AM460 [AME]
Industrial Converter and Protector IC; 工业转换器和保护IC
| 型号： | AM460 |
| 厂家： | 
ANALOG MICROELECTRONICS |
| 描述： | Industrial Converter and Protector IC |
| 文件： | 总18页 (文件大小：164K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Industrial Converter and Protector IC
AM460
PRINCIPLE FUNCTION
Amplification and conversion of voltage signals referenced to ground
Integrated protection for IC and external components
Integrated, adjustable current/voltage sources for external components
VS = 6...35V
Single-ended
input signal
IOUT = 0/4...20mA
AM460
VOUT = 0...5/10V
e.g. 0...5V, 0...1V
VREF = 5/10V
IS = e.g. 1.5mA
TYPICAL APPLICATIONS
• Peripheral processor IC (see Figure 12 on page 17)
• Industrial protector and output IC for microprocessors (Frame ASIC concept [1])
• Impedance converter
• Adjustable voltage and current source (supply unit)
• Voltage regulator with additional functions
analog microelectronics
April 2003
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
Internet: http://www.analogmicro.de
Phone: +49 (0)6131/91 073 – 0
1/18
Rev. 1.1
Fax:
+49 (0)6131/91 073 – 30
E–mail: info@analogmicro.de
Industrial Converter and Protector IC
AM460
TABLE OF CONTENTS
Features
3
3
3
4
6
6
General Description
Block Diagram
Electrical Specifications
Boundary Conditions
Detailed Description of Functions
Operating AM460
8
8
9
9
9
General information on 2- and 3-wire applications and the use of the current output
Setting the voltage gain using the voltage output
Setting the output current range using the current output
Selecting the supply voltage
Connecting OP2 as a current source
Connecting OP2 as a voltage reference
10
11
Operating AM460: Important Points to Note
12
Applications
12
12
14
Typical 3-wire application with an input signal referenced to ground
Typical 2-wire application with an input signal referenced to ground
Block Diagram and Pinout
Examples of Possible Applications
Delivery
16
17
18
18
Further Reading
TABLE OF FIGURES
Table 1: AM460 pinout
16
Figure 1: Block diagram of AM460
3
7
Figure 2: Block diagram of AM460 with external components (3-wire circuit for current output)
Figure 3: Difference between 2- and 3-wire operation
Figure 4: Working range in conjunction with the load resistor
Figure 5: Connecting up a constant current source
Figure 6: Connecting up a voltage reference
8
10
10
11
13
14
16
16
Figure 7: Typical application for input signals referenced to ground
Figure 8: Typical 2-wire application for input signals referenced to ground
Figure 9: Block diagram of AM460
Figure 10: Pinout
Figure 11: Application for input signals referenced to ground (protected output stage, impedance converter etc.)
Figure 12: Complex configuration as a peripheral processor IC
17
17
17
Figure 13: Conversion of a 0.5...4.5V sensor signal
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April 2003
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Industrial Converter and Protector IC
AM460
FEATURES
GENERAL DESCRIPTION
AM460 is a universal converter and amplifier IC
with a number of additional functions. The IC basi-
cally consists of an amplifier, whose gain can be set
externally, and parallel output stages which can con-
dition signals referenced to ground in industrial
voltage and current signals. An additional reference
voltage source for the supply of external components
is also included in the device. A further operational
amplifier can be connected up as a current source,
voltage reference or comparator.
• 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
• Operational amplifier with integrated
driver stage
• Adjustable amplification
• Analogue parallel voltage (0...5/10V) and
current output (0/4...20mA)
• Protection against reverse polarity and
short-circuiting
• Output current limit
• Low-cost device: replaces a number of
discrete elements
One of the main features of the IC is its integrated
protective circuitry. The device is protected against
reverse polarity, short-circuiting and has a built-in
output current limit. Amplifier IC AM460 enables
industrial standard voltage (e.g. 0–5/10V) and cur-
rent loop (e.g. 0/4–20mA) signals to be produced
relatively easily.
