Datasheet AS3901 Datasheet (Austria Mikro Systeme International)

Page 1
AS3901 ISM 433/315 MHz
FSK/ASK Transmitter
Data Sheet Rev. 06, August 2000
Page 2
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
1
2
3
456
7
9
10
111213
14
AS3901
Supports the European 433 MHz ISM band.
No frequency pulling by (antenna) load variation due to PLL synthesizer.
Designed to be conform to EN 300 220-1 requirements.
Supports FSK (data rates 0…32 kb/s) or ASK modulation (data rates 0…20kb/s)
No data synchronization for FSK or ASK needed.
Supports clock and reset signals for the external µC.
Supports different power down modes, one without any running XTAL oscillator.
Wide supply range between 2.7 V to 5 V.
Only one XTAL and very few external elements required.
Wide operating temperature range from –40 C to +85 C.
Low TX current, typical 7 mA.
General Description
The AS3901 is a low power FSK/ (ASK) transmitter intended for the European 433 MHz and the US 315 MHz ISM band application. It uses a PLL stabilized oscillator which avoids frequency pulling by approaching the antenna with objects as it occurs at SAW resonator based transmitters.
FSK modulation is performed by an I/Q-based continuous phase FSK modulator with a well defined frequency deviation of 16 kHz. The FSK modulator is operating completely asynchronous to the TX data stream and therefore needs no data clock or other possible by switching the driving amplifier and FSK modulator on and off by an applied transmit data stream.
The µC clock frequency and the FSK frequency deviation can be kept almost constant for both frequency bands by selecting the correct scaling factors by the 433/315 pin. As external components the AS3901 needs only a reference XTAL and 5 capacitors.
STDBY
CLK
DATA
TX
GND
VDD
XTAL2
AS3901
8
NRES GNDRF ANT1 ANT2
VDDRF 433 XTAL1
TSSOP-14
Rev. 6, August 2000 Page 2 of 18
Page 3
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
Applications
Short range radio data transmission.
Remote keyless entry systems.
Security applications and alarm systems.
Domestic and consumer remote control units.
Remote metering.
Low power telemetry.
This document contains information on products under development. Austria Mikro Systeme International AG reserves the right to change or discontinue this product without notice.
Rev. 6, August 2000 Page 3 of 18
Page 4
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
XTAL2
Detector
AS3901
1 Functional Description
The AS3901 consists of a reference XTAL oscillator, a single channel RF- synthesizer, an I/Q based asynchronous continuos phase FSK modulator, a driving amplifier and a µC interface, including µC clock divider, and a power management circuitry.
XTAL1
VDD
f =433.920 MHz
433
VDDRF
10
ANT2
11
ANT1
12
GNDRF
13
NRES
14
8
9
Driving
Amplifier.
Synthesizer
Loop-
Filter
Divider
Phase
SSB signal generation
XTAL
Oscillator VCO
Clock
µC Interface + Power up/down
7
VDD
6
GND
5
TX
4
DATA
3
CLK
2
STDBY
1
13.560 MHz XTAL
Figure 1: Block diagram of the AS3901.
1.1 RF Synthesizer
The RF synthesizer is a fully integrated single channel device with internal loop filter, generating the 433 MHz or 315 MHz transmit carrier frequency fRF by a fix, 32 times, multiplication of the reference XTAL frequency f
XTAL
.
1.2 Microprocessor Clock
The microprocesor clock frequency f by 3 or 4, dependent on the 433/315 MHz selection pin to keep the µC clock frequency f
almost constant for European and US applications.
CLK
is generated by dividing the XTAL frequency f
CLK
1.3 Modulation
The FSK modulator is an I/Q modulator based continuos phase FSK modulator. The modulating NRZ data may be in the range of 0 up to 32 kbit/s. The FSK frequency deviation f is 16 kHz, independent of the data rate. It is also kept almost constant for both transmit frequency bands by selecting proper frequency deviation multiplication factors of the XTAL reference frequency by the 433/315 MHz selection pin.
The processing clock of the data source can be different from the AS3901 reference XTAL or µC clock f
and no data synchronization of the FSK modulator is required.
