WIRELESS
DATASHEET
IA4420 Universal ISM Band
FSK Transceiver
DESCRIPTION
Integration’s IA4420 is a single chip, low power, multi-channel FSK transceiver
designed for use in applications requiring FCC or ETSI conformance for unlicensed
use in the 315, 433, 868 and 915 MHz bands. The IA4420 transceiver is a part of
Integration’s EZRadio
TM
product line, which produces a flexible, low cost, and
highly integrated solution that does not require production alignments. The chip
is a complete analog RF and baseband transceiver including a multi-band PLL
synthesizer with PA, LNA, I/Q down converter mixers, baseband filters and
amplifiers, and an I/Q demodulator. All required RF functions are integrated.
Only an external crystal and bypass filtering are needed for operation.
The IA4420 features a completely integrated PLL for easy RF design, and its rapid
settling time allows for fast frequency-hopping, bypassing multipath fading and
interference to achieve robust wireless links. The PLL’s high resolution allows the
usage of multiple channels in any of the bands. The receiver baseband bandwidth
(BW) is programmable to accommodate various deviation, data rate and crystal
tolerance requirements. The transceiver employs the Zero-IF approach with I/Q
demodulation. Consequently, no external components (except crystal and
decoupling) are needed in most applications.
The IA4420 dramatically reduces the load on the microcontroller with the
integrated digital data processing features: data filtering, clock recovery, data
pattern recognition, integrated FIFO and TX data register. The automatic frequency
control (AFC) feature allows the use of a low accuracy (low cost) crystal. To
minimize the system cost, the IA4420 can provide a clock signal for the
microcontroller, avoiding the need for two crystals.
For low power applications, the IA4420 supports low duty cycle operation based
on the internal wake-up timer.
IA4420
PIN ASSIGNMENT
revC and later
SDI
SCK
nSEL
SDO
nIRQ
FSK / DATA / nFFS
DCLK / CFIL / FFIT
CLK
nINT / VDI
ARSSI
VDD
RF1
RF2
VSS
nRES
XTL / REF
See back page for ordering information.
FEATURES
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Fully integrated (low BOM, easy design-in)
No alignment required in production
Fast-settling, programmable, high-resolution PLL synthesizer
Fast frequency-hopping capability
High bit rate (up to 115.2 kbps in digital mode and 256 kbps
in analog mode)
Direct differential antenna input/output
Integrated power amplifier
Programmable TX frequency deviation (15 to 240 KHz)
Programmable RX baseband bandwidth (67 to 400 kHz)
Analog and digital RSSI outputs
Automatic frequency control (AFC)
Data quality detection (DQD)
Internal data filtering and clock recovery
RX synchron pattern recognition
SPI compatible serial control interface
Clock and reset signals for microcontroller
16 bit RX Data FIFO
Two 8 bit TX data registers
Low power duty cycle mode
Standard 10 MHz crystal reference
Wake-up timer
2.2 to 5.4 V supply voltage
Low power consumption
Low standby current (0.3
µA)
Compact 16 pin TSSOP package
FUNCTIONAL BLOCK DIAGRAM
MIX
I
DCLK /
CFIL /
FFIT /
FSK /
DATA /
nFFS
AMP
OC
clk
I/Q
DEMOD
Data Filt
CLK Rec
7
RF1 13
LNA
RF2 12
MIX
Q
Self cal.
data
6
AMP
OC
FIFO
PA
TYPICAL APPLICATIONS
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Remote control
Home security and alarm
Wireless keyboard/mouse and other PC peripherals
Toy controls
Remote keyless entry
Tire pressure monitoring
Telemetry
Personal/patient data logging
Remote automatic meter reading
PLL & I/Q VCO
with cal.
RF Parts
BB Amp/Filt./Limiter
RSSI
COMP
DQD
AFC
Data processing units
CLK div
Xosc
WTM
with cal.
LBD
Low Power parts
Controller
Bias
8
CLK
9
XTL /
REF
15
ARSSI
1
SDI
2
SCK
3
4
5
nIRQ
10
nRES
16
nINT /
VDI
11
VSS
14
VDD
nSEL SDO
1
IA4420-DS Rev 1.4r 0705
PRELIMINARY
www.integration.com
IA4420
DETAILED FEATURE-LEVEL DESCRIPTION
The
IA4420 FSK transceiver is designed to cover the unlicensed
frequency bands at 315, 433, 868 and 915 MHz. The devices
facilitate compliance with FCC and ETSI requirements.
The receiver block employs the Zero-IF approach with I/Q
demodulation, allowing the use of a minimal number of external
components in a typical application. The IA4420 incorporates a
fully integrated multi-band PLL synthesizer, PA with antenna tuning,
an LNA with switchable gain, I/Q down converter mixers, baseband
filters and amplifiers, and an I/Q demodulator followed by a data
filter.