• 2- and 3-wire operation
BLOCK DIAGRAM
VREF
VSET
SET
CVREF
1
16
15
13
AM460
CVSET
INP
11
10
9
I
RS+
VCC
RS-
2
3
Voltage Reference
OP2
VBG
V
8
IOUT
OP1
12
OP3
VOUT
5
6
4
7
14
GND
INN
OUTAD
INDAI INDAV
Figure 1: Block diagram of AM460
analog microelectronics
April 2003
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
Internet: http://www.analogmicro.de
Phone: +49 (0)6131/91 073 – 0
Fax: +49 (0)6131/91 073 – 30
E–mail: info@analogmicro.de
3/18
Rev. 1.1
Industrial Converter and Protector IC
AM460
ELECTRICAL SPECIFICATIONS
Tamb = 25°C, VCC = 24V, VREF = 5V, IREF = 1mA (unless otherwise stated), currents flowing into the IC are negative
Parameter
Symbol
VCC
Conditions
Min.
Typ.
Max.
Unit
Supply Voltage Range
Quiescent Current
Temperature Specifications
Operating
6
35
V
ICC
Tamb = – 40...+85°C, IREF = 0mA
1.5
mA
Tamb
Tst
–40
–55
85
°C
°C
Storage
125
150
Junction
TJ
°C
Thermal Resistance
DIL16 plastic package
70
°C/W
°C/W
Θja
Θja
SO16 narrow plastic package
140
Voltage Reference
Voltage
VREF
VSET not connected
4.75
9.5
4.5
0
5.00
10.0
5.25
10.5
VREF10
10.0
±140
80
V
V
VREF10
VREFADJ
IREF
VSET = GND, VCC ≥ 11V
Trim Range
V
Current
*
mA
VREF vs. Temperature
Line Regulation
dVREF/dT
dVREF/dV
dVREF/dV
dVREF/dI
dVREF/dI
CL
Tamb = – 40...+85°C
VCC = 6V...35V
±90
30
ppm/°C
ppm/V
ppm/V
%/mA
%/mA
µF
60
150
V
CC = 6V...35V, IREF ≈ 5mA
Load Regulation
0.05
0.06
2.2
0.10
0.15
5.0
IREF ≈ 5mA
Load Capacitance
1.9
Current/Voltage Source OP2
Internal Reference
VBG
1.20
1.27
1.35
V
VBG vs. Temperature
dVBG/dT
Tamb = – 40...+85°C
±60
±140
ppm/°C
Current Source: ICV = VBG/RSET, from Figure 5
Adjustable Current Range
Output Voltage
ICV
*
0
10
VCC – 4
15
mA
V
VCV
VCV
VCC < 19V
CC ≥ 19V
VBG
VBG
V
V
Voltage Source: VCV = VBG (1 + R7 / R6), from Figure 6
Adjustable Voltage Range
VCV
VCV
VCC < 19V
CC ≥ 19V
0.4
0.4
VCC – 4
15
V
V
V
Output Current
ICV
ICV
CL
*
Source
10
mA
µA
nF
Sink
–100
10
Load Capacitance
Source mode
0
1
Operational Amplifier Gain Stage (OP1)
Adjustable Gain
GGAIN
IR
1
0
Input Range
VCC < 10V
VCC – 5
V
V
IR
0
5
V
CC ≥ 10V
Power Supply Rejection Ratio
Offset Voltage
PSRR
VOS
80
90
±0.5
±3
dB
±2
±7
mV
µV/°C
VOS vs. Temperature
dVOS/dT
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Industrial Converter and Protector IC
AM460
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
Operational Amplifier Gain Stage (OP1) (cont.)
