MICRF102
Micrel
MICRF102
QwikRadio™ UHF ASK Transmitter
General Description
The MICRF102 is a single chip Transmitter IC for remote
wireless applications. The device employs Micrel’s latest Qwi-
kRadio™ technology. This device is a true “data-in, antenna-
out” monolithic device. All antenna tuning is accomplished
automatically within the IC which eliminates manual tuning,
and reduces production costs. The result is a highly reliable
yet extremely low cost solution for high volume wireless
applications. Because the MICRF102 is a true single-chip
radio transmitter, it is easy to apply, minimizing design and
production costs, and improving time to market.
The MICRF102 uses a novel architecture where the external
loop antenna is tuned to the internal output stage. This trans-
mitter is designed to comply with worldwide UHF unlicensed
band intentional radiator regulations. The IC is compatible with
virtually all ASK/OOK (Amplitude Shift Keying/On-Off Keyed)
UHF receiver types from wide-band super-regenerative radios
to narrow-band, high performance super-heterodyne receiv-
ers. The transmitter is designed to work with transmitter data
rates from 100 to 20k bits per second.
The automatic tuning, in conjunction with the external resistor,
ensures that the transmitter output power stays constant for
the life of the battery.
When used with Micrel’s family of QwikRadio™ receivers,
the MICRF102 provides the lowest cost and most reliable
remote actuator and RF link system available.
Data sheets and support documentation can be found on
Micrel’s web site at: www.micrel.com.
Features
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QwikRadio™
Complete UHF transmitter on a monolithic chip
Frequency range 300MHz to 470MHz
Data rates to 20kbps
Automatic antenna alignment, no manual adjustment
Low external part count
Low standby current <0.04µA
Remote Keyless Entry systems (RKE)
Remote fan/light control
Garage door opener transmitters
Remote sensor data links
Tire Pressure Monitoring System (TPMS)
Telemetry
Applications
Ordering Information
Part Number
Standard
MICRF102BM
Pb-Free
MICRF102YM
Temperature
Range
-40°C to +85°C
Package
8-Pin SOIC
Typical Application
4.7µF
+5V
ASK DATA INPUT
RP1
100k
MICRF102
PC
ASK
ANTP
ANTN
STBY
C2
8.2pF 50V
(4.7pF 50V)
0.1µF
RP2
6.8k
VDD
VSS
REFOSC
C3
12pF 50V
(2.7pF 50V)
PCB Antenna
L1
Y1
100k
+5V
QwikRadio is a trademark of Micrel, Inc. The QwikRadio ICs were developed under a partnership agreement with AIT of Orlando, Florida
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
December 2006
1
MICRF102
MICRF102
Micrel
Pin Configuration
PC 1
VDD 2
VSS 3
REFOSC 4
8 ASK
7 ANTP
6 ANTN
5 STBY
8-Pin SOIC (M)
Pin Description
Pin Number
1
2
3
4
Pin Name
PC
VDD
VSS
REFOSC
Pin Function
Power Control Input. The voltage at this pin should be set between 0.15V to
0.35V for normal operation.
Positive power supply input for the IC. This pin requires a large capacitor for
ripple decoupling. A 4.7µF is recommended.
This pin is the ground return for the IC. A power supply bypass capacitor
connected from V
DD
to V
SS
should have the shortest possible path.
This is the timing reference frequency which is the transmit frequency di-
vided by 32. Connect a crystal (mode dependent) between this pin and V
SS
,
or drive the input with an AC-coupled 0.5V
PP
input clock. See
“Reference
Oscillator”
section in this data sheet. The crystal needs to have a 10pF load
capacitance.
Input for transmitter stand by control pin is pulled to V
DD
for transmit opera-
tion and V
SS
for stand-by mode. The device requires 0.0 volts to be placed
in stand by.
Negative RF power output to drive the low side of the transmit loop antenna.
The RF output stage is tuned in the data transitions in the ASK pin.
Positive RF power output to drive the high side of the transmit loop antenna.
The RF output stage is tuned in the data transitions in the ASK pin.
