HART Modem Features used designs presently using SYM20C15 Si
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A5191HRT
HART Modem
Features
used designs presently using SYM20C15 Single-chip, half-duplex 1200 bits second modem Bell shift frequencies 1200Hz 2200Hz 3.3V 5.0V power supply Transmit-signal wave shaping Receive band-pass filter power: optimal intrinsically safe applications CMOS compatible Internal oscillator requires 460.8kHz crystal ceramic resonator Meets HART physical layer requirements Industrial temperature range -40°C +85°C Available 28-pin PLCC 32-pin LQFP packages
Description
A5191HRT single-chip, CMOS modem highway addressable remote transducer (HART) field instruments masters. modem external passive components provide functions needed satisfy HART physical layer requirements including modulation, demodulation, receive filtering, carrier detect, transmit-signal shaping. A5191HRT pincompatible with SYM20C15. Description Functional Description sections details compatibility with SYM20C15. A5191HRT uses phase continuous frequency shift keying (FSK) 1200 bits second. conserve power receive circuits disabled during transmit operations vice versa. This provides half-duplex operation used HART communications.
Figure 28-Pin PLCC Diagrams (Green Non-Green)
©2008 SCILLC. rights reserved. 2008 Rev.
Publication Order Number: A5191HRT/D
A5191HRT
Figure 32-Pin LQFP Diagrams (Green Non-Green)
Table Summary 28-Pin PLCC, A5191HRTP/Pg (12197-504/508) Signal Name Type Description TEST1 Input Connect TEST2 connect TEST3 connect TEST4 connect TEST5 Input Connect INRESET Input Reset digital logic when TEST7 Input Connect TEST8 Input Connect TEST9 Input Connect OTXA Output Output transmit analog, modulated HART transmit signal 4-20mA loop interface circuit IAREF Input Analog reference voltage ICDREF Input Carrier detect reference voltage OCBIAS Output Comparator bias current TEST10 Input Connect VDDA Power Analog supply voltage IRXA Input modulated HART receive signal from 4-20mA loop interface circuit ORXAF Output Analog receive filter output IRXAC Input Analog receive comparator input OXTL Output Crystal oscillator output IXTL Input Crystal oscillator input Ground Ground Power Digital supply voltage INRTS Input Request send ITXD Input Input transmit date, transmitted HART data stream from UART TEST11 connect ORXD Output Received demodulated HART data UART Output Carrier detect output TEST12 connect
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A5191HRT
Table Summary 32-Pin LQFP, A5191HRTl/Lg (12197-503/507) Signal Name Type Description TEST5 Input Connect INRESET Input Reset logic when low, connect normal operation TEST7 Input Connect TEST8 Input Connect TEST9 Input Connect Ground Digital ground OTXA Output Output transmit analog, modulated HART transmit signal 4-20mA loop interface circuit IAREF Input Analog reference voltage ICDREF Input Carrier detect reference voltage OCBIAS Output Comparator bias current TEST10 Input Connect VSSA Ground Analog ground VDDA Power Analog supply voltage IRXA Input modulated HART receive signal from 4-20mA loop interface circuit ORXAF Output Analog receive filter input IRXAC Input Analog receive comparator input OXTL Output Crystal oscillator output IXTL Input Crystal oscillator input VSSA Ground Analog ground Ground Digital ground Power Digital supply voltage INRTS Input Request send ITXD Input Input transmit data, transmit HART data stream from UART TEST11 connect ORXD Output Received demodulated HART data UART Output Carrier detect output TEST12 connect TEST1 Input Connect TEST2 connect Power Digital supply voltage TEST3 connect TEST4 connect
Descriptions
Table Descriptions Symbol Name Analog reference voltage IAREF ICDREF INRESET INRTS IRXA IRXAC ITXD IXTL OCBIAS Carrier detect reference voltage Reset digital logic Request send Analog receive input Analog receive comparator input Digital transmit input (CMOS) Oscillator input Comparator bias current
Description Analog input sets operating point operational amplifiers comparators usually selected split potential between VSS. Table Analog input controls which level carrier detect (OCD) becomes active. This determined voltage difference between ICDREF IAREF. Selecting ICDREF IAREF equal 0.08 will carrier detect nominal mVp-p When logic (VSS) this input holds digital logic reset. During normal operation INRESET should VDD. INRESET should held minimum 10nS after 2.5V shown Table Active-low input selects operation modulator. OTXA enabled when this signal low. This signal must held high during power-up. Input accepts 1200/2200Hz signals from external filter. Positive input carrier detect comparator receiver filter comparator. Input modulator accepts digital data form. When ITXD low, modulator output frequency 2200Hz. When ITXD high, modulator output frequency 1200Hz. Input internal oscillator must connected parallel mode 460.8kHz ceramic resonator when using internal oscillator grounded when using external 460.8kHz clock signal. current through this output controls operating parameters internal operational amplifiers comparators. normal operation, OCBIAS current 2.54A.
