A5191HRT AMIS HART TM Modem 1.0 Features * Can be used in designs presently using the SYM20C15 * Low power: optimal for intrinsically safe applications * Single-chip, half-duplex 1200 bits per second FSK modem * CMOS compatible * Bell 202 shift frequencies of 1200 Hz and 2200 Hz * Internal oscillator requires 460.8 kHz crystal or ceramic resonator * 3.3V - 5.0V power supply * Meets HART physical layer requirements * Transmit-signal wave shaping * Industrial temperature range of -40 C to +85 C * Receive band-pass filter * Available in a 28-pin PLCC and 32-pin LQFP packages 2.0 Description TEST4 TEST3 VDD TEST2 TEST1 TEST12 OCD ORXD ORXD OCD TEST1 TEST11 24 ITXD 7 23 INRTS 8 22 VDD M XXXXYZZ 9 10 IAREF 11 A5191HRTP 12 13 14 15 16 17 18 TEST10 OTXA 21 ICDREF TEST9 32 31 30 29 28 27 26 25 25 AMI Semiconductor www.amis.com TEST5 TEST6 TEST7 TEST8 TEST9 VSS OTXA IAREF VSS 20 IXTL 19 OXTL 1 2 24 M 3 22 21 5 6 7 XXXXYZZ 20 A5191HRTL 18 8 19 17 9 10 11 12 13 14 15 16 1 23 4 ICDREF OCBIAS TEST10 VSSA VDDA IRXA ORXAF IRXAC TEST8 28 27 26 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. IRXAC TEST7 1 ORXAF 6 2 IRXA INRESET 3 VDDA 5 4 OCBIAS TEST5 TEST12 Figure 2: 32-Pin LQFP Pinout Diagram TEST2 Figure 1: 28-Pin PLCC Pinout Diagram TEST3 and Functional Description sections for details on pin compatibility with the SYM20C15. TEST4 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 HART physical layer requirements including modulation, demodulation, receive filtering, carrier detect and transmit-signal shaping. The A5191HRT is pincompatible with the SYM20C15. See the Pin Description TEST11 ITXD INRTS VDD VSS VSSA IXTL OXTL A5191HRT AMIS HART TM Modem Table 1: Pinout Summary 28-Pin PLCC, A5191HRTP (12197-504) Pin No. Signal Name Type Pin Description 1 TEST1 Input 2 TEST2 - No connect 3 TEST3 - No connect 4 TEST4 - No connect 5 TEST5 Input Connect to Vss 6 INRESET Input Reset all digital logic when low 7 TEST7 Input Connect to Vss 8 TEST8 Input Connect to Vss 9 TEST9 Input Connect to Vss 10 OTXA Output 11 IAREF Input Analog reference voltage 12 ICDREF Input Carrier detect reference voltage 13 OCBIAS Output 14 TEST10 Input Connect to Vss 15 VDDA Power Analog supply voltage 16 IRXA Input FSK modulated HART receive signal from 4-20 mA loop interface circuit 17 ORXAF Output 18 IRXAC Input 19 OXTL Output 20 IXTL Input 21 VSS Ground 22 VDD Power Digital supply voltage 23 INRTS Input Request to send 24 ITXD Input Input transmit date. Transmitted HART data stream from UART. 25 TEST11 - 26 ORXD Output Received demodulated HART data to UART 27 OCD Output Carrier detect output 28 TEST12 - AMI Semiconductor www.amis.com Connect to Vss Output transmit analog. FSK modulated HART transmit signal to 4-20 mA loop interface circuit. Comparator bias current Analog receive filter output Analog receive comparator input Crystal oscillator output Crystal oscillator input Ground No connect No connect 2 A5191HRT AMIS HART TM Modem Table 2: Pinout Summary 32-Pin LQFP, A5191HRTL (12197-503) Pin No. Signal Name Type Pin Description 1 TEST5 Input Connect to Vss 2 INRESET Input Reset all digital logic when low. Connect to VDD for normal operation 3 TEST7 Input Connect to Vss 4 TEST8 Input Connect to Vss 5 TEST9 Input Connect to Vss 6 VSS Ground Digital ground 7 OTXA Output Output transmit analog. FSK modulated HART transmit signal to 4-20 mA loopinterface circuit. 