MICRF022BM-SW48 [MICREL]
300-440MHz QwikRadio⑩ASK Receiver; 300-440MHz QwikRadio系列™ ASK接收器
| 型号： | MICRF022BM-SW48 |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 300-440MHz QwikRadio⑩ASK Receiver |
| 文件： | 总16页 (文件大小：180K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
MICRF002/RF022
300-440MHz QwikRadio™ASK Receiver
Final Information
General Description
The MICRF002 is a single chip ASK/OOK (ON-OFF Keyed)
RF receiver IC. This device is a true “antenna-in to data-out”
monolithic device. All RF and IF tuning is accomplished
automatically within the IC which eliminates manual tuning
and reduces production costs. The result is a highly reliable
yet low cost solution.
QwikRadio™
Features
• 300MHz to 440MHz frequency range
• Data-rate up to 10kbps (fixed-mode)
• Low Power Consumption
• 2.2mA fully operational (315MHz)
• 0.9µA in shutdown
• 220µA in polled operation (10:1 duty-cycle)
• Wake-up output flag to enable decoders and micropro-
cessors
The MICRF002 is a fully featured part in 16-pin packaging,
the MICRF022 is the same part packaged in 8-pin packaging
with a reduced feature set (see “Ordering Information” for
more information).
The MICRF002 is an enhanced version of the MICRF001
and MICRF011. The MICRF002 provides two additional
functionsovertheMICRF001/011, (1)aShutdownpin, which
may be used to turn the device off for duty-cycled operation,
and (2) a “Wake-up” output, which provides an output flag
indicatingwhenanRFsignalispresent.Thesefeaturesmake
the MICRF002 ideal for low and ultra-low power applications,
such as RKE and remote controls.
• Very low RF reradiation at the antenna
• Highly integrated with extremely low external part count
Applications
All IF filtering and post-detection (demodulator) data filtering
is provided within the MICRF002, so no external filters are
necessary. Oneoffourdemodulatorfilterbandwidthsmaybe
selected externally by the user.
• Automotive Remote Keyless Entry (RKE)
• Remote controls
• Remote fan and light control
• Garage door and gate openers
The MICRF002 offer two modes of operation; fixed-mode
(FIX) and sweep-mode (SWP). In fixed mode the MICRF002
functions as a conventional superhet receiver. In sweep
mode the MICRF002 employs a patented sweeping function
to sweep a wider RF spectrum. Fixed-mode provides better
selectivity and sensitivity performance and sweep mode
enables the MICRF002 to be used with low cost, imprecise
transmitters.
Typical Application
1/4 Wave Monopole
MICRF002
SEL0
SWEN
4.8970MHz
VSSRF REFOSC
12pF
68nH
VSSRF
ANT
SEL1
CAGC
WAKEB
SHUT
DO
VDDRF
VDDBB
+5V
4.7uF
Data
Output
CTH
NC
12nH
0.047uF
VSSBB
315MHz 800bps On-Off Keyed Receiver
QwikRadio is a trademark of Micrel, Inc. The QwikRadio ICs were developed under a partnership agreement with AIT of Orlando, Florida.
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
March 2003
1
MICRF002/RF022
MICRF002/RF022
Micrel
Ordering Information
Demodulator
WAKEB
Part Number
Bandwidth
User Programable
5000Hz
Operating Mode
Fixed or Sweep
Sweep
Shutdown
Yes
Output Flag
Package
16-Pin SOP
8-Pin SOP
8-Pin SOP
8-Pin SOP
8-Pin SOP
MICRF002BM
Yes
Yes
No
MICRF022BM-SW48
MICRF022BM-FS12
MICRF022BM-FS24
MICRF022BM-FS48
No
1250Hz
Fixed
Yes
2500Hz
Fixed
Yes
No
5000Hz
Fixed
Yes
No
Pin Configuration
MICRF002Bx
SEL0 1
VSSRF 2
16 SWEN
15 REFOSC
14 SEL1
MICRF022Bx-xxxx
VSSRF 3
ANT 4
VSSRF 1
ANT 2
8
REFOSC
CAGC
13 CAGC
12 WAKEB
11 SHUT
10 DO
7
6
5
VDDRF 5
VDDBB 6
CTH 7
VDDRF 3
CTH 4
SHUT/WAKEB
DO
NC 8
9
VSSBB
Standard 16-Pin or 8-Pin SOP (M) Packages
8-Pin Options
The standard 16-pin package allows complete control of all
configurable features. Some reduced function 8-pin versions
are also available, see “Ordering Information” above.
For high-volume applications additional customized 8-pin
devices can be produced. SWEN, SEL0 and SEL1 pins are
internally bonded to reduce the pin count. pin 6 may be
configured as either SHUT or WAKEB.
Demodulator Bandwidth
SEL0
SEL1
Sweep Mode FIXED Mode
1
0
1
0
1
1
0
0
5000Hz
2500Hz
1250Hz
625Hz
10000Hz
5000Hz
2500Hz
1250Hz
Table 1. Nominal Demodulator Filter Bandwidth vs.
SEL0, SEL1 and Operating Mode
MICRF002/RF022
2
March 2003
MICRF002/RF022
Micrel
Pin Description
Pin Number
16-Pin Pkg.
Pin Number
8-Pin Pkg.
