Precision amplifier for bridge circuits
AM467
EXTERNAL COMPONENTS
Parameter
Output Capacitor
Compensation Capacitor
Stabilization Capacitor (optional)
EMV Protection Capacitor (optional)
Load Resistor to GND, to V
CC
Symbol
C
1
C
2
C
3
C
4
R
L
Vout = max. Vout
20
Conditions
Min.
1
100
100
470
Typ.
Max.
5
Unit
nF
pF
nF
pF
kΩ
Table 2:
External components of the calibration network
Recommended:
ceramic capacitors
DESCRIPTION OF FUNCTIONS
AM457 is an integrated precision circuit for the signal amplification of high-impedance signal
sources and for the signal conditioning of sensor bridges with low sensitivity, particularly for
ceramic and DMS sensing elements or GMR measuring cells.
The IC generates a rail-to-rail output signal of 0.2 V to Vcc-0.2 V. The amplification and offset can
be set independently of one another using external resistors. Through the suitable dimensioning of
external resistors in particular an output voltage of 0.5...4.5 V can also be provided. As these values
are standard the following description refers to this output voltage.
AM467 works on the principle of ratiometry with a supply voltage of 5 V ±5%. The IC is
distinguished by its low offset and extremely low thermal offset drift across a wide temperature
range, enabling it to be classified as a precision amplifier.
The sink and source output stage is protected internally against short-circuiting.
The AM467 design incorporates protective measures against interference from EMV and ESD
using suitable semiconductor structures.
With the exception of the additional operational amplifier and the diagnostic unit the IC is
compatible with AM457. AM467 thus has a smaller chip surface and a lower power consumption.
AM467 can be used as an autonomous signal conditioning IC or as a preamplifier for an A/D
converter for back-end digitization.
EXAMPLE APPLICATION
AM457 is suitable for the amplification of resistance networks connected up as a Wheatstone
bridge with four resistors and which have a low sensitivity, such as 1.0 to 3.5 mV/V with a 5 V
supply, for example. By way of example a sensor application is described herein which is
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
info@analogmicro.de
February 2007
5/9
Rev. 1.0
AME [ ANALOG MICROELECTRONICS ]
