AM457 PRINCIPLE FUNCTION Adjustable amplification differenti

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AM457 PRINCIPLE FUNCTION Adjustable amplification differenti

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Precision amplifier bridge circuits
AM457
PRINCIPLE FUNCTION
Adjustable amplification differential voltage signals ±100mV adjustable, ratiometric output voltage between Vcc-0.2Volt with diagnostic unit
Differential input voltages 100mV
Diagnostic unit
AM457
e.g. VOUT 0.2.VCC-0.2V (adjustable) e.g. 0.5.4.5V ratiometric
Iout
TYPICAL APPLICATIONS
Precision amplifiers bridge circuits with sensitivity: ceramic measurement cells sensing elements sensing elements Sensor amplification with functional control
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 1/10 Rev.
Precision amplifier bridge circuits
TABLE CONTENTS
Features Block diagram General description Electrical specifications Circuit Description functions Example application Block diagram pinout Delivery options Further reading
AM457
TABLE FIGURES TABLES
Table Specifications Table Circuit Table configuration Figure Block diagram Figure Schematic circuit diagram resistance bridges with sensitivity Figure Block diagram AM457 Figure AM457 Figure Package dimensions
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 2/10 Rev.
Precision amplifier bridge circuits
AM457
High input sensitivity Wide differential input voltage range (±5.±100mV offset offset drift input noise High CMRR: 120dB Wide operating temperature range: -40. +125°C Adjustable output voltage Rail-to-rail output stage: VOUT 0.2V 0.2V Sink/source output Single ratiometric supply: Integrated current source: Integrated diagnostic unit Separate function groups Integrated protective circuitry Short-circuit-proofing Small-scale design
FEATURES
GENERAL DESCRIPTION
AM457 high-precision integrated amplifier which been developed condition signals from small differential input voltages within range millivolts ±100mV FS). chief component highly accurate, low-noise amplifier circuit (AMP). additional integrated operational amplifier (OP) used supply sensing element with current record temperature sensor bridges powered voltage, example. entire system (sensing element plus amplifier) monitored integrated diagnostic unit which logs sensing element errors defects, system undervoltage, overloads excessive temperature. various function groups mutually dependent another; operated independently example. functionality both component groups (AMP autonomous with regard diagnostic unit. AM457 combination high-impedance precision amplifier, additional extensive diagnostic unit, enabling self-monitoring sensor system assembled using very components.
BLOCK DIAGRAM
AM457
OUTOP
INOP
Temp
Diagnostic unit
DIAG
Figure Block diagram
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 3/10 Rev.
Precision amplifier bridge circuits
ELECTRICAL SPECIFICATIONS
Tamb 25°C, (unless otherwise stated)
Parameter Voltage Range Quiescent Current Temperature Specifications Operating Storage Junction Thermal Resistance Amplifier Offset Voltage Temperature Temperature Input Bias Current Temperature Differential Input Voltage Input Offset Current Temperature Input Resistance Input Capacitance Common Mode Input Range Common Mode Rejection Ratio Open Loop Gain Adjustable Gain Output Voltage Range Output Current Output Load Capacitance Output Load Resistance Power Supply Rejection Ratio Gain Bandwidth Product dVOS/dT dVOS/dT dIB/dT dIOS/dT CMIR CMRR VOUT IOUT PSRR 1nF; Including filters protection Linearity Slew Rate Input Voltage Noise 1nF; Tamb, Source Impedance 10-4 Sink source Sink source Tamb= -45.105°C Tamb= 105.125°C 2.5V Tamb= -45.125°C =VIN+ VINVCM 2.5V Tamb= -45.125°C IB,typ (VCM 2.5V) ±0.5 ±2.5 -130 ±0.1 ±0.5 ±0.3 ±1.2 ±120 -600 ±100 Tamb DIL8 plastic package narrow plastic package Symbol Tamb -40.+85°C Conditions Min. Typ. Max.
AM457
Unit °C/W °C/W µV/°C pA/°C pA/°C
V/µs nV/Hz
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 4/10 Rev.
Precision amplifier bridge circuits
Error Monitoring (Diagnosis) Output Voltage Error (high) Output Voltage without Error (low) Output Current Error Output Current without Error VDIAG VDIAG IERR INOERR VDIAG 2.5V VDIAG 2.5V With regard sensing element GND+ -3.5 -1.5
AM457
Threshold Temperature Error Monitor- TERR Threshold Output Current (AMP) Error Monitoring Threshold Supply Voltage Error Monitoring Threshold High Input Voltage (AMP) Error Monitoring Threshold Input Voltage (AMP) Error Monitoring Operational Amplifier (OP) Offset Voltage Temperature Temperature Input Bias Current Temperature Input Resistance Input Capacitance Common Mode Input Range Open Loop Gain Output Voltage Range Output Source Current Output Load Capacitance Gain Bandwidth Product Slew Rate dVOS/dT dVOS/dT dIB/dT CMIR G0.2mA VOUT IOUT GGAIN 1nF; 1.25k GGAIN 100; 1nF; Open Collector Output I0ut =0.1mA I0ut =2mA Tamb= -45.125°C IB,typ (VCM 0.5V) Tamb= -45.105°C Tamb= 105.125°C IIA,ERR VCC,ERR VIN,high,ERR VIN,low,ERR
6.25
±320
µV/°C pA/°C
V/µs
Table Specifications
Currents flowing into negative. Positive input operational amplifier (fixed internally): 0.1VCC Input Common Mode Voltage
CIRCUIT
Parameter Output Capacitor Compensation Capacitor DIAG Output Capacitor (optional) Output Capacitor (optional) Stabilization Capacitor (optional) Protection Capacitor (optional) Load Resistor Symbol Conditions Min. Typ. Max. Unit
Table Circuit Components
Recommendation: Ceramic capacitor
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 5/10 Rev.
Precision amplifier bridge circuits
