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universal amplifier ic AM400 analog microelectronics februar 2006 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 1 / 21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.3 internet: http://www.analogmicro.de email: info@analogmicro . de principle function amplification and conversion of differential input voltages or those referenced to ground to industrial standard curren t (0/4...20ma) or voltage signals (e.g. 0...5/10v, 0.5...4.5v) typical applications ? transducer for sensor applications ? analog industrial output stage for microprocessor applications ? modular signal conditioning with dig ital correction (frame asic [1]) ? protected output stage power network ? impedance converter i out = 0/4...20ma AM400 v = 6?35v cc i = max 10ma s differential input voltage 400mv input voltage referenced to ground 0...v -5v cc v = 0...v - 5v adjustable, e.g. 0...5/10v out cc v = 5/10v ref
universal amplifier ic AM400 analog microelectronics februar 2006 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 2 / 21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.3 internet: http://www.analogmicro.de email: info@analogmicro . de contents features 3 general description 3 block diagram 3 electrical specifications 4 boundary conditions 7 detailed descriptio n 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
universal amplifier ic AM400 analog microelectronics februar 2006 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 3 / 21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.3 internet: http://www.analogmicro.de email: info@analogmicro . de features ? 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: -40c...+85c ? individually accessible function modules ? rohs compliant ? two package variants: sop and ssop general description 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 feat ure 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 net- work, 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 vref in + in- vout set outad indai gnd vset indav gain za outia inop 3 4 iout rs + rs- vcc cvref cvset v bg 17 5 ia 7 6 10 18 15 14 13 12 11 20 v i 16 19 voltage reference 1 9 op1 8 3 4 2 AM400-0 op2 op3 figure 1: block diagram of AM400 in the 20-pole version
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 4/ 21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev. 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de electrical specifications t amb = 25c, v cc = 24v, v ref = 5v, i ref = 1ma (unless otherwise stated); curren ts flowing into the ic are negative. parameter symbol conditions min. typ. max. unit supply voltage range v cc 6 35 v quiescent current i cc t amb = ? 40...+85c, i ref = 0ma 1.5 ma temperature specifications operating t amb ?40 85 c storage t st ?55 125 c junction t j 150 c voltage reference voltage v ref vset not connected 4.75 5.00 5.25 v v ref ** vset = gnd , v cc 11v 9.5 10.0 10.5 v trim range v r 10 ** 4.5 v r 10 v current i ref * 0 10.0 ma v ref vs. temperature d v ref /d t t amb = - 40...+85c 90 140 ppm/c line regulation d v ref /d v v cc = 6v...35v 30 80 ppm/v d v ref /d v v cc = 6v...35v, i ref 5ma 60 150 ppm/v load regulation d v ref /d i 0.05 0.10 %/ma d v ref /d i i ref 5ma 0.06 0.15 %/ma load capacitance c l 1.9 2.2 5.0 f current/voltage source op3 internal reference v bg 1.20 1.27 1.35 v v bg vs. temperature d v bg /d t t amb = - 40...+85c 60 140 ppm/c current source: i cv = v bg / r ext adjustable current range i cv * 0 10 ma output voltage v cv v cc < 19v v bg v cc ? 4 v v cv v cc 19v v bg 15 v voltage source: v cv = v bg ( r ext 1 + r ext 2 ) / r ext 2 adjustable voltage range v cv v cc < 19v 0.4 v cc ? 4 v v cv v cc 19v 0.4 15 v output current i cv * source 10 ma i cv sink ?100 a load capacitance c l source mode 0 1 10 nf instrumentation amplifier internal gain g ia 4.9 5 5.1 differential input voltage range v in 0 400 mv common mode input range cmir v cc < 9v, i cv < 2ma 1.5 v cc ? 3 v cmir v cc 9v, i cv < 2ma 1.5 6.0 v common mode rejection ratio cmrr 80 90 db power supply rejection ratio psrr 80 90 db offset voltage v os 1.5 6 mv