Amplitude Shift Key modulation data input pin. For CW operation, connect
this pin to V
DD
. Several transitions of highs and lows are required to tune the
output RF stages.
5
STBY
6
7
8
ANTN
ANTP
ASK
MICRF102
2
December 2006
MICRF102
Micrel
Absolute Maximum Ratings
(Note 1)
Supply Voltage(V
DD
)...................................................... +6V
Voltage on I/O Pins ...............................V
SS
–0.3 to V
DD
+0.3
Storage Temperature Range ................... –65°C to + 150°C
Lead Temperature (soldering, 10 seconds) ............ + 300°C
ESD Rating ...............................................................
Note 3
Operating Ratings
(Note 2)
Supply Voltage (V
DD
)......................................4.75V to 5.5V
Maximum Supply Ripple Voltage ................................ 10mV
PC Input Range .............................. 150mV < V
PC
< 350mV
Ambient Operating Temperature (T
A
) .......... -40°C to +85°C
Programmable Transmitter Frequency Range:
......................................................300MHz to 470MHz
Specifications apply for 4.75V < V
DD
< 5.5V, V
PC
= 0.35V, T
A
= 25°C, freq
REFOSC
= 12.1875MHz, STBY = V
DD
.
Bold
values indicate
-40°C
≤
T
A
≤
85°C unless otherwise noted.
Parameter
Power Supply
Standby Supply Current, I
Q
MARK Supply Current, I
ON
SPACE Supply Current, I
OFF
Mean Operating Current
V
STBY
< 0.5V, V
ASK
< 0.5V or V
ASK
> V
DD
– 0.5V
@315MHz,
Note 5
@433MHz,
Note 5
@315MHz
@433MHz
33% mark/space ratio at 315MHz,
Note 5
33% mark/space ratio at 433MHz,
Note 5
RF Output Section and Modulation Limits:
Output Power Level, P
OUT
Harmonics Output,
Note 7
@315MHz;
Note 5, Note 6
@433MHz;
Note 5, Note 6
@315MHz
@433 MHz
Extinction Ratio for ASK
Varactor Tuning Range
Reference Oscillator Section
Reference Oscillator Input
Impedance
Reference Oscillator Source
Current
Reference Oscillator Input
Voltage (peak-to-peak)
Note 1.
Note 2.
Note 3.
Note 4.
Note 5.
Exceeding the absolute maximum rating may damage the device.
The device is not guaranteed to function outside its operating rating.
Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Specification for packaged product only.
Supply current and output power are a function of the voltage input on the PC (power control) pin. All specifications in the
“Electrical Charac-
teristics”
table applies for condition V
PC
= 350mV. Increasing the voltage on the PC pin will increase transmit power and also increase MARK
supply current. Refer to the graphs
“Output Power Versus PC Pin Voltage”
and
“Mark Current Versus PC Pin Voltage.”
Output power specified into a 50Ω equivalent load using the test circuit in Figure 2.
The MICRF102 was tested to be compliant to part 15.231 for maximum allowable TX power. The transmitted power is measured 3 meters
from the antenna using transmitter board TX102-2A in Figure 1. Measurement results are summarized in Table 1.
The Varactor capacitance tuning range indicates the allowable external antenna component variation to maintain tun-over-normal production
tolerances of external components. Guaranteed by design, not tested in production.
Electrical Characteristics
(Note 4)
Condition
Min
Typ
0.04
6
8
4
6
4.7
6.7
–4
–4
Max
Units
µA
10.5
12
6
8.5
mA
mA
mA
mA
mA
mA
dBm
dBm
dBc
dBc
dBc
2nd harm.
3rd harm.
2nd harm.
3rd harm.
40
3
–46
–45
–50
–41
52
5
300
6
0.2
0.5
7
Note 8
pF
kΩ
µA
V
PP
Note 6.
Note 7.
Note 8.
December 2006
3
MICRF102
MICRF102
Parameter
Digital / Control Section
Calibration Time
Power Amplifier Output Hold Off
Time from STBY
Transmitter Stabilization Time
from STBY
Maximum Data Rate
– ASK modulation
V
STBY
ASK pin
ASK input current
Note 9.
