RCV420KPG4

® RCV420 RCV 420 Precision 4mA to 20mA CURRENT LOOP RECEIVER FEATURES APPLICATIONS ● COMPLETE 4-20mA TO 0-5V CONVERSION ● PROCESS CONTROL ● INTERNAL SENSE RESISTORS ● PRECISION 10V REFERENCE ● BUILT-IN LEVEL-SHIFTING ● INDUSTRIAL CONTROL ● FACTORY AUTOMATION ● DATA ACQUISITION ● ±40V COMMON-MODE INPUT RANGE ● 0.1% OVERALL CONVERSION ACCURACY ● HIGH NOISE IMMUNITY: 86dB CMR ● SCADA ● RTUs ● ESD ● MACHINE MONITORING DESCRIPTION transmitter compliance voltage is at a premium. The 10V reference provides a precise 10V output with a typical drift of 5ppm/°C. The RCV420 is a precision current-loop receiver designed to convert a 4–20mA input signal into a 0–5V output signal. As a monolithic circuit, it offers high reliability at low cost. The circuit consists of a premium grade operational amplifier, an on-chip precision resistor network, and a precision 10V reference. The RCV420 features 0.1% overall conversion accuracy, 86dB CMR, and ±40V common-mode input range. The RCV420 is completely self-contained and offers a highly versatile function. No adjustments are needed for gain, offset, or CMR. This provides three important advantages over discrete, board-level designs: 1) lower initial design cost, 2) lower manufacturing cost, and 3) easy, cost-effective field repair of a precision circuit. The circuit introduces only a 1.5V drop at full scale, which is useful in loops containing extra instrument burdens or in intrinsically safe applications where V+ V– Ref In 16 4 12 RCV420 300kΩ –In 92kΩ 11.5kΩ 99kΩ 1 15 Rcv fB RS 75Ω CT 11 Ref Out 2 RS 75Ω +In 14 Rcv Out +10V Ref 1.01kΩ 3 300kΩ 100kΩ 13 5 Rcv Com Ref Com 10 Ref fB 8 Ref Trim 7 Ref Noise Reduction International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 • Twx: 910-952-1111 Internet: http://www.burr-brown.com/ • FAXLine: (800) 548-6133 (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 ® © 1988 Burr-Brown Corporation SBVS019 PDS-837E 1 RCV420 Printed in U.S.A. October, 1997 SPECIFICATIONS ELECTRICAL At T = +25°C and VS = ±15V, unless otherwise noted. RCV420KP, JP CHARACTERISTICS MIN TYP GAIN Initial Error Error—JP Grade vs Temp Nonlinearity(1) 0.3125 0.05 15 0.0002 OUTPUT Rated Voltage (IO = +10mA, –5mA) Rated Current (EO = 10V) Impedance (Differential) Current Limit (To Common) Capacitive Load (Stable Operation) INPUT Sense Resistance Input Impedance (Common-Mode) Common-Mode Voltage CMR(2) vs Temp (DC) (TA = TMIN to TMAX) AC 60Hz OFFSET VOLTAGE (RTO)(3) Initial vs Temp vs Supply (±11.4V to ±18V) vs Time 10 +10, –5 MAX 0.15 0.25 0.002 12 75 200 70 80 76 80 75.75 ±40 ZERO ERROR(4) Initial Initial—JP Grade vs Temp 0.025 Ω kΩ V dB dB dB 1 mV µV/°C dB µV/mo 0.075 0.15 % of span % of span ppm of span/°C 10 90 200 74 V/mA % of span % of span ppm/°C % of span V mA Ω mA pF 0.01 +49, –13 1000 74.25 UNITS 10 OUTPUT NOISE VOLTAGE fB = 0.1Hz to 10Hz fO = 10kHz 50 800 µVp-p nV/√Hz DYNAMIC RESPONSE Gain Bandwidth Full Power Bandwidth Slew Rate Settling Time (0.01%) 150 30 1.5 10 kHz kHz V/µs µs VOLTAGE REFERENCE Initial Trim Range(5) vs Temp vs Supply (±11.4V to ±18V) vs Output Current (IO = 0 to +10mA) vs Time Noise (0.1Hz to 10Hz) Output Current POWER SUPPLY Rated Voltage Range(6) Quiescent Current (VO = 0V) TEMPERATURE RANGE Specification Operation Storage Thermal Resistance, θJA 9.99 10.01 ±4 5 0.0002 0.0002 15 5 +10, –2 ±15 –5, +11.4 3 0 –25 –40 ±18 4 +70 +85 +85 80 V % ppm/°C %/V %/mA ppm/kHz µVp-p mA V V mA °C °C °C °C/W NOTES: (1) Nonlinearity is the max peak deviation from best fit straight line. (2) With 0 source impedance on Rcv Com pin. (3) Referred to output with all inputs grounded including Ref In. (4) With 4mA input signal and Voltage Reference connected (includes VOS, Gain Error, and Voltage Reference Errors). (5) External trim slightly affects drift. (6) IO Ref = 5mA, IO Rcv = 2mA. ® RCV420 2 ABSOLUTE MAXIMUM RATINGS(1) PIN CONFIGURATION Top View DIP –In 1 16 V+ CT 2 15 Rcv fB +In 3 14 Rcv Out V– 4 13 Rcv Com Ref Com 5 12 Ref In NC 6 11 Ref Out Ref Noise Reduction 7 10 Ref fB Ref Trim 8 9 NC Supply ............................................................................................... ±22V Input Current, Continuous ................................................................ 