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 5/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de parameter symbol conditions min. typ. max. unit instrumentation amplifier (cont.) v os vs. temperature d v os /d t 5 v/c input bias current i b ?100 ?250 na i b vs. temperature d i b /d t ?0.4 ?0.9 na/c output voltage range v outia v cc < 9v, r lia 10k ? 0*** v cc ? 4 v v outia v cc 9v, r lia 10k ? 0*** 5 v minimum output voltage v outiamin without external load resistance r lia 4.5 16 mv load capacitance c l ** 250 pf zero adjust stage internal gain g za 0,94 1 1,06 input voltage v za v za v outia - g ia v in 0 v outia v offset voltage v os 0.5 2.0 mv v os vs. temperature d v os /d t 1.6 5 v/c input bias current i b 47 120 na i b vs. temperature d i b /d t 18 30 pa/c operational amplifier gain stage (op1) adjustable gain g gain 1 input range ir v cc < 10v 0 v cc ? 5 v ir v cc 10v 0 5 v power supply rejection ratio psrr 80 90 db offset voltage v os 0.5 2 mv v os vs. temperature d v os /d t 3 7 v/c input bias current i b 10 25 na i b vs. temperature d i b /d t 7 20 pa/c output voltage limitation v lim v ref v output voltage range v outad v cc < 10v 0 v cc ? 5 v v outad v cc 10v 0 v ref v load capacitance c l 250 pf operational amplifier output stage (op2) internal gain g op 2.15 2.20 2.25 input range ir v cc < 11v 0 v cc ? 5 v ir v cc 11v 0 6 v power supply rejection ratio psrr 80 90 db offset voltage v os 0.5 2 mv v os vs. temperature d v os /d t 3 7 v/c input bias current i b 10 25 na i b vs. temperature d i b /d t 7 20 pa/c output voltage range v out v cc < 19v 0 v cc ? 5 v v out v cc 19v 0 14 v output current limitation i lim v out 10v 5 7 10 ma output current i out 0 i lim ma load resistance r l 2 k ? load capacitance c l 500 nf
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 6/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de parameter symbol conditions min. typ. max. unit v/i converter internal gain g vi 0,120 0.125 0,130 trim range adjustable by r 0 0.75 1.00 1.25 voltage range at r 0 fs v r 0 fs 350 750 mv offset voltage v os f 100 2 4 mv v os vs. temperature d v os /d t f 100 7 14 v/c input resistance r in 120 160 k ? r in vs. temperature d r in /d t 0.2 0.3 k ? /c output offset current i outos 3-wire operation ?25 ?35 a i outos vs. temperature d i outos /d t 3-wire operation 16 26 na/c output offset current i outos 2-wire operation 9.5 14 a i outos vs. temperature d i outos /d t 2-wire operation 6 8 na/c output control current i outc 2-wire operation, v r 0 /100mv 6 8 a i outc vs. temperature d i outc /d t 2-wire operation ?10 ?15 na/c output voltage range v out v out = r l i out , v cc < 18v 0 v cc ? 6 v v out v out = r l i out , v cc 18v 0 12 v output current range fs i outfs i out = v r 0 /r 0 , 3-wire operation 20 ma output resistance r out 0.5 1.0 m ? load capacitance c l 0 500 nf set stage internal gain g set 0.5 input voltage v set 0 1.15 v offset voltage v os 0.5 1.5 mv v os vs. temperature d v os /d t 1.6 5 v/c input bias current i b 8 20 na i b vs. temperature d i b /d t 7 18 pa/c protection functions voltage limitation at r 0 v limr 0 v r 0 = v in g i , set = gnd only if op2 and v/i-converter are connected v ref /8 mv v limr 0 v in = 0, v r 0 = v set /2 580 635 690 mv protection against reverse polarity ground vs. v s vs. v out 35 v ground vs. v s vs. i out 35 v current in case of reverse polarity ground = 35v, v s = i out = 0 4.5 ma system parameters nonlinearity ideal input 0.05 0.15 %fs * in 2-wire operation a maximum current of i outmin ? i cc is valid ** only available in die form or in an ssop 20 version *** depending on external load resistance at output ia ( r lia 10k ? ? v outia < 3mv ); internal load resistance is 100k ?
