UNIVERSAL AMPLIFIER IC AM400 PRINCIPLE FUNCTION Amplification and conversion of differential input voltages or those referenced to ground to industrial standard current (0/4...20mA) or voltage signals (e.g. 0...5/10V, 0.5...4.5V) VCC = 6…35V Differential input voltage 400mV IOUT = 0/4...20mA AM400 Input voltage referenced to ground 0...VCC-5V VOUT = 0...VCC- 5V adjustable, e.g. 0...5/10V IS = max 10mA VREF= 5/10V TYPICAL APPLICATIONS • • • • • Transducer for sensor applications Analog industrial output stage for microprocessor applications Modular signal conditioning with digital correction (Frame ASIC [1]) Protected output stage power network Impedance converter analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] Februar 2006 1/21 Rev.: 4.3 UNIVERSAL AMPLIFIER IC AM400 CONTENTS FEATURES 3 GENERAL DESCRIPTION 3 BLOCK DIAGRAM 3 ELECTRICAL SPECIFICATIONS 4 BOUNDARY CONDITIONS 7 DETAILED DESCRIPTION OF FUNCTIONS 7 OPERATING AM400 10 General information on 2- and 3-wire applications 10 Setting the voltage gain using the voltage output 11 Setting the output current range and compensating for the offset using the current output 11 Selecting the supply voltage 11 POINTS TO NOTE: INITIAL OPERATION OF AM400 12 APPLICATIONS 13 1) Typical 3-wire application with a differential input signal 13 2) Typical 3-wire application with an input signal referenced to ground 14 3) Typical 2-wire application with a differential input signal 15 4) Application for the 16-pole version of AM400 (3-wire application) 17 BLOCK DIAGRAM, 20-POLE PINOUT AND DICE 18 BLOCK DIAGRAM AND 16-POLE PINOUT 19 EXAMPLE APPLICATIONS 20 DELIVERY 21 PACKAGE DIMENSIONS 21 FURTHER READING 21 analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] Februar 2006 2/21 Rev.: 4.3 UNIVERSAL AMPLIFIER IC AM400 FEATURES GENERAL DESCRIPTION • Instrumentation amplifier with a wide input voltage range • Adjustable gain and offset • Parallel analog voltage (e.g. 0...5/10V) and current (e.g. 0/4...20mA) output • Two and three-wire operation • Protection against reverse polarity and short-circuiting • Output current limitation • Integrated current source • Adjustable integrated reference voltage source: 4.5 to 10V • Supply voltage: 6...35V • Wide operating temperature range: -40°C...+85°C • Individually accessible function modules • RoHS compliant • Two package variants: SOP and SSOP AM400 is a monolithically integrated measuring amplifier with a parallel current and voltage output which has been specifically developed for the processing of differential input signals. AM400 consists of various functional modules. It contains both an instrumentation amplifier input and an input for signals referenced to ground. One particular feature of the device is the current and voltage outputs which can be used simultaneously. The output ranges can be selected using external resistors, enabling AM400 to be configured for the analog 0/4...20mA and 0...5/10V industrial power network, for example. Integrated voltage and current sources covering a wide range of values can be used to power external components. AM400 has been designed for ideal use with external processors (such as a microprocessor, for example, for signal correction [1]). BLOCK DIAGRAM SET VSET VREF 20 19 16 CVREF 1 AM400-0 CVSET I 2 OP3 13 Voltage reference 12 VBG IN+ 14 V 11 3 IA OP1 4 OP2 15 INZA 7 OUTIA INOP GAIN 17 5 6 8 9 10 OUTAD INDAI INDAV GND RS+ VCC RSIOUT VOUT 18 Figure 1: Block diagram of AM400 in the 20-pole version analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] Februar 2006 3/21 Rev.: 4.3 UNIVERSAL AMPLIFIER IC AM400 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 1.5 mA °C Temperature Specifications Operating Tamb –40 85 Storage Tst –55 125 °C Junction TJ 150 °C Voltage Reference Voltage VREF VSET not connected VREF** VSET = GND, VCC ≥ 11V Trim Range VR10** Current IREF* VREF vs. Temperature dVREF/dT Tamb = - 40...+85°C Line Regulation dVREF/dV VCC = 6V...35V dVREF/dV VCC = 6V...35V, IREF ≈ 5mA Load Regulation 5.00 5.25 V 9.5 10.0 10.5 V 4.5 VR10 V 0 10.0 mA ±90 ±140 ppm/°C 30 80 ppm/V 60 150 ppm/V dVREF/dI dVREF/dI Load Capacitance 4.75 0.05 0.10 %/mA 0.06 0.15 %/mA 1.9 2.2 5.0 µF 1.20 1.27 1.35 V ±60 ±140 ppm/°C IREF ≈ 5mA CL Current/Voltage Source OP3 Internal Reference VBG VBG vs. Temperature dVBG/dT Tamb = - 40...