40mA Input Current Momentary, 0.1s ........................... 250mA, 1% Duty Cycle Common-Mode Input Voltage, Continuous ....................................... ±40V Lead Temperature (soldering, 10s) ............................................... +300°C Output Short Circuit to Common (Rcv and Ref) ..................... Continuous NOTE: (1) Stresses above these ratings may cause permanent damage. PACKAGE INFORMATION PRODUCT PACKAGE PACKAGE DRAWING NUMBER(1) RCV420KP RCV420JP 16-Pin Plastic DIP 16-Pin Plastic DIP 180 180 NOTE: (1) For detailed drawing and dimension table, please see end of data sheet, or Appendix C of Burr-Brown IC Data Book. ORDERING INFORMATION PRODUCT PERFORMANCE GRADE PACKAGE RCV420KP RCV420JP 0°C to +70°C 0°C to +70°C 16-Pin Plastic DIP 16-Pin Plastic DIP The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant any BURR-BROWN product for use in life support devices and/or systems. ® 3 RCV420 TYPICAL PERFORMANCE CURVES At TA = +25°C, VS = ±15V, unless otherwise noted. STEP RESPONSE NO LOAD SMALL SIGNAL RESPONSE RL = ∞, CL = 1000pF SMALL SIGNAL RESPONSE NO LOAD POSITIVE COMMON-MODE VOLTAGE RANGE vs POSITIVE POWER SUPPLY VOLTAGE NEGATIVE COMMON-MODE VOLTAGE RANGE vs NEGATIVE POWER SUPPLY VOLTAGE –80 Negative Common-Mode Range (V) Positive Common-Mode Range (V) 80 TA = –55°C 70 TA = +25°C 60 TA = +125°C 50 Max Rating = 40V 40 –VS = –5V to –20V –70 TA = +25°C –60 –50 Max Rating = –40V TA = –55°C to +125°C –40 –30 +VS = +11.4V to +20V –20 –10 30 11 12 11.4 13 14 15 16 17 18 19 –5 20 –10 –20 –15 Positive Power Supply Voltage (V) Negative Power Supply Voltage (V) COMMON-MODE REJECTION vs FREQUENCY POWER-SUPPLY REJECTION vs FREQUENCY 100 100 90 80 PSR (dB) CMR (dB) 80 60 V+ V– 60 40 40 1 10 100 1k 10k 100k 1 Frequency (Hz) 100 1k Frequency (Hz) ® RCV420 10 4 10k 100k necessary level shifting. If the Ref In pin is not used for level shifting, then it must be grounded to maintain high CMR. THEORY OF OPERATION Refer to the figure on the first page. For 0 to 5V output with 4–20mA input, the required transimpedance of the circuit is: GAIN AND OFFSET ADJUSTMENT VOUT /IIN = 5V/16mA = 0.3125V/mA. Figure 2 shows the circuit for adjusting the RCV420 gain. Increasing the gain of the RCV420 is accomplished by inserting a small resistor in the feedback path of the amplifier. Increasing the gain using this technique results in CMR degradation, and therefore, gain adjustments should be kept as small as possible. For example, a 1% increase in gain is typically realized with a 125Ω resistor, which degrades CMR by about 6dB. To achieve the desired output (0V for 4mA and 5V for 20mA), the output of the amplifier must be offset by an amount: VOS = –(4mA)(0.3125V/mA) = –1.25V. The input current signal is connected to either +In or –In, depending on the polarity of the signal, and returned to ground through the center tap, CT. The balanced input—two matched 75Ω sense resistors, RS—provides maximum rejection of common-mode voltage signals on CT and true differential current-to-voltage conversion. The sense resistors convert the input current signal into a proportional voltage, which is amplified by the differential amplifier. The voltage gain of the amplifier is: A decrease in gain can be achieved by placing matched resistors in parallel with the sense resistors, also shown in Figure 2. The adjusted