Input Bias Current
IB vs. Temperature
Output Voltage Limit
Output Voltage Range
IB
10
7
25
20
nA
pA/°C
V
dIB/dT
VLIM
VREF
VOUTAD
VOUTAD
CL
VCC < 10V
CC ≥ 10V
0
0
VCC – 5
VREF
V
V
V
Load Capacitance
250
pF
Operational Amplifier Output Stage (OP3)
Internal Gain
GOP
IR
2.15
0
2.20
2.25
VCC – 5
6
Input Range
VCC < 11V
CC ≥ 11V
V
V
IR
0
V
Power Supply Rejection Ratio
Offset Voltage
PSRR
VOS
80
90
±0.5
±3
10
dB
±2
±7
mV
µV/°C
nA
VOS vs. Temperature
Input Bias Current
dVOS/dT
IB
25
IB vs. Temperature
dIB/dT
VOUT
VOUT
ILIM
IOUT
RL
7
20
pA/°C
V
Output Voltage Range
VCC < 19V
0
0
5
0
2
VCC – 5
14
V
V
V
CC ≥ 19V
Output Current Limitation
Output Current
7
10
mA
mA
kΩ
OUT ≥ 10V
ILIM
Load Resistance
Load Capacitance
V/I Converter
CL
500
nF
Internal Gain
GVI
0.125
1.00
Trim Range
Adjustable by R0
0.75
350
1.25
750
±4
Voltage Range at R0 FS
Offset Voltage
VR0FS
VOS
mV
mV
±2
±7
160
0.3
–25
16
βF ≥ 100
βF ≥ 100
VOS vs. Temperature
Input Resistance
dVOS/dT
RIN
±14
µV/°C
kΩ
120
0.2
RIN vs. Temperature
Output Offset Current
IOUTOS vs. Temperature
Output Offset Current
IOUTOS vs. Temperature
Output Control Current
IOUTC vs. Temperature
Output Voltage Range
dRIN/dT
IOUTOS
dIOUTOS/dT
IOUTOS
dIOUTOS/dT
IOUTC
kΩ/°C
µA
3-wire operation
–35
26
3-wire operation
nA/°C
µA
2-wire operation
9.5
6
14
2-wire operation
8
nA/°C
µA
2-wire operation, VR0/100mV
2-wire operation
6
8
dIOUTC/dT
VOUT
–10
–15
VCC – 6
12
nA/°C
V
VOUT = RL IOUT, VCC < 18V
VOUT = RL IOUT, VCC ≥ 18V
IOUT = VR0/R0, 3-wire operation
0
0
VOUT
V
Output Current Range FS
Output Resistance
IOUTFS
ROUT
20
mA
0.5
0
1.0
MΩ
nF
Load Capacitance
CL
500
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Industrial Converter and Protector IC
AM460
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
SET Stage
Internal Gain
GSET
0.5
Input Voltage
VSET
0
1.15
±1.5
±5
V
Offset Voltage
VOS
±0.5
±1.6
8
mV
VOS vs. Temperature
Input Bias Current
IB vs. Temperature
Protection Functions
Voltage Limitation at R0
dVOS/dT
IB
µV/°C
nA
20
dIB/dT
7
18
pA/°C
VLIMR0
VLIMR0
VR0 = VINDAI GVI, SET = GND
VINDAI = 0, VR0 = GSET VSET
Ground vs. VS vs. VOUT
580
580
635
635
690
690
35
mV
mV
V
Protection against reverse polarity
Ground vs. VS vs. IOUT
35
V
Current with reverse polarity
System Parameters
Nonlinearity
Ground = 35V, VS = IOUT = 0
4.5
mA
Ideal input
0.05
0.15
%FS
* In 2-wire operation a maximum current of IOUTmin – ICC is valid
BOUNDARY CONDITIONS
Parameter
Symbol
Conditions
IOUTFS = 20mA
Min.
Typ.
Max.
Unit
Sense Resistor
R0
R0
17
c ⋅ 17
35
27
c ⋅ 27
40
38
c ⋅ 38
45
Ω
Ω
c = 20mA/IOUTFS
Stabilisation Resistor
IOUTFS = 20mA
R5
Ω
c = 20mA/IOUTFS
R5
c ⋅ 35
0
c ⋅ 40
c ⋅ 45
600
200
200
5.0
Ω
Load Resistor
RL
Only for 3-wire operation
Ω
Sum Gain Resistors
Sum Offset Resistors
VREF Capacitor
R1 + R2
R3 + R4
C1
20
kΩ
kΩ
µF
nF
V
20
Ceramic
1.9
90
2.2
100
50
Output Capacitor
C2
Only for 2-wire operation
250
D1 Breakdown Voltage
T1 Forward Current Gain
VBR
βF
35
BCX54/55/56, for example
50
150
DETAILED DESCRIPTION OF FUNCTIONS
AM460 is a modular, universal converter and protector IC which has been specially developed for the condi-
tioning of voltage signals referenced to ground. It has been conceived for both 2- and 3-wire operation1 in in-
dustrial applications (cf. application on page 8). The functions of AM460 are depicted in the block diagram
(Figure 2) which also illustrates how few external components are required for the operation of this particular
device. Electrical specifications for the external components are given on page 6.
