Precision amplifier for bridge circuits
AM457
GENERAL DESCRIPTION
FEATURES
• High input sensitivity
• Wide differential input voltage range
(±5...±100mV FS)
AM457 is a high-precision integrated amplifier which
has been developed to condition signals from small
differential input voltages within a range of a few
millivolts (±5 to ±100mV FS). The chief component
of the IC is a highly accurate, low-noise amplifier
circuit (AMP). An additional integrated operational
amplifier (OP) can be used to supply a sensing
element with current or record temperature for sensor
bridges powered by voltage, for example. The entire
system (sensing element plus amplifier) is monitored
by the integrated diagnostic unit which logs any
sensing element errors or defects, system
undervoltage, AMP overloads and excessive
temperature. The various function groups are not
mutually dependent on one another; the AMP can be
operated independently of the OP, for example. The
functionality of both component groups (AMP and
OP) is autonomous with regard to the diagnostic unit.
• Low offset
• Low offset drift
• Low input noise
• High CMRR: > 120dB
• Wide operating temperature range:
-40... +125°C
• Adjustable output voltage
• Rail-to-rail output stage:
V
OUT = 0.2V ... Vcc – 0.2V
• Sink/source output
• Single ratiometric supply: VCC = 5V
• Integrated current source: ≤ 2mA
• Integrated diagnostic unit
• Separate function groups
• Integrated EMV protective circuitry
• Short-circuit-proofing
AM457 is a combination of high-impedance precision
amplifier, additional OP and extensive diagnostic unit,
enabling a self-monitoring sensor system to be
assembled using very few components.
• Small-scale design
BLOCK DIAGRAM
AM457
8
VCC
VCC
OUTOP
7
OP
9k
1k
Diagnostic
unit
5
1
DIAG
OUT
IN+
Temp
AMP
_
6
INOP
4
GND
Figure 1: Block diagram
analog microelectronics
May 2005
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
Internet: www.analogmicro.de
Phone: +49 (0)6131/91 073 – 0
Fax: +49 (0)6131/91 073 – 30
Email: info@analogmicro.de
3/10
Rev. 2.2
AME [ ANALOG MICROELECTRONICS ]