8 IAREF Input Analog reference voltage 9 ICDREF Input 10 OCBIAS Output 11 TEST10 Input Connect to Vss 12 VSSA Ground Analog ground 13 VDDA Power Analog supply voltage 14 IRXA Input FSK modulated HART receive signal from 4-20 mA loop interface circuit 15 ORXAF Output 16 IRXAC Input 17 OXTL Output 18 IXTL Input 19 VSSA Ground Analog ground 20 VSS Ground Digital ground 21 VDD Power Digital supply voltage 22 INRTS Input Request to send 23 ITXD Input Input transmit data. Transmitted HART data stream from UART. 24 TEST11 - 25 ORXD Output Received demodulated HART data to UART 26 OCD Output Carrier detect output 27 TEST12 - 28 TEST1 Input 29 TEST2 - 30 VDD Power 31 TEST3 - No connect 32 TEST4 - No connect AMI Semiconductor www.amis.com Carrier detect reference voltage Comparator bias current Analog receive filter output Analog receive comparator input Crystal oscillator output Crystal oscillator input No connect No connect Connect to Vss No connect Digital supply voltage 3 A5191HRT AMIS HART TM Modem 3.0 Pin Descriptions IAREF: Analog Reference Voltage is 2200 Hz. When ITXD is high, the modulator output frequency is 1200 Hz. This analog input sets the dc operating point of the operational amplifiers and comparators and is usually selected to split the dc potential between VDD and VSS. See IAREF in DC Characteristics on page 8. IXTL: Oscillator Input This 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. ICDREF: Carrier Detect Reference Voltage This analog input controls at which level the carrier detect (OCD) becomes active. This is determined by the dc voltage difference between ICDREF and IAREF. Selecting ICDREF - IAREF equal to 0.08 VDC will set the carrier detect to a nominal 100 mVp-p. OCBIAS: Comparator Bias Current The current through this output controls the operating parameters of the internal operational amplifiers and comparators. For normal operation, OCBIAS current is set to 2.5 4A. INRESET: Reset Digital Logic OCD: Carrier Detect Output When at logic low (VSS) this input holds all the digital logic in Reset. During normal operation INRESET should be at VDD. INRESET should be held low for a minimum of 10 nS after VDD = 2.5 V as shown in Figure 3 below. This output goes high when a valid input is recognized on IRXA. If the received signal is greater than the threshold specified on ICDREF for four cycles of the IRXA signal, the valid input is recognized. Figure 3: Reset Timing ORXAF*: Analog Receive Filter Output This signal is the square wave output of the receiver highpass filter. 2.5 V VDD ORXD: Digital Receive Output (CMOS) 0 VDD INRESET 10 nS This signal outputs the digital receive data. When the received signal (IRXA) is 1200 Hz, ORXD outputs logic high. When the received signal (IRXA) is 2200 Hz, ORXD outputs logic low. ORXD is qualified internally with OCD. 0 OTXA: Analog Transmit Output This output provides the trapezoidal signal controlled by ITXD. When ITXD is low, the output frequency is 2200 Hz. When ITXD is high, the output frequency is 1200 Hz. This output is active when INRTS is low and 0.5 VDC when INRTS is high. Note: This signal is also present on the LSI 20C15. It is labeled as Test6. The 20C15 datasheet mentions the reset function of this pin but does not emphasize its use to reset the chip. Reliable operation of the modem requires a hardware reset as shown in Figure 3. This is true for the AMIS 12197-503 and 12197-504 as well as the LSI 20C15. OXTL: Oscillator Output This 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. INRTS: Request To Send This active-low input selects the operation of the modulator. OTXA is enabled when this signal is low. This signal must be held high during power-up. TEST(12:1): Factory Test These are factory test pins. For normal operation, tie these signals as per Table 1 and Table 2. IRXA*: Analog Receive Input This input accepts the 1200/2200 Hz signals from the external filter. VDD: Digital Power IRXAC: Analog Receive Comparator Input VDDA: Analog Supply Voltage This is the power for the digital modem circuitry. This is the positive input of the carrier detect comparator