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? semiconductor components industries, llc, 2013 march, 2013 ? rev. 6 1 publication order number: a5191hrt/d a5191hrt hart modem description the a5191hrt is a single ? chip, cmos modem for use in highway addressable remote transducer (hart) field instruments and masters. the modem and a few external passive components provide all of the functions needed to satisfy ha rt physical layer requirements including modulation, demodulation, receive filtering, carrier detect, and transmit ? signal shaping. the a5191hrt uses phase continuous frequency shift keying (fsk) at 1200 bits per second. to conserve power the receive circuits are disabled during transmit operations and vice versa. this provides the half ? duplex operation used in hart communications. features ? single ? chip, half ? duplex 1200 bits per second fsk modem ? bell 202 shift frequencies of 1200 hz and 2200 hz ? 3.0 v ? 5.5 v power supply ? transmit ? signal wave shaping ? receive band ? pass filter ? low power: optimal for intrinsically safe applications ? compatible with 3.3 v or 5 v microcontroller ? internal oscillator requires 460.8 khz crystal or ceramic resonator ? meets hart physical layer requirements ? industrial temperature range of ? 40 c to +85 c ? available in 28 ? pin plcc, 32 ? pin qfn and 32 ? pin lqfp packages ? these are pb ? free devices applications ? hart multiplexers ? hart modem interfaces ? 4 ? 20 ma loop powered transmitters http://onsemi.com see detailed ordering and shipping information in the package dimensions section on page 14 of this data sheet. ordering information plcc ? 28 p suffix case 776aa qfn ? 32 n suffix case 488am lqfp ? 32 l suffix case 561ab marking diagrams xxxxyzz a5191hrtpg xxxxyzz a5191 hrtlg a5191hrtxx = specific device code xx = p (plcc), l (lqfp) or n (qfn) xxxx = date code y = plant identifier zz = traceability code a = assembly location wl = wafer lot yy = year ww = work week g or = pb ? free package (top views) a5191 hrtng awlyyww 1 1 32 128
a5191hrt http://onsemi.com 2 block diagram figure 1. block diagram a5191hrt demodulator logic rx hp filter rx comp carrier detect counter carrier comp sine shaper numeric controlled oscillator demodulator modulator crystal oscillator bias a5191hrt rxaf vdd rxa rxafi rxd aref cdref txa cd txd rts cbias vdda vss vssa fsk_out fsk_in xin xout reset kvde20130228.2 electrical specifications table 1. absolute maximum ratings (notes 1 and 2) symbol parameter min max units t a ambient ? 40 +85 c t s storage temperature ? 55 150 c v dd supply voltage ? 0.3 6.0 v v in , v out dc input, output ? 0.3 vdd + 0.3 v stresses exceeding maximum ratings may damage the device. maximum ratings are stress ratings only. functional operation above t he recommended operating conditions is not implied. extended exposure to stresses above the recommended operating conditions may af fect device reliability. 1. cmos devices are damaged by high ? energy electrostatic discharge. devices must be stored in conductive foam or with all pins shunted. precautions should be taken to avoid application of voltages higher than the maximum rating. stresses above absolute maximum ra tings may result in damage to the device. 2. remove power before insertion or removal of this device.