1The principle of AM460 is such that only the current output can be used in 2-wire operation.
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Industrial Converter and Protector IC
AM460
VREF
R3
R4
VCVREF
C1
VS
VSET
1
16
15
13
AM460
VCVSET
11
10
9
I
R0
2
3
Voltage Reference
OP2
VBBGG
V
8
T1
VINP
D1
VOUT
OP1
12
OP3
5
6
4
7
14
R5
IOUT
R1
VINDAI VINDAV
R2
VOUTAD
Ground
Figure 2: Block diagram of AM460 with external components (3-wire circuit for current output)
AM460 consist of several modular function blocks (operational amplifiers, voltage-to-current converters and
references) which depending on external configurations can either be switched together or operated separately
(see the basic circuitry in Figure 2):
1. Operational amplifier stage OP1 enables a positive voltage signal to be amplified. OP1 gain GGAIN can be set
via external resistors R1 and R2. Protective circuitry against overvoltage is integrated into the chip, limiting
the voltage to the set value of the reference voltage. Output voltage VOUTAD at pin OUTAD is calculated as:
R1
VOUTAD = VINP ⋅GGAIN with GGAIN =1+
(1)
R2
where VINP is the voltage at OP1 input pin INP.
2. Using the current-limited operational amplifier stage OP3 with its integrated protection against reverse po-
larity an industrial voltage signal (VOUT) can be realised. The internal amplification of OP3 is set to a fixed
value of GOP = 2.2. The output is configured as a driver so that OP3 is particularly suitable as an output
stage. For OP3 output voltage VOUT at pin VOUT of the IC the following applies:
VOUT = GOP ⋅VINDAV
(2)
with VINDAV the voltage at pin INDAV (OP3 input).
3. The voltage-to-current converter (V/I converter) provides a voltage-controlled current signal at IC output
IOUT (pin 8) which activates an external transistor T1; this in turn supplies the actual output current IOUT. To
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Industrial Converter and Protector IC
AM460
reduce power dissipation the transistor is an external component and 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 inter-
nal voltage reference and an external voltage divider as shown in Figure 2, 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 provided by T1 the following ratio applies:
VINDAI
VSET
IOUT
=
+ ISET with ISET
=
(3)
8R0
2R0
with VINDAI the voltage at INDAI and VSET the voltage at pin SET (V/I converter inputs, Figure 2)2.
4. The AM460 reference voltage source enables voltage to be supplied to external components (such as sen-
sors, microprocessors, etc.). The reference voltage value VREF can be set via pin 13 VSET. If pin VSET is not
connected, VREF = 5V; if VSET is switched to ground, VREF = 10V. Values between these can be set if two
external resistors are used (inserted between pin VREF and pin VSET and between pin VSET and GND).
External (ceramic) capacitor C1 at pin VREF stabilises the reference voltage. It must be connected even if
the voltage reference is not in use.
5. The additional operational amplifier stage OP2 can be used as a current or voltage source to supply external
components. OP2's positive input is connected internally to voltage VBG so that the output current or output
voltage can be set across a wide range using one or two external resistors.
OPERATING AM460
General information on 2- and 3-wire applications and the use of the current output
In 3-wire operation (cf. Figure 3 right and Figure 7) the ground of the IC (pin GND) is connected up to the ex-
ternal 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-. 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.
2-wire system
signal source and
conditioning IC
3-wire system
signal source and
conditioning IC
VCC
IOUT
IOUT
RL
VS
VCC = VS
GND
RL
GND
≠
Ground
VS
GND = Ground
VCC = VS
VCC
≠
Ground
Figure 3: Difference between 2- and 3-wire operation
Ground = GND
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.
