November 8, 2001
1
MICRF104
MICRF104
Micrel
MICRF104
1.8V, QwikRadioTM UHF ASK Transmitter
Final Information
General Description
The MICRF104 is a low voltage Transmitter IC for remote
wireless applications. The device employs Micrel's latest
QwikRadioTM technology. This device is a true "data-in,
antenna-out" 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. The MICRF104 incorporates a DC/DC con-
verter to boost the input voltage up to 5V for the RF portion of
the IC. This feature enables the MICRF104 to operate off
supply voltages as low as 1.8V and transmit at power in
excess of 2dBm.
The MICRF104 uses a novel architecture where the external
loop antenna is tuned to the internal UHF synthesizer. This
transmitter is designed to comply 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-regenera-
tive radios to narrow-band, high performance super-hetero-
dyne receivers. 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,
insures that the transmitter output power stays constant for
the life of the battery.
When coupled with Micrel's family of QwikRadioTM receivers,
the MICRF104 provides the lowest cost and most reliable
remote actuator and RF link system available.
Typical Application
VDDPWR
VSS
REFOSC
VSS
5V
EN
MICRF104
DATA IN
0.1
F
100pF 10
F
10
F
L1
22
H
8
9
10
11
12
13
14
1
2
3
4
5
6
7
VSS
SW
PC
RFSTBY
VDDRF
ASK
ANTM
ANTP
Power
Control
RF Standby
1.8V to 4V
Supply
LOOP
ANTENNA
(PCB TRACE)
Figure 1
Features
Complete UHF transmitter on a chip
Frequency range 300MHz to 470MHz
Data rates to 20kbps
Automatic antenna alignment, no manual adjustment
Low external part count
Applications
Remote Keyless Entry Systems (RKE)
Remote Fan/Light Control
Garage Door Opener Transmitters
Remote Sensor Data Links
Ordering Information
Part Number
Temperature Range
Package
MICRF104BM
0
C to +85
C
14-Pin SOIC
Micrel, Inc. 1849 Fortune Drive San Jose, CA 95131 USA tel + 1 (408) 944-0800 fax + 1 (408) 944-0970 http://www.micrel.com
QwikRadio is a trademark of Micrel, Inc. The QwikRadio ICs were developed under a partnership agreement with AIT of orlando, Florida
MICRF104
Micrel
MICRF104
2
November 8, 2001
Pin Description
Pin Number
Pin Name
Pin Function
1
VDDPWR
Positive power supply input for the DC/DC converter.
2, 4, 13
VSS
Ground return
3
5V
5V Output from the DC / DC converter
5
REFOSC
This is the timing reference frequency which is the transmit frequency
divided by 32. Connect a crystal (mode dependent) between this pin and
VSS, or drive the input with an AC coupled 0.5Vpp input clock. See
Refer-
ence Oscillator Section in this data sheet
6
RFSTBY
Input for transmitter standby control pin is pulled to VDDRF for transmit
operation and VSS for stand-by mode.
7
ANTM
Negative RF power output to drive the low side of the transmit loop antenna
8
ANTP
Positive RF power output to drive the high side of the transmit loop antenna
9
ASK
Amplitude Shift Key modulation data input pin.
10
VDDRF
Positive power supply input for the RF circuit. A power supply bypass
capacitor connected from VDDRF to VSS should have the shortest possible
path.
11
PC
Power Control Input. The voltage at this pin should be set between 0.3V to
0.4V for normal operation.
12
SW
DC/DC converter Switch. NPN output switch transistor collector.
14
EN
Chip Enable input. Active high
Pin Configuration
1
VDDPWR
VSS
5V
VSS
REFOSC
RFSTBY
ANTM
14 EN
VSS
SW
PC
VDDRF
ASK
ANTP
13
12
11
10
9
8
2
3
4
5
6
7
MICRF104BM
November 8, 2001
3
MICRF104
MICRF104
Micrel
Electrical Characteristics
Specifications apply for V
DDPWR
= 1.8V, V
PC
= 0.35V, freq
REFOSC
= 12.1875MHz, RFSTBY = V
DDRF
, EN = V
DDPWR
.
T
A
= 25
C, bold values indicate 0
C
T
A
85
C unless otherwise noted.