Pin Name
Pin Function
1
SEL0
Bandwidth Selection Bit 0 (Digital Input): Used in conjunction with SEL1 to
set the desired demodulator filter bandwidth. See Table 1. Internally pulled-
up to VDDRF
2, 3
4
1
2
VSSRF
ANT
RF Power Supply: Ground return to the RF section power supply.
Antenna (Analog Input): For optimal performance the ANT pin should be
impedance matched to the antenna. See “Applications Information” for
information on input impedance and matching techniques
5
6
3
4
VDDRF
VDDBB
RF Power Supply: Positive supply input for the RF section of the IC
Base-Band Power Supply: Positive supply input for the baseband section
(digital section) of the IC
7
CTH
Data Slicing Threshold Capacitor (Analog I/O): Capacitor connected to this
pin extracts the dc average value from the demodulated waveform which
becomes the reference for the internal data slicing comparator
8
9
NC
Not internally connected
VSSBB
Base-Band Power Supply: Ground return to the baseband section power
supply
10
11
5
6
DO
Data Output (Digital Output)
SHUT
Shutdown (Digital Input): Shutdown-mode logic-level control input. Pull low
to enable the receiver. Internally pulled-up to VDDRF
12
13
14
WAKEB
CAGC
SEL1
Wakeup (Digital Output): Active-low output that indicates detection of an
incoming RF signal
7
8
Automatic Gain Control (Analog I/O): Connect an external capacitor to set
the attack/decay rate of the on-chip automatic gain control
Bandwidth Selection Bit 1 (Digital Input): Used in conjunction with SEL0 to
set the desired demodulator filter bandwidth. See Table 1. Internally pulled-
up to VDDRF
15
16
REFOSC
SWEN
Reference Oscillator: Timing reference, sets the RF receive frequency.
Sweep-Mode Enable (Digital Input): Sweep- or Fixed-mode operation
control input. SWEN high= sweep mode; SWEN low = conventional
superheterodyne receiver. Internally pulled-up to VDDRF
March 2003
3
MICRF002/RF022
MICRF002/RF022
Micrel
Absolute Maximum Ratings (Note 1)
Operating Ratings (Note 2)
Supply Voltage (V
, V
)....................................+7V
Supply Voltage (V
, V
)................ +4.75V to +5.5V
DDRF
DDBB
DDRF
DDBB
Input/Output Voltage (V ) ................. V –0.3 to V +0.3
RF Frequency Range............................. 300MHz to 440Hz
Data Duty-Cycle ...............................................20% to 80%
Reference Oscillator Input Range ............0.1V to 1.5V
PP
I/O
SS
DD
Junction Temperature (T ) ...................................... +150°C
J
Storage Temperature Range (T ) ............ –65°C to +150°C
S
PP
Lead Temperature (soldering, 10 sec.) ................... +260°C
ESD Rating, Note 3
Ambient Temperature (T ) ......................... –40°C to +85°C
A
Electrical Characteristics
VDDRF = VDDBB = VDD where +4.75V ≤ VDD ≤ 5.5V, VSS = 0V; CAGC = 4.7µF, CTH = 100nF; SEL0 = SEL1 = VSS; fixed mode ( SWEN
= VSS); fREFOSC = 4.8970MHz (equivalent to fRF = 315MHz); data-rate = 1kbps (Manchester encoded). TA = 25°C, bold values indicate
–40°C ≤ TA ≤ +85°C; current flow into device pins is positive; unless noted.
Symbol
Parameter
Condition
Min
Typ
2.2
Max
3.2
Units
mA
µA
IOP
Operating Current
continuous operation, fRF = 315MHz
polled with 10:1 duty cycle, fRF = 315MHz
continuous operation, fRF = 433.92MHz
polled with 10:1 duty cycle, fRF = 433.92MHz
VSHUT = VDD
220
3.5
mA
µA
350
0.9
ISTBY
Standby Current
µA
RF Section, IF Section
Receiver Sensitivity (Note 4)
fRF = 315MHz
fRF = 433.92MHz
Note 6
–97
–95
0.86
0.43
–20
30
dBm
dBm
fIF
IF Center Frequency
IF Bandwidth
MHz
fBW
Note 6
MHz
Maximum Receiver Input
Spurious Reverse Isolation
AGC Attack to Decay Ratio
AGC Leakage Current
RSC = 50Ω
dBm
ANT pin, RSC = 50Ω, Note 5
tATTACK ÷ tDECAY
TA = +85°C
µVrms
0.1
100
nA
Reference Oscillator
ZREFOSC
Reference Oscillator
Input Impedance
Note 8
290
5.2
kΩ
Reference Oscillator Source
Current
uA
Demodulator
ZCTH
CTH Source Impedance
CTH Leakage Current
Note 7
145
100
kΩ
IZCTH(leak)
TA = +85°C
nA
Demodulator Filter Bandwidth
Sweep Mode
(SWEN = VDD or OPEN)
Note 6
V
SEL0 = VDD. VSEL1 = VDD
4000
2000
1000
500
Hz
Hz
Hz
Hz
VSEL0 = VSS. VSEL1 = VDD
VSEL0 = VDD. VSEL1 = VSS
VSEL0 = VSS. VSEL1 = VSS
Demodulator Filter Bandwidth
Fixed Mode
(SWEN = VSS
V
SEL0 = VDD. VSEL1 = VDD
8000
4000
2000
1000
Hz
Hz
Hz
Hz
VSEL0 = VSS. VSEL1 = VDD
VSEL0 = VDD. VSEL1 = VSS
VSEL0 = VSS. VSEL1 = VSS
Note 6
MICRF002/RF022
4
March 2003
MICRF002/RF022
Micrel
Symbol
Parameter
Condition
Min
Typ
Max
0.8
Units
Digital/Control Section
VIN(high)
VIN(low)
IOUT
Input-High Voltage
SEL0, SEL1, SWEN
VDD
VDD
µA
Input-Low Voltage
SEL0, SEL1, SWEN
0.2
0.9
Output Current
DO, WAKEB pins, push-pull
DO, WAKEB pins, IOUT = –1µA
DO, WAKEB pins, IOUT = +1µA
DO, WAKEB pins, CLOAD = 15pF
10
10
VOUT(high)
VOUT(low)
tR, tF
Output High Voltage
Output Low Voltage
Output Rise and Fall Times
VDD
VDD
µs
0.1
Note 1. Exceeding the absolute maximum rating may damage the device.