a5191hrt http://onsemi.com 3 table 2. dc characteristics (v dd = 3.0 v to 5.5 v, v ss = 0 v, t a = ? 40 c to +85 c) symbol parameter v dd min typ max units v il input voltage, low 3.0 ? 5.5 v 0.3 * v dd v v ih input voltage, high 3.0 ? 5.5 v 0.7 * v dd v v ol output voltage, low (i ol = 0.67 ma) 3.0 ? 5.5 v 0.4 v v oh output voltage, high (i oh = ? 0.67 ma) 3.0 ? 5.5 v 2.4 v c in input capacitance of: analog input rxa digital input 2.9 25 3.5 pf pf pf i il /i ih input leakage current 500 na i oll output leakage current 10 a i dda power supply current (rbias = 500 k , aref = 1.235 v) 3.3 v 5.0 v 150 150 330 300 450 600 a a i ddd dynamic digital current 5.0 v 25 200 a a ref analog reference 3.3 v 5.0 v 1.2 1.235 2.5 2.6 v v cd ref (note 3) carrier detect reference (aref ? 0.08 v) 3.3 v 5.0 v 1.15 2.42 v c bias comparator bias current (rbias = 500 k , aref = 1.235 v) 2.5 a 3. the hart specification requires carrier detect (cd) to be active between 80 and 120 mvp ? p. setting cdref at aref ? 0.08 vdc will set the carrier detect to a nominal 100 mvp ? p. table 3. ac characteristics (v dd = 3.0 v to 5.5 v, v ss = 0 v, t a = ? 40 c to +85 c) (note 4) pin name description min typ max units rxa receive analog input leakage current frequency ? mark (logic 1) frequency ? space (logic 0) 1190 2180 1200 2200 150 1210 2220 na hz hz rxaf output of the high ? pass filter slew rate gain bandwidth (gbw) voltage range 150 0.15 0.025 v dd ? 0.15 v/ms khz v rxafi carrier detect and receive filter input leakage current 500 na txa modulator output frequency ? mark (logic 1) frequency ? space (logic 0) amplitude (aref 1.235 v) slew rate ? mark (logic 1) slew rate ? space (logic 0) loading (aref = 1.235 v) 30 1196.9 2194.3 500 1860 3300 hz hz mv v/s v/s k rxd receive digital output rise/fall time 20 ns cd carrier detect output rise/fall time 20 ns 4. the modular output frequencies are proportional to the input clock frequency (460.8 khz).
a5191hrt http://onsemi.com 4 table 4. modem characteristics (v dd = 3.0 v to 5.5 v, v ss = 0 v, t a = ? 40 c to +85 c) parameter min typ max units demodulator jitter conditions 1. input frequencies at 1200 hz 10 hz, 2200 hz 20 hz 2. clock frequency of 460.8 khz 0.1% 3. input (rxa) asymmetry, 0 12 % of 1 bit table 5. ceramic resonator ? external clock specifications (v dd = 3.0 v to 5.5 v, v ss = 0 v, t a = ? 40 c to +85 c) parameter min typ max units resonator tolerance frequency 460.8 1.0 % khz external clock frequency duty cycle amplitude 456.2 40 460.8 50 v oh ? v ol 465.4 60 khz % v typical application figure 2. application diagram a5191hrt a5191hrt xout xin 46 0.8 khz cbias vss vssa c vdda 4 ? 20 ma dac out hart & 4?20ma out hart in power 3.0 to 5.5 v txa cdref aref rxa rxaf rxafi vdda vdd rxd cd txd rts kvde 20130 228.1 cat808 lm285 reset
a5191hrt http://onsemi.com 5 8 9 10 11 7 6 5 12 13 14 15 16 17 18 22 21 20 19 23 24 25 4 3 2 1 28 27 26 test4 test3 test2 test1 test12 cd rxd a5191hrt reset test5 test7 test8 test9 txa aref cdref cbias test10 vdda rxa rxaf rxafi test11 txd rts vdd vss xin xout figure 3. pin out a5191hrt in 28-pin plcc table 6. pin out summary 28 ? pin plcc pin no. signal name type pin description 1 test1 input connect to vss 2, 3, 4 test2, 3, 4 ? do not connect 5 test5 input connect to vss 6 resetb input reset all digital logic when low 7, 8, 9 test7, 8, 9 input connect to vss 10 txa output transmit data modulator output 11 aref input analog reference voltage 12 cdref input carrier detect reference voltage 13 cbias output comparator bias current 14 test10 input connect to vss 15 vdda power analog supply voltage 16 rxa input receive data m odulator input 17 rxaf output analog receive filter output 18 rxafi input analog receive comparator input 19 xout output crystal oscillator output 20 xin input crystal oscillator input 21 vss ground ground 22 vdd power digital supply voltage 23 rtsb input request to send 24 txd input input transmit date, transmitted hart data stream from microcontroller 25 test11 ? do not connect 26 rxd output received demodulated hart data to microcontroller 27 cd output carrier detect output 28 test12 ? do not connect
