Micrel Inc.

1849 Fortune Drive San Jose, Ca 95131

USA

tel + 1 (408) 944-0800

fax + 1 (408) 944-0970

http://www.micrel.com

MICRF002 / 022

QwikRadio

Low Power UHF Receiver

Preliminary Information

General Description

The MICRF002, an enhanced version of the MICRF001 and MICRF011,
is a single chip OOK (ON-OFF Keyed) Receiver IC for remote wireless
applications, employing Micrel's latest QwikRadio

technology. This

device is a true "antenna-in, data-out" monolithic device. All RF and IF
tuning is accomplished automatically within the IC, which eliminates
manual tuning and reduces production costs. Receiver functions are
completely integrated. The result is a highly reliable yet extremely low
cost solution for high volume wireless applications. Because the
MICRF002 is a true single-chip radio receiver, it is extremely easy to
apply, minimizing design and production costs, and improving time to
market.

The MICRF002 provides two fundamental modes of operation, FIXED
and SWP. In FIXED mode, the device functions like a conventional
superheterodyne receiver, with an (internal) local oscillator fixed at a
single frequency based on an external reference crystal or clock. As with
any conventional superheterodyne receiver, the transmit frequency must
be accurately controlled, generally with a crystal or SAW (Surface
Acoustic Wave) resonator.

In SWP mode, the MICRF002 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
super-regenerative receivers. Thus the MICRF002 can 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 MICRF002 provides two feature enhancements over the
MICRF001/011, (1) a Shutdown Mode, which may be used for duty-
cycle operation, and (2) a "Wakeup" function, which provides a logical
indication of an incoming RF signal. These features make the
MICRF002 ideal for low and ultra-low power applications, such as RKE
and RFID.

All post-detection (demodulator) data filtering is provided on the
MICRF002, so no external filters need to be designed. Any one of four
filter bandwidths may be selected externally by the user. Bandwidths
range in binary steps, from 0.625kHz to 5kHz (SWP mode) or 1.25kHz to
10kHz (FIXED mode). The user only needs to program the appropriate
filter selection based on data rate and code modulation format.

Features

Complete UHF receiver on a monolithic chip

Frequency range 300 to 440 MHz

Typical range over

200 meters with monopole

antenna

Data rates to 2.5kbps (SWP), 10kbps (FIXED)

Automatic tuning, no manual adjustment

No Filters or Inductors required

Low Operating Supply Current--240

A at 315MHz

(10:1 Duty Cycle)

Shutdown Mode for Duty-Cycle Operation in excess
of 100:1

Wakeup Function to Enable External Decoders and
Microprocessors

Very low RF re-radiation at the antenna

CMOS logic interface to standard decoder and
microprocessor ICs

Extremely low external part count

Applications

Automotive Remote Keyless Entry

Long Range RFID

Remote Fan/Light Control

Garage Door/Gate Openers

Typical Operating Circuit

385.5 MHz, 1200 bps OOK RECEIVER

QwikRadio

July 1999

MICRF002

MICRF002

Micrel

Pin Description (Pin numbers for the 8-pin version are identified in parentheses)

Pin Number

Pin Name

Pin Function

SEL0

This pin, in conjunction with SEL1, programs the desired Demodulator Filter Bandwidth. This pin is
internally pulled-up to VDD. See Table 1.

2/3

VSSRF

This pin is the ground return for the RF section of the IC. The bypass capacitor connected from VDDRF to
VSSRF should have the shortest possible lead length. For best performance, connect VSSRF to VSSBB
at the power supply only (i.e., keep VSSBB currents from flowing through VSSRF return path).

(1)

VSS

This pin is the ground return for the IC. The bypass capacitor connected from VDD to VSS should have
the shortest possible lead length.

(2)

ANT

This is the receive RF input, internally ac-coupled. Connect this pin to the receive antenna. Input
impedance is high (FET gate) with approximately 2pF of shunt (parasitic) capacitance. For applications
located in high ambient noise environments, a fixed value band-pass network may be connected between
the ANT pin and VSSRF to provide additional receive selectivity and input overload protection. (See
"Application Note TBD".)

VDDRF

This pin is the positive supply input for the RF section of the IC. VDDBB and VDDRF should be connected
directly at the IC pins. Connect a low ESL, low ESR decoupling capacitor from this pin to VSSRF, as short
as possible.