CLK
XTAL
Rev. 6, August 2000 Page 4 of 18
Page 5
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
1.4 Driving Amplifier
The driving amplifier has a differential open collector output optimized for driving of small, symmetrical high-impedance loop antennas. The amplifier drives a nominal RF current of 0.7 mA
.The maximal differential voltage swing is about 4 VPP. Therefore the
rms
output power ist a function of the connected load impedance. With a 2 k differential load a nominal peak output power (to the antenna) of 1 mW is obtained. Please note that the finally radiated power (from antenna) is lower and strongly dependent on the efficiency (function of the size) of the antenna to be used.
1.5 ASK Modulation
ASK modulation with a date rate upt to 20 kbits/s can be achieved by turning the driving amplifier and the FSK modulator by the TX/ASK pin on and off, where a TX/ASK = „H“ means a turned on state.
1.6 Power Management and Operation Modes
For normal operation the switching between different operation modes follows a Grey­coded scheme to avoid unwanted switching between operation modes due to inaccurate occurrence of edges of STDBY and TX/ASK.
Mode STDBY TX/ASK Function
Standby 1 1 All Off Clock generator operation 1 0 XTAL oscillator on and CLOCK output
active.
Transmit operation 0 1 XTAL oscillator, PLL, FSK modulator
running, (FSK operation or „H“ transmitted at ASK).
Turned off power 0 0 XTAL oscillator and PLL running, output
amplifier and FSK modulator off, („L“ transmitted at ASK).
1.7 µC Interface and Timing
The AS3901 contains a direct interface to a microcontroller (µC). The µC interface of the AS3901 consists of three input and two outputs pins:
„Standby input“ (STDBY). „Transmit / ASK input“ (TX/ASK). „µC reset output (Active „L“)“ (NRES). „µC clock output“ (CLK). „FSK data input“ (DATA).
These lines support the µC with the required reset, clock and data signals. Lines 1 to 4 control the AS3901 internal power on/off circuit which wakes up and shuts down the whole transmitter consisting of the AS3901 and the µC.
Figure 2 shows a typical interconnection of the AS3901 with a typical µC. Figure 3 presents a related timing for power up and down of the transmitter.
Rev. 6, August 2000 Page 5 of 18
Page 6
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
uC
I
O
O
I
I
I
I
O
O
O
TX/ASK
CLK
NRES
STDBY
standby
TX on
3 clocks
reset
init
PLLon
AS3901
STDBY
DATA
TX/ASK
STDBY DATA
TX/ASK RESETNRES CLKCLK
10k
SW
Transmit switch
Figure 2: Interconnection of the AS3901 with a typical µC.
Note: At room temperature, resistor values of 10 k are suggested for the µC interface.
For other temperatures to be calculated from figure 5.
XTon
uC
transmitting
standby
Figure 3: µC interface timing for a transmission cycle.
Note: Activating the transmit switch results in a „weak L state“ at TX/ASK. It can be overridden by the microcontroller so that the transmission cycle remains unaffected by the duration the switch is pressed. The STDBY and TX/ASK inputs have internal pullup resistors of ~100k
Rev. 6, August 2000 Page 6 of 18
Page 7
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
1.7.1 Interface Description
Wake-up sequence: TX/ASK=H, STDBY=H: Standby. All off low current state.
TX/ASKL, STDBY=H; XTAL oscillator starts up. NRES goes L, resetting (starting) the µC for
NRES returns to H, µC initializes.
plus 3 clock cycles.
tXTON
After µC is initialized, it sets STDBYL; PLL is turned on, after t
a stable RF carrier
PLLon
is generated. TX/ASKH, STDBY=L; TX is turned on, t
later the RF signal is available and data
TXON
can be transmitted. To switch the AS3901 „on“ a „push button“ with series resistance ~10-20 k can be
used to make TX/ASK = „L“. The „push-button“ must be pushed long enough (typ. > 3ms) for the µC to reset and sustain the TX/ASK „L“ state.