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A5191HRT
ORXAF ORXD OTXA OXTL TEST(12:1) VDDA VSSA Carrier detect output Analog receive filter output Digital receive output (CMOS) Analog transmit output Oscillator output Factory test Digital power Analog supply voltage Ground Analog ground Output goes high when valid input recognized IRXA. received signal greater than threshold specified ICDREF four cycles IRXA signal, valid input recognized. Signal square wave output receiver high-pass filter. Signal outputs digital receive data. When received signal (IRXA) 1200Hz, ORXD outputs logic high. When received signal (IRXA) 2200Hz, ORXD outputs logic low. ORXD qualified internally with OCD. Output provides trapezoidal signal controlled ITXD. When ITXD low, output frequency 2200Hz. When ITXD high, output frequency 1200Hz. This output active when INRTS when INRTS high. Output from internal oscillator must connected external 460.8kHz clock signal parallel mode 460.8kHz ceramic resonator when using internal oscillator. Factory test pins; normal operation, these signals Table Table Power digital modem circuitry Power analog modem circuitry Analog digital ground
Figure Reset Timing Note: This signal also present 20C15. labeled Test6. 20C15 data sheet mentions reset function this does emphasize reset chip. Reliable operation modem requires hardware reset shown Figure This true AMIS 12197-503 12197-504 well 20C15.
Functional Description
A5191HRT functional equivalent SYM20C15 HART Modem. contains transmit data modulator signal shaper, carrier detect circuitry, analog receiver demodulator circuitry oscillator, shown Figure
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A5191HRT
internal HART modem modulates transmit-signal demodulates receive signal. transmit-signal shaper enables A5191HRT transmit HART compliant signal. carrier detected comparing receiver filter output with difference between external voltage references. analog receive circuitry band-pass filters received signal input modem carrier detect circuitry. oscillator provides modem with stable time base using either simple external resonator external clock source.
Figure A5191HRT Block Diagram
A5191HRT Logic modem consists modulator demodulator. modem uses shift frequencies nominally 1200Hz (for 220Hz (for rate 1200 bits/second. 4.1.1. Modulator modulator accepts digital data form ITXD input generates modulated signal OTXA output. INRTS must logic modulator active. 4.1.2. Demodulator demodulator accepts signal IRXA input reproduces original modulating signal ORXD output. nominal rate 1200 bits second. Figure illustrates demodulation process.
Figure Demodulator Signal Timing
output demodulator qualified with carrier detect signal (OCD), therefore, only IRXA signals large enough detected (100mVp-p typically) carrier detect circuit produce received serial data ORXD. Maximum demodulator jitter percent given input frequencies within HART specifications, clock frequency 460.8kHz (±1.0 percent) zero input (IRXA) asymmetry.
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A5191HRT
Transmit-Signal Shaper transmit-signal shaper generates HART compliant modulated signal OTXA. Figure Figure show transmitsignal forms A5191HRT. IAREF 1.235 VDC, OTXA will have voltage swing from approximately 0.25 0.75 VDC.