DESCRIPTION FUNCTIONS
AM457
AM457 integrated precision circuit high-impedance amplification conditioning signals monitoring sensor bridges with sensitivity, particularly ceramic sensing elements. generates rail-to-rail output signal 0.2V Vcc-0.2V. With suitable dimensioning output voltage 0.5.4.5V also provided. these values standard following description refers this output voltage. Besides amplifying conditioning signals also display range system errors ("system" this context refers sensor bridge plus voltage supply). AM457 works principle ratiometry with supply voltage ±5%. distinguished offset, extremely thermal offset drift ability cope with wide range temperature, enabling classified precision amplifier.
FUNCTIONS
AM457 made three modular function blocks (see Figure which accessed individually operated suitable combinations. These are: precision amplifier (AMP) with sink/source facility amplification conditioning bridge signals within range ±5.±100mV including output stage. output stage protected against short circuits. amplification offset fixed using external resistors. operational amplifier (OP) whose positive input internally reference point 0.1VCC. negative input accessible externally, with which inverter. used current source power bridge, example, output line driver record temperature when sensing element supplied voltage. latter application allows temperature dependency sensing element bridge resistors exploited, example. diagnostic unit which monitors system features. With signal source bridge configuration this displays following faults errors: Lack bridge voltage Lack bridge ground Missing signal connection missing signal connections least four bridge resistors high impedance Malfunction signal conditioning unit overload Malfunction signal conditioning unit undervoltage Detection excessive temperature signal conditioning unit.
event more disruptions output DIAG (pin switches logic high (see electrical specifications). otherwise indicated. precision amplifier (AMP) additional operational amplifier (OP) operated independently another without diagnostic unit.
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 6/10 Rev.
Precision amplifier bridge circuits
EXAMPLE APPLICATION
AM457
Offset span compensation Wheatstone bridge with discrete adjusting resistors. AM457 suitable amplification resistance bridge circuits (four-resistor bridges) with sensitivity. compensate calibrate offset span amplify signal necessary network developed (see Figure four-resistor resistance bridge circuit (such sensing element, example) consisting resistance bridge, AM457 four resistors maximum capacitors (see [1]). AM457's characteristics define network amplifies bridge output signal required output values.
AM457
OUTOP
VCC=5V
ININOP
Temp
Diagnostic unit
DIAG
VDIAG VOUT
Figure Schematic circuit diagram resistance bridges with sensitivity
formulae used here calibrate offset span bridge circuit calculated using model which based classic Wheatstone bridge circuit four resistors. basis this model three simple equations were approximated setting resistors; they also suitable calibration using minimum data pertinent sensing element without need further correction.
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 7/10 Rev.
Precision amplifier bridge circuits
formulae used are:
AM457
Span adjustment
Auxiliary resistor Offset adjustment
whereby following applies individual sensing elements: Bridge resistance ohms Span/supply voltage mV/V Offset/supply voltage mV/V order calculate discrete adjusting resistors offset, span bridge resistance sensing element calibrated first determined. sensing element then connected AM457 form circuit illustrated Figure resistors dimensioned applied according given formulae. values capacitors selected according Table (Capacitors C3.C6 designated decoupling capacitors; their therefore optional.) Using calculated resistances given capacitors offset span (0.5.4.5V) should set. Discrepancies between resistors used theoretical value enter offset error proportionally. calibration suggested this article suitable sufficient accuracy sensing elements which consist four bridge resistors which permit calibration with discrete resistors which have sensitivity ±5.±100mV where span signal greater than offset.
Depending level accuracy required, when using sensing elements which have additional resistors (such ceramic sensing elements offset correction, example) discrete adjusting resistors must corrected discrepancy between model sensing element (see [2]).
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 8/10 Rev.
Precision amplifier bridge circuits
BLOCK DIAGRAM PINOUT
AM457
AM457
OUTOP
Diagnostic unit Temp
DIAG
Figure Block diagram AM457
NAME ININ+
EXPLANATION Output Negative Input Positive Input Ground Output Diagnosis Negative Input Output Supply Voltage
ININ+
OUTOP INOP DIAG
DIAG INOP OUTOP
Figure AM457
Table configuration
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 9/10 Rev.
Precision amplifier bridge circuits
DELIVERY OPTIONS
AM457 available Dice blue foil request)
AM457
Figure package dimensions
FURTHER READING
www.analogmicro.de
Application notes AN1011: AM457 amplifier sensing elements Application notes AN1012: AM457 amplifier ceramic sensing elements
analog microelectronics
Analog Microelectronics GmbH Fahrt 55124 Mainz Internet: www.analogmicro.de Phone: Fax: Email: (0)6131/91 (0)6131/91 info@analogmicro.de
2005 10/10 Rev.

AM457 PRINCIPLE FUNCTION Adjustable amplification differenti

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