Note 2. The device is not guaranteed to function outside its operating rating.
Note 3. Devices are ESD sensitive, use appropriate ESD precautions. Meets class 1 ESD test requirements, (human body model HBM), in accor-
dance with MIL-STD-883C, method 3015. Do not operate or store near strong electrostatic fields.
-2
Note 4: Sensitivity is defined as the average signal level measured at the input necessary to achieve 10 BER (bit error rate). The RF input is
assumed to be matched to 50Ω.
Note 5: Spurious reverse isolation represents the spurious components which appear on the RF input pin (ANT) measured into 50Ω with an input RF
matching network.
Note 6: Parameter scales linearly with reference oscillator frequency f . For any reference oscillator frequency other than 4.8970MHz, compute
T
new parameter value as the ratio:
fREFOSCMHz
× (parameter value at 4.8970MHz)
4.8970MHz
Note 7: Parameter scales inversely with reference oscillator frequency f . For any reference oscillator frequency other than 4.8970MHz, compute
T
new parameter value as the ratio:
4.8970MHz
× (parameter value at 4.8970MHz)
fREFOSCMHz
Note 8: Series resistance of the resonator (ceramic resonator or crystal) should be minimized to the extent possible. In cases where the resonator
series resistance is too great, the oscillator may oscillate at a diminished peak-to-peak level, or may fail to oscillate entirely. Micrel recom-
mends that series resistances for ceramic resonators and crystals not exceed 50Ohms and 100Ohms respectively. Refer to Application Hint
35 for crystal recommendations.
March 2003
5
MICRF002/RF022
MICRF002/RF022
Micrel
Typical Characteristics
Supply Current
vs. Frequency
Supply Current
vs. Temperature
3.5
3.0
2.5
2.0
1.5
6.0
TA = 25°C
DD = 5V
f = 315MHz
DD = 5V
V
V
4.5
3.0
1.5
Sweep Mode,
Continuous Operation
Sweep Mode,
Continuous Operation
-40 -20
0
20 40 60 80 100
250 300 350 400 450 500
TEMPERATURE (°C)
FREQUENCY (MHz)
MICRF002/RF022
6
March 2003
MICRF002/RF022
Micrel
Functional Diagram
CAGC
CAGC
AGC
Control
Switched-
Capacitor
Resistor
2nd Order
Programmable
Low-Pass Filter
5th Order
Band-Pass Filter
fRX
fIF
ANT
RF
Amp
IF
Amp
IF
Amp
Peak
Detector
DO
Compa-
rator
RSC
430kHz
fLO
VDD
VSS
CTH
Programmable
Synthesizer
CTH
UHF Downconverter
OOK Demodulator
SEL0
SEL1
Control
Logic
WAKEB
Resettable
Counter
SWEN
SHUT
fT
REFOSC
Reference and Control
Wakeup
Reference
Oscillator
Cystal
or
Ceramic
MICRF002
Resonator
Figure 1. MICRF002 Block Diagram
Applications Information and Functional
Description
Step 1: Selecting The Operating Mode
Fixed-Mode Operation
For applications where the transmit frequency is accurately
set (that is, applications where a SAW or crystal-based
transmitter is used) the MICRF002 may be configured as a
standard superheterodyne receiver (fixed mode). In fixed-
mode operation the RF bandwidth is narrower making the
receiver less susceptible to interfering signals. Fixed mode is
selected by connecting SWEN to ground.
Refer to figure 1 “MICRF002 Block Diagram”. Identified in the
block diagram are the four sections of the IC: UHF
Downconverter, OOK Demodulator, Reference and Control,
and Wakeup. Also shown in the figure are two capacitors
(C , C
) and one timing component, usually a crystal or
TH
AGC
ceramicresonator. Withtheexceptionofasupplydecoupling
capacitor, and antenna impedance matching network, these
are the only external components needed by the MICRF002
to assemble a complete UHF receiver.
