Datasheet AS3901 Datasheet (Austria Mikro Systeme International)

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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

456

111213

AS3901

Key Features

• 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

GND

VDD

XTAL2

AS3901

NRES GNDRF ANT1 ANT2

VDDRF 433 XTAL1

TSSOP-14

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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.

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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

ANT2

ANT1

GNDRF

NRES

Driving

Amplifier.

Synthesizer

Loop-

Filter

Divider

Phase

SSB signal generation

XTAL

Oscillator VCO

Clock

µC Interface + Power up/down

VDD

GND

DATA

CLK

STDBY

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

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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 kΩ 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.

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ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet

AS3901

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

Transmit switch

Figure 2: Interconnection of the AS3901 with a typical µC.

Note: At room temperature, resistor values of ≈10 kΩ are suggested for the µC interface.

For other temperatures to be calculated from figure 5.

XTon

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 ~100kΩ

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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/ASK→L, 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 STDBY→L; PLL is turned on, after t

a stable RF carrier

PLLon

is generated. TX/ASK→H, 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 kΩ 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.

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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

Voltage on input pins -0.5 VDD+0.5 V ESD Electrostatic discharge 1000 V 1) T

STG

LEAD

Note:

1) HBM: R = 1.5 kΩ, 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

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ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet

AS3901

2.3 Transmit Operation

= 23 °C, VDD = 3.0 V, unless specified otherwise.

AMB

Symbol Parameter Conditions Min Typ Max Units Note

RF, EU

RF, US

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.

CLK, EU

CLK, US

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

PLLon

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

= 23 °C, VDD = 3.0 V, unless specified otherwise.

AMB

Symbol Parameter Conditions Min Typ Max Units Note

OUT

Available peak output power

In 2 kΩ, STDBY = ”L”, TX/ASK = ”H”

-1.5 0 1.5 dB

1) 3)

OUT

Leakage peak output power

3rd

OUT

Radiated third harmonic output power

Spurious power

In 2 kΩ, STDBY = ”L”, TX/ASK = ”L”

Antenna attenuation> 20 dB

In distance of f f

from carrier. No

XTAL

CLK

antenna selectivity assumed.

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

2) 3)

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ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet

AS3901

2.3.2 FSK Operation

= 23 °C, VDD = 3.0 V, unless specified otherwise.

AMB

Symbol Parameter Conditions Min Typ Max Units Note

,FSK

OUT

Available peak output power

3rd

OUT

Radiated third harmonic output power

In 2 kΩ, STDBY = ”L”, TX/ASK = ”H”

Antenna and band pass filter attenuation> 20 dB

-1.5 0 1.5 dB

-36 dB

1) 3)

Spurious power

In distance of f f

from carrier. No

XTAL

CLK

-45 -25 dB

antenna selectivity assumed.

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)

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ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet

AS3901

2.4 Digital Pin Characteristics

= 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

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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

µA µA

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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 kΩ pull 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

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ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet

100P

10P

141312

321

13.56MHZ

DATA

GND

VDD

XTAL2

XTAL1

433

VDDRF

ANT1

AS3901

4 Application Schematic

VDD

C3 100N

STDBY

CLK

STDBY CLK

NRESET

NRES

GNDRF

VDD

5 6 7

TX/ASK

AS3901

ANT2

10 9

443_315

LOOP ANTENNA

Figure 4: Basic application schematic of the AS3901.

Figure 5: Pull Up characteristics for the TX/ASK pin.

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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.

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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.

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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

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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

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.

0° - 8°

Rev. 6, August 2000 Page 18 of 18