Figure OTXA Waveform (1200Hz)
Figure OTXA Waveform (2200Hz)
Carrier Detect Circuitry carrier detect comparator shown Figure generates logic output IRXAC voltage below ICDREF. comparator output into carrier detect block (see Figure carrier detect block drives carrier detect output high INRTS high four consecutive pulses comparator have arrived. stays high long INRTS high next comparator pulse received less than 2.5ms. Once goes inactive, takes four consecutive pulses comparator
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A5191HRT
assert again. Four consecutive pulses amount 3.33ms when received signal 1200Hz 1.82ms when received signal 2200HZ.
Analog Receiver Circuitry 4.4.1. Voltage References A5191HRT requires voltage references, IAREF ICDREF. IAREF sets operating point internal operational amplifiers comparators. 1.235 reference (Analog Devices AD589) suitable IAREF. level which (carrier detect) becomes active determined voltage difference (ICDREF IAREF). Selecting voltage difference 0.08 will carrier detect nominal mVp-p.
4.4.2. Bias Current Resistor A5191HRT requires bias current resistor connected between OCBIAS VSS. bias current controls operating parameters internal operational amplifiers comparators. value bias current resistor determined reference voltage IAREF following formula:
recommended bias current resistor 500KW when IAREF equal 1.235 VDC. Figure external capacitor values have tolerance percent resistors have tolerance percent, except which tolerance percent. External A5191HRT, filter exhibits three-pole, high-pass filter 624Hz one-pole, low-pass filter 2500Hz. Internally, A5191HRT high-pass pole 35Hz low-pass pole 90kHz. lowpass pole vary much percent. input impedance entire filter greater than 150MW frequencies below 50kHz.
Figure Receive Filter Schematic
Oscillator A5191HRT requires 460.8kHz clock signal OXTL. This provided external clock external components connected A5191HRT internal oscillator.
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A5191HRT
4.5.1. Internal Oscillator Option oscillator cell will function with either 460.8kHz crystal ceramic resonator. parallel resonant ceramic resonator connected between OXTL IXTL. Figure illustrates crystal option clock generation using 460.8kHz percent tolerance) parallel resonant crystal tuning capacitors. actual values capacitors depend recommendations manufacturer resonator. Typically, capacitors range 100pF 470pF used. 4.5.2. External Clock Option desirable external 460.8kHz clock shown Figure rather than internal oscillator because high cost availability ceramic resonators. addition, A5191HRT consumes less current when external clock used. Minimum current consumption occurs with clock connected OXTL IXTL connected VSS.
Figure Crystal Oscillator
Figure Oscillator with External Clock
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A5191HRT
Ordering Information
A5191HRT available 28-pin plastic leaded chip carrier (PLCC) 32-pin low-profile quad flat pack (LQFP). following part number when ordering. Contact your local sales representative more information: www.onsemi.com.
Part Number A5191HRTLG-XTD A5191HRTLG-XTP A5191HRTPG-XTD A5191HRTPG-XTP Package 32-pin LQFP Green/RoHS compliant 32-pin LQFP Green/RoHS compliant 28-pin PLCC Green/RoHS compliant 28-pin PLCC Green/RoHS compliant Shipping Configuration Tube/Tray Tape Reel Tube/Tray Tape Reel Temperature Range -40°C +85°C (Industrial) -40°C +85°C (Industrial) -40°C +85°C (Industrial) -40°C +85°C (Industrial)
Electrical Specifications
Table Absolute Maximums Symbol Parameter Min. Max. Units Ambient Storage temperature Supply voltage -0.3 VIN, VOUT input, output -0.3 Re-flow solder profile IPC/JEDEC J-STD-020C Cautions: CMOS devices damaged high-energy electrostatic discharge. Devices must stored conductive foam with pins shunted. Precautions should taken avoid application voltages higher than maximum rating. Stresses above absolute maximum ratings result damage device. Remove power before insertion removal this device. Table Characteristics 3.0V 5.5V, -40°C +85°C Symbol Parameter Input voltage, Input voltage Output voltage, (IOL 0.67mA) Output voltage, high (IOH -0.67mA) Input capacitance Analog input IRXA Digital input IIL/IH Input leakage current IOLL Output leakage current Power supply current (RBIAS 500k, IAREF 1.235V)
Min.