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Industrial Converter and Protector IC
AM460
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 − IOUT
(VIN
)
RL
(4)
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 VCC = VS, as the IC ground is connected to the ground of the system.
Setting the voltage gain using the voltage output
Using amplifier stages OP1 and OP3 for signal conditioning the overall gain can be set by selecting suitable ex-
ternal resistors R1 and R2. The transfer function for the output voltage is calculated by multiplying Equations 1
and 2 as follows:
VOUT = VINP ⋅GGAIN ⋅GOP
(5)
with GGAIN = 1 + R1/R2 and GOP = 2.2.
Setting the output current range using the current output
When using amplification stage OP1 together with the V/I converter for signal conditioning the offset of the
output current should first be compensated for by suitable selection of resistors R3 and R4. To this end the OP1
input must be connected to ground (VINP = 0). With the short circuit at the input and by connecting up V/I con-
verter pin VSET as shown in Figure 2 the values of the output current according to Equation 3 are as follows:
VREF
R4
IOUT
(
VINDAI = 0
)
= ISET
=
⋅
(6)
2R0 R3 + R4
and thus for the ratio of the resistors R3/R4:
R3
VREF
=
−1
(7)
R4 2R0 ISET
The output current area is set in conjunction with the selection of external resistors R1 and R2 (or fine adjustment
with R0 ). With Equations 1 and 3 the following is calculated for output current IOUT
:
GGAIN
R1
R2
IOUT = VINP
+ ISET with GGAIN = 1+
(8)
8R0
Selecting the supply voltage
System supply voltage VS needed to operate AM460 is dependent on the selected mode of operation.
•
When using voltage output pin VOUT the minimum VS needed for operation is determined by the maximum
output voltage VOUTmax required by the application. This is expressed as follows:
VS ≥ VOUT max + 5V
(9)
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AM460
VCCmin = 6V
RLmax = 600
RL [
Ω
]
−
VS VCCmin
RL
≤
Ω
IOUTmax
IOUTmax = 20mA
600
300
0
Operating range
24
0
6
12
18
35
VS [V]
Figure 4: Working range in conjunction with the load resistor
•
When using current output pin IOUT (in conjunction with the external transistor) the value of VS is depend-
ent on that of the relevant load resistor RL (max. 600Ω) used by the application. The minimum system sup-
ply voltage VS is then:
VS ≥ IOUT max RL +VCC min
(10)
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
(11)
The working range resulting from Equation 10 is described in Figure 4. Example calculations and typical values
for the external components can be found in the example applications from page 12 onwards.
Connecting OP2 as a current source
The additional operational amplifier OP2 can easily be connected up as a constant current source. Using the cir-
OP2 connected as current source
IS
1
AM460
2
OP2
VBG
RSET
Figure 5: Connecting up a constant current source
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Industrial Converter and Protector IC
AM460
cuit in Figure 5 the following applies:
VBG
1.27V
(12)
IS
=
=
RSET
RSET
The bridge symbol represents the component to be supplied with current (e.g. a piezoresistive sensing element
or temperature sensor).
Example 1:
A supply current of IS = 1mA is to be set. Using Equation 12 the following value is calculated for external re-
sistor RSET, which in turn stipulates the size of the current:
VBG
IS
1.27V
1mA
RSET
=
=
= 1.27kΩ
Connecting 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 miniaturisation of devices and need for ever lower levels of power dissipation in digital
components is today of growing importance.
The additional operational amplifier OP2 can easily be connected up as a voltage reference. Using the circuit in
Figure 6 the following applies:
R6
R7
R6
R7
(13)
VCVREF = VBG 1+
= 1.27 V 1 +
Example 2:
A voltage of VCVREF = 3.3V is to be set. Using Equation 13 the following ratio is calculated for external resistors
OP2 connected as voltage
reference
VCVREF
1
AM460
R6
R7
µP
2
OP2
VBG
Figure 6: Connecting up a voltage reference
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AM460
R6 and R7:
R6 VCVREF
=
− 1 ≈ 2.6 − 1 = 1.6
R7
VBG
The following example values are produced for the resistors:
R7 = 10kΩ R6 = 16kΩ
OPERATING AM460: IMPORTANT POINTS TO NOTE
1. When using AM460 it is imperative that external capacitor C1 (a top-grade ceramic capacitor) is always
connected (cf. Figure 2). Care must be taken that the value of the capacitor, also within the temperature
range, does not exceed the range of values given in the boundary conditions on page 6. In 2-wire operation
ceramic capacitor C2 must also be used (cf. Figure 8)
2. In a 2-wire setup the power consumption of the entire system (AM460 plus all external components, in-
cluding the configuration resistors) must not exceed the sum of IOUTmin (usually 4mA).
