Industrial V/I Converter and Protector IC AM462 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 VCC = 6...35V Single-ended input voltage AM462 0...VCC-5V VREF = 5/10V IOUT = e.g. 0/4...
Industrial V/I Converter and Protector IC AM462 CONTENTS CONTENTS 2 FEATURES 3 GENERAL DESCRIPTION 3 BLOCK DIAGRAM 3 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
Industrial V/I Converter and Protector IC AM462 FEATURES GENERAL DESCRIPTION • 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...
Industrial V/I Converter and Protector IC AM462 ELECTRICAL SPECIFICATIONS Tamb = 25°C, VCC = 24V, VREF = 5V, IREF = 1mA (unless otherwise stated); currents flowing into the IC are negative. Parameter Symbol Supply Voltage Range VCC Quiescent Current ICC Conditions Min. Typ. 6 Tamb = - 40...+85°C, IREF = 0mA Max. Unit 35 V 1.
Industrial V/I Converter and Protector IC AM462 Parameter Symbol Conditions Min. Typ. Max. Unit µV/°C Operational Amplifier Gain Stage (OP1) (cont.) VOS vs. Temperature dVOS/dT ±3 ±7 Input Bias Current IB 10 25 nA IB vs. Temperature dIB/dT 7 20 pA/°C Output Voltage Limitation VLIM Output Voltage Range VOUTAD VCC < 10V 0 VCC – 5 V VOUTAD VCC ≥ 10V 0 VREF V 250 pF Load Capacitance VREF CL V V/I Converter Internal Gain GVI Trim Range Adjustable by R0 0,12 0.
Industrial V/I Converter and Protector IC AM462 BOUNDARY CONDITIONS Parameter Symbol Conditions Sense Resistor R0 IOUTFS = 20mA R c = 20mA/IOUTFS Stabilization Resistor R5 IOUTFS = 20mA R5 c = 20mA/IOUTFS RL Limitation only for 3-wire operation Load Resistance Sum Gain Resistors R1 + R2 Sum Offset Resistors R3 + R4 Min. Typ. Max. 17 27 38 c ⋅ 17 c ⋅ 27 c ⋅ 38 35 40 45 c ⋅ 35 c ⋅ 40 c ⋅ 45 Unit 0 600 20 200 k 200 k VREF Capacitance C1 Ceramic 1.9 20 2.2 5.
Industrial V/I Converter and Protector IC AM462 V VINDAI ⋅ G IV V + I SET = INDAI + I SET with I SET = SET 2R 0 R0 8 R0 with VINDAI the voltage at pin 6 (INDAI) and VSET the voltage at pin 16 (SET) 1. I OUT = VREF VCVREF 1 AM462 VCVSET C1 R3 15 13 R4 16 VS VSET I 2 OP2 (2) 11 R0 10 Voltage Reference 9 VBG V VINP 8 T1 D1 3 OP1 5 4 R2 R1 VOUTAD 6 14 R5 IOUT VINDAI Ground 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 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-.
Industrial V/I Converter and Protector IC AM462 I OUT (V INDAI = 0 ) = I SET = V REF R4 ⋅ 2 R 0 R3 + R 4 (4) and thus for the ratio of the resistors R3/R4: R3 VREF = −1 R4 2R0 I SET (5) The output current range is set in conjunction with the selected external resistors R1 and R2 (or fine adjustment with R0 ).
Industrial V/I Converter and Protector IC AM462 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.
Industrial V/I Converter and Protector IC AM462 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 microprocessors, 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.
Industrial V/I Converter and Protector IC AM462 POINTS TO NOTE: INITIAL OPERATION OF AM462 1. When operating AM462 it is imperative that external capacitor C1 is always connected (cf. Figure 2). Care must be taken that the value of the capacitance does not lie beyond its given range, even across the range of temperature (see Boundary Conditions on page 7). In 2-wire operation ceramic capacitor C2 must also be used (cf. Figure 8). 2.