Sweep-Mode Operation
When used in conjunction with low-cost L-C transmitters the
MICRF002 should be configured in sweep-mode. In sweep-
mode, while the topology is still superheterodyne, the LO
(local oscillator) is swept over a range of frequencies at rates
greater than the data rate. This technique effectively in-
creases the RF bandwidth of the MICRF002, allowing the
device to operate in applications where significant transmit-
ter-receiver frequency misalignment may exist. The transmit
frequency may vary up to 0.5% over initial tolerance, aging,
and temperature. In sweep-mode a band approximately
1.5%aroundthenominaltransmitfrequencyiscaptured. The
transmitter may drift up to 0.5% without the need to retune
the receiver and without impacting system performance.
For optimal performance is highly recommended that the
MICRF002isimpedancematchedtotheantenna, thematch-
ing network will add an additional two or three components.
Four control inputs are shown in the block diagram: SEL0,
SEL1, SWEN, and SHUT. Using these logic inputs, the user
cancontroltheoperatingmodeandselectablefeaturesofthe
IC. These inputs are CMOS compatible, and are internally
pulled-up. IF Bandpass Filter Roll-off response of the IF Filter
is 5th order, while the demodulator data filter exhibits a 2nd
order response.
Design Steps
The following steps are the basic design steps for using the
MICRF002 receiver:
The swept-LO technique does not affect the IF bandwidth,
therefore noise performance is not degraded relative to fixed
mode. The IF bandwidth is 430kHz whether the device is
operating in fixed or sweep-mode.
1). Select the operating mode (sweep or fixed)
2). Select the reference oscillator
Due to limitations imposed by the LO sweeping process, the
upper limit on data rate in sweep mode is approximately
5.0kbps.
3). Select the C capacitor
TH
4). Select the C
capacitor
AGC
Similar performance is not currently available with crystal-
based superheterodyne receivers which can operate only
with SAW- or crystal-based transmitters.
5). Select the demodulator filter bandwidth
March 2003
7
MICRF002/RF022
MICRF002/RF022
Micrel
In sweep-mode, a range reduction will occur in installations
where there is a strong interferer in the swept RF band. This
is because the process indiscriminately includes all signals
within the sweep range. An MICRF002 may be used in place
of a superregenerative receiver in most applications.
Frequency f is in MHz. Connect a crystal of frequency f to
REFOSC on the MICRF002. Four-decimal-place accuracy
on the frequency is generally adequate. The following table
T
T
identifies f for some common transmit frequencies when the
T
MICRF002 is operated in fixed mode.
Step 2: Selecting The Reference
Oscillator
All timing and tuning operations on the MICRF002 are de-
rived from the internal Colpitts reference oscillator. Timing
and tuning is controlled through the REFOSC pin in one of
three ways:
Transmit
Frequency
fTX
Reference Oscillator
Frequency
fT
315MHz
390MHz
4.8970MHz
6.0630MHz
6.4983MHz
6.7458MHz
418MHz
1. Connect a ceramic resonator
2. Connect a crystal
433.92MHz
Table 2. Fixed Mode Recommended Reference
Oscillator Values For Typical Transmit Frequencies
(high-side mixing)
3. Drive this pin with an external timing signal
The specific reference frequency required is related to the
system transmit frequency and to the operating mode of the
receiver as set by the SWEN pin.
Selecting REFOSC Frequency f
(Sweep Mode)
T
Crystal or Ceramic Resonator Selection
Selection of the reference oscillator frequency f in sweep
T
Do not use resonators with integral capacitors since capaci-
tors are included in the IC, also care should be taken to
ensure low ESR capacitors are selected. Application Hint 34
and Application Hint 35 provide additional information and
recommended sources for crystals and resonators.
mode is much simpler than in fixed mode due to the LO
sweeping process. Also, accuracy requirements of the fre-
quency reference component are significantly relaxed.
In sweep mode, f is given by Equation 3:
T
If operating in fixed-mode, a crystal is recommended. In
sweep-mode either a crystal or ceramic resonator may be
used. When a crystal of ceramic resonator is used the
f
LO
f =
(3)
T
64.25
In SWEEP mode a reference oscillator with frequency accu-
rate to two-decimal-places is generally adequate. A crystal
may be used and may be necessary in some cases if the
transmit frequency is particularly imprecise.
minimum voltage is 300mV . If using an externally applied
PP
signal it should be AC-coupled and limited to the operating
range of 0.1V to 1.5V
PP
PP.
Selecting Reference Oscillator Frequency f
(Fixed Mode)
T
Transmit
Frequency
fTX
Reference Oscillator
Frequency
fT
As with any superheterodyne receiver, the mixing between
the internal LO (local oscillator) frequency f and the incom-
LO
315MHz
390MHz
4.88MHz
6.05MHz
6.48MHz
6.73MHz
ing transmit frequency f ideally must equal the IF center
TX
frequency. Equation 1 may be used to compute the appropri-
418MHz
ate f for a given f
:
LO
TX
433.92MHz
fTX
315
f
= fTX
0.86
(1)
LO
Table 3. Recommended Reference Oscillator Values
For Typical Transmit Frequencies (sweep-mode)
Frequencies f and f are in MHz. Note that two values of
TX
LO
f
existforanygivenf , distinguishedas“high-sidemixing”
LO
TX
and “low-side mixing.” High-side mixing results in an image
frequency above the frequency of interest and low-side
mixing results in a frequency below.