and the receiver filter comparator. This is the power for the analog modem circuitry. VSS: Ground ITXD: Digital Transmit Input (CMOS) This is the analog and digital ground. This input to the modulator accepts digital data in NRZ form. When ITXD is low, the modulator output frequency AMI Semiconductor www.amis.com VSSA: Analog Ground 4 A5191HRT AMIS HART TM Modem 4.0 Functional Description The A5191HRT is a functional equivalent of the SYM20C15 HART Modem. It contains a transmit data modulator and signal shaper, carrier detect circuitry, analog receiver and demodulator circuitry and an oscillator, as shown in Figure 4. The output of the demodulator is qualified with the carrier detect signal (OCD), therefore, only IRXA signals large enough to be detected (100 mVp-p typically) by the carrier detect circuit produce received serial data at ORXD. Figure 4: A5191HRT Block Diagram Maximum demodulator jitter is 12 percent of one bit given input frequencies within HART specifications, a clock frequency of 460.8 kHz (1.0 percent) and zero input (IRXA) asymmetry. ITXD INRTS Modulator and Transmit Wave Shaping Control Logic ORXD OCD IXTL OXTL Carrier Detect OTXA 4.2 TRANSMIT-SIGNAL SHAPER The transmit-signal shaper generates a HART compliant FSK modulated signal at OTXA. Figure 6 and Figure 7 show the transmit-signal forms of the A5191HRT. IRXA IRXAC ORXAF IAREF ICDREF OCBIAS Receive Filter and Demodulator Oscillator For IAREF = 1.235 VDC, OTXA will have a voltage swing from approximately 0.25 to 0.75 VDC. The internal HART modem modulates the transmit-signal and demodulates the receive signal. The transmit-signal shaper enables the A5191HRT to transmit a HART compliant signal. The carrier is detected by comparing the receiver filter output with the difference between two external voltage references. The analog receive circuitry band-pass filters the received signal for input to the modem and the carrier detect circuitry. The oscillator provides the modem with a stable time base using either a simple external resonator or an external clock source. Figure 6: OTXA Waveform (1200 Hz) T 4.1 A5191HRTLOGIC The modem consists of a modulator and demodulator. The modem uses shift frequencies of nominally 1200 Hz (for a 1) and 2200 Hz (for a 0). The bit rate is 1200 bits/second. Modulator Ch3 The modulator accepts digital data in NRZ form at the ITXD input and generates the FSK modulated signal at the OTXA output. INRTS must be a logic low for the modulator to be active. 200mV M 200s Ch 3 4mV Figure 7: OTXA Waveform (2200 Hz) Demodulator The demodulator accepts an FSK signal at the IRXA input and reproduces the original modulating signal at the ORXD output. The nominal bit rate is 1200 bits per second. Figure 5 illustrates the demodulation process. T Figure 5: Demodulator Signal Timing IRXA ORXD 1 1 0 1 1 Ch3 1/1200 Sec AMI Semiconductor www.amis.com 5 200mV M 200s Ch 3 4mV A5191HRT AMIS HART TM Modem 4.3 CARRIER DETECT CIRCUITRY The Carrier Detect Comparator shown in Figure 8 below generates logic low output if the IRXAC voltage is below ICDREF. The comparator output is fed into a carrier detect block (see Figure 4 on page 5). The carrier detect block drives the carrier detect output pin OCD high if INRTS is high and four consecutive pulses out of the comparator have arrived. OCD stays high as long as INRTS is high and the next comparator pulse is received in less than 2.5 ms. Once OCD goes inactive, it takes four consecutive pulses out of the comparator to assert OCD 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. Bias Current Resistor The A5191HRT requires a bias current resistor to be connected between OCBIAS and VSS. The bias current controls the operating parameters of the internal