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 7/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de boundary conditions parameter symbol conditions min. typ. max. unit sense resistor r 0 i outfs = 20ma 17 27 38 ? r 0 c = 20ma/ i outfs c ? 17 c ? 27 c ? 38 ? stabilization resistor r 5 i outfs = 20ma 35 40 45 ? r 5 c = 20ma/ i outfs c ? 35 c ? 40 c ? 45 ? load resistance r l limitation only for 3-wire operation 0 600 ? sum gain resistors r 1 + r 2 20 200 k ? sum offset resistors r 3 + r 4 20 200 k ? v ref capacitance c 1 min. value for t amb 85c 1.9 2.2 5.0 f output capacitance c 2 only for 2-wire operation 90 100 250 nf d 1 breakdown voltage v br 35 50 v t 1 forward current gain f bcx54/55/56, for example 50 150 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 operation 1 in industrial applications (cf. applications on pages 14 until 19). am462?s various functions are depicted in the block diagram (f igure 1) which also illustrates how few external components are required for the operation of th is particular device. AM400 consists of a number of mo dular functional blocks which thro ugh external gating can either operate together or se parately (see figure 2). 1. the instrumentation amplifier (ia) with an internal gain of g ia = 5 acts as an input stage for differential voltage signals. its special constr uction permits a high comm on mode rejection ratio (cmrr). the amplifier reference potentia l is set externally using the AM400 pin za . output voltage v outia at pin outia is calculated for v za > 0 as: za in ia outia v v g v + = with 0 > outia v (1) where v in is the differential voltage between inputs pin in+ and pin in- of the ia and v za 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 g gain can be set using external resistors r 1 and r 2 . protection against overvoltage has been integrated in to the device; this protective circ uitry 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.
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 8/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de output voltage v outad at pin outad is calculated as: gain inop outad g v v ? = with ? ? ? ? ? ? ? ? + = 1 2 1 r r g gain (2) where v inop is the voltage at the op1 input pin inop . alternatively, the op1 input pin inop can also be used as an input for signals refe renced to ground (see application 2, figure 6). 3. the ic?s voltage output v out is realized via the current-limited operational amplifier stage (op2) which has integrated protection against revers e polarity. the internal gain of op2 is set to a fixed value of g op = 2.2. the output is engineered as a driver stage. the following applies to op2?s output voltage v out at the ic pin vout : indav op out v g v ? = (3) where v indav is the voltage at pin indav (op2 input). v bg 17 5 ia 7 6 10 18 15 14 13 12 11 20 v i 16 19 voltage reference 1 9 op1 8 ground v s i out r 1 r 2 c 1 r 0 t 1 d 1 r 5 3 4 2 AM400-0 v ref op2 op3 v out v za v inop v set v outad v in+ v in- v cvref v cvset v outia r 3 r 4 v indai v indav figure 2: block diagram of AM400 showing ex ternal components (3-wire circuit with a current out p ut )
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 9/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de 4. the voltage-to-current converter (v/i converter) provides a voltage -controlled current signal at ic output iout which activates an external transistor t 1 ; this reduces the pow er dissipation of the ic and supplies the output current i out . the external transistor is protected against reverse polarity by an additional diode d 1 . via pin set an offset current i set can be set at output iout (with the help of the internal voltage referen ce and an external voltage divider as shown in figure 5, for example). external resistor r 0 permits the output current to be finely adjusted with parallel operation of current and the voltage output. for the output current i out boosted by t 1 the following ratio applies: set indai out i r v i + = 0 8 with 0 2 r v i set set = (4) with v indai the voltage at pin indai and v set the voltage at pin set (v/i converter inputs, see figure1) 2 . 5. the AM400 reference voltage source enables voltage to be suppl ied to external components (such as sensors, microprocessors, etc.). the reference voltage value v ref can be set via pin vset . if pin vset is not connected, v ref = 5v; if vset is switched to ground, v ref = 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 ). external capacitor c 1 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 in ternally to voltage v bg 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 i out is largely independent of the current amplification f of external transistor t 1 . production-specific variations in the current amplification of the transistors used are compensated for internally by the v/i converter.