a5191hrt http://onsemi.com 6 a5191hrt 1 2 3 4 5 6 7 8 32 31 30 29 28 27 26 25 9 10 11 12 13 14 15 16 24 23 22 21 20 19 18 17 test5 test7 test8 test9 txa aref reset vss cdref cbias test10 vdda rxa rxaf rxafi vssa test11 txd rts vdd vss xin xout vssa test4 test3 test2 test1 test12 cd rxd vdd a5191hrt 1 2 3 4 5 6 7 8 32 31 30 29 28 27 26 25 9 10 11 12 13 14 15 16 24 23 22 21 20 19 18 17 test5 test7 test8 test9 txa aref reset vss cdref cbias test10 vdda rxa rxaf rxafi vssa test11 txd rts vdd vss xin xout vssa test4 test3 test2 test1 test12 cd rxd vdd figure 4. pin out a5191hrt in 32-pin qfn and lqfp (top view) table 7. pin out summary 32 ? pin qfn and lqfp pin no. signal name type pin description 1 test5 input connect to vss 2 resetb input reset all logic when low, connect to vdd for normal operation 3, 4, 5 test7, 8, 9 input connect to vss 6 vss ground digital ground 7 txa output transmit data modulator output 8 aref input analog reference voltage 9 cdref input carrier detect reference voltage 10 cbias output comparator bias current 11 test10 input connect to vss 12 vssa ground analog ground 13 vdda power analog supply voltage 14 rxa input receive data m odulator input 15 rxaf output analog receive filter input 16 rxafi input analog receive comparator input 17 xout output crystal oscillator output 18 xin input crystal oscillator input 19 vssa ground analog ground 20 vss ground digital ground 21 vdd power digital supply voltage 22 rtsb input request to send 23 txd input input transmit data, transmit hart data stream from microcontroller 24 test11 ? do not connect 25 rxd output received demodulated hart data to microcontroller 26 cd output carrier detect output 27 test12 ? do not connect 28 test1 input connect to vss 29 test2 ? do not connect 30 vdd power digital supply voltage 31, 32 test3, 4 ? do not connect ep exposed pad power connect to vss (qfn only)
a5191hrt http://onsemi.com 7 pin descriptions table 8. pin descriptions symbol pin name description aref analog reference voltage receiver reference voltage. normally 1.23 v is selected (in combination with vdda = 3.3 v). see table 2. cdref carrier detect reference voltage carrier detect reference voltage. the value should be 85 mv below aref to set the carrier detection to a nominal of 100 mv p ? p . resetb reset digital logic when at logic low (v ss ) this input holds all the digital logic in reset. during normal operation resetb should be at v dd . resetb should be held low for a minimum of 10 ns after v dd = 2.5 v as shown in figure 14. rtsb request to send active ? low input selects the operation of the modulator. txa is enabled when this signal is low. this signal must be held high during power ? up. rxa analog receive input receive data demodulator input. accepts a hart 1200 / 2200 hz fsk modu- lated square wave serial data stream as input. rxafi analog receive comparator input positive input of the carrier detect comparator and the receiver filter comparator. txd digital transmit input input to the modulator accepts digital data in nrz form. when txd is low, the modulator output frequency is 2200 hz. when txd is high, the modulator output frequency is 1200 hz. xin oscillator input input to the internal oscillator must be connected to a parallel mode 460.8 khz ceramic resonator when using the internal oscillator or grounded when using an external 460.8 khz clock signal. cbias comparator bias current connection to the external bias resistor. r bias should be selected such that aref / r bias = 2.5 a 5 % cd carrier detect output output goes high when a valid input is recognized on rxa. if the received signal is greater than the threshold specified on cdref for four cycles of the rxa sig- nal, the valid input is recognized. rxaf analog receive filter output the output of the three pole high pass receive data filter rxd digital receive output signal outputs the digital receive data. when the received signal (rxa) is 1200 hz, rxd outputs logic high. when the received signal (rxa) is 2200 hz, rxd outputs logic low. the hart receive data