AM462

AM462 ANALOGMICRO | Alldatasheet

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Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 1/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de PRINCIPLE FUNCTION Conversion of input voltage referenced to ground to output current Integrated protection for IC and external components Integrated, adjustable current/voltage sources for external components TYPICAL APPLICATIONS

• Adjustable voltage-to-current (V/I) converter
• Adjustable voltage and current source (supply unit)
• Voltage regulator with additional functions
• Industrial protector and output IC for microprocessors (the Frame ASIC concept [1])
• Peripheral processor IC
• For examples of typical applications see Example Applications VREF = 5/10V AM462 VCC = 6...35V ICC = up to 10mA Single-ended input voltage 0...V -5VCC

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 2/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de

CONTENTS

ELECTRICAL SPECIFICATIONS 4 BOUNDARY CONDITIONS 6 DETAILED DESCRIPTION OF FUNCTIONS 6 INITIAL OPERATION OF AM462 8 General information on 2- and 3-wire applications and the use of current 8 Setting the output current range 8 Selecting the supply voltage 9 Using OP2 as a current source 10 Using OP2 as a voltage reference 11 POINTS TO NOTE: INITIAL OPERATION OF AM462 12 APPLICATIONS 12 Typical 3-wire application with an input signal referenced to ground 12 Typical 2-wire application with an input signal referenced to ground 13 Application for an input signal with an offset 15 BLOCK DIAGRAM AND PINOUT 17 EXAMPLE APPLICATIONS 18 DELIVERY 20 PACKAGE DIMENSIONS 20 FURTHER READING 20

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 3/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de

FEATURES

• Supply voltage: 6...35V
• Wide working temperature range: –40°C...+85°C
• Adjustable integrated reference voltage source: 4.5 to 10V
• Additional voltage/current source
• Adjustable amplification
• Adjustable offset
• Industrial current output (e.g. 0/4...20mA)
• Protection against reverse polarity
• Short-circuit protection
• Output current limitation
• Low-cost device: replaces a number of discrete elements
• 2- and 3-wire operation
• Individually configurable function modules
• RoHS compilant GENERAL DESCRIPTION AM462 is a universal V/I converter and amplifier IC with a number of additional functions. The IC basically consists of an amplifier, whose gain can be set externally, and an output stage which can convert voltage signals referenced to ground to industrial current signals. An additional reference voltage source for the supply of external components is also included in the device. A further operational amplifier can be connected up as a current source, voltage reference or comparator. One of the main featur es of the IC is its integrated protective circuitry. The device is protected against reverse polarity and has a built-in output current limit. Converter IC AM462 enables industrial current loop signals (e.g. of 0/4–20mA) to be pr oduced relatively easily. Using the Frame ASIC concept [1] the IC can be connected up to a processor for signal correction. BLOCK DIAGRAM Figure 1: Block diagram of AM462 (individually configurable function modules) VREF SET OUTAD INDAI GND VSET INN INP IOUT RS+ VCC CVREF CVSET VBG V I 13 15 V oltage Reference OP1 AM462 OP2 RS-