After choosing one of the two acceptable values of f , use
LO
Equation 2 to compute the reference oscillator frequency f :
T
f
LO
f =
(2)
T
64.5
MICRF002/RF022
8
March 2003
MICRF002/RF022
Micrel
Selecting C
Capacitor in Continuous Mode
Step 3: Selecting The CTH Capacitor
Extraction of the dc value of the demodulated signal for
purposes of logic-level data slicing is accomplished using the
AGC
A C
capacitor in the range of 0.47µF to 4.7µF is typically
AGC
recommended. The value of the C
should be selected to
AGC
minimize the ripple on the AGC control voltage by using a
sufficiently large capacitor. However if the capacitor is too
large the AGC may react too slowly to incoming signals. AGC
settling time from a completely discharged (zero-volt) state is
given approximately by Equation 6:
external threshold capacitor C and the on-chip switched-
TH
capacitor “resistor” R , shown in the block diagram.
SC
Slicing level time constant values vary somewhat with de-
coder type, data pattern, and data rate, but typically values
range from 5ms to 50ms. Optimization of the value of C is
TH
∆t = 1.333C
− 0.44
(6)
required to maximize range.
AGC
Selecting Capacitor C
where:
TH
The first step in the process is selection of a data-slicing-level
time constant. This selection is strongly dependent on sys-
tem issues including system decode response time and data
codestructure(thatis, existenceofdatapreamble, etc.). This
issue is covered in more detail in Application Note 22.
C
is in µF, and ∆t is in seconds.
AGC
Selecting C
Capacitor in Duty-Cycle Mode
AGC
Voltage droop across the C
capacitor during shutdown
AGC
should be replenished as quickly as possible after the IC is
enabled. As mentioned above, the MICRF002 boosts the
push-pull current by a factor of 45 immediately after start-up.
This fixed time period is based on the reference oscillator
frequency f . The time is 10.9ms for f = 6.00MHz, and varies
The effective resistance of R
is listed in the electrical
SC
characteristics table as 145kΩ at 315MHz, this value scales
linearly with frequency. Source impedance of the CTH pin at
T
T
otherfrequenciesisgivenbyequation(4), wheref isinMHz:
T
inversely with f . The value of C
capacitor and the
T
AGC
durationoftheshutdowntimeperiodshouldbeselectedsuch
that the droop can be replenished within this 10ms period.
4.8970
RSC = 145kΩ
(4)
fT
Polarity of the droop is unknown, meaning the AGC voltage
could droop up or down. Worst-case from a recovery stand-
point is downward droop, since the AGC pull-up current is
1/10th magnitude of the pulldown current. The downward
droop is replenished according to the Equation 7:
τ of 5x the bit-rate is recommended. Assuming that a slicing
level time constant τ has been established, capacitor C
TH
may be computed using equation
τ
CTH
=
(5)
RSC
I
∆V
∆t
=
(7)
C
A standard 20% X7R ceramic capacitor is generally suffi-
AGC
cient. RefertoApplicationHint42forC andC
examples.
selection
TH
AGC
where:
I = AGC pullup current for the initial 10ms (67.5µA)
= AGC capacitor value
Step 4: Selecting The CAGC Capacitor
The signal path has AGC (automatic gain control) to increase
input dynamic range. The attack time constant of the AGC is
C
AGC
∆t = droop recovery time
∆V = droop voltage
set externally by the value of the C
capacitor connected
AGC
For example, if user desires ∆t = 10ms and chooses a 4.7µF
to the CAGC pin of the device. To maximize system range, it
is important to keep the AGC control voltage ripple low,
preferably under 10mVpp once the control voltage has at-
tained its quiescent value. For this reason capacitor values of
at least 0.47µF are recommended.
C
, then the allowable droop is about 144mV. Using the
AGC
same equation with 200nA worst case pin leakage and
assuming 1µA of capacitor leakage in the same direction, the
maximum allowable ∆t (shutdown time) is about 0.56s for
droop recovery in 10ms.
The AGC control voltage is carefully managed on-chip to
allow duty-cycle operation of the MICRF002. When the
device is placed into shutdown mode (SHUT pin pulled high),
the AGC capacitor floats to retain the voltage. When opera-
tion is resumed, only the voltage droop due to capacitor
leakage must be replenished. A relatively low-leakage ca-
pacitor is recommended when the devices are used in duty-
cycled operation.
The ratio of decay-to-attack time-constant is fixed at 10:1
(that is, the attack time constant is 1/10th of the decay time
constant). Generally the design value of 10:1 is adequate for
the vast majority of applications. If adjustment is required the
constantmaybevariedbyaddingaresistorinparallelwiththe
C
capacitor. Thevalueoftheresistormustbedetermined
AGC
on a case by case basis.
Step 5: Selecting The Demod Filter
Bandwidth
The inputs SEL0 and SEL1 control the demodulator filter
bandwidth in four binary steps (625Hz to 5000Hz in sweep,
1250Hz to 10000Hz in fixed mode), see Table 1. Bandwidth
must be selected according to the application. The demodu-
lator bandwidth should be set according to equation 8.
Tofurtherenhanceduty-cycledoperation, theAGCpushand
pull currents are boosted for approximately 10ms immedi-
ately after the device is taken out of shutdown. This compen-
sates for AGC capacitor voltage droop and reduces the time
to restore the correct AGC voltage. The current is boosted by
a factor of 45.