stream is only active if carrier detect (cd) is high. txa analog transmit output transmit data modulator output. a trapezoidal shaped waveform with a fre- quency of 1200 hz or 2200 hz corresponding to a data value of 1 or 0 respect- ively applied to txd. txa is active when rtsb is low. txa equals 0.5 v when rtsb is high. xout oscillator output output from the internal oscillator must be connected to an external 460.8 khz clock signal or to a parallel mode 460.8 khz ceramic resonator when using the internal oscillator. test(12:1) factory test factory test pins; for normal operation, tie these signals as per tables 6 and 7 vdd digital power power for the digital modem circuitry vdda analog supply voltage power for the analog modem circuitry vss ground digital ground (and analog ground in the case of plcc package) vssa analog ground analog ground
a5191hrt http://onsemi.com 8 functional description the a5191hrt is a single-chip modem for use in highway addressable remote transducer (hart) field instruments and masters. the modem ic contains a transmit data modulator with signal shaper, carrier detect circuitry, an analog receiver, demodulator circuitry and a crystal oscillator, as shown in the block diagram in figure 1. the modulator accepts digital data at its digital input txd and generates a sine shaped fsk modulated signal at the analog output txa. a digital ?1? or mark is represented with a frequency of 1200 hz. a digital ?0? or space is represented with a frequency of 2200 hz. the used bit rate is 1200 baud. the demodulator receives the fsk signal at its analog input, filters it with a band-pass filter and generates 2 digital signals: rxd: received data and cd: carrier detect. at the digital output rxd the original modulated signal is received. cd outputs the carrier detect signal. it goes logic high if the received signal is above 100 mvpp during 4 consecutive carrier periods. the oscillator provides the modem with a stable time base using either a simple external resonator or an external clock source. detailed description modulator the modulator accepts digital data in nrz form at the txd input and generates the fsk modulated signal at the txa output. sine shaper numeric controlled oscillator modulator txa txd rts fsk_out figure 5. modulator block diagram a logic ?1? or mark is represented by a frequency fm = 1200 hz. a logic ?0?or space is represented by a frequency fs = 2200 hz. t t bit = 833 s ?1? = mark 1.2 khz ?0? = space 2.2 khz t bit = 454 s figure 6. modulation timing the numeric controlled oscillator nco works in a phase continuous mode preventing abrupt phase shifts when switching between mark and space frequency. the control signal request to send rtsb enables the nco. when rtsb is logic low the modulator is active and a5191hrt is in transmit mode. when r tsb is logic high the modulator is disabled and a5191hrt is in receive mode. the digital outputs of the nco are shaped in the wave shaper block to a trapezoidal signal. this circuit controls the rising and falling edge to be inside the standard hart waveshape limits. figure 7 shows the transmit-signal forms captured at txa for mark and space frequency. the slew rates are sr m = 1860 v/s at the mark frequency and sr s = 3300 v/s at the space frequency. for aref = 1.235 v, txa will have a voltage swing from approximately 0.25 to 0.75 v dc . t (ms) 0 v txa 0.5 v 1 2 t (ms) v txa ?1? = mark; f m =1.2 khz ?0? = space; f s =2.2 khz 0 1 2 sr m = 1860 v/s 0.5 v sr s = 3300 v/s 0. 5 v 0.5 v figure 7. modulator shaped output signal for mark and space frequency at txa pin. demodulator the demodulator accepts a fsk signal at the rxa input and reconstructs the original modulated signal at the rxd output. figure 8 illustrates the demodulation process. t bit idle (mark) lsb msb idle (mark) t bit 8 data bits d0 start d1 d2 d3 d4 d5 d6 d7 stop par ?0? ?1? ?0? ?1? ?0? ?1? ?0? ?0? ?0? ?1? fsk_in rxd figure 8. modulation timing this hart bit stream follows a standard 11-bit uart frame with 1 startbit, 8 databits, 1 paritybit (odd) and 1 stopbit. the communication speed is 1200 baud.