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 4/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de ELECTRICAL SPECIFICATIONS Tamb = 25°C, VCC = 24V, VREF = 5V, IREF = 1mA (unless otherwise stated); currents flowing into the IC are negative. Parameter Symbol Conditions Min. Typ. Max. Unit Supply Voltage Range VCC 6 35 V Quiescent Current ICC Tamb = - 40...+85°C, IREF = 0mA 1.5 mA Temperature Specifications Operating Tamb -40 85 °C Storage Tst -55 125 °C Junction TJ 150 °C Thermal Resistance Θja DIL16 plastic package 70 °C/W Θja SO16 narrow plastic package 140 °C/W Voltage Reference Voltage VREF VSET not connected 4.75 5.00 5.25 V VREF10 VSET = GND, VCC ≥ 11V 9.5 10.0 10.5 V Trim Range VREFADJ 4.5 VREF10 V Current IREF* 0 10.0 mA VREF vs. Temperature d VREF/dT Tamb = - 40...+85°C ±90 ±140 ppm/°C Line Regulation d VREF/dV VCC = 6V...35V 30 80 ppm/V d VREF/dV VCC = 6V...35V, IREF ≈ 5mA 60 150 ppm/V Load Regulation d VREF/dI 0.05 0.10 %/mA d VREF/dI IREF ≈ 5mA 0.06 0.15 %/mA Load Capacitance CL 1.9 2.2 5.0 µF Current/Voltage Source OP2 Internal Reference VBG 1.20 1.27 1.35 V VBG vs. Temperature d VBG/dT Tamb = – 40...+85°C ±60 ±140 ppm/°C Current Source: ICV = VBG/RSET, from Figure 5 Adjustable Current Range ICV* 0 10 mA Output Voltage VCV V CC < 19V VBG VCC – 4 V VCV VCC ≥ 19V VBG 15 V Voltage Source: VCV = VBG (1 + R7 / R6), from Figure 6 Adjustable Voltage Range VCV V CC < 19V 0.4 VCC – 4 V VCV VCC ≥ 19V 0.4 15 V Output Current ICV* Source 10 mA ICV Sink –100 µA Load Capacitance CL Source mode 0 1 10 nF Operational Amplifier Gain Stage (OP1) Adjustable Gain GGAIN 1 Input Range IR V CC < 10V 0 VCC – 5 V IR VCC ≥ 10V 0 5 V Power Supply Rejection Ratio PSRR 80 90 dB Offset Voltage VOS ±0.5 ±2 mV

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 5/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de Parameter Symbol Conditions Min. Typ. Max. Unit Operational Amplifier Gain Stage (OP1) (cont.) VOS vs. Temperature d VOS/dT ±3 ±7 µV/°C Input Bias Current IB 10 25 nA IB vs. Temperature d IB/dT 7 20 pA/°C Output Voltage Limitation VLIM VREF V Output Voltage Range VOUTAD VCC < 10V 0 VCC – 5 V VOUTAD VCC ≥ 10V 0 VREF V Load Capacitance CL 250 pF V/I Converter Internal Gain GVI 0,12 0.125 0,13 Trim Range Adjustable by R0 0.75 1.00 1.25 Voltage Range at R0 FS VR0FS 350 750 mV Offset Voltage VOS Forward Current Gain of T1 βF ≥ 100 ±2 ±4 mV VOS vs. Temperature d VOS/dT Forward Current Gain of T1 βF ≥ 100 ±7 ±14 µV/°C Input Resistance RIN 120 160 kΩ RIN vs. Temperature d RIN/dT 0.2 0.3 kΩ/°C Output Offset Current IOUTOS 3-wire operation –25 –35 µA IOUTOS vs. Temperature d IOUTOS/dT 3-wire operation 16 26 nA/°C Output Offset Current IOUTOS 2-wire operation 9.5 14 µA IOUTOS vs. Temperature d IOUTOS/dT 2-wire operation 6 8 nA/°C Output Control Current IOUTC 2-wire operation, VR0/100mV 6 8 µA IOUTC vs. Temperature d IOUTC/dT 2-wire operation –10 –15 nA/°C Output Voltage Range VOUT V OUT = RL IOUT, VCC < 18V 0 VCC – 6 V VOUT VOUT = RL IOUT, VCC ≥ 18V 0 12 V Output Current Range FS IOUTFS IOUT = VR0/R0, 3-wire operation 20 mA Output Resistance ROUT 0.5 1.0 MΩ Load Capacitance CL 0 500 nF SET Stage Internal Gain GSET 0.5 Input Voltage VSET 0 1.15 V Offset Voltage VOS ±0.5 ±1.5 mV VOS vs. Temperature d VOS/dT ±1.6 ±5 µV/°C Input Bias Current IB 8 20 nA IB vs. Temperature d IB/dT 7 18 pA/°C Protection Functions Voltage Limitation at R0 VLIMR0 VINDAI = 0, VR0 = GSET VSET 580 635 690 mV Protection against reverse polarity Ground vs. VS vs. VOUT 35 V Ground vs. VS vs. IOUT 35 V Current in the event of reverse polarity Ground = 35V, VS = IOUT = 0 4.5 mA System Parameters Nonlinearity Ideal input 0.05 0.15 %FS * In 2-wire operation a maximum current of IOUTmin – ICC is valid

