February 9, 2000

1

MICRF004/RF044

MICRF004/RF044

Micrel

MICRF004

QwikRadio™ Low-Power VHF Receiver

Advance Information

Typical Application

SEL0

SEL0

SWEN

VSSRF

REFOSC

VSSRF

SEL1

ANT

CAGC

VDDRF

WAKEB

VDDBB

SHUT

CTH

DO

NC

VSSBB

0.047µF

4.85MHz

(ceramic resonator)

Data

Output

MICRF004

4.7µF

+5V

150MHz 1200b/s On-Off Keyed Receiver

Features

• Complete VHF receiver on a monolithic chip

• 140MHz to 200MHz frequency range

• >200 meters typical range with monopole antenna

• 2.5kb/s sweep- and 10kb/s fixed-mode data rates

• Automatic tuning, no manual adjustment

• No filters or inductors required

• Low 240

µA operating supply current at 150MHz

(10:1 duty cycle)

• Shutdown mode for >100:1 duty-cycle operation

• Wakeup for enabling decoders and microprocessors

• Very low RF antenna reradiation

• CMOS logic interface for standard ICs

• Extremely low external part count

Applications

• Automotive remote keyless entry

• Long range RF identification

• Remote fan and light control

• Garage door and gate openers

Ordering Information

Part Number

Junction Temp. Range

Package

MICRF004BM

–40

°C to +85°C

16-Lead SOP

MICRF004BN

–40

°C to +85°C

16-Pin DIP

8-pin versions available. See “Custom 8-Pin Options,” following page.

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.

General Description

The MICRF004 QwikRadio™ VHF receiver is a single-chip

OOK (on-off keyed) receiver IC for remote wireless applica-

tions. This device is a true single-chip, “antenna-in, data-out”

device. All RF and IF tuning is accomplished automatically

within the IC which eliminates manual tuning production

costs and results in a highly reliable, extremely low-cost

solution for high-volume wireless applications.

The MICRF004 is extremely easy to apply, minimizing design

and production costs, and improving time to market. The

MICRF004 provides two fundamental modes of operation,

fixed and sweep.

In fixed mode, the device functions as a conventional super-

heterodyne receiver with an internal local oscillator operating

at a single frequency based on an external reference crystal

or clock. Fixed mode is for use with accurately-controlled

transmitters utilizing crystal or SAW (surface acoustic wave)

resonators.

In sweep mode, the MICRF004 sweeps the internal local

oscillator at rates greater than the baseband data rate. This

effectively broadens the RF bandwidth of the receiver to a

value equivalent to conventional superregenerative receiv-

ers. This allows the MICRF004 to operate with less expensive

LC transmitters without additional components or tuning,

even though the receiver topology is still superheterodyne. In

this mode the reference crystal can be replaced with a less

expensive

±0.5% ceramic resonator.

The MICRF004 features a shutdown control, which may be

used for duty-cycled operation, and a wake-up output, which

provides a logical indication of an incoming RF signal. These

features make the MICRF004 ideal for low- and ultra-low-

power applications, such as RKE (remote keyless entry) and

RFID (RF identification).

Since all post-detection (demodulator) data filtering is pro-

vided on the MICRF004, no external filters are required. One

of the four internal filter bandwidths must be externally

selected based on data rate and code modulation format.

Bandwidths range in binary steps, from 0.55kHz to 4.4kHz

(sweep mode) or 1.1kHz to 8.8kHz (fixed mode).