March 2003
9
MICRF002/RF022
MICRF002/RF022
Micrel
(8) Demoulator bandwidth = 0.65 / Shortest pulse-width
It should be noted that the values indicated in table 1 are
nominal values. The filter bandwidth scales linearly with
frequency so the exact value will depend on the operating
frequency. Refer to the “Electrical Characteristics” for the
exact filter bandwidthat a chosen frequency.
Demodulator Bandwidth
SEL0
SEL1
Sweep Mode FIXED Mode
1
0
1
0
1
1
0
0
5000Hz
2500Hz
1250Hz
625Hz
10000Hz
5000Hz
2500Hz
1250Hz
Table 1. Nominal Demodulator Filter Bandwidth vs.
SEL0, SEL1 and Operating Mode
MICRF002/RF022
10
March 2003
MICRF002/RF022
Micrel
Additional Applications Information
Frequency
(MHz)
ZIN(
Z11
)
S11
LSHUNT (nH)
LSERIES (nH)
In addition to the basic operation of the MICRF002 the
following enhancements can be made. In particilar it is
strongly recommended that the antenna impedance is
matched to the input of the IC.
300
305
310
315
320
325
330
335
340
345
350
355
360
365
370
375
380
385
390
395
400
405
410
415
420
425
430
435
440
12– j166
12– j165
0.803– j0.529
0.800– j0.530
15
15
15
15
15
12
12
12
15
15
12
12
10
10
12
12
10
10
10
10
10
10
10
10
10
10
10
10
8.2
72
72
72
72
68
68
68
68
56
56
56
56
56
56
47
47
47
47
43
43
43
39
39
39
36
36
33
33
33
12 – j163 0.796– j0.536
13 – j162 0.791– j0.536
12 – j160 0.789– j0.543
12 – j157 0.782– j0.550
Antenna Impedance Matching
As shown in table 4 the antenna pin input impedance is
frequency dependant.
The ANT pin can be matched to 50 Ohms with an L-type
circuit. That is, a shunt inductor from the RF input to ground
and another in series from the RF input to the antenna pin.
12 - j155
12 – j152 0.770– j0.564
11 - j150 0.767– j0.572
0.778– j0.556
Inductor values may be different from table depending on
PCBmaterial, PCBthickness, groundconfiguration, andhow
long the traces are in the layout. Values shown were charac-
terized for a 0.031 thickness, FR4 board, solid ground plane
on bottom layer, and very short traces. MuRata and Coilcraft
wire wound 0603 or 0805 surface mount inductors were
tested, however any wire wound inductor with high SRF (self
resonance frequency) should do the job.
11 – j148 0.762– j0.578
11 – j145 0.753– j0.586
11 – j143 0.748– j0.592
11 – j141 0.742– j0.597
11 – j139 0.735– j0.603
10 – 137 0.732– j0.612
10 – j135 0.725– j0.619
10 – j133 0.718– j0.625
10 – j131 0.711– j0.631
10 – j130 0.707– j0.634
10 – j128 0.700– j0.641
10 – j126 0.692– j0.647
10 – j124 0.684– j0.653
10 – j122 0.675– j0.660
10 – j120 0.667– j0.667
10 – j118 0.658– j0.673
10 – j117 0.653– j0.677
10 – j115 0.643– j0.684
10 – j114 0.638– j0.687
Shutdown Function
Duty-cycled operation of the MICRF002 (often referred to as
polling) is achieved by turning the MICRF002 on and off via
the SHUT pin. The shutdown function is controlled by a logic
state applied to the SHUT pin. When V
is high, the
SHUT
device goes into low-power standby mode. This pin is pulled
high internally, it must be externally pulled low to enable the
receiver.
LSERIES
LSHUNT
8 – j112
0.635– j0.704
Table 4. Input Impedance Versus Frequency
j100
j25
50
0
∞
–j25
–j100
March 2003
11
MICRF002/RF022
MICRF002/RF022
Micrel
Power Supply Bypass Capacitors
where:
VDDBBandVDDRFshouldbeconnectedtogetherdirectlyat
the IC pins. Supply bypass capacitors are strongly
recommended. They should be connected to VDDBB and
VDDRF and should have the shortest possible lead lengths.
For best performance, connect VSSRF to VSSBB at the
f = reference oscillator frequency
T
f = system clock frequency
S
P = system clock period
S
The Wake-Up counter will reset immediately after a detected
RF carrier drops. The duration of the Wake-Up signal output
is then determined by the required wake up time plus an
additional RF carrier on time interval to create a wake up
pulse output.
power supply only (that is, keep V
currents from flowing
SSBB
through the V
return path).
SSRF
Increasing Selectivity With an Optional BandPass
Filter
WAKEB Output Pulse Time = T
Carrier On Time
+ Additional RF
WAKE
For applications located in high ambient noise environments,
a fixed value band-pass network may be connected between
the ANT pin and VSSRF to provide additional receive selec-
tivityandinputoverloadprotection. Aminimuminputconfigu-
ration is included in figure 7a. it provides some filtering and
necessary overload protection.
For designers who wish to use the wakeup function while
squelching the output, a positive squelching offset voltage
must be used. This simply requires that the squelch resistor
be connected to a voltage more positive than the quiescent
voltage on the CTH pin so that the data output is low in
absence of a transmission.