3. All AM460 function blocks not required by the application must be connected to a defined (and allowed)
potential.
4. With operation of the voltage output the load resistance at pin VOUT must be at least 2kΩ.
5. When operating the current output a maximum load resistance of 600Ω is permitted.
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 6.
APPLICATIONS
Typical 3-wire application with an input signal referenced to ground
Figure 7 shows a 3-wire application in which AM460 amplifies and converts a positive voltage signal refer-
enced to ground. The unused blocks (e.g. OP2) have been set to defined operating points. Alternatively, these
function groups can also be used here (e.g. to supply external components).
In this particular application, using Equations 1 and 2 output voltage VOUT is calculated as:
R
1
VOUT = GV VINP with GV = GGAIN GOP = 1+
⋅ 2.2
(14)
R2
For output current IOUT the following applies according to Equation 3:
GI
R1
R2
IOUT =VINP
⋅
+ ISET with GI = GGAIN =1+
and ISET = 0
8R0
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Industrial Converter and Protector IC
AM460
3-wire connection
C1
VS
ISET = 0
16
15
1
13
AM460
11
I
R0
2
3
10
9
Voltage Reference
OP2
VBG
V
8
T1
VINP
D1
VOUT
OP1
12
OP3
6
7
14
5
4
R5
IOUT
Single-ended
input voltage
R1
R2
RL
Ground
Connections setting unused function blocks to a defined operating point
Figure 7: Typical application for input signals referenced to ground
Example 3:
To obtain a signal of VINP = 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 0...20mA (i.e. ISET = 0 ⇒ SET = GND) and the output voltage one of
0...10V.
Using Equation 14 the output voltage is defined as follows:
R1
R2
R1
VOUT
10V
VOUT =VINP ⋅ 1+
⋅ 2.2 ⇒
=
−1=
−1≈ 3.55
R2 2.2 ⋅VINP
2.2 ⋅1V
R1
i.e. GGAIN = 1+
= 4.55
R2
The following then applies to the output current:
GI
GGAIN
GGAIN
4.55
8⋅ 20mA
IOUT =VINP
⋅
+ ISET =VINP
⋅
⇒
R0 =VINP
⋅
=1V
≈ 28.44Ω
8R0
8R0
8IOUT
Observing the boundary conditions, the following values are obtained for the external components:
R0 ≈ 28.44Ω
R5 = 39Ω
R1 ≈ 35.5kΩ
RL = 0...600Ω
R2 = 10kΩ
C1 = 2.2µF
analog microelectronics
April 2003
13/18
Industrial Converter and Protector IC
AM460
Typical 2-wire application with an input signal referenced to ground
In 2-wire operation (cf. Figure 8) 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 re-
sistor RL which connects current output IOUT to the system ground.
For output current IOUT the following applies according to Equation 3:
GI
R1
R2
VREF
R4
IOUT = VINP
⋅
+ ISET with GI = GGAIN =1+
and ISET
=
⋅
8R0
2R0 R3 + R4
Example 4:
To obtain a signal of VINP = 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.
GI
GGAIN
IOUT =VINP
⋅
+ ISET =VINP
⋅
+ 4mA
8R0
8R0
With R0 = 27Ω Equation 7 produces the following:
R3
VREF
5V
=
−1=
−1≈ 22.15
R4 2R0 ISET
2⋅27Ω⋅4mA
and thus the following value for the gain to be set:
C1
R3
R4
VS
C2
16
15
1
13
AM460
R0
11
10
9
I
2
3
Voltage Reference
OP2
VBG
V
8
T1
D1
VINP
OP1
12
2-wire
connection
OP3
6
7
14
5
4
R5
IOUT
Single-ended
input voltage
R1
IC ground: GND
System ground: Ground
Different
potentials!