a5191hrt http://onsemi.com 9 receive filter and comparator the received fsk signal first is filtered using a band-pass filter build around the low noise receiver operational amplifier ?rx hp filter?. this filter blocks interferences outside the hart signal band. rx comp rx hp filter rxaf rxa rxafi aref demodulator hart in 1.235 v dc c 1 c 2 c 3 r 1 r 2 r 3 r 4 r 6 r 5 c 4 15 m figure 9. demodulator receive filter and signal comparator the filter output is fed into the rx comparator. the threshold value equals the analog ground making the comparator to toggle on every zero crossing of the filtered fsk signal. the maximum demodulator jitter is 12 % of one bit given the input frequencies are within the hart specifications, a clock frequency of 460.8 khz ( 1.0 %) and zero input (rxa) asymmetry. carrier detect circuitry low hart input signal levels increases the risk for the generation of bit errors. therefore the minimum signal amplitude is set to 80 ? 120 mvpp. if the received signal is below this level the demodulator is disabled. this level detection is done in the carrier detector. the output of the demodulator is qualified with the carrier detect signal (cd), therefore, only rxa signals large enough to be detected (100 mvp-p typically) by the carrier detect circuit produce received serial data at rxd. rxd cd demodulator logic rx comp carrier detect counter carrier comp demodulator rxafi aref cdref 15 m filtered hart in 1.235 v dc v aref ?80mv figure 10. demodulator carrier and signal comparator the carrier detect comparator shown in figure 10 generates logic low output if the rxafi voltage is below cdref. the comparator output is fed into a carrier detect block. the carrier detect block drives the carrier detect output pin cd high if rtsb is high and four consecutive pulses out of the comparator have arrived. cd stays high as long as rtsb is high and the next comparator pulse is received in less than 2.5 ms. once cd goes inactive, it takes four consecutive pulses out of the comparator to assert cd again. four consecutive pulses amount to 3.33 ms when the received signal is 1200 hz and to 1.82 ms when the received signal is 2200 hz. miscellaneous analog circuitry voltage references the a5191hrt requires two voltage references, aref and cdref. aref sets the dc operating point of the internal operational amplifiers and is the reference for the rx comparator. if a5191hrt operates at v dd = 3.3 v the on semiconductor lm285d 1.235 v reference is recommended. the level at which cd (carrier detect) becomes active is determined by the dc voltage dif ference (cdref - aref). selecting a voltage difference of 80 mv will set the carrier detect to a nominal 100 mv p-p . bias current resistor the a5191hrt requires a bias current resistor r bias to be connected between cbias and v ss . the bias current controls the operating parameters of the internal operational amplifiers and comparators and should be set to 2.5 a. bias cbias opa aref 2. 5 a r bias figure 11. bias circuit the value of the bias current resistor is determined by the reference voltage aref and the following formula: r bias aref 2.5 a the recommended bias current resistor is 500 k when aref is equal to 1.235 v. oscillator the a5191hrt requires a 460.8 khz clock signal. this can be provided by an external clock or a resonator connected to the a5191hrt internal oscillator.
