AMC1100_15 Datasheet, PDF (15/33 Pages) Texas Instruments – AMC1100 Fully-Differential Isolation Amplifier

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8 Application and Implementation
AMC1100
SBAS562A – APRIL 2012 – REVISED DECEMBER 2014
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The AMC1100 offers unique linearity, high input common-mode rejection, and low dc errors and drift. These
features make the AMC1100 a robust, high-performance isolation amplifier for industrial applications where users
and subsystems must be protected from high voltage potentials.
8.2 Typical Applications
8.2.1 The AMC1100 in Frequency Inverters
A typical operation for the AMC1100 is isolated current and voltage measurement in frequency inverter
applications (such as industrial motor drives, photovoltaic inverters, or uninterruptible power supplies), as
conceptually shown in Figure 33. Depending on the end application, only two or three phase currents are being
sensed.
DC Link
Gate Driver
Gate Driver
Gate Driver
RSHUNT
Gate Driver
AMC1100
VDD1 VDD2
GND1 GND2
VINP VOUTP
VINN VOUTN
Gate Driver
RSHUNT
RSHUNT
Gate Driver
AMC1100
VDD1 VDD2
GND1 GND2
VINP VOUTP
VINN VOUTN
AMC1100
VDD1 VDD2
GND1 GND2
VINP VOUTP
VINN VOUTN
AMC1100
VDD1 VDD2
GND1 GND2
VINP VOUTP
VINN VOUTN
ADC1P
ADC1N
ADC2P
ADC2N
ADC3P
ADC3N
ADC4P
ADC4N
Figure 33. Isolated Current and Voltage Sensing in Frequency Inverters
8.2.1.1 Design Requirements
Current measurement through the phase of a motor power line is done via the shunt resistor R_SHUNT (in a two-
terminal shunt); see Figure 34. For better performance, the differential signal is filtered using RC filters
(components R₂, R₃, and C₂). Optionally, C₃ and C₄ can be used to reduce charge dumping from the inputs. In
this case, care must be taken when choosing the quality of these capacitors; mismatch in values of these
capacitors leads to a common-mode error at the modulator input. Using NP0 capacitors is recommended, if
necessary.
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