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 10/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de operating AM400 general information on 2- and 3-wire applications in 3-wire operation (cf. figure 5, fo r example) the ground of the ic (pin gnd ) is connected up to the external mass of the system ground . the system's supply voltage v s is connected to pin vcc and pin vcc to pin rs +. in 2-wire operation (cf. fi gure 7) system supply voltage v s is connected to pin rs+ and pin vcc to rs- . the ground of the ic (pin gnd ) is connected to the node between resistor r 5 and load resistor r l (current output i out ). ic ground ( gnd ) is not the same as system ground ( ground )!! the output signal is picked up via load resistor r l which connects current output i out 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 v cc changes according to the current. as a rule, the following equation applies to 2-wire operation: () l in out s cc r v i v v ? = (5) the reason for this is that in 2-wire operation the ic is connected in series to the actual load resistor r l . 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 supp ly voltage can be expressed thus: s cc v v = (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 i out min (usually 4ma). r l v s 2- wire system signal source and conditioning ic gnd ground v cc v s ground r l 3- wire system signal source and conditioning ic gnd ground = v cc = v s ground gnd = gnd v cc i out i out vv cc s = figure 3: the difference between 2- and 3-wire operation
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 11/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de setting the voltage gain using the voltage output when using the ia and amplifier stages op1 a nd op2 for further signal conditioning the overall gain can be set using the suitabl y selected external resistors r 1 and r 2 . the transfer function for the output voltage is calculated by multiplying equations 1, 2 and 3 to: () op gain za in ia out g g v v g v ? ? + = (7) with g ia = 5, g gain = ( r 1 /r 2 ) + 1 and g op = 2.2 and the extern ally set voltage v za at pin za. setting the output current range and compensati ng for the offset using the current output when using the ia together with amplifier stag e op1 and the v/i convert er 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 (v in = 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: () set in out i v i = = 0 with 4 3 4 0 2 r r r r v i ref set + ? = (8) the output current range is set in conjuncti on with the selected external resistors r 1 and r 2 (or fine adjustment with r 0 ). using equations 2, 4 and 8 the following is calculated for output current i out : set i in out i r g v i + = 0 8 with gain ia i g g g ? = and 0 = za v (9) selecting the supply voltage system supply voltage v s needed to operate AM400 is dependent on the selected mode of operation. ? when using voltage output pin vout the minimum supply voltage v s necessary for the operation of the device depends on the maximum output voltage v out max required by the application. the following applies: v 5 max + out s v v (10) ? when using current output pin iout (in conjunction with the extern al transistor) the value of v s is dependent on that of th e relevant load resistor r l (max. 600 ? ) used by the application. the minimum system supply voltage v s is then: min max cc l out s v r i v + (11)
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 12/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de here, i out max stands for the maximum output current and v cc min for the minimum ic supply voltage which is dependent on th e selected reference voltage: v 1 min + ref cc v v (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 c 1 (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 th e range of temperature (see boundary conditions on page 7). in 2-wire operation ceramic capacitor c 2 must also be used. 2. all of the AM400 function blocks not used by the a pplication (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 ope ration the load resistance at pin vout must be at least 2k ?. 5. a load resistance of 600 ? maximum is permitted with operation of the current output. 6. the values of external resistors r 0 , r 1 , r 2 , r 3 , r 4 and r 5 must be selected within the permissible range given in the boundary conditions on page 7. v s [v] r l [ ? ] 6 35 v cc min = 6v r lmax = 600 ? i outmax = 20ma 18 r vv i l s ccmin outmax ? 24 12 600 working range 0 300 0 figure 4: working range in conjunction with the load resistor