Standby procedure (for sleep-mode ( IDD1 <1µA): The µC outputs a „H“ to TX/ASK and STDBY. After minimal 3 CLK cycles the XTAL
oscillator will be switched off. The pull-up resistors at the AS3901 TX/ASK and STDBY inputs will sustain the sleep mode.
Note: Multiple „push buttons“ for different functions can be used.
Rev. 6, August 2000 Page 7 of 18
Page 8
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
2 Electrical Characteristics
2.1 Absolute Maximum Ratings ( non operating)
Symbol Parameter Min Max Units Note
VDD Positive supply voltage -0.5 7 V GND Negative supply voltage 0 0 V V
IN
Voltage on input pins -0.5 VDD+0.5 V ESD Electrostatic discharge 1000 V 1) T
STG
T
LEAD
Note:
1) HBM: R = 1.5 k, C = 100 pF. The pins ANT1, ANT2, XTAL1 and XTAL2 have 500 V ESD protection.
2) 260°C for 10 s (reflow and wave soldering), 360 °C for 3 s (manual soldering).
Storage temperature -55 125 °C
Lead temperature 260 °C 2)
2.2 Operating Conditions
Symbol Parameter Min Typ Max Unit Note
VDD Positive supply voltage 2.7 3.0 5.0 V GND Negative supply voltage 0 0 0 V IDD1 Supply current,
STDBY = ”H”, TX/ASK = ”H” IDD2 Supply current,
STDBY = ”H”, TX/ASK = ”L”
350 850 µA 2)
1 µA 1)
IDD3 Supply current,
7 9 mA 3)
STDBY = ”L”, TX/ASK = ”H” IDD4 Supply current,
3.5 4.5 mA 4)
STDBY = ”L”, TX/ASK = ”L” T
AMB
Note:
1) Standby: T
2) Clock generator operation: T
3) Transmit operation: T
4) Turned off TX power: T
Rev. 6, August 2000 Page 8 of 18
Ambient temperature range -40 +85 °C
= 23 °C, Synthesizer and driving amplifier are turned off.
AMB
= 23 °C XTAL oscillator and µC clock divider on. RF driving amplifier and PLL off, no
AMB
external load connected to CLK pin.
= 23 °C, Synthesizer and driving amplifier are turned on.
AMB
= 23 °C, XTAL oscillator and µC clock divider and PLL on RF driving amplifier off.
AMB
Page 9
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
2.3 Transmit Operation
T
= 23 °C, VDD = 3.0 V, unless specified otherwise.
AMB
Symbol Parameter Conditions Min Typ Max Units Note
f
RF, EU
f
RF, US
f
offset
Transmit frequency (Europe) f Transmit frequency (US) f Frequency tolerance
= 13.560 MHz 433.920 MHz 1)
XTAL
= 9.84375 MHz 315.000 MHz 1)
XTAL
After t
, no XTAL
TXON
2 kHz
tolerance.
f
CLK, EU
f
CLK, US
t
TXon
µC clock frequency (Europe) f µC clock frequency (US) f Transmitter turn on time
= 13.560 MHz 3.390 MHz
XTAL
= 9.84375 MHz 3.28125 MHz
XTAL
FSK modulator and
20 µs
driver amplifier
t
PLLon
T
XTon
Note:
1) XTAL tolerances will slightly change the typical transmit frequency.
PLL turn on time t.b.d. ms XTAL oscillator turn on time 5 ms
2.3.1 ASK Operation
T
= 23 °C, VDD = 3.0 V, unless specified otherwise.
AMB
Symbol Parameter Conditions Min Typ Max Units Note
P
OUT
,H
Available peak output power
In 2 k, STDBY = ”L”, TX/ASK = ”H”
-1.5 0 1.5 dB
1) 3)
m
P
,L
OUT
Leakage peak output power
P
3rd
OUT
Radiated third harmonic output power
P
SP
Spurious power
In 2 k, STDBY = ”L”, TX/ASK = ”L”
Antenna attenuation> 20 dB
In distance of f f
from carrier. No
XTAL
CLK
or
antenna selectivity assumed.
R
ASK
ASK data rate range
For a RF packet duty
0 20 Kb/s
cycle ≥25 %.