Micrel
Condition
Note 9,
ASK data rate 20kbps
Note 10,
STDBY transition from LOW to HIGH
Crystal, ESR < 20Ω
From External Reference (500mVpp)
Crystal, ESR < 20Ω
Duty cycle of the modulating signal = 50%
I
STBY
= V
DD
V
IH
, input high voltage
V
IL
, input low voltage
ASK = 0V, 5.0V input current
–10
0.1
20
0.75V
DD
0.6V
DD
5
0.8V
DD
6.5
0.2V
DD
10
Min
Typ
25
6
10
19
Max
Unit
ms
ms
ms
ms
kbits/s
V
µA
V
V
µA
Enable voltage
STBY Sink Current
When the device is
fi
rst powered up or it loses power momentarily, it goes into the calibration mode to tune up the transmit antenna.
Note 10.
After the release of the STDBY, the device requires an initialization time to settle the REFOSC and the internal PLL. The
fi
rst MARK state
(ASK HIGH) after exit from STDBY needs to be longer than the initialization time. After that, highs and lows in the ASK pin callibrates the
output RF stage. See Figures 2, 3, and 4.
+5VSW
R1
100k
R3
100k
Data
C2
8.2pF 50V
(4.7pF 50V)
R2
6.8k
+5VTX
C1
0.1µF
16V
MICRF102
PC
VDD
ASK
ANTP
ANTN
STBY
C4
100pF
50V
C5
4.7µF
6.3V
VSS
REFOSC
C3
12pF 50V
(2.7pF 50V)
L1
pcbant
REFOSC
C6 (np)
4.7µF
6.3V
+5VSW
Y1
9.84375MHz
(13.560MHz)
R4
(np)
R5
0Ω
+5VTX
Figure 1.
Frequency Antenna Height Azimuth
(MHz)
Polarity (meters) (0-360)
434.03
868.5
434.03
868.5
1302
1736
1302
1736
V
V
H
H
V
V
H
H
2.5
1
1
1.5
1
1
2.5
1
140
150
150
295
195
280
110
113
EMI Meter Duty Cycle Corrected
Reading Correction Reading
(dBµV/m)
(dB)
(dBµV/m)
64.2
5.4
58.8
53.1
5.4
47.7
76.1
5.4
70.7
60.1
5.4
54.7
41.1
5.4
35.7
51.3
5.4
45.9
49.4
5.4
44
44.5
5.4
39.2
Corrected 15:231b Limit Margin
Reading
(dBµV/m)
(dB)
(µV/m)
871.00
80.8
22
242.70
60.8
33.1
3427.80
80.8
10.1
543.30
60.8
26.1
61.00
54
18.3
197.20
60.8
14.9
158.50
54
10
91.20
60.8
21.6
Note. Higher order harmonics were found to be below the noise
fl
oor of the receiving system for testing.
Table 1. Transmitted Power Measurement with Transmitted Frequency 433.92MHz, FCC Limits and Compliance
MICRF102
4
December 2006
MICRF102
Micrel
Typical Characteristics
Output Power vs.
PC Pin Voltage
Mark Current vs.
PC Pin Voltage
5
OUTPUT POWER (dBm)
0
25
20
CURRENT (mA)
15
10
5
0
0
-5
-10
-15
-20
-25
-30
-35
0
100 200 300 400 500 600
V
PC
(mV)
100 200 300 400 500 600
V
PC
(mV)
RF Output Callibration Time
Figure 2. RF Out CAL Time Example (45ms)
Ch 1 - ASK Pin, 1ms Period
Ch 2 RF Field
Figure 3. RF Out CAL Time Example from Standby
cycle (15ms)
Ch 1 - ASK Pin, 1ms Period
Ch 2 RF Field
Figure 4. RF Out after shut down cycle example (11ms)
Ch 1 - ASK pin, 1ms period
Ch 2 RF Field, ch 4 - Standby Pin
December 2006
5
MICRF102
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