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 6/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de BOUNDARY CONDITIONS Parameter Symbol Conditions Min. Typ. Max. Unit Sense Resistor R0 IOUTFS = 20mA 17 27 38 R c = 20mA/IOUTFS c ⋅ 17 c ⋅ 27 c ⋅ 38 Stabilization Resistor R5 I OUTFS = 20mA 35 40 45 R5 c = 20mA/IOUTFS c ⋅ 35 c ⋅ 40 c ⋅ 45 Load Resistance RL Limitation only for 3-wire operation 0 600 Sum Gain Resistors R1 + R2 20 200 k Sum Offset Resistors R3 + R4 20 200 k VREF Capacitance C1 Ceramic 1.9 2.2 5.0 µF Output Capacitance C2 Only for 2-wire operation 90 100 250 nF D1 Breakdown Voltage VBR 35 50 V T1 Forward Current Gain βF BCX54/55/56, for example 50 150 DETAILED DESCRIPTION OF FUNCTIONS AM462 is a modular, universal V/I converter and protector IC which has been specially developed for the conditioning of voltage signals referenced to ground. It is designed for both 2- and 3-wire operation in industrial applications (cf. appli cation in Figure 8). AM462’s various functions are depicted in the block diagram (Figure 2) which also illustrates how few external components are required for the operation of this particular device. AM462 consists of several modular function bloc ks (operational amplifiers, voltage-to-current converters and references) which, depending on extern al configurations, can either be switched to one another or operated separately (see the basic circuitry in Figure 2): 1. Operational amplifier stage OP1 enables a positive voltage signal to be amplified. OP1 gain GGAIN can be set via external resistors R1 and R2. Protective circuitry against overvoltage is integrated into the chip, limiting the voltage to the set value of the reference voltage. Output voltage VOUTAD at pin OUTAD is calculated as: GAININPOUTAD GVV ⋅= with 11 R RGGAIN += (1) where VINP is the voltage at OP1’s input pin 6 (INP). 2. The internal voltage-to-current converter (V/I converter) provides a voltage-controlled current signal at IC output IOUT (pin 8) which activates an external transistor T1; this in turn supplies the actual output current IOUT. To reduce power dissipation the transistor is an external component and protected against reverse polarity by an additional diode D1. Via pin SET an offset current ISET can be set at output IOUT (with the help of the inte rnal voltage reference and an external voltage divider as shown in Figure 2, for example). External resistor R0 permits the output current to be finely adjusted with parallel operation of current and the voltage output. For the output current provided by T1 the following ratio applies:

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 7/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de SET IVINDAI OUT IR GVI +⋅= = SET INDAI IR V + 08 with 02R VI SET SET = (2) with VINDAI the voltage at pin 6 (INDAI) and VSET the voltage at pin 16 (SET) 1. 3. The AM462 reference voltage source enables voltage to be supplied to external components (such as sensors, microprocessors, etc.). The reference voltage value VREF can be set via pin 13 VSET. If pin VSET is not connected, VREF = 5V; if VSET is switched to ground, VREF = 10V. Values between the above can be set if two exte rnal resistors are used (inserted between pin VREF and pin VSET and between pin VSET and GND; see Figure 2). External (ceramic) capacitor C1 at pin VREF stabilizes the reference voltage. It must be connected even if the voltage reference is not in use. 4. The additional operational amplifier stage OP2 can be used as a current or voltage source to supply external components. OP2's positive i nput is connected internally to voltage VBG so that the output current or output voltage can be set across a wide range using external resistors. 1 The construction of the V/I converter is such that output current IOUT is largely independent of the current amplification βF of external transistor T1. Production-specific variations in the current amplification of the transistors used are compensated for internally by the V/I converter. VBG Ground VS IOUT VINP VSET VOUTAD VCVREF VCVSET VBG OP1 AM462 OP2 VREF 13 15 Voltage Ref er ence 1 16 VINDAI V I Figure 2: Block diagram of AM462 (3-wire circuit for current output). Pin 1 and 2 have to be connected.