Typ.
Max.
Units
1.235 IAREF Analog reference ICDREF* Carrier detect reference (IAREF 0.08V) 1.15 OCBIAS Comparator bias current (RBIAS IAREF 1.235V) *The HART specification requires carrier detect (OCD) active between mVp-p. Setting ICDREF IAREF 0.08 will carrier detect nominal mVp-p.
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A5191HRT
Table Characteristics 3.0V 5.5V, -40°C +85°C Name Description Min. Typ. Max. Receive analog input ±150 Leakage current IRXA 1210 1200 1190 Frequency mark (logic 2220 2200 2180 Frequency space (logic Output high-pass filter Slew rate 0.025 ORXAF Gain bandwidth (GBW) Voltage range 0.15 0.15 Carrier detect receive filter input IRXAC Leakage current ±500 Modulator output Frequency mark (logic Frequency mark (logic 1196.9 OTXA Amplitude (IAREF 1.235V) 2194.3 Slope Loading (IAREF 1.235V) 2.79 Receive digital output ORXD Rise/fall time Carrier detect output Rise/fall time modular output frequencies proportional input clock frequency (460.8kHz). Units mVDD mV/s
Table Modem Characteristics 3.0V 5.5V, -40°C +85°C Parameter Demodulator jitter Conditions Input frequencies 1200Hz ±10Hz, 2200Hz 20Hz Clock frequency 460.8kHz 0.1% Input (HLXA) asymmetry,
Min.
Typ.
Max.
Units
Table Ceramic Resonator External Clock Specifications 3.0V 5.5V, -40°C +85°C Parameter Min. Typ. Max. Resonator Tolerance Frequency 460.8 External Clock frequency 456.2 460.8 Duty cycle 465.4 Amplitude
Units
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A5191HRT
Mechanical Specifications
Symbol
Min. .165 .099 .485 .450 .390 .485 .450 .390
Nom. .172 .101 .490 .452 .420 .300 .490 .452 .420 .300 .050
Max. .180 .110 .495 .495 .430 .495 .455 .430
Figure Lead PLCC
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A5191HRT
Symbol
Min. 0.05 1.35
0.45 0.30 0.09
Nom. 0.10 1.40 9.00 4.50 7.00 9.00 4.50 7.00 0.60 0.80 0.37
Max. 1.60 0.15 1.45
0.75 0.45 0.20 0.10 0.20
Figure Lead LQFP
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A5191HRT
Revision History
Revision Date March 2005 2008 Modification Update Semiconductor template
Semiconductor registered trademarks Semiconductor Components Industries, (SCILLC). SCILLC reserves right make changes without further notice products herein. SCILLC makes warranty, representation guarantee regarding suitability products particular purpose, does SCILLC assume liability arising application product circuit, specifically disclaims liability, including without limitation special, consequential incidental damages. "Typical" parameters which provided SCILLC data sheets and/or specifications vary different applications actual performance vary over time. operating parameters, including "Typicals" must validated each customer application customer's technical experts. SCILLC does convey license under patent rights rights others. SCILLC products designed, intended, authorized components systems intended surgical implant into body, other applications intended support sustain life, other application which failure SCILLC product could create situation where personal injury death occur. Should Buyer purchase SCILLC products such unintended unauthorized application, Buyer shall indemnify hold SCILLC officers, employees, subsidiaries, affiliates, distributors harmless against claims, costs, damages, expenses, reasonable attorney fees arising directly indirectly, claim personal injury death associated with such unintended unauthorized use, even such claim alleges that SCILLC negligent regarding design manufacture part. SCILLC Equal Opportunity/Affirmative Action Employer. This literature subject applicable copyright laws resale manner.
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