operational amplifiers and comparators. The value of the bias current resistor is determined by the reference voltage IAREF and the following formula: The recommended bias current resistor is 500K when IAREF is equal to 1.235 VDC. 4.4 ANALOG RECEIVER CIRCUITRY In Figure 8 all external capacitor values have a tolerance of 5 percent and the resistors have a tolerance of 1 percent, except the 3 M which has a tolerance of 5 percent. External to the A5191HRT, the filter exhibits a three-pole, high-pass filter at 624 Hz and a one-pole, low-pass filter at 2500 Hz. Internally, the A5191HRT has a high-pass pole at 35 Hz and a low-pass pole at 90 kHz. The low-pass pole can vary as much as 30 percent. The input impedance of the entire filter is greater than 150 M at frequencies below 50 kHz. Voltage References The A5191HRT requires two voltage references, IAREF and ICDREF. IAREF sets the dc operating point of the internal operational amplifiers and comparators. A 1.235 VDC reference (Analog Devices AD589) is suitable as IAREF. The level at which OCD (carrier detect) becomes active is determined by the dc voltage difference (ICDREF IAREF). Selecting a voltage difference of 0.08 VDC will set the carrier detect to a nominal 100 mVp-p. Figure 8: Receive Filter Schematic Hart_In C3 470pf R6 422k C2 1 nf R5* 215k C1 1 nf (15) ORXAF R1* 499k R4* R3 215k 787k (14) + IRXA Recieve Filter Amplifier R2 3M - R7 216k 300pf 220pf (16)IRXAC + 15M Receive Comparator - To Receive Demodulator 214k 40pf V+ + Carrier Detect Comparator 44k R8 - R9 14.7k Z1 1.235V AMI Semiconductor www.amis.com R10* 200k To Carrier Detect (8)IAREF Modem3 (9)ICDREF 6 A5191HRT AMIS HART TM Modem 4.5 OSCILLATOR The A5191HRT requires a 460.8 kHz clock signal on OXTL. This can be provided by an external clock or external components may be connected to the A5191HRT internal oscillator. 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. External Clock Option It may be desirable to use an external 460.8 kHz clock as shown in Figure 10 rather than the internal oscillator because of the high cost and low availability of ceramic resonators. In addition, the A5191HRT consumes less current when an external clock is used. Minimum current consumption occurs with the clock connected to OXTL and IXTL connected to VSS. 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 OXTL and IXTL. Figure 9 illustrates the crystal option for clock generation using a 460.8 kHz (I percent tolerance) parallel resonant crystal and two tuning capacitors. The actual values of the Figure 9: Crystal Oscillator C1 Figure 10: Oscillator with External Clock 460.8 kHz OXTL OXTL OSCILLATOR CELL OSCILLATOR CELL Frequency 460.8 kHz Out IXTL IXTL Frequency Out Package Type Part Name Part Number 32-pin LQFP A5191HRTL 12197-503 28-pin PLCC A5191HRTP 12197-504 C2 5.0 Ordering Information The A5191HRT is available in a 28-pin plastic leaded chip carrier (PLCC) and 32-pin low-profile quad flat pack (LQFP). Use the following part number when ordering. Contact your local sales representative for more information: www.amis.com/sales. 6.0 Electrical Specifications ABSOLUTE MAXIMUMS Min. Max. Units TA Ambient -40 +85 C TS Storage Temperature -55 VDD Supply Voltage -0.3 150 6.0 DC Input, Output -0.3 Parameter Symbol VIN , VOUT TL Lead Temperature (Soldering 10 VDD+0.3 250 C V V C Cautions: 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 ratings may result in damage to the device. 