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 8/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de INITIAL OPERATION OF AM462 General information on 2- and 3-wire applications and the use of current In 3-wire operation (cf. Figure 3 right and Figure 7) the ground of the IC (pin GND) is connected up to the external mass of the system Ground. The system's supply voltage VS is connected to pin VCC and pin VCC to pin RS+. In 2-wire operation (cf. Figure 3 left and Figure 7) system supply voltage VS is connected to pin RS+ and pin VCC to RS-. The ground of the IC (pin GND) is connected to the node between resistor R5 and load resistor RL (current output IOUT). IC ground ( GND) is not the same as system ground (Ground)!! The output signal is picked up via load resistor RL which connects current output IOUT to the system ground. In 2-wire operation the IC ground is "virtual" (floa ting), as with a constant load resistance the supply voltage of the device VCC changes according to the current. As a rule, the following equation applies to 2-wire operation: () LINOUTSCC RVIVV −= (3) The reason for this is that in 2-wire operation the IC is connected in series to the actual load resistor RL. This is illustrated in Figure 3. In 3-wire operation VCC = VS, as the IC ground is connected to the ground of the system. Setting the output current range When using amplification stage OP1 together with the V/I converter for voltage-to-current conversion the offset of the output current should first be compensated for by suitable selection of resistors R3 and R4. To this end the OP1 input must be connected to ground ( VINP = 0). With the short circuit at the input and by connecting up V/I converter pin VSET as shown in Figure 2 the values of the output current according to Equation 2 are as follows: RL VS 2-wire system signal source and conditioning IC GND Ground ≠ VCC ≠VS Ground RL 3-wire system signal source and conditioning IC GND Ground = VCC = VS Ground GND = GND VCC IOUT IOUT VVCC S = Figure 3: The difference between 2- and 3-wire operation

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 9/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de 020 RR R R VIVI REF SETINDAIOUT +⋅=== (4) and thus for the ratio of the resistors R3/R4: 12 04 3 −= SET REF IR V R R (5) The output current range is set in conjunction with the selected external resistors R1 and R2 (or fine adjustment with R0 ). Using Equations 1 and 2 the following is calculated for output current IOUT : SET GAIN INPOUT IR GVI += 08 with 11 R RGGAIN += (6) Selecting the supply voltage System supply voltage VS needed to operate AM462 is dependent on the selected mode of operation. When using current output pin IOUT (in conjunction with the extern al transistor) the value of VS is dependent on that of the relevant load resistor RL (max. 600 Ω) used by the application. The minimum system supply voltage VS is then: minmax CCLOUTS VRIV +≥ (7) Here, IOUTmax stands for the maximum output current and VCCmin for the minimum IC supply voltage which is dependent on the selected reference voltage: V1min +≥ REFCC VV (8) VS [V] RL [Ω] 6 35 VCCmin = 6V RLm ax = 600Ω IOUTmax = 20mA 18 2412 600 W orking range 300 R VV IL SC C m i n OUTmax Figure 4: Working range in conjunction with the load resistor

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 10/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de The working range resulting from Equation Fehler! Verweisquelle konnte nicht gefunden werden. is described in Figure 4. Example calculations and typical values for the external components can be found in the example applications from page 13 onwards. Using OP2 as a current source The additional operational amplifier OP2 can easily be connected up as a constant current source. Using the circuit in Figure 5 the following applies: Example : OP2 as courrent source SETSET BG S RR VI V27.1== (9) The bridge symbol represents the component to be supplied with current (e.g. a piezoresistive sensing element or temperature sensor). A supply current of IS = 1mA is to be set. Using Equation Fehler! Verweisquelle konnte nicht gefunden werden. the following value is calculated for external resistor RSET, which in turn stipulates the size of the current: Ω=== k27.1mA1 V27.1 S BG SET I VR VBG AM462 OP2 RSET OP2 connected as current source IS Figure 5: Using OP2 as a constant current source