PLL
The programmable PLL synthesizer determines the operating
frequency, while preserving accuracy based on the on-chip crystal-
controlled reference oscillator. The PLL’s high resolution allows the
usage of multiple channels in any of the bands.
The RF VCO in the PLL performs automatic calibration, which requires
only a few microseconds. Calibration always occurs when the
synthesizer starts. If temperature or supply voltage changes
significantly, VCO recalibration can be invoked easily. Recalibration
can be initiated at any time by switching the synthesizer off and
back on again.
Data Filtering and Clock Recovery
Output data filtering can be completed by an external capacitor or by
using digital filtering according to the final application.
Analog operation: The filter is an RC type low-pass filter followed
by a Schmitt-trigger (St). The resistor (10 kOhm) and the St are
integrated on the chip. An (external) capacitor can be chosen according
to the actual bit rate. In this mode, the receiver can handle up to 256
kbps data rate. The FIFO can not be used in this mode and clock is
not provided for the demodulated data.
Digital operation: A digital filter is used with a clock frequency at
29 times the bit rate. In this mode there is a clock recovery circuit
(CR), which can provide synchronized clock to the data. Using this
clock the received data can fill a FIFO. The CR has three operation
modes: fast, slow, and automatic. In slow mode, its noise immunity
is very high, but it has slower settling time and requires more accurate
data timing than in fast mode. In automatic mode the CR automatically
changes between fast and slow mode. The CR starts in fast mode,
then after locking it automatically switches to slow mode
(Only the digital data filter and the clock recovery use the bit rate
clock. For analog operation, there is no need for setting the correct
bit rate.)
RF Power Amplifier (PA)
The power amplifier has an open-collector differential output and
can directly drive a loop antenna with a programmable output power
level. An automatic antenna tuning circuit is built in to avoid costly
trimming procedures and the so-called “hand effect.”
LNA
The LNA has 250 Ohm input impedance, which functions well with
the proposed antennas (see: Application Notes available from
http://www.integration.com)
If the RF input of the chip is connected to 50 Ohm devices, an
external matching circuit is required to provide the correct matching
and to minimize the noise figure of the receiver.
The LNA gain can be selected (0, –6, –14, –20 dB relative to the
highest gain) according to RF signal strength. It can be useful in an
environment with strong interferers.
Baseband Filters
The receiver bandwidth is selectable by programming the bandwidth
(BW) of the baseband filters. This allows setting up the receiver
according to the characteristics of the signal to be received.
An appropriate bandwidth can be chosen to accommodate various
FSK deviation, data rate and crystal tolerance requirements. The
filter structure is 7th order Butterworth low-pass with 40 dB
suppression at 2*BW frequency. Offset cancellation is done by
using a high-pass filter with a cut-off frequency below 7 kHz.
2
IA4420
Data Validity Blocks
RSSI
A digital RSSI output is provided to monitor the input signal level. It
goes high if the received signal strength exceeds a given
preprogrammed level. An analog RSSI signal is also available. The
RSSI settling time depends on the external filter capacitor. Pin 15 is
used as analog RSSI output. The digital RSSI can be can be monitored
by reading the status register.
Analog RSSI Voltage vs. RF Input Power
When the microcontroller turns the crystal oscillator off by clearing
the appropriate bit using the
Configuration Setting Command,
the
chip provides a fixed number (196) of further clock pulses (“clock
tail”) for the microcontroller to let it go to idle or sleep mode.
Low Battery Voltage Detector
The low battery detector circuit monitors the supply voltage and
generates an interrupt if it falls below a programmable threshold
level. The detector circuit has 50 mV hysteresis.
Wake-Up Timer
P1
RSSI
voltage
[V]
The wake-up timer has very low current consumption (1.5 uA typical)
and can be programmed from 1 ms to several days with an accuracy
of ±5%.
It calibrates itself to the crystal oscillator at every startup, and then
at every 30 seconds. When the crystal oscillator is switched off, the
calibration circuit switches it back on only long enough for a quick
calibration (a few milliseconds) to facilitate accurate wake-up timing.
P3
P2
P4
Input Power [dBm]
Event Handling
P1
P2
P3
P4
-65 dBm
-65 dBm
-100 dBm
-100 dBm
1300 mV
1000 mV
600 mV
300 mV
In order to minimize current consumption, the transceiver supports
different power saving modes. Active mode can be initiated by several
wake-up events (negative logical pulse on nINT input, wake-up timer
timeout, low supply voltage detection, on-chip FIFO filled up or
receiving a request through the serial interface).
