AS3901

AS3901 ISM 433/315 MHz FSK/ASK Transmitter Data Sheet Rev. 06, August 2000 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet 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 TX GND VDD XTAL2 1 2 14 13 NRES GNDRF ANT1 ANT2 VDDRF 433 XTAL1 AS3901 TSSOP-14 3 4 5 6 7 12 11 10 9 8 Rev. 6, August 2000 Page 2 of 18 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 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet 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 XTAL2 8 433 Synthesizer AS3901 Divider 32:1 LoopFilter Phase Detector XTAL Oscillator 7 VDD 13.560 MHz XTAL 9 VDDRF 6 GND VCO 10 ANT2 VDD f =433.920 MHz 5 TX Clock 11 ANT1 Driving Amplifier. SSB signal generation 4 DATA 12 GNDRF 3 CLK 13 NRES µC Interface + Power up/down 2 STDBY 14 1 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 fXTAL. 1.2 Microprocessor Clock The microprocesor clock frequency fCLK is generated by dividing the XTAL frequency fXTAL by 3 or 4, dependent on the 433/315 MHz selection pin to keep the µC clock frequency fCLK almost constant for European and US applications. 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 ≈ kHz, independent of the data rate. It is also kept almost constant for 16 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 fCLK and no data synchronization of the FSK modulator is required. Rev. 6, August 2000 Page 4 of 18 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 mArms.The maximal differential voltage swing is about 4 VPP. Therefore the 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 ≈ mW is obtained. Please note 1 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 Standby Clock generator operation Transmit operation STDBY 1 1 0 TX/ASK 1 0 1 Function All Off XTAL oscillator on and CLOCK output active. XTAL oscillator, PLL, FSK modulator running, (FSK operation or „ transmitted H“ at ASK). XTAL oscillator and PLL running, output amplifier and FSK modulator off, („ L“ transmitted at ASK). Turned off power 0 0 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). „ reset output (Active „ )“(NRES). µC L“ „ clock output“(CLK). µC „ 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 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet AS3901 AS3901 STDBY DATA TX/ASK NRES CLK I I I O O O O O I I uC STDBY DATA TX/ASK RESET CLK 10k SW Transmit switch Figure 2: Note: Interconnection of the AS3901 with a typical µC. At room temperature, resistor values of ≈ kΩ are suggested for the µC interface. 10 For other temperatures to be calculated from figure 5. TX/ASK CLK NRES STDBY XTon standby reset uC init PLLon TX on transmitting 3 clocks 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 Rev. 6, August 2000 Page 6 of 18 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 tXTON plus 3 clock cycles. NRES returns to H, µC initializes. After µC is initialized, it sets STDBY→ L; PLL is turned on, after tPLLon a stable RF carrier is generated. TX/ASK→ H, STDBY=L; → TX is turned on, tTXON later the RF signal is available and data can be transmitted. To switch the AS3901 „ a „ on“ push button“with series resistance ~10-20 kΩ can be used to make TX/ASK = „ . The „ L“ push-button“must be pushed long enough (typ. > 3ms) for the µC to reset and sustain the TX/ASK „ state. L“ Standby procedure (for sleep-mode ( IDD1 20 dB In distance of fCLK or fXTAL from carrier. No antenna selectivity assumed. For a RF packet duty cycle ≥25 %. 0 -45 Min -1.5 Typ 0 Max 1.5 -50 -39 -25 Units dBm dBm dBm dBC 2) 2) 3) Note 1) 3) RASK ASK data rate range 20 Kb/s Note: 1) Output power depends on load impedance, differential output current is typical 0.7 mArms. Maximum differential voltage swing 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 Rev. 6, August 2000 Page 9 of 18 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet AS3901 2.3.2 FSK Operation TAMB = 23 °C, VDD = 3.0 V, unless specified otherwise. Symbol Parameter Conditions In 2 kΩ , STDBY = ” , L” TX/ASK = ” H” Antenna and band pass filter attenuation> 20 dB In distance of fCLK or fXTAL from carrier. No antenna selectivity assumed. 