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AS3901 ism 433/315 mhz fsk/ask transmitter data sheet rev. 06, august 2000
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 2 of 18 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 c. 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 c 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. tssop-14 stdby clk data tx nres ant1 ant2 gndrf AS3901 gnd vdd 1 2 3 4 5 6 7 xtal2 433 xtal1 vddrf 8 9 10 11 12 13 14
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 3 of 18 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.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 4 of 18 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 c interface, including c clock divider, and a power management circuitry. AS3901 ssb signal generation ant2 vddrf 433 xtal1 f =433.920 mhz vdd tx 4 stdby clk data 3 2 1 driving amplifier. loop- filter synthesizer xtal oscillator vco clock 13.560 mhz xtal gnd vdd xtal2 7 6 5 nres gndrf ant1 14 13 12 11 10 9 8 phase detector divider 32:1 c interface + power up/down 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 f rf by a fix, 32 times, multiplication of the reference xtal frequency f xtal . 1.2 microprocessor clock the microprocesor clock frequency f clk is generated by dividing the xtal frequency f xtal by 3 or 4, dependent on the 433/315 mhz selection pin to keep the c clock frequency f clk 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 d 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 c clock f clk and no data synchronization of the fsk modulator is required.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 5 of 18 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 rms .the maximal differential voltage swing is about 4 v pp . therefore the output power ist a function of the connected load impedance. with a 2 k w 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 grey- coded 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 c interface and timing the AS3901 contains a direct interface to a microcontroller (c). the c interface of the AS3901 consists of three input and two outputs pins: ? standby input? (stdby). ? transmit / ask input? (tx/ask). ?c reset output ( active ?l?)? (nres). ?c clock output? (clk). ?fsk data input? (data). these lines support the c 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 c. figure 2 shows a typical interconnection of the AS3901 with a typical c. figure 3 presents a related timing for power up and down of the transmitter.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 6 of 18 AS3901 stdby data tx/ask reset nres tx/ask uc 10k transmit switch sw stdby i o o i data i clk clk i i o o o figure 2: interconnection of the AS3901 with a typical c. note: at room temperature, resistor values of ? 10 k w are suggested for the c interface. for other temperatures to be calculated from figure 5. tx/ask clk nres stdby standby xton tx on transmitting 3 clocks standby reset uc init pllon figure 3: c 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 w
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 7 of 18 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 c for txton plus 3 clock cycles. nres returns to h, c initializes. after c is initialized, it sets stdby ? l; pll is turned on, after t pllon a stable rf carrier is generated. tx/ask ? h, stdby=l; ? tx is turned on, t txon later the rf signal is available and data can be transmitted. to switch the AS3901 ? on? a ? push button? with series resistance ~10-20 k w can be used to make tx/ask = ?l?. the ? push-button? must be pushed long enough (typ. > 3ms) for the c to reset and sustain the tx/ask ?l? state. standby procedure ( for sleep-mode ( idd1 <1a): the c 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.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 8 of 18 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 storage temperature -55 125 c t lead lead temperature 260 c 2) note: 1) hbm: r = 1.5 k w , c = 100 pf. the pins ant1, ant2, xtal1 and xtal2 have 500 v esd protection. 2) 260c for 10 s ( reflow and wave soldering), 360 c for 3 s ( manual soldering). 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? 1 a 1) idd2 supply current, stdby = ?h?, tx/ask = ?l? 350 850 a 2) idd3 supply current, stdby = ?l?, tx/ask = ?h? 7 9 ma 3) idd4 supply current, stdby = ?l?, tx/ask = ?l? 3.5 4.5 ma 4) t amb ambient temperature range -40 +85 c note: 1) standby: t amb = 23 c, synthesizer and driving amplifier are turned off. 2) clock generator operation: t amb = 23 c xtal oscillator and c clock divider on. rf driving amplifier and pll off, no external load connected to clk pin. 3) transmit operation: t amb = 23 c, synthesizer and driving amplifier are turned on. 4) turned off tx power: t amb = 23 c, xtal oscillator and c clock divider and pll on rf driving amplifier off.