inductor
can be calculated:
Although the frequencies in this design are low by RF
standards, careful layout and good decoupling are still good
practice. The high gain limiter and IF blocks should be
decoupled as shown in the application circuit as near the IC
as possible for best receiver performance. Also the TTL
levels from the reference oscillator and the wide current
swing applied to the IR LEDs can easily be picked up on V
,
CC
creating problems for the sensitive phase detector circuits
and receiver RF inputs. Avoid long parallel traces and use
plenty of decoupling to keep the supply rail clean.
R = QX = (7) • (2π) • (1.372 E6) • (56 E–6)
L
R = 3.3 kΩ
The 10.7 MHz ceramic filters also need to be wide enough
to pass the full frequency range which will include some
14
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Typical Performance
(Measured using Application Circuit in Figure 15)
Figure 14. VCO Frequency versus
Varactor Voltage
Figure 13. RSSI Output Current versus
RF Input Level
30
25
20
15
10
5.0
16
15
14
13
12
11
FSK Modulator
Master PLL
10
9.0
– 140 –120
– 100
– 80
– 60
– 40
– 20
0
20
– 0.5
0
0.5
1.0
1.5
2.0
2.5
3.00
3.5
RF INPUT LEVEL (dBm)
VARACTOR VOLTAGE (V)
Figure 15. Application Circuit
MC33202
V
CC
V
V
CC
CC
110 k 10 nF
1.0 nF
100 k
110 k
1.0 nF
2.0 M
220 k
V
X1
CC
1.0
V
EE
100 k
24 k
µ
10 k
100 nF
+
24 k
V
CC
10 k
220 k
100
1.0 k
10 nF
µ
H
1N4001
MC74HCU04
(See
Note 6)
CC
V
10
+
µ
CC
V
CC
V
V
CC
10 p
100 nF
3.9
1.0 n
MV209
µ
H
20 k
20 k
270 p
470 p
V
V
CC
CC
10 k
SFH484–2
V
200 p
CC
10 k
36 k
SFH485–2
MPS3904
V
V
CC
CC
62 k
+
0.68
4.7
µ
32
25
µ
F
H
MV209
1
24
V
V
CC CC
10 (See
Note 5)
100 n
V
CC
V
CC
3.0 k
10 k
V
CC
10 k
10 k
V
CC
1.0
100 n
100 p
µ
F
100 n
2.2 M
33 n
390 p
220 p
2.2 k
MC13173
82
8.2 k
3.6 k
µ
H
15 k
SFH206K
56
10 k
MPF102
V
CC
33 n
8
17
110 k
V
CC
F1
180 p
2.0 k
150 p
1.5
µ
H
9
16
510
V
CC
100 n
µ
V
CC
100 n
V
CC
2.2 n
F2
NOTES:
1) F1 & F2 – 10.7 MHz ceramic filter, Toko 107MA–AE–10
(360 kHz), Toko 107M0 AE–10 (330 kHz) or equivalent.
2) Tunable shielded inductors:
0.01
47 k
1.0 n
1.0 n
1.0 n
1.0 n
µ
F
56 µH Toko A119ANS–T1042Z
82 µH Toko A119ANS–T1044Z
1.0 µH Toko 292KNS–T1372Z
1.5 µH Toko 292KNS–T1373Z
V
CC
3) Crystal – 32.768 kHz C – Type tuning fork crystal. Digikey
part number SE3201 or equivalent.
4) LEDs and Detectors SFH484–2, SFH485–2 and SFH206K
are made by Siemens.
5) Optimum bias resistor depends on the LEDs used.
6) May be fixed or tunable.
15
MOTOROLA ANALOG IC DEVICE DATA
MC13173
Figure 16. Detailed Internal Block Diagram
32K
32
12M
1
D
27
E
26
MaPLL 31
2 V
3 R
EE1
4 RF
5 RF
in1
in2
6 MIX
out
7 V
CC1
8 IF
9 IF
in
dec1
10 IF
dec2
TxPLL 30
11 IF
out
12 V
CC2
13 LIM
14 LIM
15 LIM
in
dec1
dec2
16 RSSI
LED Feedback 24
LED Driver 25
T 28
17 Carrier Detect
14M 29
18 Quad Coil
19 Demod
20 DS
in
21 V
EE2
22 DATA
out
23 V
EE3
16
MOTOROLA ANALOG IC DEVICE DATA
MC13173
OUTLINE DIMENSIONS
FTB SUFFIX
PLASTIC TQFP PACKAGE
CASE 873–01
L
24
17
16
25
–B–
B
–A–
L
V
B
B
DETAIL A
32
9
P
1
8
–D–
A
–A–,–B–,–D–
M
S
S
S
S
0.20 (0.008)
A–B
A–B
D
D
C
H
DETAIL A
0.05 (0.002) A–B
S
F
BASE METAL
M
0.20 (0.008)
DETAIL C
M
J
N
E
C
DATUM
PLANE
–H–
D
–C–
M
S
S
0.20 (0.008)
C
A–B
D
0.01 (0.004)
H
M
SEATING
G
PLANE
SECTION B–B
VIEW ROTATED 90° CLOCKWISE
MILLIMETERS
MIN MAX
6.95
6.95
1.40
INCHES
NOTES:
DIM
A
B
C
D
E
MIN
MAX
0.280
0.280
0.063
0.015
0.059
—
U
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
7.10 0.274
7.10 0.274
1.60 0.055
0.373 0.010
1.50 0.051
2. CONTROLLING DIMENSION: MILLIMETER.
3. DATUM PLANE –H– IS LOCATED AT BOTTOM OF
LEAD AND IS COINCIDENT WITH THE LEAD WHERE
THE LEAD EXITS THE PLASTIC BODY AT THE
BOTTOM OF THE PARTING LINE.
4. DATUMS –A–, –B– AND –D– TO BE DETERMINED AT
DATUM PLANE –H–.
0.273
1.30
T
F
0.273
—
0.010
0.80 BSC
0.031 BSC
G
H
J
K
L
M
N
P
Q
R
S
T
U
V
R
–H–
DATUM
PLANE
—
0.20
—
0.008
0.008
0.022
0.119
0.33
0.197 0.005
0.57 0.013
5. DIMENSIONS S AND V TO BE DETERMINED AT
SEATING PLANE –C–.
5.6 REF
0.220 REF
6. DIMENSIONS A AND B DO NOT INCLUDE MOLD
PROTRUSION. ALLOWABLE PROTRUSION IS 0.25
(0.010) PER SIDE. DIMENSIONS A AND B DO
INCLUDE MOLD MISMATCH AND ARE DETERMINED
AT DATUM PLANE –H–.
7. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR PROTRUSION
SHALL BE 0.08 (0.003) TOTAL IN EXCESS OF THE D
DIMENSION AT MAXIMUM MATERIAL CONDITION.
DAMBAR CANNOT BE LOCATED ON THE LOWER
RADIUS OR THE FOOT.
6°
8°
6
°
8
°
K
0.119
0.40 BSC
10
0.135 0.005
0.016 BSC
10
0.005
Q
5°
°
5
°
°
X
0.15
8.85
0.15
0.25 0.006
9.15 0.348
0.25 0.006
0.010
0.360
0.010
DETAIL C
5
8.85
°
11
9.15 0.348
1.0 REF 0.039 REF
°
5
°
11
°
0.360
X
17
MOTOROLA ANALOG IC DEVICE DATA
MC13173
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the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and
specificallydisclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be provided in Motorola
datasheetsand/orspecificationscananddovaryindifferentapplicationsandactualperformancemayvaryovertime. Alloperatingparameters,including“Typicals”
must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of
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