Note:
1) Output power depends on load impedance, differential output current is typical 0.7 mA is typical 4 VPP.
2) Measurement bandwidth (close to EN 300 220-1) see also figure 10.
3) Actual E.R.P. depends on antenna efficiency
-50 dB
-39 dB
-45 -25 dB
. Maximum differential voltage swing
rms
m
m
C
2)
2) 3)
Rev. 6, August 2000 Page 9 of 18
Page 10
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
2.3.2 FSK Operation
T
= 23 °C, VDD = 3.0 V, unless specified otherwise.
AMB
Symbol Parameter Conditions Min Typ Max Units Note
P
,FSK
OUT
Available peak output power
P
3rd
OUT
Radiated third harmonic output power
In 2 k, STDBY = ”L”, TX/ASK = ”H”
Antenna and band pass filter attenuation> 20 dB
-1.5 0 1.5 dB
-36 dB
1) 3)
m
2)
m
P
SP
Spurious power
In distance of f f
from carrier. No
XTAL
CLK
or
-45 -25 dB
C
antenna selectivity assumed.
R
FSK
f
Note:
1) Output power depends on load impedance, differential output current is typical 0.7 mAms. Maximum differential voltage
2) Measurement bandwidth (close to EN 300 220-1) see also figure 10.
3) Actual E.R.P. depends on antenna efficiency
4) Guaranteed by design
FSK data rate range 0 32 kb/s 4) FSK frequency deviation 16 kHz
swing is typical 4 VPP.
2) 3)
Rev. 6, August 2000 Page 10 of 18
Page 11
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
2.4 Digital Pin Characteristics
T
= 23 °C, VDD = 3.0 V, unless specified otherwise. GND is the 0 V reference.
AMB
Symbol Parameter Conditions Min Typ Max Units Note
CLK (µC clock output)
VOH High level output voltage IOH = -1 mA VDD-0.7 - VDD V
VOL Low level output voltage IOL = 1 mA GND - 1.2 V
tr Rise time CLoad = 10 pF 20 ns
td Fall time CLoad = 10 pF 20 ns
jcc Cycle to cycle jitter +/-5 % 1)
NRES (Inverted reset output)
VOH High level output voltage IOH = -1 mA VDD-0.3 - VDD V
VOL Low level output voltage IOL = 1 mA GND - 0.2 V
tr Rise time CLoad = 10 pF 20 ns
td Fall time CLoad = 10 pF 20 ns
TX/ASK (Driving amplifier and FSK modulator on/off (ASK) input)
VIH High level input voltage VDD-0.5 - VDD V
VIL Low level input voltage GND - 0.3 V
IIH High level input current VIH = VDD 1
IIL Low level input current VIL = 0 V.
-40
internal pull-up
DATA (FSK data input)
VIH High level input voltage VDD-0.5 - VDD V
VIL Low level input voltage GND - 0.3 V
IIH High level input current VIH = VDD 1
IIL Low level input current VIL = 0 V -1
µA
µA µA
Rev. 6, August 2000 Page 11 of 18
Page 12
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
433/315 (Band selection (division ratio))
VIH High level input voltage VDD-0.5 -
VDD
VIL Low level input voltage GND - 0.3 V
IIH High level input current VIH = VDD 1
IIL Low level input current VIL = 0 V. -1
STANDBY (Standby input)
VIH High level input voltage VDD-0.5 VDD V
VIL Low level input voltage
GND
- 0.3 V
IIH High level input current VIH = VDD 1
1IIL Low level input current VIL = 0 V.