0 16 -45 Min -1.5 Typ 0 Max 1.5 -36 -25 Units dBm dBm dBC Note 1) 3) 2) 2) 3) POUT,FSK Available peak output power POUT 3rd PSP Radiated third harmonic output power Spurious power RFSK ∆f Note: 1) 2) 3) 4) FSK data rate range FSK frequency deviation 32 kb/s kHz 4) Output power depends on load impedance, differential output current is typical 0.7 mAms. Maximum differential voltage swing is typical 4 VPP. Measurement bandwidth (close to EN 300 220-1) see also figure 10. Actual E.R.P. depends on antenna efficiency Guaranteed by design Rev. 6, August 2000 Page 10 of 18 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet AS3901 2.4 Digital Pin Characteristics TAMB = 23 °C, VDD = 3.0 V, unless specified otherwise. GND is the 0 V reference. Symbol Parameter CLK (µC clock output) VOH VOL tr td jcc High level output voltage IOH = -1 mA Low level output voltage Rise time Fall time Cycle to cycle jitter IOL = 1 mA CLoad = 10 pF CLoad = 10 pF VDD-0.7 GND 20 20 +/-5 VDD 1.2 V V ns ns % 1) Conditions Min Typ Max Units Note NRES (Inverted reset output) VOH VOL tr td High level output voltage IOH = -1 mA Low level output voltage Rise time Fall time IOL = 1 mA CLoad = 10 pF CLoad = 10 pF VDD-0.3 GND 20 20 VDD 0.2 V V ns ns TX/ASK (Driving amplifier and FSK modulator on/off (ASK) input) VIH VIL IIH IIL High level input voltage Low level input voltage High level input current Low level input current VIH = VDD VIL = 0 V. internal pull-up DATA (FSK data input) VIH VIL IIH IIL High level input voltage Low level input voltage High level input current Low level input current VIH = VDD VIL = 0 V -1 VDD-0.5 GND VDD 0.3 1 V V µA µA -40 VDD-0.5 GND VDD 0.3 1 µA V V Rev. 6, August 2000 Page 11 of 18 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet AS3901 433/315 (Band selection (division ratio)) VIH VIL IIH IIL High level input voltage Low level input voltage High level input current Low level input current VIH = VDD VIL = 0 V. -1 VDD-0.5 GND VDD 0.3 1 V V µA µA STANDBY (Standby input) VIH VIL IIH 1IIL High level input voltage Low level input voltage High level input current Low level input current VIH = VDD VIL = 0 V. internal pull-up Notes 1) VDD-0.5 GND - VDD 0.3 1 V V µA µA -40 Guaranteed by design Rev. 6, August 2000 Page 12 of 18 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet AS3901 3 Pin-out Information Pin Name STDBY CLK DATA TX/ASK on/off ASK GND VDD XTAL2 XTAL1 433/315 VDDRF ANT2 ANT1 GNDRF NRESET Input / Output Dig. Input, 100 kΩ pull up Dig. Output Dig. Input Dig. Input, 100 kΩ pull up Power Power Analog Analog Dig. Input Power Analog open collector output Analog open collector output Power Dig. Output Description Power down for all functions Clock output (CMOS level) Transmit data input (CMOS level) Power off for TX (PLL and XTAL working) ASK modulation Ground Positive supply (2.7 V-5.0 V) XTAL pin2 XTAL pin1 Selects division factors for constant µC Clock frequency and deviation Positive supply (2.7 V-5.0 V) To loop antenna To loop antenna Ground Reset, „ state resets a microcontroller L“ Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Rev. 6, August 2000 Page 13 of 18 ISM 433/315 MHz FSK/ASK Transmitter – Data Sheet AS3901 4 Application Schematic VDD C3 100N VDD STDBY U1 CLK DATA TX 1 2 3 4 5 6 7 STDBY CLK DATA TX/ASK GND VDD XTAL2 NRESET GNDRF ANT1 ANT2 VDDRF 433 XTAL1 14 13 12 11 10 9 8 NRES A1 C5 3P 443_315 LOOP ANTENNA C4 100P C1 10P AS3901 U2 13.56MHZ C2 10P Figure 4: Basic application schematic of the AS3901. Figure 5: Pull Up characteristics for the TX/ASK pin. Page 14 of 18 Rev. 6, August 2000 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 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 300-2201Recommendation 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 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 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) A A1 b D e E E1 L α 4.30 0.45 0° 0.05 0.19 4.90 Nominal (mm) 0.65 BSC 6.40 4.50 0.75 8° Maximal (mm) 1.20 0.15 0.30 5.10 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. Rev. 6, August 2000 Page 18 of 18