R2
RL
}
GND
Ground
Connections setting unused function blocks to a defined operating point
Figure 8: Typical 2-wire application for input signals referenced to ground
analog microelectronics
April 2003
14/18
Industrial Converter and Protector IC
AM460
IOUT max − I
16mA
1V
R1
R2
GGAIN = 8R0
SET = 8⋅ 27Ω ⋅
= 3.456
⇒
= 3.456 −1 = 2.456
VINP
Observing the boundary conditions, the following values are obtained for the external components:
R1 ≈ 24.56kΩ
R0 = 27Ω
R2 = 10kΩ
R5 = 39Ω
R3 ≈ 44.3kΩ
RL = 0...600Ω
R4 = 2kΩ
C1 = 2.2µF
C2 = 100nF
analog microelectronics
April 2003
15/18
Industrial Converter and Protector IC
AM460
BLOCK DIAGRAM AND PINOUT
VREF
VSET
SET
CVREF
1
16
15
13
AM460
CVSET
INP
11
10
9
I
RS+
2
3
Voltage Reference
OP2
VCC
RS-
VBG
V
8
IOUT
OP1
12
OP3
VOUT
5
6
4
7
14
GND
INN
OUTAD
INDAI INDAV
Figure 9: Block diagram of AM460
PIN
NAME
EXPLANATION
CVREF
CVSET
INP
SET
16
15
14
13
12
11
10
9
1
2
1
2
CVREF
CVSET
INP
Current/Voltage reference
Current/Voltage reference set
Positive input
VREF
GND
VSET
VOUT
RS+
3
3
4
5
6
7
8
4
INN
Negative input
INN
5
OUTAD System amplification output
OUTAD
INDAI
INDAV
IOUT
6
INDAI
INDAV
IOUT
RS-
Current output stage input
Voltage output stage input
Current output
7
8
VCC
RS−
9
Sensing resistor -
10
11
12
13
14
15
16
VCC
Supply voltage
RS+
Sensing resistor +
Figure 10: Pinout
VOUT
VSET
GND
VREF
SET
Voltage output
Reference voltage source set
IC ground
Reference voltage source output
Output offset current set
Table 1: AM460 pinout
analog microelectronics
April 2003
16/18
Industrial Converter and Protector IC
AM460
EXAMPLES OF POSSIBLE APPLICATIONS
•
Conditioning signals referenced to ground (protected output stage, impedance converter etc.)
Protection agains
short-circuiting and
reverse polarity
6...35V
0/4...20mA
VIN = 0...1, 0...5V
others
AM460
0...5/10V
Figure 11: Application for input signals referenced to ground (pro-
tected output stage, impedance converter etc.)
•
Complex configuration as a peripheral processor IC
Protection agains
short-circuiting and
reverse polarity
6...35V
VCVREF = 3.3V
VREF = 5V
0/4...20mA
D
AM460
µP
A
0...5/10V
Figure 12: Complex configuration as a peripheral processor IC
•
Conversion of a 0.5...4.5V sensor signal
Protection agains
short-circuiting and
reverse polarity
6...35V
VREF = 5V
4...20mA
VOUT = 0.5...4.5V
Sensor
AM460
1...6V
Figure 13: Conversion of a 0.5...4.5V sensor signal
analog microelectronics
April 2003
17/18
Industrial Converter and Protector IC
AM460
DELIVERY
The AM460 converter and protector IC is available as the following packages:
• DIP16
• SO16(n) (maximum power dissipation PD = 300mW)
• Dice on 5" blue foil
FURTHER READING
[1] The Frame ASIC concept: http://www.Frame-ASIC.de/
[2] The Analog Microelectronics GmbH website: http://www.analogmicro.de/
NOTES
Analog Microelectronics reserves the right to make amendments to any dimensions, technical data or other information herein without further notice.
analog microelectronics
April 2003
18/18
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