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 11/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de Using OP2 as a voltage reference In addition to the integrated voltage reference OP2 can also be used to supply voltage to external components, such as A/D converters and micropr ocessors, for example. Lower voltages can be generated (e.g. 3.3V) which with the increasing miniaturization of devices and need for ever lower levels of power dissipation in digital components is today of growing importance. The additional operational amplifier OP2 can easily be connected up as a voltage reference. Using the circuit in Figure 6 the following applies:  +=  += 6 1V27.11 R R R RVV BGCVREF (10) Example : OP2 as voltage reference A voltage of VCVREF = 3.3V is to be set. Using Equation (10) the following ratio is calculated for external resistors R6 and R7: 6,116,21 6 =−≈−= BG CVREF V V R R The following example values are produced for the resistors: R7 = 10kΩ R 6 = 16kΩ VBG AM462 OP2 OP2 connected as voltage reference VCVR EF µP Figure 6: Using OP2 as a voltage reference

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 13/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de 32.4V1 mA202788 0 ≈⋅Ω⋅== INP OUT GAIN V IRG ⇒ 32.3132.4 1 =−=R R Observing the boundary conditions the following values are obtained for the external components: Typical 2-wire application with an input signal referenced to ground In a 2-wire version (cf. Figure 8) system supply voltage VS is connected up to pin 11 ( RS+) and pin 10 (VCC) to pin9 (RS-). The ground of the IC at pin14 (GND) is connected to the node between resistor R5 and load resistor RL. IC ground ( GND) is not the same as system ground ( Ground). The output signal is picked up via load resistor RL which connects current output IOUT to the system ground. It must be ensured that in 2-wire operation an additional current load (use of current/voltage source) is limited to 4mA due to the domestic current supply and limitation. For output current IOUT the following applies according to Equations (1) (2) and (4): SET Gain INPOUT IR GVI +⋅= 08 with 11 R RGG GAINI +== and 02 RR R R VI REF SET +⋅= Ground RL Single-ended input voltage Connections setting unused function blocks to a defined operating point 3-wire connection AM462 OP2 OP1 Volta ge Ref er enc e 146 V I 15 16 ISET = 0 VINP VS IOUT VBG Figure 7: Typical application for input signals referenced to ground

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 14/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de Example : 4…20mA Voltage-To-Current Converter in 2-wire application To convert a signal of VINP = 0...1V at the OP1 input the external components are to be dimensioned in such a way that the output current has a range of 4...20mA. The following applies: mA488 00 +⋅=+⋅= R GVIR GVI GAIN INPSET GAIN INPOUT With R0 = 27Ω and ISET = 4mA. Equation(4) produces the following relation between resistor R3 and R4: 15.221mA4272 V512 04 SET REF IR V R R and thus the following value for the gain: 456.3V1 mA162788 max 0 =⋅Ω⋅=−= INP SETOUT GAIN V IIRG ⇒ 456.21456.3 1 =−=R R Observing the given boundary conditions, the follo wing values are obtained for the external components: R1 ≈ 24.56kΩ R 2 = 10kΩ R3 ≈ 44.3kΩ R 4 = 2kΩ R0 = 27Ω R5 = 39Ω RL = 0...600Ω C1 = 2.2µF C2 = 100nF Ground RL Single-ended input voltage Connections setting unused function blocks to a defined operating point AM462 OP2 OP1 R3C1 146 13 15 16 IC ground: GND System ground: Ground} different potentials! GND 2-wire connection V I Voltage Reference VINP VS IOUT VBG Figure 8: Typical 2-wire operation for input signals referenced to ground

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 15/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de Application for an input signal with an offset 1V for a 1..6V input signal). For signals such as thes e an offset current is generated at the IC output also when ISET = 0. In this case the output current will be always: I OUT≠0. The circuit can then be dimensioned as described in the following. According to Equation (2) the following applies for a required current swing at the output of ∆IOUT = IOUTmax – IOUTmin: VI PIN OUT ∆=∆ ⇒ OUTPIN IRV ∆=∆ 06 8 (11) For an input current swing of ∆VIN = VINmax – VINmin the necessary gain is calculated as: IN PIN V VG ∆ ∆= 6 (12) If G < 1, the input signal can be routed directly to pin 6 ( INDAI) via a voltage divider without OP1 having to be used (see Figure 9). With this circuitry the following results: RR R V VG IN PIN +=∆ ∆= ⇒ 1 6 −∆ PIN IN V V R R (13) From input offset VINmin the following output current is then obtained when ISET = 0: 076 minmin RRR RVVI ININOUT ⋅+⋅= (14) Using the SET pin and Equation 2 the required minimum output current IOUTmin can then be set: SETINOUT IRRR RVI +⋅+⋅= 076 1 with 02 RR R R VI REF SET +⋅= (15) Example: 4..20mA Voltage-To-Current Converter with Input Signal Offset (3-wire application) as input stage to have a high ohmic input and to profite from internal overvoltage protection. OP2 is not used here. It is, however, available to the user as an additiona l OP. The pin 1 and 2 has to be connected. With reference to Equation (11) and with R0 = 27Ω, a voltage swing is obtained at pin 6 of: V 456.3mA162788 063 =⋅Ω⋅=∆=∆=∆ OUTPINPIN IRVV