VDDBB

This pin is the positive supply input for the baseband section of the IC. VDDBB and VDDRF should be
connected directly at the IC pins.

(3)

VDD

This pin is the positive supply input for the IC. Connect a low ESL, low ESR decoupling capacitor from this
pin to VSSRF, as short as possible.

(4)

CTH

This capacitor extracts the (DC) average value from the demodulated waveform, which becomes the
reference for the internal data slicing comparator. Treat this as a low-pass RC filter with source impedance
of 118k

(for REFOSC frequency ft = 4.90MHz, see Note 5). A standard

20% X7R ceramic capacitor is

generally sufficient.

N/C

Unused Pin

VSSBB

This is the ground return for the baseband section of the IC. The bypass and output capacitors connected
to VSSBB should have the shortest possible lead lengths. For best performance, connect VSSRF to
VSSBB at the power supply only (i.e., keep VSSBB currents from flowing through VSSRF return path).

(5)

The output data signal. CMOS level compatible.

(6)

SHUT

A logic input for Shutdown Mode control. Pull this pin low to place the IC into operation. This pin in
internally pulled-up to VDD.

WAKEB

An output signal, active low when the IC detects an incoming RF signal, determined by monitoring for data
preamble. CMOS level compatible.

(7)

CAGC

Integrating capacitor for on-chip AGC (Automatic Gain Control). The Decay/Attack time-constant (TC) ratio
is nominally set as 10:1. Use of 0.47uF or greater is strongly recommended for best range performance.
Use low-leakage type capacitors for duty-cycle operation (Dip Tantalum, Ceramic, Polyester). (See
"Application Note TBD.)

SEL1

This pin, in conjunction with SEL0, programs the desired Demodulator Filter Bandwidth. This pin in
internally pulled-up to VDD. See Table 1.

(8)

REFOSC

This is the timing reference for on-chip tuning and alignment. Connect either a ceramic resonator or crystal
(mode dependent) between this pin and VSSBB, or drive the input with an AC coupled 0.5Vpp input clock.
Use ceramic resonators without integral capacitors. Note that if operating in FIXED mode, a crystal must
be used; however in SWP mode, one may use either a crystal or ceramic resonator. See "Application Note
TBD" for details on frequency selection and accuracy.

SWEN

This logic pin controls the operating mode of the MICRF002. When SWEN = HIGH, the MICRF002 is in
SWP mode. When SWEN = LOW, the device operates as a conventional single-conversion
superheterodyne receiver. (See "Application Note TBD" for details.) This pin is internally pulled-up to VDD.

SEL0

SEL1

Demodulator Bandwidth (Hz)

SWP Mode FIXED Mode

5000 10000

2500 5000

1250 2500

625 1250

Table 1

Nominal Demodulator (Baseband) Filter Bandwidth

vs. SEL0, SEL1 and Mode

QwikRadio

July 1999

MICRF002

MICRF002

Micrel

ABSOLUTE MAXIMUM RATINGS

Supply Voltage (VDDRF, VDDBB)..................................+7V
Voltage on any I/O Pin........................VSS-0.3 to VDD+0.3
Junction Temperature..............................................+150

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

C to + 150

Lead Temperature (soldering, 10 seconds)..............+ 260

Operating Ratings

Supply Voltage (VDDRF, VDDBB)..................4.75V to 5.5V
Ambient Operating Temperature (T

)............-40

C to +85

Package Thermal Resistance

(16 Pin DIP).........90

C/W

Package Thermal Resistance

(16 Pin SOIC)....120

C/W

This device is ESD sensitive: Meets Class 1ESD
test requirements (Human body Model, HBM), in
accordance with MIL-STD-883C, Method 3015. Do
not operate or store near strong electrostatic
fields. Use appropriate ESD precautions.

Electrical Characteristics

Unless otherwise stated, these specifications apply for Ta = -40

C to 85

C, 4.75<VDD<5.5V. All voltages are with respect to

Ground; Positive currents flow into device pins. CAGC = 4.7µF, CTH = .047µF, VDDRF= VDDBB = VDD. REFOSC
frequency = 4.90MHz.