-40
internal pull-up
Notes
1) Guaranteed by design
V
µA µA
µA µA
Rev. 6, August 2000 Page 12 of 18
Page 13
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
3 Pin-out Information
Pin # Pin Name Input / Output Description
1 STDBY 2 CLK Dig. Output Clock output (CMOS level) 3 DATA Dig. Input 4 TX/ASK
on/off ASK 5 GND Power Ground 6 VDD Power Positive supply (2.7 V-5.0 V) 7 XTAL2 Analog XTAL pin2 8 XTAL1 Analog XTAL pin1 9 433/315 Dig. Input
10 VDDRF Power Positive supply (2.7 V-5.0 V) 11 ANT2 Analog open collector output To loop antenna 12 ANT1 Analog open collector output To loop antenna 13 GNDRF Power Ground 14 NRESET Dig. Output Reset, „L“ state resets a microcontroller
Dig. Input, 100 kpull up
Dig. Input, 100 kpull up
Power down for all functions
Transmit data input (CMOS level) Power off for TX (PLL and XTAL working)
ASK modulation
Selects division factors for constant µC Clock frequency and deviation
Rev. 6, August 2000 Page 13 of 18
Page 14
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
100P
10P
10P
141312
11
8
4
321
C5
13.56MHZ
DATA
DATA
GND
VDD
XTAL2
XTAL1
433
VDDRF
ANT1
AS3901
4 Application Schematic
VDD
C3 100N
STDBY
CLK
STDBY CLK
U1
NRESET
NRES
GNDRF
VDD
A1
TX
C2
5 6 7
TX/ASK
AS3901
U2
ANT2
10 9
443_315
LOOP ANTENNA
C4
C1
Figure 4: Basic application schematic of the AS3901.
3P
Figure 5: Pull Up characteristics for the TX/ASK pin.
Rev. 6, August 2000 Page 14 of 18
Page 15
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
5 Typical Measurements
Figure 6: Narrow band output spectrum of the AS3901 FSK modulated with pseudo
random data at 32 kbit/s.
Figure 7: Modulation bandwidth of the AS3901 in FSK operation at 32.6 kbit/s, measured
close to the EN 300-220-1 recommendation for wide-band equipment, clause 8.6. Instead of 5 kHz video bandwidth (VBW) 10 kHz was used. The markers were set up to the band edges. (433.050 MHz, 434.790 MHz) The recommendation says that the spectrum should be observed at least 1MHz form the ISM band edges, but it was measured with larger frequency span.
Rev. 6, August 2000 Page 15 of 18
Page 16
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
Figure 8: Modulation bandwidth of the AS3901 in AKS operation at 9.2 kbit/s, measured
close to the EN 300-220-1 recommendatio for wide-band equipment, clause 8.6. Instead of 5 kHz video bandwidth (VBW) 10 kHz was used. The markers were set up to the band edges. (433.050 MHz, 434.790 MHz) The recommendation says that the spectrum should be observed at least 1 MHz from the ISM band edges, but it was measured with larger frequency span.
Figure 9: Spurious emissions of the AS3901 in FSK operation, measured close to the EN 300-220-
1Recommendation for wide-band equipment, clause 8.7, without modulation. (Only difference: 100 kHz RBW was used instead of 120 kHz). From the measurement it can be seen that the main critical spurious emission is generated by the 13.56 MHz clock frequency. The level of CLK spurious is near –48 dBM so the suppression is 45 dB for this component.
Rev. 6, August 2000 Page 16 of 18
Page 17
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
Figure 10: Typical out spectrum in ASK 9.2 kb/s PRN modulation.
Figure 11: Transmission power as function of time at ASK modulation with an 9.2 kbit/s 0101.. data
pattern.
Rev. 6, August 2000 Page 17 of 18
Page 18
ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet
AS3901
6 Package Information
Figure 12: Physical dimensions of TSSOP-14.
Common Dimensions
Symbol
Minimal (mm) Nominal (mm) Maximal (mm)
A - - 1.20
A1 0.05 - 0.15
b 0.19 - 0.30 D 4.90 - 5.10 e 0.65 BSC E - 6.40 -
E1 4.30 - 4.50
L 0.45 - 0.75
α
Copyright 2000, Austria Mikro Systeme International AG, Schloß Premstätten, 8141 Unterpremstätten, Austria. Tel.: +43-(0)3136-500-0, Fax: +43-(0)3136-52501, E-Mail: info@amsint.com
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, without the prior permission in writing by the copyright holder. To the best of its knowledge, Austria Mikro Systeme International asserts that the information contained in this publication is accurate and correct.
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Rev. 6, August 2000 Page 18 of 18
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