+85°C Current Source: ICV = VBG/REXT Adjustable Current Range ICV* 0 10 mA Output Voltage VCV VCC < 19V VBG VCC – 4 V VCV VCC ≥ 19V VBG 15 V Voltage Source: VCV = VBG (REXT1 + REXT2) / REXT2 Adjustable Voltage Range Output Current Load Capacitance VCV VCC < 19V 0.4 VCC – 4 V VCV VCC ≥ 19V 0.4 15 V ICV* Source ICV Sink CL Source mode 10 mA –100 µA nF 0 1 10 5 5.1 Instrumentation Amplifier Internal Gain GIA 4.9 Differential Input Voltage Range VIN 0 ±400 Common Mode Input Range CMIR VCC < 9V, ICV < 2mA 1.5 VCC – 3 V CMIR VCC ≥ 9V, ICV < 2mA 1.5 6.0 V Common Mode Rejection Ratio CMRR 80 90 Power Supply Rejection Ratio PSRR 80 90 Offset Voltage VOS ±1.5 analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] mV dB dB ±6 mV October 2005 4/21 Rev. 4.2 UNIVERSAL AMPLIFIER IC AM400 Parameter Symbol Conditions Min. Typ. Max. Unit Instrumentation Amplifier (cont.) VOS vs. Temperature dVOS/dT µV/°C ±5 Input Bias Current IB –100 –250 nA IB vs. Temperature dIB/dT –0.4 –0.9 nA/°C Output Voltage Range VOUTIA VCC < 9V, RLIA ≤ 10kΩ 0*** VCC – 4 V VOUTIA VCC ≥ 9V, RLIA ≤ 10kΩ 0*** 5 V Minimum Output Voltage VOUTIAmin Without external load resistance RLIA 16 mV Load Capacitance CL** 250 pF 4.5 Zero Adjust Stage Internal Gain GZA Input Voltage VZA 0,94 Offset Voltage VOS ±0.5 VOS vs. Temperature dVOS/dT ±1.6 Input Bias Current IB 47 IB vs. Temperature dIB/dT 18 30 pA/°C VZA ≤ VOUTIA - GIA VIN 1 0 1,06 VOUTIA V ±2.0 mV ±5 µV/°C 120 nA Operational Amplifier Gain Stage (OP1) Adjustable Gain GGAIN Input Range IR VCC < 10V 1 0 VCC – 5 V IR VCC ≥ 10V 0 5 V ±0.5 ±2 mV ±7 µV/°C Power Supply Rejection Ratio PSRR Offset Voltage VOS VOS vs. Temperature dVOS/dT ±3 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 80 90 dB VREF CL V Operational Amplifier Output Stage (OP2) Internal Gain GOP Input Range IR VCC < 11V 2.15 0 VCC – 5 V IR VCC ≥ 11V 0 6 V ±0.5 ±2 mV ±7 µV/°C 80 2.20 2.25 Power Supply Rejection Ratio PSRR Offset Voltage VOS VOS vs. Temperature dVOS/dT ±3 Input Bias Current IB 10 25 nA IB vs. Temperature dIB/dT 7 20 pA/°C Output Voltage Range VOUT VCC – 5 V VCC < 19V 0 VOUT VCC ≥ 19V 0 Output Current Limitation ILIM VOUT ≥ 10V 5 Output Current IOUT 0 Load Resistance RL 2 Load Capacitance CL 7 dB 14 V 10 mA ILIM mA kΩ 500 analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de 90 Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] nF October 2005 5/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 Parameter Symbol Conditions Min. Typ. Max. 0,120 0.125 0,130 0.75 1.00 1.25 Unit V/I Converter Internal Gain GVI Trim Range Adjustable by R0 Voltage Range at R0 FS VR0FS 350 Offset Voltage VOS βF ≥ 100 VOS vs. Temperature dVOS/dT βF ≥ 100 Input Resistance RIN RIN vs. Temperature dRIN/dT Output Offset Current IOUTOS 3-wire operation –25 –35 µA IOUTOS vs. Temperature dIOUTOS/dT 3-wire operation 16 26 nA/°C Output Offset Current IOUTOS 2-wire operation 9.5 14 µA IOUTOS vs. Temperature dIOUTOS/dT 2-wire operation 6 8 nA/°C Output Control Current IOUTC 2-wire operation, VR0/100mV IOUTC vs. Temperature dIOUTC/dT 2-wire operation Output Voltage Range VOUT VOUT = 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 Output Resistance ROUT Load Capacitance CL 120 0.2 0.5 750 mV ±2 ±4 mV ±7 ±14 µV/°C 160 kΩ 0.3 kΩ/°C 6 8 µA –10 –15 nA/°C 20 mA 1.0 MΩ 0 500 nF SET Stage Internal Gain GSET 0.5 Input Voltage VSET 1.15 V Offset Voltage VOS ±0.5 ±1.5 mV VOS vs. Temperature dVOS/dT ±1.6 ±5 µV/°C 0 Input Bias Current IB 8 20 nA IB vs. Temperature dIB/dT 7 18 pA/°C Protection Functions Voltage Limitation at R0 VLIMR0 VR0 = VIN GI, SET = GND VREF/8 mV Only if OP2 and V/I-Converter are connected VLIMR0 VIN = 0, VR0 = VSET/2 580 635 Protection against reverse polarity Ground vs. VS vs. VOUT Current in case of reverse polarity Ground = 35V, VS = IOUT = 0 4.5 Ideal input 0.05 Ground vs. VS vs. IOUT 690 mV 35 V 35 V mA System Parameters Nonlinearity 0.15 %FS * In 2-wire operation a maximum current of IOUTmin – ICC is valid ** Only available in die form or in an SSOP 20 version *** Depending on external load