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 13/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de applications 1) typical 3-wire application wi th 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 v s is connected to pin vcc and pin vcc to pin rs +. figure 5 shows a 3-wire application in which th e differential output signa l of a current-powered measuring bridge is amplified and converted. operational amplifier op3 supplies the measuring bridge with current. bridge supply current i s can be set using resistor r set : set set bg s r r v i v 27 . 1 = = (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 fo llowing then applies to output voltage v out: in v out v g v = with 2 . 2 1 5 2 1 ? ? ? ? ? ? ? ? + = = r r g g g g op gain ia v (14) ground v s i out r 1 r 2 r ial r 3 r 4 c 1 r 0 t 1 d 1 r 5 r l r set 3-wire connection load resistor to minimize the offset voltage at the i a output. 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. v bg 17 5 ia 7 6 10 18 15 14 13 12 11 20 v i 16 19 voltage reference 1 9 op1 8 3 4 2 AM400-0 op2 op3 v out figure 5: typical 3-wire application for differential input
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 14/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de according to equation 4 the following is then relevant to output current i out : set i in out i r g v i + = 0 8 with 0 = za v (15) with ? ? ? ? ? ? ? ? + = = 2 1 1 5 r r g g g gain ia i and 4 3 4 0 2 r r r r v i ref set + ? = . example 1: v in = 0...100mv (differential), i out = 4...20ma and v out = 0...10v for a measuring bridge with a signal of v in = 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. r 1 and r 2 are dimensioned in accordance with equation 14, r 0 according to equation 4 and r 3 and r 4 according to equation 8. observing the boundary conditions for the external components the following values are then obtained: r 0 35.5 ? r 1 80.9k ? r 2 = 10k ? r 3 = 83k ? r 4 = 5k ? r 5 = 39 ? r l = 0...600 ? r ial 10k ? c 1 = 2.2f 2) typical 3-wire application with an input signal referenced to ground ground v s i out v out r 1 r 2 r 3 r 4 c 1 r 0 t 1 d 1 r 5 r l 1 v in input voltage referenced to ground connections setting unused function blocks to a defined operating point 3-wire connection v bg 17 5 ia 7 6 10 18 15 14 13 12 11 20 v i 16 19 voltage reference 1 9 op1 8 3 4 2 AM400-0 op2 op3 figure 6: typical application for input signals referenced to ground
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 15/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de figure 6 shows a 3-wire application in whic h AM400 amplifies and converts a voltage signal referenced to ground. the blocks unused by the applic ation (ia and op3) ar e set to a defined operating point. alternatively, thes e function blocks can also be us ed for the supply of external components, for example. in the above applic ation output voltage v out is calculated using equations 2 and 3 as: in v out v g v = with 2 . 2 1 2 1 ? ? ? ? ? ? ? ? + = = r r g g g op gain v according to equation 4 the follo wing applies to output current i out : set i in out i r g v i + = 0 8 with ? ? ? ? ? ? ? ? + = = 2 1 1 r r g g gain i and 4 3 4 0 2 r r r r v i ref set + ? = example 2: v in =0?1v (referenced to ground), i out = 4...20ma and v out = 0...10v for a signal of v in = 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 valu es are obtained for the external components: r 0 35.5 ? r 1 35.5k ? r 2 = 10k ? r 3 = 83k ? r 4 = 5k ? r 5 = 39 ? r l = 0...600 ? c 1 = 2.2f 3) typical 2-wire application wi th a differential input signal in 2-wire operation (cf. figure 7) system supply voltage v s 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 r 5 and load resistor r l (current output i out ). ic ground ( gnd ) is not the same as system ground ( ground )!! the output signal is picked up via load resistor r l which connects current output i out to the system ground. figure 7 shows a typical 2-wire ap plication in which the differential output signal of a current- powered 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 i s can be set using resistor r set according to equation 13. according to equation 4 the following applies to the output current of the 2-wire application: set i in out i r g v i + = 0 8 with ) to connected ( 0 gnd za v za =
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 16/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de where ? ? ? ? ? ? ? ? + = = 2 1 1 5 r r g g g gain ia i and 4 3 4 0 2 r r r r v i ref set + ? = example 3: v in = 0..100mv (differential) and i out = 4...20ma for a measuring bridge with a signal of v in = 0...100mv at the ia input the external components of the AM400 circuitry are to be dime nsioned in such a way that th e 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 r 1 to r 4 . up to a certain point the value of resistor r 0 is freely selectable and can be set to 27 ?. observing the boundary conditions for the exte rnal components the follo wing values are then obtained: r 0 = 27 ? r 1 59.12k ? r 2 = 10k ? r 3 = 82k ? r 4 = 5k ? r 5 = 39 ? r l = 0...600 ? r ial 10k ? c 1 = 2.2f c 2 = 100nf in this specific application particular attention mu st be paid to the current consumption which at a temperature of 85c may not exceed 4ma. negative offset voltages can be compensated for using pin za. if the pin is not in use it be connected to ic ground gnd. must ground v s i out r 1 r 2 r ial r 3 r 4 c 1 r 0 t 1 d 1 r 5 r l r set 2-wire connection c 2 ic ground: gnd system ground: ground } different potentials! gnd v bg 17 5 ia 7 6 10 18 15 14 13 12 11 20 v i 16 19 voltage reference 1 9 op1 8 3 4 2 AM400-0 op2 op3 figure 7: typical 2-wire application for differential input signals