gain is given by the following expression VOUT/IIN = 0.3125 x RX /(RX + RS). A 1% decrease in gain can be achieved with a 7.5kΩ resistor. It is important to match the parallel resistance on each sense resistor to maintain high CMR. The TCR mismatch between the two external resistors will effect gain error drift and CMR drift. AD = 5V/(16mA)(75Ω) = 4.1667V/V. The tee network in the feedback path of the amplifier provides a summing junction used to generate the required –1.25V offset voltage. The input resistor network provides high-input impedance and attenuates common-mode input voltages to levels suitable for the operational amplifier’s common-mode signal capabilities. There are two methods for nulling the RCV420 output offset voltage. The first method applies to applications using the internal 10V reference for level shifting. For these applica- BASIC POWER SUPPLY AND SIGNAL CONNECTIONS –In Figure 1 shows the proper connections for power supply and signal. Both supplies should be decoupled with 1µF tantalum capacitors as close to the amplifier as possible. To avoid gain and CMR errors introduced by the external circuit, connect grounds as indicated, being sure to minimize ground resistance. The input signal should be connected to either +In or –In, depending on its polarity, and returned to ground through the center tap, CT. The output of the voltage reference, Ref Out, should be connected to Ref In for the IIN 4–20mA +In 3 CT 2 –In RS 75Ω RS 75Ω 1 200Ω(1) CT +In 10kΩ(1) 10kΩ(1) RX 1µF V– 14 RCV420 Rcv Out 3 FIGURE 2. Optional Gain Adjustment. +10V Reference 4 ±0.5% Gain Adjustment NOTE: (1) Typical values. See text. 1 16 2 RX RCV420 V+ R1 15 13 Rcv Com 12 Ref In 15 Rcv fB 14 11 Rcv Out Ref Out 10 8 7 VO (0–5V) Ref fB Ref Trim Ref Noise Reduction 5 Ref Com 1µF FIGURE 1. Basic Power Supply and Signal Connections. ® 5 RCV420 tions, the voltage reference output trim procedure can be used to null offset errors at the output of the RCV420. The voltage reference trim circuit is discussed under “Voltage Reference.” using the Rcv Com pin. It is important to use a low-output impedance amplifier to maintain high CMR. With this method of zero adjustment, the Ref In pin must be connected to the Rcv Com pin. When the voltage reference is not used for level shifting or when large offset adjustments are required, the circuit in Figure 3 can be used for offset adjustment. A low impedance on the Rcv Com pin is required to maintain high CMR. MAINTAINING COMMON-MODE REJECTION Two factors are important in maintaining high CMR: (1) resistor matching and tracking (the internal resistor network does this) and (2) source impedance. CMR depends on the accurate matching of several resistor ratios. The high accuracies needed to maintain the specified CMR and CMR temperature coefficient are difficult and expensive to reliably achieve with discrete components. Any resistance imbalance introduced by external circuitry directly affects CMR. These imbalances can occur by: mismatching sense resistors when gain is decreased, adding resistance in the feedback path when gain is increased, and adding series resistance on the Rcv Com pin. ZERO ADJUSTMENT Level shifting the RCV420 output voltage can be achieved using either the Ref In pin or the Rcv Com pin. The disadvantage of using the Ref In pin is that there is an 8:1 voltage attenuation from this pin to the output of the RCV420. Thus, use the Rcv Com pin for large offsets, because the voltage on this pin is seen directly at the output. Figure 4 shows the circuit used to level-shift the output of the RCV420 –In 1 CT 2 The two sense resistors are laser-trimmed to typically match within 0.01%; therefore, when adding parallel resistance to decrease gain, take care to match the parallel resistance on each