resistance at output IA (RLIA ≤ 10kΩ ⇒ VOUTIA < 3mV); internal load resistance is ≈ 100kΩ analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 6/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 BOUNDARY CONDITIONS Parameter Symbol Sense Resistor Conditions R0 IOUTFS = 20mA R0 c = 20mA/IOUTFS Stabilization Resistor R5 IOUTFS = 20mA R5 c = 20mA/IOUTFS Load Resistance RL Limitation only for 3-wire operation Min. Typ. Max. 17 27 38 Unit Ω c ⋅ 17 c ⋅ 27 c ⋅ 38 Ω 35 40 45 Ω c ⋅ 35 c ⋅ 40 c ⋅ 45 Ω 0 600 Ω Sum Gain Resistors R1 + R2 20 200 kΩ Sum Offset Resistors R3 + R4 20 200 kΩ VREF Capacitance C1 Min. value for Tamb 85°C 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 T1 Forward Current Gain βF 50 150 BCX54/55/56, for example V DETAILED DESCRIPTION OF FUNCTIONS AM462 is a modular, monolithically integrated universal amplifier which has been specifically developed for the conditioning of differential voltage signals and those referenced to ground. It is designed for both 2- and 3-wire operation1 in industrial applications (cf. applications on pages 14 until 19). AM462’s various functions are depicted in the block diagram (Figure 1) which also illustrates how few external components are required for the operation of this particular device. AM400 consists of a number of modular functional blocks which through external gating can either operate together or separately (see Figure 2). 1. The instrumentation amplifier (IA) with an internal gain of GIA = 5 acts as an input stage for differential voltage signals. Its special construction permits a high common mode rejection ratio (CMRR). The amplifier reference potential is set externally using the AM400 pin ZA. Output voltage VOUTIA at pin OUTIA is calculated for VZA > 0 as: VOUTIA = GIA VIN + VZA with VOUTIA > 0 (1) where VIN is the differential voltage between inputs pin IN+ and pin IN- of the IA and VZA is the voltage at pin ZA. 2. The ensuing operational amplifier stage (OP1) permits the IA output signal to be amplified further. OP1’s gain of GGAIN can be set using external resistors R1 and R2. Protection against overvoltage has been integrated into the device; this protective circuitry limits the voltage to the set reference voltage value (cf. paragraph 5 in this section). 1 The principle of design is such that only the current output can be used in 2-wire operation. analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 7/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 Output voltage VOUTAD at pin OUTAD is calculated as: R VOUTAD = VINOP ⋅ GGAIN with GGAIN = 1 + 1 R2 (2) where VINOP is the voltage at the OP1 input pin INOP. Alternatively, the OP1 input pin INOP can also be used as an input for signals referenced to ground (see Application 2, Figure 6). VREF VCVREF 1 AM400-0 VCVSET R3 C1 20 19 16 R4 VS VSET I 2 OP3 VIN- R0 13 Voltage reference 12 VBG VIN+ 14 V 11 3 T1 D1 IA OP1 4 17 5 6 8 7 VZA VOUTIAVINOP OP2 R2 R1 VOUTAD 9 10 15 18 R5 VOUT IOUT VINDAI VINDAV Ground Figure 2: Block diagram of AM400 showing external components (3-wire circuit with a current output) 3. The IC’s voltage output VOUT is realized via the current-limited operational amplifier stage (OP2) which has integrated protection against reverse polarity. The internal gain of OP2 is set to a fixed value of GOP = 2.2. The output is engineered as a driver stage. The following applies to OP2’s output voltage VOUT at the IC pin VOUT: VOUT = GOP ⋅ VINDAV (3) where VINDAV is the voltage at pin INDAV (OP2 input). analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 8/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 4. The voltage-to-current converter (V/I converter) provides a voltage-controlled current signal at IC output IOUT which activates an external transistor T1; this reduces the power dissipation of the IC and supplies the output current IOUT. The external transistor is 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 internal voltage reference and an external voltage divider as shown in Figure 5, 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 IOUT boosted by T1 the following ratio applies: I OUT = VINDAI V + I SET with I SET = SET 8 R0 2R 0 (4) with VINDAI the voltage at pin INDAI and VSET the voltage at pin SET (V/I converter inputs, see Figure1)2. 