MICRF112
QwikRadio
®
UHF ASK/FSK Transmitter
General Description
The MICRF112 is a high performance, easy to use, single
chip ASK / FSK Transmitter IC for remote wireless
applications in the 300 to 450MHz frequency band. This
transmitter IC is a true “data-in, antenna-out” monolithic
device.
MICRF112 is high performance in three areas: power
delivery, operating voltage, and operating temperature. In
terms of power, the MICRF112 is capable of delivering +10
dBm into a 50Ω load. This power level enables a small
form factor transmitter (lossy antenna) such as a key fob
transmitter to operate near the maximum limit of
transmission regulations. In terms of operating voltage,
the MICRF112 operates from 3.6V to 1.8V.
Many
transmitter ICs in the same frequency band stop operating
below 2.0V. The MICRF112 will work with most batteries
to the end of their useful limits. In terms of operating
temperature, the MICRF112 operates from -40°C to
+125°C. This wide operating temperature range makes
MICRF112 an ideal candidate for the demanding
applications such as a tire pressure monitoring system.
The MICRF112 is easy to use. One only needs a
reference frequency (RF carrier frequency divided by 32
times) generated from a crystal with a few additional
external parts to create a complete versatile transmitter.
The MICRF112 operates with ASK/OOK (Amplitude Shift
Keying/On-Off Keyed) UHF receiver types from wide-band
super-regenerative
radios
to
narrow-band,
high
performance
super-heterodyne
receivers.
The
MICRF112’s maximum ASK data rate is 50kbps
(Manchester Encoding). It operates with FSK receivers as
well. The chip is designed to support narrow band FSK
(Frequency Shift Modulation) by switching an external
capacitor in parallel with the reference crystal. The
MICRF112’s maximum FSK data rate is 10kbps.
Features
•
•
•
•
•
•
•
•
Complete UHF transmitter
Frequency range 300MHz to 450MHz
Data rates up to 50kbps ASK, 10kbps FSK
Output Power to 10dBm
Low external part count
Low standby current <1µA
Low voltage operation (down to 1.8V)
Operate with crystals or ceramic resonators
Applications
•
•
•
•
•
•
Remote Keyless Entry Systems (RKE)
Remote Control (STB, HVAC and Appliances)
Garage Door Opener Transmitters
Remote Sensor Data Links
Infrared Transmitter Replacement
Tire Pressure Monitor System (TPMS)
Ordering Information
Part Number
MICRF112YMM
Temp. Range
–40°C to +125°C
Package
10-Pin MSOP
QwikRadio is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
March 2008
M9999-031008
(408) 944-0800
Micrel, Inc.
MICRF112
Absolute Maximum Ratings
(Note 1)
Supply Voltage VDD ...................................................+5.0V
Voltage on PAOUT......................................................+7.2V
Voltage on I/O Pins ............................ VSS–0.3 to VDD+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 VDD ........................................ 1.8V to 3.6V
Ambient Operating Temperature (TA) ...... –40°C to +125°C
Programmable Transmitter Frequency Range:
....................................................... 300MHz to 450MHz
Electrical Characteristics
(Note 4)
Specifications apply for VDD = 3.0V, TA = 25°C, Freq
REFOSC
= 13.560MHz, EN = VDD. Bold values indicate –40°C to 125°C unless
otherwise noted. 1kbps data rate 50% duty cycle. RL 50ohm load (matched)
Parameter
Power Supply
Standby supply current, Iq
Mark Supply Current I
ON
SPACE supply current, I
OFF
EN = V
SS
@ 315MHz, P
OUT
= +10dBm
@ 433.92MHz, P
OUT
= +10dBm
@ 315MHz
@ 433.92 MHz
RF Output Section and Modulation Limits:
Output power level, P
OUT
FSK or ASK "mark"
Harmonics output for 315
MHz
Harmonics output for
433.92 MHz
Extinction ratio for ASK
FSK Modulation
Frequency Deviation
Data Rate
ASK Modulation
Data Rate
Occupied Bandwidth
VCO Section
315 MHz Single Side Band
Phase Noise
433.92 MHz Single Side
Band Phase Noise
Reference Oscillator Section
XTLIN, XTLOUT, XTLMOD
External Capacitance
Oscillator Startup Time
Note 5
Condition
Min
Typ
.05
12.3
12.5
2
2
10
10
-39
-53
-55
-55
70
Max
1µA
Units
µA
mA
mA
mA
mA
dBm
dBm
dBc
dBc
dBc
dBc
dBc
kHz
@315MHz,
Note 4
@433.92MHz,
@ 630MHz,
@945MHz,
Note 4
Note 4
Note 4
2nd harm.
2nd harm.
3rd harm.
3rd harm.
@ 867.84MHz,
@1301.76MHz,
Note 4
Note 4
load capacitor = 10pF, crystal type = HC49/U
22
10
50
kbps
kbps
kHz
kHz
dBc/Hz
dBc/Hz
dBc/Hz
dBc/Hz
pF
pF
µs
@315MHz, Note 6
@433.92MHz, Note 6
@ 100kHz from Carrier
@ 1000kHz from Carrier
@ 100kHz from Carrier
@ 1000kHz from Carrier
Pin capacitance
See Schematic C17 & C18
Crystal: HC49S
<700
<1000
-76
-79
-72
-81
2
18
300
Digital / Control Section
Output Blanking
STDBY transition from LOW to HIGH
500
µs
March 2008
4
M9999-031008
(408) 944-0800
Micrel, Inc.
MICRF112
Electrical Characteristics (cont.)
Parameter
Digital Input (EN, ASK and
FSK)
Digital Input Leakage
Current
(EN, ASK and FSK Pins)
Under Voltage Lock Out
(UVLO)
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. Measured using Test Circuit in Figure 2.
Note 5. Dependent on crystal
Note 6. RBW = 100kHz, OBW measured at -20dBc.
Condition
High (V
IH
)
Low (V
IL
)
High (V
IH
)
Low (V
IL
)
Min
0.8×V
DD
Typ
Max
0.2×V
DD
Units
V
V
µA
µA
V
0.05
0.05
1.6
March 2008
5
M9999-031008
(408) 944-0800
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