am452 AME, Inc., am452 Datasheet
am452
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am452 Summary of contents
Page 1
... AM452 – Voltage-to-current transducer IC with a differential input Amplification and conversion of differential input voltages (±400mV with a CMIR of 1.5 – V -3V) into an adjustable current output of 0/4...20mA, for example. The CC offset and maximum output currents are independently adjustable in a wide range. The IC is suitable for both 2- and 3-wire applications and as a HART Differential input ± ...
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... Voltage-to-current converter (V/I converter) Reference voltage source Additional operational amplifier OP2 OPERATING AM452 2- and 3-wire applications in general [2] Differences in the AM452 circuitry with 2- and 3-wire applications Selecting the supply voltage Setting the offset and output current range for V OPERATING AM452: IMPORTANT POINTS TO NOTE DIMENSIONING ...
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... Figure 1: Block diagram of AM452 Figure 1: Schematic of AM452 Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz GENERAL DESCRIPTION AM452 is an integrated transducer with an adjustable current output which has been specifically designed for the conditioning of differential input independent adjustment of the offset and full- scale current using just a few components ...
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... AM452 – Voltage-to-current transducer IC with a differential input ELECTRICAL SPECIFICATIONS T = 25° 24V 5V, I amb CC REF Parameter Symbol V Supply Voltage Range CC I Quiescent Current CC Temperature Specifications Operating T amb Storage T st Junction T J Voltage Reference Voltage V REF V REF Current I * REF V vs. Temperature ...
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... AM452 – Voltage-to-current transducer IC with a differential input Parameter Symbol Instrumentation Amplifier (cont.) Internal Gain G IA Differential Input Voltage Range V IN Common Mode Input Range CMIR CMIR Common Mode Rejection Ratio CMRR Power Supply Rejection Ratio PSRR Offset Voltage vs. Temperature ...
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... AM452 – Voltage-to-current transducer IC with a differential input Parameter Symbol V/I Converter Internal Gain G VI Trim Range Voltage Range Offset Voltage vs. Temperature dV / Input Resistance vs. Temperature dR / Output Offset Current I OUTOS I vs. Temperature ...
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... OP1 IN- 4 ZERO Stage Figure 2: Block diagram of AM452 (3-wire version). Analog Microelectronics GmbH An der Fahrt 13, D – 55124 Mainz Conditions I = 20mA OUTFS c = 20mA/I OUTFS I = 20mA OUTFS c = 20mA/I OUTFS Only for 3-wire operation Min. value for T 85° ...
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... AM452 – Voltage-to-current transducer IC with a differential input DETAILED DESCRIPTION OF FUNCTIONS AM452 is a modular, monolithically integrated transducer which has been specially developed for the conditioning of differential voltage signals. It consists of several function blocks, the values of which are described in detail in the electrical specifications. Its various function blocks are depicted in the block diagram (Figure 2) and described in the following ...
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... AM452 – Voltage-to-current transducer IC with a differential input SET stage The SET stage permits the adjustment of the offset output current I with the V/I converter it effects the output current I I can be set at pin 8 (IOUT) e.g. with the help of the internal voltage reference and an SET external voltage divider as shown in Figure 2, for example ...
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... R . This is illustrated in Figure 2-wire system the power consumption of the overall system (AM452 plus all external components including the signal source and adjusting resistors) may not be more than I (e.g. 4mA). In 3-wire operation Equation (5) no longer applies as the IC ground is connected to the ground of the system ...
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... L Ground Figure 4: Differences in 2-and 3-wire circuitry in conjunction with AM452 AM452 is constructed in such a way that by changing the external circuitry it is suitable for both 2-wire and 3-wire operation. In 3-wire operation (see Figure 4, right) the IC's connection to ground (pin 14 or GND) is connected to the system ground (Ground) which is applied externally. System supply voltage V is connected to pin 10 (VCC) and pin VCC to pin 11 (RS+) ...
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... Setting the offset and output current range for V When adjusting AM452 a preset should first be made. To this end the offset of the output current is compensated for, in which the two IA inputs are first short-circuited (V then both set to a permitted potential (c.f. CMIR in ELECTRICAL SPECIFICATIONS). With ...
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... the offset of the AM452 signal source and input amplifier (IA) is such that it cannot be ignored, when setting the output current range (gain) must possibly be accounted for by making a fine adjustment to R signal source and input amplifier is not relevant to the required degree of precision, Equations (9) and (10) continue to apply ...
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... Dimensioning according to the equations given in the data sheet enables all modules to be used, making it possible for the setup to be adapted to suit the most diverse application requirements rule the offset of the AM452 input signal must be taken into account input signal offset is present and an offset current of I condition then applies: ...
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... In 3-wire operation (see Figure 6) the IC's connection to ground (pin 14 or GND) is connected to the system ground (Ground) which is applied externally. System supply voltage V connected to pin 10 or VCC and pin VCC to pin 11 or RS+. In this configuration AM452's quiescent current does then not flow via resistor R Figure 6 depicts the 3-wire application in which the differential output signal of a measuring bridge supplied with current is amplified and converted ...
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... AM452 – Voltage-to-current transducer IC with a differential input Here the overall gain of the instrumentation amplifier (IA) and the back-end operational I amplifier (OP1 the additional offset current which is set using a voltage at the SET SET pin and which can raise the output current of the VI/ converter by a constant value. ...
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... In order to determine the system resistors R For a measuring bridge with a signal of V the external components in the AM452 circuitry should be dimensioned in such a way that the output current range is 4...20mA. AM452 is configured in such a way that the entire current, including the chip's quiescent current, flows through Example 1, R and R can be freely selected within the boundary conditions ...
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... AM452 – Voltage-to-current transducer IC with a differential input By solving the above system of equations and taking the given defaults for the external components into account, the following values are computed 74.48k 89. 0...900 C = 2.2µ the 2-wire application particular attention must be paid to the overall power consumption which may not exceed a value of 4mA across the entire temperature range ...
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... AM452 – Voltage-to-current transducer IC with a differential input Using OP2 as a current source The additional operational amplifier OP2 can easily be configured as a constant current source. Using the circuitry shown in Figure 8 the following equation is generated The bridge symbol is supposed to represent the component to be supplied with current (such as a piezoresistive sensing element or a temperature sensor, for example) ...
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... AM452 – Voltage-to-current transducer IC with a differential input BLOCK DIAGRAM AND PINOUT CVREF VSET VREF AM452 CVSET 2 OP2 Voltage Reference OP1 GAIN Figure 10: Simplified block diagram Figure 10: Simplified block diagram PIN NAME EXPLANATION ...
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... AM452 – Voltage-to-current transducer IC with a differential input DELIVERY AM452 is available as an: SO16(n) PACKAGE DIMENSIONS Please see the data sheet on our website: package.pdf FURTHER READING [1] The Frame ASIC concept: The following links refer to the Analog Microelectronics website: http://www.analogmicro.de/ [2] Technical article: PR1012 – AM462 Voltage-to-current converter IC for 2-wire current ...