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 17/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de 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 differe nt from those of the 3-wire setup illustrated in figure 5; no detailed descri ption shall thus be given here. one di fference, however, lies in the fact that the minimum voltage at the ia output cannot be reduced by conn ecting up external load resistor r lia . particularly with small differential input signs and the large g op gain these entail a ?correct? value of 0v cannot be obtained at ic output vout (cf. the comments on v outia in the electrical specifications). for this reason the 20-pole version of AM400 is preferable for small signals. ground v s i out v out r 1 r 2 r 3 r 4 c 1 r 0 t 1 d 1 r 5 r l r set AM400-1 3 4 2 v bg 13 5 14 12 11 10 9 8 16 v i 15 5v reference op3 1 7 6 ia op1 3-wire connection v outia the minimum voltage at the ia output is 16ma op2 AM400-1 figure 8: typical application for the 16-pole version of AM400 (3-wire)
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 18/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de block diagram, 20-po le pinout and dice pin name explanation 1 cvref current/voltage reference 2 cvset current/voltage reference set 3 in + positive input ia 4 in? negative input ia 5 outia output ia 6 inop positive amplification op input 7 gain gain set 8 outad system gain output 9 indai current output stage input 10 indav voltage output stage input 11 iout current output 12 rs ? sensor resistor ? 13 vcc supply voltage 14 rs + sensor resistor + 15 vout voltage output 16 vset set reference voltage source 17 za zero adjustment (offset) 18 gnd ic ground 19 vref reference voltage source output 20 set output offset current set table 1: pinout of the 20- pole version of AM400 vref in + in- vout set outad indai gnd vset indav gain za outia inop 3 4 iout rs + rs- vcc cvref cvset v bg 17 5 ia 7 6 10 18 15 14 13 12 11 20 v i 16 19 voltage reference 1 9 op1 8 3 4 2 AM400-0 op2 op3 figure 9: block diagram of AM400 in the 20-pole version 1 20 2 19 318 4 17 5 16 615 7 14 813 9 12 10 11 cvref cvset in+ in- outia inop gain outad indai indav set vref gnd za vset vout rs+ vcc rs- iout figure 10: pinout of the 20-pole version of AM400
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 19/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de block diagram and 16-pole pinout vref in + in- vout set outad inda gnd za gain 3 4 v bg 13 5 14 12 iout rs + rs- vcc 11 10 9 8 16 v i 15 5v reference 1 7 6 ia AM400-1 cvref cvset 2 op1 op2 op3 figure 11: block diagram of AM400 in the 16-pole version pin name explanation 1 cvref current/voltage reference 2 cvset current/voltage reference set 3 in + positive input ia 4 in? negative input ia 5 gain gain set 6 outad system gain output 7 inda output stage input 8 iout current output 9 rs ? sensor resistor ? 10 vcc supply voltage 11 rs + sensor resistor + 12 vout voltage output 13 za zero adjustment (offset) 14 gnd ic ground 15 vref reference voltage source output 16 set output offset current set table 2: pinout of the 16-pol e version of AM400 1 16 2 15 3 14 4 13 5 12 6 11 7 10 89 cvref cvset in+ in- gain outad inda iout set vref gnd za vout rs+ vcc rs- figure 12: pinout of the 16-pole version of AM400
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 20/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de example applications ? signal conditioning for ceramic and piezoresistive pressure sensing elements with an optional external processor for error compensation ? application as a converter ic ? conditioning of signals referenced to ground (protected output stag e, impedance converter, etc.) v s = 6...35v AM400 sensor supply voltage or current p 0/4...20ma 0...5/10v figure 13: application for ceramic and piezoresis tive pressure sensors and an external microcontroller 5 v AM400 6...35v 0/4...20ma cav424 0...5/10v c x1 c x2 figure 14: application as a converter ic together w ith cav424 for the measurement of capacitive v424 signals AM400 6...35v 0/4...20ma v in = 0...1, 0...5v others protection agains t short-circuiting and reverse polarity figure 15: application for input signals referenced to ground (protect ed output stage, impedance converter, etc.)
universal amplifier ic AM400 analog microelectronics october 2005 analog microelectronics gmbh phone: +49 (0)6131/91 073 ? 0 21/21 an der fahrt 13, d ? 55124 mainz fax: +49 (0)6131/91 073 ? 30 rev.: 4.2 internet: http://www.analogmicro.de email: info@analogmicro . de 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 (dat a 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 inform ation contained herein without further notice.

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