If any wake-up event occurs, the wake-up logic generates an interrupt
signal, which can be used to wake up the microcontroller, effectively
reducing the period the microcontroller has to be active. The source
of the interrupt can be read out from the transceiver by the
microcontroller through the SDO pin.
DQD
The Data Quality Detector is based on counting the spikes on the
unfiltered received data. For correct operation, the “DQD threshold”
parameter must be filled in by using the
Data Filter Command.
Interface and Controller
AFC
By using an integrated Automatic Frequency Control (AFC) feature,
the receiver can minimize the TX/RX offset in discrete steps, allowing
the use of:
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Inexpensive, low accuracy crystals
Narrower receiver bandwidth (i.e. increased sensitivity)
Higher data rate
An SPI compatible serial interface lets the user select the frequency
band, center frequency of the synthesizer, and the bandwidth of the
baseband signal path. Division ratio for the microcontroller clock,
wake-up timer period, and low supply voltage detector threshold are
also programmable. Any of these auxiliary functions can be disabled
when not needed. All parameters are set to default after power-on;
the programmed values are retained during sleep mode. The interface
supports the read-out of a status register, providing detailed
information about the status of the transceiver and the received
data.
The transmitter block is equipped with an 8 bit wide TX data register.
It is possible to write 8 bits into the register in burst mode and the
internal bit rate generator transmits the bits out with the predefined
rate.
It is also possible to store the received data bits into a FIFO register
and read them out in a buffered mode.
Crystal Oscillator
The IA4420 has a single-pin crystal oscillator circuit, which provides
a 10 MHz reference signal for the PLL. To reduce external parts and
simplify design, the crystal load capacitor is internal and
programmable. Guidelines for selecting the appropriate crystal can
be found later in this datasheet.
The transceiver can supply the clock signal for the microcontroller;
so accurate timing is possible without the need for a second crystal.
3
IA4420
PACKAGE PIN DEFINITIONS
Pin type key: D=digital, A=analog, S=supply, I=input, O=output, IO=input/output
SDI
SCK
nSEL
SDO
nIRQ
FSK / DATA / nFFS
DCLK / CFIL / FFIT
CLK
nINT / VDI
ARSSI
VDD
RF1
RF2
VSS
nRES
XTL / REF
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Name
SDI
SCK
nSEL
SDO
nIRQ
FSK
DATA
nFFS
DLCK
CFIL
FFIT
CLK
XTL
REF
nRES
VSS
RF2
RF1
VDD
ARSSI
nINT
VDI
Type
DI
DI
DI
DO
DO
DI
DO
DI
DO
AIO
DO
DO
AIO
AIO
DIO
S
AIO
AIO
S
AO
DI
DO
Function
Data input of the serial control interface (SPI compatible)
Clock input of the serial control interface
Chip select input of the serial control interface (active low)
Serial data output with bus hold
Interrupt request output (active low)
Transmit FSK data input
Received data output (FIFO not used)
FIFO select input (active low) In FIFO mode, when bit
ef
is set in
Configuration Setting Command
Received data clock output (Digital filter used, FIFO not used)
External data filter capacitor connection (Analog filter used)
FIFO interrupt (active high) Number of the bits in the RX FIFO that reach the preprogrammed limit
In FIFO mode, when bit
ef
is set in
Configuration Setting Command
Microcontroller clock output
Crystal connection (the other terminal of crystal to VSS) or external reference input
External reference input. Use 33 pF series coupling capacitor
Open drain reset output with internal pull-up and input buffer (active low)
Ground reference voltage
RF differential signal input/output
RF differential signal input/output
Positive supply voltage
Analog RSSI output
Interrupt input (active low)
Valid data indicator output
Note: The actual mode of the multipurpose pins (pin 6 and 7) is determined by the TX/RX data I/O settings of the
transceiver.
4
IA4420
Typical Application
Typical application with FIFO usage
VCC
C1
1u
C2
100p
C3
10p
Microcontroller
P7
P6
P5
P4
P3
P2
P1
P0
CLKin
nRES
VDI
SDI
SCK
nSEL
SDO
nIRQ
nFFS
FFIT
CLK
nRES
(optional)
1
2
3
4
5
(optional)
(optional)
(optional)
(optional)
6
7
8
16
15
14
13
12
11
10
9
TP
(optional)
C4
2.2n
IA4420
X1
10MHz
PCB
Antenna
Pin 6
Transmit mode
el=0 in
Configuration Setting Command
Transmit mode
el=1 in
Configuration Setting Command
Receive mode
ef=0 in
Configuration Setting Command
Receive mode
ef=1 in
Configuration Setting Command
TX Data input
Connect to logic high
RX Data output
nFFS input
Pin 7
-
-
RX Data clock output
FFIT output
5
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