sense resistor. To maintain high CMR when increasing the gain of the RCV420, keep the series resistance added to the feedback network as small as possible. Whether the Rcv Com pin is grounded or connected to a voltage reference for level shifting, keep the series resistance on this pin as low as possible. For example, a resistance of 20Ω on this pin degrades CMR from 86dB to approximately 80dB. For applications requiring better than 86dB CMR, the circuit shown in Figure 5 can be used to adjust CMR. 15 +In 14 RCV420 VO 5 3 13 +15V 12 OPA237 100kΩ 100kΩ ±150mV adjustment at output. 1kΩ PROTECTING THE SENSE RESISTOR The 75Ω sense resistors are designed for a maximum continuous current of 40mA, but can withstand as much as 250mA for up to 0.1s (see absolute maximum ratings). There are several ways to protect the sense resistor from –15V FIGURE 3. Optional Output Offset Nulling Using External Amplifier. –In Use 10V Ref for + and 10V Ref with INA105 for –. 1 15 CT +In 2 VO = (0.3125)(I IN ) + V ZERO 14 RCV420 VO 13 11 3 10 1kΩ 2 5 13 +10V 3 5 INA105 12 Procedure: 1. Connect CMV to C T. 2. Adjust potentiometer for near zero at the output. RCV420 6 1kΩ –10V 1 OPA237 V ZERO 200Ω CMR Adjust 1kΩ OPA237 ±5V adjustment at output. 10kΩ 1kΩ 50kΩ 10kΩ FIGURE 4. Optional Zero Adjust Circuit. FIGURE 5. Optional Circuit for Externally Trimming CMR. ® RCV420 6 overcurrent conditions exceeding these specifications. Refer to Figure 6. The simplest and least expensive method is a resistor as shown in Figure 6a. The value of the resistor is determined from the expression V+ VRX RX 4–20mA RX = VCC /40mA – 75Ω 3 15 2 and the full scale voltage drop is RCV420 14 1 VRX = 20mA x RX. For a system operating off of a 32V supply RX = 725Ω and VRX = 14.5V. In applications that cannot tolerate such a large voltage drop, use circuits 6b or 6c. In circuit 6b a power JFET and source resistor are used as a current limit. The 200Ω potentiometer, RX, is adjusted to provide a current limit of approximately 30mA. This circuit introduces a 1–4V drop at full scale. If only a very small series voltage drop at full scale can be tolerated, then a 0.032A series 217 fast-acting fuse should be used, as shown in Figure 6c. VO a) RX = (V+)/40mA – 75Ω V+ 2N3970 RX 200Ω 4–20mA 3 15 2 For automatic fold-back protection, use the circuit shown in Figure 15. RCV420 14 1 VO b) RX set for 30mA current limit at 25°C. VOLTAGE REFERENCE The RCV420 contains a precision 10V reference. Figure 8 shows the circuit for output voltage adjustment. Trimming the output will change the voltage drift by approximately 0.007ppm/°C per mV of trimmed voltage. Any mismatch in TCR between the two sides of the potentiometer will also affect drift, but the effect is divided by approximately 5. The trim range of the voltage reference using this method is typically ±400mV. The voltage reference trim can be used to trim offset errors at the output of the RCV420. There is an 8:1 voltage attenuation from Ref In to Rcv Out, and thus the trim range at the output of the receiver is typically ±50mV. V+ f1 4–20mA 3 15 2 RCV420 1 14 VO c) f1 is 0.032A, Lifflefuse Series 217 fast-acting fuse. Request Application Bulletin AB-014 for details of a more complete protection circuit. The high-frequency noise (to 1MHz) of the voltage reference is typically 1mVp-p. When the voltage reference is used for level shifting, its noise contribution at the output of the receiver is typically 125µVp-p due to the 8:1 attenuation from Ref In to Rcv Out. The reference noise can be reduced by connecting an external capacitor between the Noise Reduction pin and ground. For example, 0.1µF capacitor reduces the high-frequency noise to about 200µVp-p at the output of the reference and about 25µVp-p at the output of the receiver. FIGURE 6. Protecting