November 8, 2001

1

MICRF104

MICRF104

Micrel

MICRF104

1.8V, QwikRadio™ 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

QwikRadio™ 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 QwikRadio™ 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

µF 100pF 10µF

10

µF

L1

22

µH

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