5. The AM400 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 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 external resistors are used (inserted between pin VREF and pin VSET and between pin VSET and GND). External capacitor C1 stabilizes the reference voltage. It must be connected even if the voltage reference is not in use. It also must not exceed the minimum value. 6. The additional operational amplifier (OP3) can be used as a current or voltage source for the supply of external components. OP3’s positive input is connected internally to voltage VBG so that the output current or voltage can be set across a wide range using one or two external resistors. 2 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. analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 9/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 OPERATING AM400 General information on 2- and 3-wire applications In 3-wire operation (cf. Figure 5, for example) 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 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" (floating), 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: VCC = VS − I OUT (VIN ) RL (5) 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 Equation 5 no longer applies as the IC ground is connected to the ground of the system. For 3-wire operation the supply voltage can be expressed thus: VCC = VS (6) In a 2-wire setup the power consumption of the overall system (AM400 and all external components including the adjusting resistors) may not exceed IOUTmin (usually 4mA). 2-wire system Signal source and conditioning IC GND ≠ Ground VCC ≠ VS 3-wire system Signal source and conditioning IC VCC IOUT GND RL VS GND = Ground VCC = VS Ground IOUT VCC = VS RL Ground = GND Figure 3: The difference between 2- and 3-wire operation analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 10/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 Setting the voltage gain using the voltage output When using the IA and amplifier stages OP1 and OP2 for further signal conditioning the overall gain can be set using the suitably selected external resistors R1 and R2. The transfer function for the output voltage is calculated by multiplying Equations 1, 2 and 3 to: VOUT = (GIAVIN + VZA ) ⋅ GGAIN ⋅ GOP (7) with GIA = 5, GGAIN = (R1 /R2) + 1 and GOP = 2.2 and the externally set voltage VZA at pin ZA. Setting the output current range and compensating for the offset using the current output When using the IA together with amplifier stage OP1 and the V/I converter for further signal conditioning the offset of the output current should first be compensated for. To this end the two IA inputs must be short-circuited (VIN = 0) and connected up to a permitted potential (cf. CMIR in the electrical specifications on page 5). With the short circuit at the input the values of the output current according to Equation 4 and an external voltage divider (e.g. Figure 5) are as follows: I OUT (V IN = 0 ) = I SET with I SET = VREF R4 ⋅ 2R0 R3 + R4 (8) The output current range is set in conjunction with the selected external resistors R1 and R2 (or fine adjustment with R0 ). Using Equations 2, 4 and 8 the following is calculated for output current IOUT : I OUT = VIN GI + I SET with GI = GIA ⋅ GGAIN and VZA = 0 8R0 (9) Selecting the supply voltage System supply voltage VS needed to operate AM400 is dependent on the selected mode of operation. • When using voltage output pin VOUT the minimum supply voltage VS necessary for the operation of the device depends on the maximum output voltage VOUTmax required by the application. The following applies: VS ≥ VOUT max + 5V • (10) When using current output pin IOUT (in conjunction with the external transistor) the value of VS is dependent on that of the relevant load resistor RL (max. 600Ω) used by the application. The minimum system supply voltage VS is then: VS ≥ I OUT max RL + VCC min (11) analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 11/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 Here, IOUTmax stands for the maximum output current and