Data Squelching
During quiet periods (no signal) the data output (DO pin)
transitions randomly with noise. Most decoders can
descriminate between this random noise and actual data but
for some system it does present a problem. There are three
possible approaches to reducing this output noise:
I/O Pin Interface Circuitry
Interface circuitry for the various I/O pins of the MICRF002
are diagrammed in Figures 1 through 6. The ESD protection
diodes at all input and output pins are not shown.
1). Analog squelch to raise the demodulator threshold
2). Digital squelch to disable the output when data is not
present
CTH Pin
VDDBB
3). Output filter to filter the (high frequency) noise glitches on
the data output pin.
PHI2B
PHI2
PHI1B
Demodulator
Signal
The simplest solution is add analog squelch by introducing a
small offset, or squelch voltage, on the CTH pin so that noise
does not trigger the internal comparator. Usually 20mV to
30mV is sufficient, and may be achieved by connecting a
2.85Vdc
CTH
6.9pF
PHI1
VSSBB
VSSBB
several-megohm resistor from the CTH pin to either V or
SS
V
, depending on the desired offset polarity. Since the
DD
Figure 2. CTH Pin
MICRF002 has receiver AGC noise at the internal compara-
tor input is always the same, set by the AGC. The squelch
offsetrequirementdoesnotchangeasthelocalnoisestrength
changes from installation to installation. Introducing squelch
will reduce sensitivity and also reduce range. Only introduce
an amount of offset sufficient to quiet the output. Typical
squelch resistor values range from 6.8MΩ to 10MΩ.
Figure 2 illustrates the CTH-pin interface circuit. The CTH pin
is driven from a P-channel MOSFET source-follower with
approximately 10µA of bias. Transmission gates TG1 and
TG2 isolate the 6.9pF capacitor. Internal control signals
PHI1/PHI2 are related in a manner such that the impedance
across the transmission gates looks like a “resistance” of
approximately 100kΩ. The dc potential at the CTH pin is
approximately 1.6V
Wake-Up Function
The WAKEB output signal can be used to reduce system
power consumption by enabling the rest of a system when an
RF signal is present. The WAKEB is an output logic signal
which goes active low when the IC detects a constant RF
carrier. The wake-up function is unavailable when the IC is in
shutdown mode.
To activate the Wake-Up function, a received constant RF
carrier must be present for 128 counts or the internal system
clock. Theinternalsystemclockisderivedfromthereference
oscillator and is 1/256 the reference oscillator frequency. For
example:
f = 6.4MHz
T
f = f /256 = 25kHz
S
T
P = 1/f = 0.04ms
S
S
128 counts x 0.04ms = 5.12ms
MICRF002/RF022
12
March 2003
MICRF002/RF022
Micrel
CAGC Pin
REFOSC Pin
VDDBB
VDDBB
Active
Bias
200k
1.5µA
67.5µA
REFOSC
30pF
30pF
VSSBB
250Ω
Compa-
rator
30µA
CAGC
VSSBB
Timout
Figure 5. REFOSC Pin
15µA
675µA
The REFOSC input circuit is shown in Figure 5. Input imped-
ance is high (200kΩ). This is a Colpitts oscillator with internal
30pF capacitors. This input is intended to work with standard
ceramic resonators connected from this pin to the VSSBB
pin, although a crystal may be used when greater frequency
accuracy is required. The nominal dc bias voltage on this pin
is 1.4V.
VSSBB
Figure 3. CAGC Pin
Figure 3 illustrates the CAGC pin interface circuit. The AGC
control voltage is developed as an integrated current into a
SEL0, SEL1, SWEN, and SHUT Pins
capacitor C
. The attack current is nominally 15µA, while
AGC
VDDBB
the decay current is a 1/10th scaling of this, nominally 1.5µA,
making the attack/decay time constant ratio a fixed 10:1.
Signal gain of the RF/IF strip inside the IC diminishes as the
voltageatCAGCdecreases. Modificationoftheattack/decay
ratio is possible by adding resistance from the CAGC pin to
Q1
Q2
VSSBB
to Internal
Circuits
SHUT
Q4
either V
or V
, as desired.
DDBB
SSBB
SEL0,
SEL1,
SWEN
Q3
Both the push and pull current sources are disabled during
shutdown, which maintains the voltage across C , and
AGC
VSSBB
improves recovery time in duty-cycled applications. To fur-
therimproveduty-cyclerecovery, bothpushandpullcurrents
are increased by 45 times for approximately 10ms after
release of the SHUT pin. This allows rapid recovery of any
Figure 6a. SEL0, SEL1, SWEN
VDDBB
voltage droop on C
while in shutdown.
AGC
Q1
Q2
DO and WAKEB Pins
to Internal
Circuits
VDDBB
10µA
VSSBB
SHUT
Q3
Compa-
rator
VSSBB
DO
Figure 6b. SHUT
Control input circuitry is shown in Figures 6a and 6b. The
standard input is a logic inverter constructed with minimum
geometry MOSFETs (Q2, Q3). P-channel MOSFET Q1 is a
large channel length device which functions essentially as a
“weak” pullup to VDDBB. Typical pullup current is 5µA,
leading to an impedance to the VDDBB supply of typically
1MΩ.