Parameter
Condition
Min
Typ
Max
Units
Power Supply
Shutdown current, I
VDDPWR
EN = RFSTBY = V
SS
50
A
RF Standby supply, I
VDDPWR
RFSTBY = V
SS
, EN = V
DDPWR
1.5
mA
RF Standby supply, I
VDDPWR
RFSTBY = V
SS
, EN = V
DDPWR
= 4V
0.6
mA
MARK supply current, I
ON
Note 4,
31
41
mA
Note 4, V
DDPWR
= 4V
12
17
mA
SPACE supply current, I
OFF
22
30
mA
V
DDPWR
= 4V
9
12
mA
Mean operating current
33% mark/space ratio, Note 4
25
34
mA
33% mark/space ratio, V
DDRWR
= 4V, Note 4
10
14
mA
5V Max. output current
15
mA
Note 9, V
DDPWR
= 4V
35
mA
5V Output Voltage range
Note 9
4.75
5.25
V
RF Output Section and Modulation Limits:
Output power level, P
OUT
@315MHz; Note 4, Note 5
2
dBm
@433MHz; Note 4, Note 5
2.5
dBm
Transmitted Power
@315MHz
tbd
V/m
@433MHz
tbd
V/m
Harmonics output
@ 315MHz
2nd harm.
46
dBc
3rd harm.
45
@433 MHz
2nd harm.
50
dBc
3rd harm.
41
Extinction ratio for ASK
40
52
dBc
Varactor tuning range
Note 7
5
6.5
8
pF
Reference Oscillator Section
Reference Oscillator Input
300
k
Impedance
Reference Oscillator Source
6
A
Current
Reference Oscillator Input
0.2
0.5
V
PP
Voltage (peak to peak)
Absolute Maximum Ratings
(Note 1)
Supply Voltage(V
DDPWR
, V
DDRF
) .................................. +6V
Voltage on I/O Pin EN .................................................. [tbd]
Voltage on I/O Pins, RFSTBY, ASK, PC, ANTP, ANTM
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
DDPWR
) .................................. 1.8V to 4V
PC Input Range .................................. 0.15V < V
PC
< 0.35V
Ambient Operating Temperature (T
A
) ............ 0
C to +85
C
Programmable Transmitter Frequency Range: 300MHz to
470MHz
MICRF104
Micrel
MICRF104
4
November 8, 2001
Parameter
Condition
Min
Typ
Max
Units
Digital / Control Section
Calibration time
Note 8, ASK=HIGH
25
ms
Power amplifier output hold off
Note 9, STDBY transition from LOW to HIGH
6
ms
time from STBY
Crystal, ESR < 20
Transmitter Stabilization Time
From External Reference (500mVpp)
10
ms
From STBY
Crystal, ESR < 20
19
ms
Maximum Data rate
- ASK modulation
Duty cycle of the modulating signal = 50%
20
kbits/s
V
RFSTBY
Enable Voltage
0.75V
DDRF
0.6V
DDRF
V
STBY Sink Current
5
6.5
A
V
EN
Enable Voltage
High
0.95V
DDPWR
V
Low
0.3
V
EN pin current
10
10
A
ASK pin
V
IH
, input high voltage
0.8V
DDRF
V
V
IL
, input low voltage
0.2V
DDRF
V
ASK input current
ASK = 0V, 5.0V input current
10
0.1
10
A
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. Handling precautions recommended. Human body model, 1.5k in series with 100pF.
Note 4.
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."
Note 5.
Output power specified into a 50
equivalent load using the test circuit in Figure 5.
Note 6.
Transmitted power measured 3 meters from the antenna using transmitter board TX102-2A in Figure 6.
Note 7.
The Varactor capacitance tuning range indicates the allowable external antenna component variation to maintain tune over normal production
tolerances of external components. Guaranteed by design not tested in production.
Note 8.
When the device is first powered up or it loses power momentarily, it goes into the calibration mode to tune up the transmit antenna.
Note 9.
After the release of the STDBY, the device requires an initialization time to settle the REFOSC and the internal PLL. The first MARK state
(ASK HIGH) after exit from STDBY needs to be longer than the initialization time. The subsequent low to high transitions will be treated as
data modulation whereby the envelope transition time will apply.
Note 10. The MICRF102 was tested to be Compliant to Part 15.231 for maximum allowable TX power, when operated in accordance with a loop
antenna described in Figure 6.
November 8, 2001
5
MICRF104
MICRF104
Micrel
0
5
10
15
20
25
0
100 200 300 400 500 600
CURRENT (mA)
V
PC
(mV)
Mark Current vs
PC Pin Voltage
-35
-30
-25
-20
-15
-10
-5
0
5
0
100 200 300 400 500 600
OUTPUT POWER (dBm)
V
PC
(mV)
Output Power vs
PC Pin Voltage
Typical Characteristics
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