Parameter

Test Conditions

MIN

TYP

MAX

UNITS

Power Supply

Operating Current

Continuous Operation

2.4

Operating Current

10:1 Duty Cycle

240

Standby Current

SHUT = VDD

0.5

RF/IF Section
Receiver Sensitivity

Note 1, 3

-103

dBm

IF Center Frequency

Note 4

0.86

MHz

IF 3dB Bandwidth

Note 3, 4

0.43

MHz

RF Input Range

300

440

MHz

Receive Modulation Duty-Cycle

Maximum Receiver Input

Rsc = 50

-20

dBm

Spurious Reverse Isolation

ANT pin, Rsc = 50

Note 2

Vrms

AGC Attack / Decay ratio

T(Attack) / T(Decay)

0.1

AGC Leakage Current

Ta = 85

100

Local Oscillator Stabilization Time

To 1% of Final Value

2.5

msec

Demod Section
CTH Source Impedance

Note 5

118k

CTH Source Impedance Variation

-15

+15

CTH Leakage Current

Ta = 85

100

Demod Filter Bandwidth

SEL0 = SEL1 = SWEN = VDD, Note 4, 6

4160

Demod Filter Bandwidth

SEL0 = SEL1 = VDD, SWEN = VSS
Note 4, 6

8320

Digital/Control Section
REFOSC Input Impedance

200k

Input Pull up Current

SEL0, SEL1, SWEN, SHUT=VSS

µA

Input High Voltage

SEL0, SEL1, SWEN

0.8VDD

Input Low Voltage

SEL0, SEL1, SWEN

0.2VDD

Output Current

DO, WAKEUP pins, Push-Pull

µA

Output High Voltage

DO, WAKEUP pins, Iout = -1µA

0.9VDD

Output Low Voltage

DO. WAKEUP pins, Iout = +1µA

0.1VDD

Output Tr, Tf

DO, WAKEUP pins, Cload=15pF

µsec

QwikRadio

July 1999

MICRF002

MICRF002

Micrel

Note 1: Sensitivity is defined as the average signal level measured at the input necessary to achieve 10e-2 Bit Error Rate (BER). The

input signal is defined as a return-to-zero (RZ) waveform with 50% average duty cycle (e.g., Manchester Encoded Data) at a
data rate of 300bps. The RF input is assumed to be matched into 50

Note 2: Spurious reverse isolation represents the spurious components which appear on the RF input (ANT) pin measured into 50

with an input RF matching network.

Note 3: Sensitivity, a commonly specified Receiver parameter, provides an indication of the Receiver's input referred noise, generally

input thermal noise. However, it is possible for a more sensitive receiver to exhibit range performance no better than that of a
less sensitive receiver, if the "ether" noise is appreciably higher than the thermal noise. "Ether" noise refers to other interfering
"noise" sources, such as FM radio stations, pagers, etc.

A better indicator of achievable receiver range performance is usually given by its Selectivity, often stated as Intermediate
Frequency (IF) or Radio Frequency (RF) bandwidth, depending on receiver topology. Selectivity is a measure of the rejection
by the receiver of "ether" noise. More selective receivers will almost invariably provide better range. Only when the receiver
selectivity is so high that most of the noise on the receiver input is actually thermal will the receiver demonstrate sensitivity-
limited performance.

Note 4: Parameter scales linearly with REFOSC frequency ft. For any REFOSC frequency other than 4.90MHz, compute new

parameter value as the ratio [(REFOSC FREQ (in MHz) / 4.90] * [Parameter Value @ 4.90MHz]. Example: For REFOSC
Freq. ft = 6.00MHz, [Parameter Value @ 6.00MHz] = (6.00 / 4.90) * [Parameter Value @ 4.90MHz].

Note 5: Parameter scales inversely with REFOSC frequency ft. For any REFOSC frequency other than 4.90MHz, compute new

parameter value as the ratio [4.90 / (REFOSC FREQ (in MHz)] * [Parameter Value @ 4.90MHz]. Example: For REFOSC
Freq. ft = 6.00MHz, [Parameter Value @ 6.00MHz] = (4.90 / 6.00) * [Parameter Value @ 4.90MHz].

Note 6: Demod filter bandwidths are related in a binary manner, so any of the (lower) nominal filter values may be derived simply by

dividing this parameter value by 2, 4, or 8 as desired.

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