10µA
VSSBB
Figure 4. DO and WAKEB Pins
TheoutputstageforDO(digitaloutput)andWAKEB(wakeup
output) is shown in Figure 4. The output is a 10µA push and
10µA pull switched-current stage. This output stage is ca-
pable of driving CMOS loads. An external buffer-driver is
recommended for driving high-capacitance loads.
March 2003
13
MICRF002/RF022
MICRF002/RF022
Micrel
Applications Example
315MHz Receiver/Decoder Application
Figure 7a illustrates a typical application for the MICRF002
UHF Receiver IC. This receiver operates continuously (not
duty cycled) in sweep mode, and features 6-bit address
decoding and two output code bits.
Operation in this example is at 315MHz, and may be custom-
izedbyselectionoftheappropriatefrequencyreference(Y1),
and adjustment of the antenna length. The value of C4 would
also change if the optional input filter is used. Changes from
the 1kb/s data rate may require a change in the value of R1.
A bill of materials accompanies the schematic.
0.monopole
+5V
Supply
Input
antenna (11.6in)
6-bit
address
U1 MICRF002
SEL0 SWEN
VSSRF REFOSC
U2 HT-12D
4.8970MHz
Y1
C4
Optional Filter
8.2pF, 16.6nH
pcb foil inductor
1in of 30mil trace
A0
A1
A2
A3
A4
A5
A6
A7
VSS
VDD
VT
R2
1k
R1
L1
VSSRF
ANT
SEL1
CAGC
WAKEB
SHUT
DO
OSC1
OSC2
DIN
68k
4.7µF
VDDRF
VDDBB
CTH
C1
4.7µF
D11
D10
D9
Code Bit 0
Code Bit 1
C2
2.2µF
NC
VSSBB
D8
RF Baseband
(Analog) (Digital)
Ground Ground
Figure 7a. 315MHz, 1kbps On-Off Keyed Receiver/Decoder
Item
U1
Part Number
MICRF002
Manufacturer
Micrel
Description
UHF receiver
logic decoder
U2
HT-12D
Holtek
CR1
D1
CSA6.00MG
SSF-LX100LID
Murata
6.00MHz ceramic resonator
red LED
Lumex
R1
68k 1/4W 5%
R2
Vishay
Vishay
Vishay
Vishay
Vishay
1k 1/4W 5%
C1
4.7µF dipped tantalum capacitor
4.7µF dipped tantalum capacitor
2.2µF dipped tantalum capacitor
8.2pF COG ceramic capacitor
C3
C2
C4
Figure 7b. Bill of Material
Vendor
Vishay
Holtek
Lumex
Murata
Telephone
FAX
(203) 268-6261
—
(408) 894-9046
(800) 278-5666
(800) 241-6574
(408) 894-0838
(847) 359-8904
(770) 436-3030
Figure 7c. Component Vendors
MICRF002/RF022
14
March 2003
MICRF002/RF022
Micrel
PCB Layout Information
The MICRF002 evaluation board was designed and charac-
terized using two sided 0.031 inch thick FR4 material with 1
ounce copper clad. If another type of printed circuit board
material were to be substituted, impedance matching and
characterization data stated in this document may not be
valid. The gerber files for this board can be downloaded from
the Micrel website at www.micrel.com.
PCB Component Side Layout
PCB Silk Screen
PCB Solder Side Layout
J2
C5
(Not Placed)
REF.OSC.
GND
MICRF002
SEL0 SWEN
JP1
JP3
1
16
Y1
2
3
4
15
14
13
VSSRF
VSSRF
ANT
REFOSC
SEL1
6.7458MHz
JP2
J1
RF INPUT
C4(CAGC)
4.7µF
Z1
Z2
CAGC
WAKEB
SHUT
DO
5
12
VDDRF
VDDBB
CTH
Z3
Z4
6
7
8
11
10
9
J5
SHUT
GND
R1
N/C
VSSBB
R2
10k
Squelch
Resistor
(Not Placed)
DO
GND
J4
J3
C3(CTH)
0.047µF
+5V
GND
C1
4.7µF
C2
0.1µF
March 2003
15
MICRF002/RF022
MICRF002/RF022
Micrel
Package Information
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
REF
0.020 (0.51)
0.013 (0.33)
0.050 (1.27)
BSC
45°
0.0098 (0.249)
0.0040 (0.102)
0°–8°
0.050 (1.27)
0.016 (0.40)
0.394 (10.00)
0.386 (9.80)
SEATING
PLANE
0.0648 (1.646)
0.0434 (1.102)
0.244 (6.20)
0.228 (5.79)
16-Pin SOP (M)
0.026 (0.65)
MAX)
PIN 1
0.157 (3.99)
0.150 (3.81)
DIMENSIONS:
INCHES (MM)
0.020 (0.51)
0.013 (0.33)
0.050 (1.27)
TYP
45°
0.0098 (0.249)
0.0040 (0.102)
0.010 (0.25)
0.007 (0.18)
0°–8°
0.197 (5.0)
0.189 (4.8)
0.050 (1.27)
0.016 (0.40)
SEATING
PLANE
0.064 (1.63)
0.045 (1.14)
0.244 (6.20)
0.228 (5.79)
8-Pin SOP (M)
MICREL, INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com
The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use.
Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s
use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2003 Micrel, Incorporated.
MICRF002/RF022
16
March 2003
相关型号：
©2020 ICPDF网 联系我们和版权申明