VCCmin for the minimum IC supply voltage which is dependent on the selected reference voltage: VCC min ≥ VREF + 1V (12) The working range resulting from Equation 11 is described in Figure 4. Example calculations and typical values for the external components can be found in the example applications. POINTS TO NOTE: INITIAL OPERATION OF AM400 1. When operating AM400 it is imperative that external capacitance C1 (a high-grade ceramic capacitor) 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. RL [Ω] RL ≤ VCCmin = 6V VS − VCCmin IOUTmax RLmax = 600Ω IOUTmax = 20mA 600 300 Working range 0 0 6 12 18 24 35 VS [V] Figure 4: Working range in conjunction with the load resistor 2. All of the AM400 function blocks not used by the application (e.g. OP3) must be connected up to a defined (and permitted) potential. 3. The voltages at the IA inputs (pins IN+ and IN–) must always lie within input voltage range CMIR, even if the IA is not used. 4. When the voltage output is in operation the load resistance at pin VOUT must be at least 2kΩ. 5. A load resistance of 600Ω maximum is permitted with operation of the current output. 6. The values of external resistors R0, R1, R2, R3, R4 and R5 must be selected within the permissible range given in the boundary conditions on page 7. analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 12/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 APPLICATIONS 1) Typical 3-wire application with a differential input signal In 3-wire operation (cf. Figure 5, for example) the IC ground (pin GND) is connected up to the external ground of the system (Ground). The system’s supply voltage VS is connected to pin VCC and pin VCC to pin RS+. C1 1 AM400-0 R3 VS 20 19 16 3-wire connection R4 I 2 OP3 R0 13 Voltage reference 12 VBG RSET 14 V 11 3 D1 IA OP1 4 17 T1 5 6 RIAL Negative offset voltages can be compensated for using pin ZA. If the pin is not in use it must be connected to IC ground GND. OP2 8 7 R2 9 10 R1 15 18 R5 VOUT IOUT RL Ground Load resistor to minimize the offset voltage at the IA output. Figure 5: Typical 3-wire application for differential input Figure 5 shows a 3-wire application in which the differential output signal of a current-powered measuring bridge is amplified and converted. Operational amplifier OP3 supplies the measuring bridge with current. Bridge supply current IS can be set using resistor RSET: IS = V BG 1 .27 V = R SET R SET (13) For the above application it is assumed that no negative input voltages are present. Pin ZA is first connected to the IC’s ground GND. According to Equation 3 the following then applies to output voltage VOUT: R VOUT = GV VIN with GV = GIA GGAIN GOP = 5 1 + 1 2.2 (14) R2 analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 13/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 According to Equation 4 the following is then relevant to output current IOUT: I OUT = VIN GI + I SET with VZA = 0 8R0 (15) V R4 R . with GI = GIA GGAIN = 5 1 + 1 and I SET = REF ⋅ R2 2 R0 R3 + R 4 Example 1: VIN = 0...100mV (differential), IOUT = 4...20mA and VOUT = 0...10V For a measuring bridge with a signal of VIN = 0...100mV at the IA input the external components are to be dimensioned in such a way that the output current has a range of 4...20mA and the output voltage one of 0...10V. R1 and R2 are dimensioned in accordance with Equation 14, R0 according to Equation 4 and R3 and R4 according to Equation 8. Observing the boundary conditions for the external components the following values are then obtained: R0 ≈ 35.5Ω R5 = 39Ω R1 ≈ 80.9kΩ RL = 0...600Ω R2 = 10kΩ RIAL ≤ 10kΩ R3 = 83kΩ C1 = 2.2µF R4 = 5kΩ 2) Typical 3-wire application with an input signal referenced to ground C1 1 AM400-0 R3 I 2 OP3 VS 20 19 16 3-wire connection R4 14 R0 13 Voltage reference 12 VBG V 11 3 D1 IA OP1 4 17 5 6 OP2 8 7 VIN Input voltage referenced to ground T1 R2 9 10 R1 15 18 R5 VOUT IOUT RL Connections setting unused function blocks to a defined operating point Ground Figure 6: Typical application for input signals referenced to ground analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 14/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 Figure 6 shows a 3-wire