September 2002

MICRF102

Micrel

MICRF102

QwikRadioTM UHF ASK Transmitter

Final Information

General Description

The MICRF102 is a single chip Transmitter IC for remote
wireless applications. The device employs Micrel's latest
QwikRadioTM technology. This device is a true "data-in,
antenna-out" monolithic device. All antenna tuning is accom-
plished 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 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 MICRF102 provides the lowest cost and most reliable
remote actuator and RF link system available.

Typical Application

VDD

VSS

REFOSC

ASK

MICRF102

ASK DATA INPUT

RP2
6.8k

0.1

4.7

RP1
100k

+5V

ANTP

ANTM

STBY

LOOP

ANTENNA

(PCB TRACE)

100k

Figure 1

Features

ˇ Complete UHF transmitter on a monolithic chip
ˇ Frequency range 300MHz to 470MHz
ˇ Data rates to 20kbps
ˇ Automatic antenna alignment, no manual adjustment
ˇ Low external part count
ˇ Low standby current <0.04

Applications

ˇ Remote Keyless Entry Systems (RKE)
ˇ Remote Fan/Light Control
ˇ Garage Door Opener Transmitters
ˇ Remote Sensor Data Links

Ordering Information

Part Number

Temperature Range

Package

MICRF102BM

C to +85

8-Pin SOIC

Micrel, Inc. ˇ 1849 Fortune Drive ˇ San Jose, CA 95131 ˇ USA ˇ tel + 1 (408) 944-0800 ˇ fax + 1 (408) 944-0970 ˇ 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

MICRF102

Micrel

MICRF102

September 2002

Pin Description

Pin Number

Pin Name

Pin Function

Power Control Input. The voltage at this pin should be set between 0.15V to
0.35V for normal operation.

VDD

Positive power supply input for the IC.

VSS

This pin is the ground return for the IC. A power supply bypass capacitor
connected from VDD to VSS should have the shortest possible path.

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

STBY

Input for transmitter stand by control pin is pulled to VDD for transmit
operation and VSS for stand-by mode.

ANTM

Negative RF power output to drive the low side of the transmit loop antenna

ANTP

Positive RF power output to drive the high side of the transmit loop antenna

ASK

Amplitude Shift Key modulation data input pin. For CW operation, connect
this pin to VDD

Pin Configuration

VDD

VSS

REFOSC

ASK

ANTP

ANTM

STBY

MICRF102BM

September 2002

MICRF102

Micrel

Electrical Characteristics

Specifications apply for 4.75V < V

< 5.5V, V

= 0.35V, T

= 25

C, freq

REFOSC

= 12.1875MHz, STBY = V

. Bold values indicate

C unless otherwise noted.

Parameter

Condition

Min

Typ

Max

Units

Power Supply

Standby Supply Current, I

STBY

< 0.5V, V

ASK

< 0.5V

or V

ASK

> V

0.5V

0.04

MARK Supply Current, I

@315MHz, Note 4

10.5

@433MHz, Note 4

SPACE Supply Current, I

OFF

@315MHz

@433MHz

8.5

Mean Operating Current

33% mark/space ratio at 315MHz, Note 4

4.7

33% mark/space ratio at 433MHz, Note 4

6.7

RF Output Section and Modulation Limits:

Output Power Level, P

OUT

@315MHz; Note 4, Note 5

tbd

dBm

@433MHz; Note 4, Note 5

tbd

dBm

Transmitted Power

@315MHz

tbd

V/m

@433MHz

tbd

V/m

Harmonics Output, Note 10

@ 315MHz

2nd harm.

dBc

3rd harm.

@433 MHz

2nd harm.

dBc

3rd harm.

Extinction Ratio for ASK

dBc

Varactor Tuning Range

Note 7

Reference Oscillator Section

Reference Oscillator Input

300

Impedance

Reference Oscillator Source

Current

Reference Oscillator Input

0.2

0.5

Voltage (peak to peak)

Absolute Maximum Ratings

(Note 1)

Supply Voltage(V

) ..................................................... +6V

Voltage on I/O Pins ............................. V

0.3 to V

+0.3

Storage Temperature Range .................. 65

C to + 150

Lead Temperature (soldering, 10 seconds) ........... + 300

ESD Rating .............................................................. Note 3

Operating Ratings

(Note 2)

Supply Voltage (V

) .................................... 4.75V to 5.5V

Maximum Supply Ripple Voltage ............................... 10mV

PC Input Range .............................. 150mV < V

< 350mV

Ambient Operating Temperature (T

) ............ 0

C to +85

Programmable Transmitter Frequency Range:

.................................................... 300MHz to 470MHz

MICRF102

Micrel

MICRF102

September 2002

Parameter

Condition

Min

Typ

Max

Unit

Digital / Control Section

Calibration Time

Note 8, ASK=HIGH

Power Amplifier Output Hold Off

Note 9, STDBY transition from LOW to HIGH

Time from STBY

Crystal, ESR < 20

Transmitter Stabilization Time

From External Reference (500mVpp)

from STBY

Crystal, ESR < 20

Maximum Data Rate

ASK modulation

Duty cycle of the modulating signal = 50%

kbits/s

STBY

Enable voltage

0.75V

0.6V

STBY Sink Current

STBY

= V

6.5

ASK pin

, input high voltage

0.75V

0.6V

, input low voltage

0.3V

0.25V

ASK input current

ASK = 0V, 5.0V input current

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. 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

= 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.

Part Number MICRF102