2. Remove power before insertion or removal of this device. AMI Semiconductor www.amis.com 7 A5191HRT AMIS HART TM Modem DC CHARACTERISTICS (VDD = 3.0 V to 5.5 V, VSS = 0V, TA = -40C to +85C) Symbol Parameter VDD Min. VIL VIH VOL Input Voltage, Low Input Voltage 3.0-5.5 3.0-5.5 0.7*VDD Output Voltage, Low (IOL = 0.67mA) 3.0-5.5 VOH Output Voltage, High (IOH= -0.67mA) 3.0-5.5 Input Capacitance Analog Input IRXA Digital Input CIN Typical Max. Units 0.3*VDD V V 0.4 V 2.4 V pF 2.9 25 3.5 IIL/IH Input Leakage Current 500 nA IOLL Output Leakage Current Power Supply Current 10 450 600 2.6 A A IDD 3.3 5.0 3.3 5.0 (RBIAS = 500k, IAREF =1.235 V) IAREF Analog Reference ICDREF1 Carrier Detect Reference 1.2 330 400 1.235 2.5 1.15 V V (IAREF - 0.08 V) OCBIAS Comparator Bias Current 2.5 (RBIAS = 500k, IAREF =1.235 V) 1. The HART specification requires Carrier Detect (OCD) to be active between 80 and 120 mVp-p. Setting ICDREF at IAREF - 0.08 VDC will set the carrier detect to a nominal 100 mVp-p. AMI Semiconductor www.amis.com 8 A A5191HRT AMIS HART TM Modem AC CHARACTERISTICS (VDD = 3.0 V to 5.5 V, VSS = 0V, TA = -40C to +85C) Pin Name IRXA ORXAF IRXAC OTXA ORXD OCD Description Receive Analog Input Leakage Current Frequency - Mark (Logic 1) Frequency - Space (Logic 0) Output of the High-pass Filter Slew Rate Gain Bandwith (GBW) Voltage Range Carrier Detect & Receive Filter Input Leakage Current Modulator Output Frequency' - Mark (Logic 1) Frequency - Space (Logic 0) Amplitude (IAREF 1.235 V) Slope Loading (IAREF = 1.235 V) Receive Digital Output Rise/Fall Time Carrier Detect Output Rise/Fall Time Min. Typical Max. Units 1190 2180 1200 2200 150 1210 2220 nA Hz Hz VDD - 0.15 V/s kHz V/s 500 nA 0.025 150 0.15 1196.9 2194.3 500 2.79 Hz Hz mVp-p mV/s k ns 30 20 ns 20 The modular output frequencies are proportional to the input clock frequency (460.8 kHz). MODEM CHARACTERISTICS (VDD = 3.0 V to 5.5 V, VSS = 0V, TA = -40C to +85C) Parameter Min. Typical Max. 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 (HLXA) asymmetry, 0 12 Units % of 1 bit CERAMIC RESONATOR - EXTERNAL CLOCK SPECIFICATIONS (VDD = 3.0 V to 5.5 V, VSS = 0V, TA = -40C to +85C) Parameter Resonator Tolerance Frequency External Clock Frequency Duty Cycle Amplitude AMI Semiconductor www.amis.com Min. Typical Max. 1.0 % kHz 465.4 60 kHz % V 460.8 456.2 40 9 460.8 50 VOH - VOL Units A5191HRT AMIS HART TM Modem 7.0 Mechanical Specifications Symbol Min. Nom. Max. A .165 .172 .180 A1 .099 .101 .110 D .485 .490 .495 D1 .450 .452 .455 D2 .390 .420 .430 D3 .300 REF E .485 .490 .495 E1 .450 .452 .455 E2 .390 .420 .430 E3 .300 REF e .050 BSC .048 / .042 2 PLCS Figure 11: 28 Lead PLCC D E1 D1 E E3 PIN 1 IDENTIFIER & ZONE Bottom View Top View D3 .032 / .026 A1 A SEATING PLANE Side View 0.076 e .021 / .013 D2 / E2 .020 min R .045 / .025 AMI Semiconductor www.amis.com 10 A5191HRT AMIS HART TM Modem Symbol Min. Nom. Max. A A1 A2 D D/2 D1 E E/2 E1 L e b c ccc ddd 0.05 1.35 0.10 1.40 9.00 BSC 4.50 BSC 7.00 BSC 9.00 BSC 4.50 BSC 7.00 BSC 0.60 0.80 BSC 0.37 - 1.60 0.15 1.45 Figure 12: 32 Lead LQFP 0.45 0.30 0.09 - 0.75 0.45 0.20 0.10 0.20 D D/2 24 E/2 E D/2 D1 17 E1 0 min b 0.08 R min INDEX E/2 0.20 min 16 25 32 0.08 / 0.20 R 9 L 1 e 0- 7 DETAIL A 8 SEE DETAIL A c A2 A 1.00 (REF) A1 (c) 2001 AMI Semiconductor, Inc. AMI Semiconductor makes no warranty for the use of its products, other than those expressly contained in the company's standard warranty contained in AMI Semiconductor's Terms and Conditions. The company assumes no responsibility for any errors which may appear in this document, reserves the right to change devices or specifications detailed herein at any time without notice, and does not make any commitment to update the information contained herein. No licenses to patents or other intellectual property of AMI Semiconductor are granted by the company in connection with the sale of AMI Semiconductor products, expressly or by implication. HART is a registered trademark of the HART Communication Foundation. AMI Semiconductor www.amis.com 11