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 9 of 18 2.3 transmit operation t amb = 23 c, vdd = 3.0 v, unless specified otherwise. symbol parameter conditions min typ max units note f rf , eu transmit frequency (europe) f xtal = 13.560 mhz 433.920 mhz 1) f rf , us transmit frequency (us) f xtal = 9.84375 mhz 315.000 mhz 1) f offset frequency tolerance after t txon , no xtal tolerance. 2 khz f clk , eu c clock frequency (europe) f xtal = 13.560 mhz 3.390 mhz f clk , us c clock frequency (us) f xtal = 9.84375 mhz 3.28125 mhz t txon transmitter turn on time fsk modulator and driver amplifier 20 s t pllon pll turn on time t.b.d. ms t xton xtal oscillator turn on time 5 ms note: 1) xtal tolerances will slightly change the typical transmit frequency. 2.3.1 ask operation t amb = 23 c, vdd = 3.0 v, unless specified otherwise. symbol parameter conditions min typ max units note p out ,h available peak output power in 2 k w , stdby = ?l?, tx/ask = ?h? -1.5 0 1.5 db m 1) 3) p out ,l leakage peak output power in 2 k w , stdby = ?l?, tx/ask = ?l? -50 db m p out 3rd radiated third harmonic output power antenna attenuation> 20 db -39 db m 2) p sp spurious power in distance of f clk or f xtal from carrier. no antenna selectivity assumed. -45 -25 db c 2) 3) r ask ask data rate range for a rf packet duty cycle 3 25 %. 0 20 kb/s note: 1) output power depends on load impedance, differential output current is typical 0.7 ma rms . maximum differential voltage swing is typical 4 v pp . 2) measurement bandwidth ( close to en 300 220-1) see also figure 10. 3) actual e.r.p. depends on antenna efficiency
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 10 of 18 2.3.2 fsk operation t amb = 23 c, vdd = 3.0 v, unless specified otherwise. symbol parameter conditions min typ max units note p out ,fsk available peak output power in 2 k w , stdby = ?l?, tx/ask = ?h? -1.5 0 1.5 db m 1) 3) p out 3rd radiated third harmonic output power antenna and band pass filter attenuation> 20 db -36 db m 2) p sp spurious power in distance of f clk or f xtal from carrier. no antenna selectivity assumed. -45 -25 db c 2) 3) r fsk fsk data rate range 0 32 kb/s 4) d f fsk frequency deviation 16 khz note: 1) output power depends on load impedance, differential output current is typical 0.7 ma ms . maximum differential voltage swing is typical 4 v pp . 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
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 11 of 18 2.4 digital pin characteristics t amb = 23 c, vdd = 3.0 v, unless specified otherwise. gnd is the 0 v reference. symbol parameter conditions min typ max units note clk (c 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. internal pull-up -40 m a 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 m a iil low level input current vil = 0 v -1 m a
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 12 of 18 433/315 (band selection (division ratio)) 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 m a iil low level input current vil = 0 v. -1 m a 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 m a 1iil low level input current vil = 0 v. internal pull-up -40 m a notes 1) guaranteed by design
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 13 of 18 3 pin-out information pin # pin name input / output description 1 stdby dig. input, 100 k w pull up power down for all functions 2 clk dig. output clock output (cmos level) 3 data dig. input transmit data input (cmos level) 4 tx/ask on/off ask dig. input, 100 k w pull up power off for tx (pll and xtal working) ask modulation 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 selects division factors for constant m c clock frequency and deviation 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
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 14 of 18 4 application schematic 3p 100p 10p 10p 100n c4 c3 c2 u1 14 13 12 11 10 9 8 7 6 5 4 3 2 1 c5 loop antenna vdd nres 443_315 c1 13.56mhz a1 stdby clk data tx stdby clk data tx/ask gnd vdd xtal2 xtal1 433 vddrf ant2 ant1 gndrf nreset AS3901 u2 vdd figure 4: basic applic ation schematic of the AS3901. figure 5: pull up characteristics for the tx/ask pin.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 15 of 18 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.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 16 of 18 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 i n 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.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 17 of 18 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.
ism 433/315 mhz fsk/ask transmitter ? data sheet AS3901 rev. 6, august 2000 page 18 of 18 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 a 0 - 8 copyright ? 2000, austria mikro systeme international ag, schlo? premst?tten , 8141 unte r premst?tten , 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 intern a tional asserts that the information contained in this publication is accurate and co r rect.

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