application in which AM400 amplifies and converts a voltage signal referenced to ground. The blocks unused by the application (IA and OP3) are set to a defined operating point. Alternatively, these function blocks can also be used for the supply of external components, for example. In the above application output voltage VOUT is calculated using Equations 2 and 3 as: R VOUT = GV VIN with GV = GGAIN GOP = 1 + 1 2.2 R2 According to Equation 4 the following applies to output current IOUT: I OUT = VIN GI + I SET 8R0 V R4 R with GI = GGAIN = 1 + 1 and I SET = REF ⋅ 2 R0 R3 + R 4 R2 Example 2: VIN =0…1V (referenced to ground), IOUT = 4...20mA and VOUT = 0...10V For a signal of VIN = 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 and the output voltage one of 0...10V. Observing the boundary conditions the following values are obtained for the external components: R0 ≈ 35.5Ω R5 = 39Ω R1 ≈ 35.5kΩ RL = 0...600Ω R2 = 10kΩ C1 = 2.2µF R3 = 83kΩ R4 = 5kΩ 3) Typical 2-wire application with a differential input signal In 2-wire operation (cf. Figure 7) system supply voltage VS is connected up to pin RS+ and pin VCC to pin 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. Figure 7 shows a typical 2-wire application in which the differential output signal of a currentpowered measuring bridge is amplified by the IA and OP1 and converted by the V/I converter. Operational amplifier OP3 supplies the measuring bridge with current. Bridge supply current IS can be set using resistor RSET according to Equation 13. According to Equation 4 the following applies to the output current of the 2-wire application: I OUT = VIN GI + I SET with VZA = 0 ( ZA connected to GND ) 8R0 analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 15/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 R V R4 where GI = GIA GGAIN = 5 1 + 1 and I SET = REF ⋅ R 2 R R 2 0 3 + R4 C1 1 AM400-0 R3 VS 20 19 16 R4 C2 I 2 OP3 R0 13 Voltage reference 12 VBG RSET 14 V 11 3 D1 IA OP1 4 17 T1 5 6 RIAL OP2 8 7 R2 9 10 2-wire connection 15 18 R5 IOUT R1 RL GND Negative offset voltages can be compensated for using pin ZA. If the pin is not in use it must be connected to IC ground GND. IC ground: GND } System ground: Ground Ground Different potentials! Figure 7: Typical 2-wire application for differential input signals Example 3: VIN = 0..100mV (differential) and IOUT = 4...20mA For a measuring bridge with a signal of VIN = 0...100mV at the IA input the external components of the AM400 circuitry are to be dimensioned in such a way that the output current has a range of 4...20mA. As only the current output is to be used, the gain and output current range can be dimensioned using resistors R1 to R4. Up to a certain point the value of resistor R0 is freely selectable and can be set to 27Ω. Observing the boundary conditions for the external components the following values are then obtained: R0 = 27Ω R5 = 39Ω R1 ≈ 59.12kΩ RL = 0...600Ω R2 = 10kΩ RIAL ≤ 10kΩ R3 = 82kΩ C1 = 2.2µF R4 = 5kΩ C2 = 100nF In this specific application particular attention must be paid to the current consumption which at a temperature of 85°C may not exceed 4mA. analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 16/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 4) Application for the 16-pole version of AM400 (3-wire application) Figure 8 gives a 3-wire application which uses the 16-pole version of AM400 (Figure 11). The dimensions of this specific application are no different from those of the 3-wire setup illustrated in Figure 5; no detailed description shall thus be given here. One difference, however, lies in the fact that the minimum voltage at the IA output cannot be reduced by connecting up external load resistor RLIA. Particularly with small differential input signs and the large GOP gain these entail a “correct” value of 0V cannot be obtained at IC output VOUT (cf. the comments on VOUTIA in the electrical specifications). For this reason the 20-pole version of AM400 is preferable for small signals. C1 AM400-1 1 R3 3-wire connection R4 16 15 I 2 OP3 RSET VS 11 R0 10 5V Reference 9 VBG V 3 IA The minimum voltage at the IA output is 16mA T1 D1 OP1 4 13 8 VOUTIA 6 5 R2 12 