Industrial V/I Converter and Protector IC AM462 3-wire connection C1 1 AM462 15 13 VS ISET = 0 16 I 2 OP2 11 R0 10 Voltage Reference 9 VBG V VINP 8 T1 D1 3 OP1 5 4 Single-ended input voltage 6 14 R5 R1 R2 IOUT RL Ground Connections setting unused function blocks to a defined operating point Figure 7: Typical application for input signals referenced to ground GGAIN = 8R0 I OUT 20mA = 8 ⋅ 27Ω ⋅ ≈ 4.32 ⇒ 1V VINP R1 = 4.32 − 1 = 3.
Industrial V/I Converter and Protector IC AM462 C1 1 AM462 R3 15 13 R4 VS 16 2 OP2 C2 R0 11 I 10 Voltage Reference 9 VBG V VINP 8 T1 D1 3 OP1 2-wire connection 6 5 4 Single-ended input voltage R2 R1 IC ground: GND 14 } System ground: Ground different potentials! R5 IOUT RL GND Ground Connections setting unused function blocks to a defined operating point Figure 8: Typical 2-wire operation for input signals referenced to ground Example : 4…20mA Voltage-To-Current Conver
Industrial V/I Converter and Protector IC AM462 Application for an input signal with an offset It is not uncommon for input signals to have an offset (e.g. of 0.5V for a 0,5...4.5V input signal or 1V for a 1..6V input signal). For signals such as these an offset current is generated at the IC output also when ISET = 0. In this case the output current will be always: IOUT≠0. The circuit can then be dimensioned as described in the following.
Industrial V/I Converter and Protector IC AM462 C1 AM462 1 R3 VS 16 15 13 3-wire connection R4 I 2 OP2 R6 R0 10 Voltage reference 9 VBG VIN 11 V 8 T1 D1 3 OP1 R7 6 5 4 14 IOUT RL R9 Signal-ended input voltage R5 Ground Connections setting unused funktion blocks in a defined operating point Figure 9: Converting an input signal with an input signal offset (3-wire-application) Using Equation (13) the following applies: R6 ∆V IN − ∆V PIN 6 4V − 3.456V = = ≈ 0.
Industrial V/I Converter and Protector IC AM462 BLOCK DIAGRAM AND PINOUT VSET VREF SET 16 15 13 CVREF 1 AM462 CVSET I 2 OP2 11 10 Voltage Reference 9 VBG V INP 8 3 RS+ VCC RSIOUT OP1 5 4 INN OUTAD 6 GND INDAI 14 Figure 10: Block diagram of AM462 PIN NAME 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 CVREF CVSET INP INN OUTAD INDAI N.C. IOUT RS– VCC RS+ N.C.
Industrial V/I Converter and Protector IC AM462 EXAMPLE APPLICATIONS • Application as a voltage-to-current converter IC 6...35V VIN = 0...1, 0...5V ... and other AM462 Protection against short circuiting and reverse polarity 0/4...20mA Figure 12: Application as a current converter IC • Converting a 0.5...4.5V sensor (voltage) signal 6...35V VREF = 5/10V Sensor VOUT = 0.5...4.5V AM462 Protection against short circuiting and reverse polarity 4...20mA Figure 13: Converting a 0.5...4.
Industrial V/I Converter and Protector IC AM462 • Application as an analog output IC and supply unit for sensors VR EF = 5/10V 6...35V VCV REF = 3.3V Sensor µP DAC AM462 Protection against short circuiting and reverse polarity 0/4...20mA Figure 15: Output IC and supply unit in sensor applications • Application as a front-end and back-end IC for microprocessors VCVREF=3.3V 6...35V VREF=5/10V Sensor AM462 Protection against short circuiting and reverse polarity 0/4...
Industrial V/I Converter and Protector IC AM462 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 integrated solution to interface a microprocessor to the industrial 4...20mA network.