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 16/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de Using Equation (13) the following applies: 157.0V456.3 V456.3V4 6 ≈−=∆ ∆−∆= PIN PININ V VV R R ⇒ 67 35.6 RR ⋅= According to Equation (14) the minimum output curre nt generated by the input offset is calculated as: mA2278 16.37 6,37V5.08 076 RVI INOUT To obtain an output current of IOUT = 4...20mA, according to the above a current of ISET = 2mA must then be added. With reference to Equation (5) the ratio of R3 to R4 is calculated thus: 2mA2 RR R R VI REF SET +⋅== ⇒ 3.451mA2272 V512 04 SET REF IR V R R Observing the given boundary conditions, the follo wing values are obtained for the external components: R0 = 27Ω R6 ≈ 10kΩ R 7 = 63.7kΩ R3 = 90.6kΩ R 4 = 2kΩ R5 = 39Ω RL = 0...600Ω C1 = 2.2µF R 9 = 47 kΩ Ground RL Signal-ended input voltage Connections setting unused funktion blocks in a defined operating point 3-wire connection VBG AM462 OP2 OP1 R3C1 146 13 15 16 V I V oltage reference VS IOUT VIN Figure 9: Converting an input signal with an input signal offset (3-wire-application)

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 17/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de BLOCK DIAGRAM AND PINOUT VREF SET OUTAD INDAI GND VSET INN INP IOUT RS+ VCC CVREF CVSET VBG V I 13 15 Voltage Reference OP1 AM462 OP2 RS- Figure 10: Block diagram of AM462 PIN NAME EXPLANATION

1 CVREF Current/Voltage reference

2 CVSET Current/Voltage reference set

3 INP Positive input

4 INN Negative input

5 OUTAD System amplification output

6 INDAI Current output stage input

7 N.C. Not connected

8 IOUT Current output

9 RS– Sensing resistor -

10 VCC Supply voltage

11 RS+ Sensing resistor +

12 N.C. Not connected

13 VSET Reference voltage source set

14 GND IC ground

15 VREF Reference voltage source output

16 SET Output offset current set

Table 1: AM462 Pin out 1 16 2 15 3 14 4 13 5 12 6 11 7 10 CVREF CVSET INP INN OUTAD INDAI N.C. IOUT SET VREF GND VSET N.C. RS+ VCC RS- Figure 11: AM462 Pin out

Industrial V/I Converter and Protector IC AM462 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Oktober 2007 – Rev.2.5 -Page 20/20 Phone: +49 (0)6131/91 073-0 Fax: +49 (0)6131/91 073-30 Internet: http://www.analogmicro.de Email: info@analogmicro.de DELIVERY The AM462 V/I converter and protector IC is available as the following packages:

• SSOP16
• SO16(n)
• Dice on 5" blue foil (on request) PACKAGE DIMENSIONS Please see our website (data sheets: package.pdf). FURTHER READING www.analogmicro.de [1] The Frame ASIC concept: See: [2] PR1011 - The AM462 can be used as an integrat ed solution to interface a microprocessor to the industrial 4...20mA network. See: Technical Articles: PR1012 - Voltage-to-current converter IC for 2-wi re current loop applications (4…20mA). See: Technical Articles AN1014 - Interfacing the µProcessor with the 4...20m A current loop signal (PLC). See: Application NOTES Analog Microelectronics reserves the right to make amendments to any dimensions, technical data or other information contained herein without further notice.