OP2 7 R1 14 R5 VOUT IOUT RL Ground Figure 8: Typical application for the 16-pole version of AM400 (3-wire) analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 17/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 BLOCK DIAGRAM, 20-POLE PINOUT AND DICE SET VSET VREF 20 19 16 CVREF 1 AM400-0 CVSET OP3 13 Voltage reference 12 VBG IN+ 14 I 2 V 11 3 IA OP1 4 OP2 15 INZA 7 OUTIA INOP GAIN 17 5 8 6 9 10 GND OUTAD INDAI INDAV RS+ VCC RSIOUT VOUT 18 Figure 9: Block diagram of AM400 in the 20-pole version PIN NAME 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 CVREF CVSET IN+ IN– OUTIA INOP GAIN OUTAD INDAI INDAV IOUT RS– VCC RS+ VOUT VSET ZA GND VREF SET EXPLANATION Current/Voltage reference Current/Voltage reference set Positive input IA Negative input IA Output IA Positive amplification OP input Gain set System gain output Current output stage input Voltage output stage input Current output Sensor resistor – Supply voltage Sensor resistor + Voltage output Set reference voltage source Zero adjustment (offset) IC ground Reference voltage source output Output offset current set CVREF CVSET IN+ INOUTIA INOP GAIN OUTAD INDAI INDAV 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 SET VREF GND ZA VSET VOUT RS+ VCC RSIOUT Figure 10: Pinout of the 20-pole version of AM400 Table 1: Pinout of the 20-pole version of AM400 analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 18/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 BLOCK DIAGRAM AND 16-POLE PINOUT VREF CVREF AM400-1 CVSET 1 SET 16 15 11 I 2 OP3 10 5V Reference 9 VBG V IN+ 8 3 IA OP1 4 12 OP2 INZA 13 GAIN 5 OUTAD 6 7 INDA GND RS+ VCC RSIOUT VOUT 14 Figure 11: Block diagram of AM400 in the 16-pole version PIN NAME 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 CVREF CVSET IN+ IN– GAIN OUTAD INDA IOUT RS– VCC RS+ VOUT ZA GND VREF SET EXPLANATION Current/Voltage reference Current/Voltage reference set Positive input IA Negative input IA Gain set System gain output Output stage input Current output Sensor resistor – Supply voltage Sensor resistor + Voltage output Zero adjustment (offset) IC ground Reference voltage source output Output offset current set CVREF CVSET IN+ INGAIN OUTAD INDA IOUT 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 SET VREF GND ZA VOUT RS+ VCC RS- Figure 12: Pinout of the 16-pole version of AM400 Table 2: Pinout of the 16-pole version of AM400 analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 19/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 EXAMPLE APPLICATIONS • Signal conditioning for ceramic and piezoresistive pressure sensing elements with an optional external processor for error compensation VS = 6...35V Sensor supply Voltage or current 0/4...20mA AM400 0...5/10V µP Figure 13: Application for ceramic and piezoresistive pressure sensors and an external microcontroller • Application as a converter IC 5V CX1 6...35V 0/4...20mA AM400 CAV424 CX2 0...5/10V Figure 14: Application as a converter IC together with CAV424 for the measurement of capacitive V424 signals • Conditioning of signals referenced to ground (protected output stage, impedance converter, etc.) 6...35V VIN = 0...1, 0...5V Others AM400 Protection against short-circuiting and reverse polarity 0/4...20mA Figure 15: Application for input signals referenced to ground (protected output stage, impedance converter, etc.) analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 20/21 Rev.: 4.2 UNIVERSAL AMPLIFIER IC AM400 DELIVERY The AM400 sensor transmitter is available as the following packages: • SSOP20 • SO16(n) • Dice on 5" blue foil (on request) PACKAGE DIMENSIONS Please see our website (data sheets: package.pdf). FURTHER READING [1] The Frame ASIC concept: http://www.Frame-ASIC.de/ [2] The Analog Microelectronics GmbH website: http://www.analogmicro.de/ Analog Microelectronics reserves the right to make amendments to any dimensions, technical data or other information contained herein without further notice. analog microelectronics Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Internet: http://www.analogmicro.de Phone: Fax: Email: +49 (0)6131/91 073 – 0 +49 (0)6131/91 073 – 30 [email protected] October 2005 21/21 Rev.: 4.2