a5191hrt http://onsemi.com 10 internal oscillator option the oscillator cell will function with either a 460.8 khz crystal or ceramic resonator. a parallel resonant ceramic resonator can be connected between xin and xout. figure 12 illustrates the crystal option for clock generation using a 460.8 khz ( 1 % tolerance) parallel resonant crystal and two tuning capacitors cx. the actual values of the capacitors may depend on the recommendations of the manufacturer of the resonator. typically, capacitors in the range of 100 pf to 470 pf are used. xout xin c x c x 460.8 khz crystal oscillator figure 12. crystal oscillator external clock option it may be desirable to use an external 460.8 khz clock as shown in figure 13 rather than the internal oscillator. in addition, the a5191hrt consumes less current when an external clock is used. minimum current consumption occurs with the clock connected to xout and xin connected to v ss . xout xin crystal oscillator 460.8 khz figure 13. oscillator with external clock power on reset during start-up the resetb pin should be kept low until the voltage level on v dd is above the minimum level v ddh = 2.5 v to guarantee correct operation of the digital circuitry. as illustrated in figure 14 resetb should be kept low for at least t por = 10 ns after this threshold level is reached. t por =10ns v ddh =2.5v vdd t reset pin figure 14. power on reset timing
a5191hrt http://onsemi.com 11 package dimensions plcc 28 lead case 776aa issue o
a5191hrt http://onsemi.com 12 package dimensions qfn ? 32, 5x5 case 488am issue o seating 32 x k 0.15 c (a3) a a1 d2 b 1 9 16 17 32 2 x 2 x e2 32 x 8 24 32 x l 32 x bottom view exposed pad top view side view d a b e 0.15 c pin one location 0.10 c 0.08 c c 25 e a 0.10 b c 0.05 c notes: 1. dimensions and tolerancing per asme y14.5m, 1994. 2. controlling dimension: millimeters. 3. dimension b applies to plated terminal and is measured between 0.25 and 0.30 mm terminal 4. coplanarity applies to the exposed pad as well as the terminals. plane dim min nom max millimeters a 0.800 0.900 1.000 a1 0.000 0.025 0.050 a3 0.200 ref b 0.180 0.250 0.300 d 5.00 bsc d2 2.950 3.100 3.250 e 5.00 bsc e2 e 0.500 bsc k 0.200 ??? ??? l 0.300 0.400 0.500 2.950 3.100 3.250 *for additional information on our pb ? free strategy and soldering details, please download the on semiconductor soldering and mounting techniques reference manual, solderrm/d. soldering footprint* 0.50 pitch 3.20 0.28 3.20 32 x 28 x 0.63 32 x 5.30 5.30
a5191hrt http://onsemi.com 13 package dimensions lqfp ? 32, 7x7 case 561ab issue o
a5191hrt http://onsemi.com 14 ordering information the a5191hrt is available in a 28 ? pin plastic leaded chip carrier (plcc), 32 ? pin quad flat no ? lead (qfn) and 32 ? pin low ? profile quad flat pack (lqfp). use the following part numbers when ordering. contact your local sales representative for more information: www.onsemi.com . table 9. ordering information part number package shipping configuration temperature range a5191hrtlg ? xtd (industrial) 32 ? pin lqfp green / rohs compliant 250 units / tray ? 40 c to +85 c a5191hrtlg ? xtp (industrial) 32 ? pin lqfp green / rohs compliant 2500 units / tape & reel ? 40 c to +85 c a5191hrtpg ? xtd (industrial) 28 ? pin plcc green / rohs compliant 37 units / tube ? 40 c to +85 c a5191hrtpg ? xtp (industrial) 28 ? pin plcc green / rohs compliant 750 units / tape & reel ? 40 c to +85 c a5191hrtng ? xtd (industrial) 32 ? pin qfn green / rohs compliant 60 units / tube/tray ? 40 c to +85 c a5191hrtng ? xtp (industrial) 32 ? pin qfn green / rohs compliant 5000 units / tape & reel ? 40 c to +85 c on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for an y particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including wi thout limitation special, consequential or incidental damages. ?typical? parameters which may be provided in scillc data sheets and/or specifications can and do vary in different application s and actual performance may vary over time. all operating parameters, including ?typicals? must be validated for each customer application by customer?s technical experts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the scillc product could create a sit uation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indemnify and hold scillc and its of ficers, employees, subsidiaries, af filiates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, direct ly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that scillc was negligent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employer. this literature is subject to all applicable copyright laws and is not for resale in any manner. publication ordering information n. american technical support : 800 ? 282 ? 9855 toll free usa/canada europe, middle east and africa technical support: phone: 421 33 790 2910 japan customer focus center phone: 81 ? 3 ? 5817 ? 1050 a5191hrt/d literature fulfillment : literature distribution center for on semiconductor p.o. box 5163, denver, colorado 80217 usa phone : 303 ? 675 ? 2175 or 800 ? 344 ? 3860 toll free usa/canada fax : 303 ? 675 ? 2176 or 800 ? 344 ? 3867 toll free usa/canada email : orderlit@onsemi.com on semiconductor website : www.onsemi.com order literature : http://www.onsemi.com/orderlit for additional information, please contact your local sales representative

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