the Sense Resistors. –In 1 15 CT +In 2 14 RCV420 VO 11 3 10 8 V REF 20kΩ ±400mV adjustment at output of reference, and ±50mV adjustment at output of receiver if reference is used for level shifting. FIGURE 7. Optional Voltage Reference External Trim Circuit. ® 7 RCV420 12 VLIN 13 4 + VIN 3 1N4148 14 IR2 +12V 11 VREG 10 V+ 1µF RG B 9 RG 402Ω RLIN1 5760Ω 1 IR1 Q1 XTR105 0.01µF 16 – VIN RZ 137Ω RTD 2 7 VO = 0 to 5V 14 13 5 4 IO = 4mA – 20mA 6 12 RCV420 IRET Pt100 100°C to 600°C 11 15 IO 2 10 3 E 8 RG 1µF –12V RCM = 1kΩ NOTE: A two-wire RTD connection is shown. For remotely located RTDs, a three-wire RTD conection is recommended. RG becomes 383Ω, RLIN2 is 8060Ω. See Figure 3 and Table I. 0.01µF FIGURE 8. RCV420 Used in Conjunction with XTR101 to Form a Complete Solution for 4-20mA Loop. 12 RLIN2 RLIN1 13 4 VLIN + VIN 1 IR1 1N4148 14 11 IR2 10 VREG V+ 0 RG RG 1µF XTR105 3 +15V 1µF B E RG 9 Q1 –15V 0.01µF 16 – 2 VIN IRET 6 11 12 2 7 IO = 4mA – 20mA 14 13 4 V+ 1 15 RCV420 IO RZ 10 3 8 Isolated Power from PWS740 9 15 ISO122 5 10 7 8 VO 0 – 5V 2 16 RTD NOTE: A three-wire RTD connection is shown. For a two-wire RTD connection eliminate RLIN2. RCM = 1kΩ 0.01µF FIGURE 9. Isolated 4-20mA Instrument Loop (RTD shown). ® RCV420 8 V– 10 4–20mA +In 3 11 3 15 12 CT –In 15 RS 2 RS 1 2 VO (0–5V) 14 RCV420 (1) CT 14 RCV420 VO (5–0V) 11 1 10 13 5 +10V 13 4–20mA 5 12 12kΩ +6.25V +6.25V OPA237 20kΩ 10 +In RG(1) 11 3 12 CT 2 –In 1 RS 15 RCV420 (N) RS VO = 6.25V – (0.3125) (IIN) VO (0–5V) 14 FIGURE 12. 4-20mA to 5-0V Conversion. 13 5 RCM(1) IL NOTE: (1) RCM and RG are used to provide a first order correction of CMR and Gain Error, respectively. Table 1 gives typical resistor values for RCM and RG when as many as three RCV420s are stacked. Table II gives typical CMR and Gain Error with no correction. Further improvement in CMR and Gain Error can be achieved using a 500kΩ potentiometer for RCM and a 100Ω potentiometer for RG. RCV420 RCM (kΩ) 1 2 3 200 67 Load RX(1) 3 CT 2 +In RG (Ω) ∞ +In 0 7 23 15 RS RX(1) 1 14 RCV420 RS VO (0-5V) 13 12 5 Power Supply –40V (max) TABLE 1. Typical Values for RCM and RG. RCV420 CMR (dB) GAIN ERROR % 1 2 3 94 68 62 0.025 0.075 0.200 +40V (max) Power Supply +In CT TABLE II. Typical CMR and Gain Error Without Correction. (1) RX –In RX(1) 15 RS RCV420 RS 14 VO (0-5V) 13 12 Load FIGURE 10. Series 4-20mA Receivers. 5 IL NOTE: (1) RX = RS/ I1 I2 +In 3 CT 2 –In 1 FIGURE 13. Power Supply Current Monitor Circuit. 15 RS 14 RCV420 RS IL MAX (16mA –1 ) VO 13 12 5 VO = 0.3125 (I1 – I2) Max Gain Error = 0.1% (RCV420BG) FIGURE 11. Differential Current-to-Voltage Converter. ® 9 RCV420 +15V –15V 4 16 RCV420 99kΩ 300kΩ 1 92kΩ 12 15 75Ω 11.5kΩ 2 VOUT 0–5V 14 10.0V 10 75Ω 1.01kΩ 10.0V Reference 11 1.27kΩ 3 300kΩ 100kΩ +5V 13 5 10kΩ +15V 8 4 8 1MΩ 10kΩ AT&T LH1191 Solid-State Relay 10kΩ 2 7 555 Timer 6 10kΩ 1µF 6.95V LM193 0.01µF 3 10kΩ 5 1 0.57V 470Ω 4–20mA Input 47kΩ 22.9kΩ 604Ω 4 2N3904 1µF Overrange Output Underrange Output See Application Bulletin AB-014 for more details. FIGURE 14. 4-20mA Current Loop Receiver with Input Overload Protection. +15V –15V 16 4 RCV420 1 300kΩ 75Ω 301Ω 12 99kΩ 92kΩ 15 11.5kΩ 2 0-20mA Input 14 10 301Ω 1.01kΩ 75Ω 10.0V Ref 3 300kΩ 11 100kΩ 13 See Application Bulletin AB-018 for more details. FIGURE 15. 0-20mA/0-5V Receiver Using RCV420. ® RCV420 10 5 VO 0-5V PACKAGE OPTION ADDENDUM www.ti.com 14-Oct-2022 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) Samples (4/5) (6) RCV420JP ACTIVE PDIP N 16 25 RoHS & Green Call TI N / A for Pkg Type 0 to 70 RCV420JP Samples RCV420KP ACTIVE PDIP N 16 25 RoHS & Green Call TI N / A for Pkg Type 0 to 70 RCV420KP Samples RCV420KPG4 ACTIVE PDIP N 16 25 RoHS & Green Call TI N / A for Pkg Type 0 to 70 RCV420KP Samples (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of