AMC1204_15 Datasheet, PDF (22/37 Pages) Texas Instruments – AMC1204 20-MHz, Second-Order, Isolated Delta-Sigma Modulator

AMC1204, AMC1204B
SBAS512E – APRIL 2011 – REVISED SEPTEMBER 2015
www.ti.com
8.2 Typical Application
8.2.1 Frequency Inverter Application
Because of their high AC and DC performance, isolated ΔΣ modulators are being widely used in new generation
frequency inverter designs. Frequency inverters are critical parts of industrial motor drives, photovoltaic inverters
(string and central inverters), uninterruptible power supplies (UPS), electrical and hybrid vehicles, and other
industrial applications. The input structure of the AMC1204 is optimized for use with low-impedance shunt
resistors and is therefore tailored for isolated current sensing using shunts.
DC link
Gate Driver
Gate Driver
Gate Driver
RSHUNT
RSHUNT
RSHUNT
Gate Driver
5.0 V
AMC1204
AVDD DVDD
AINP DOUT
AINN CLKIN
AGND DGND
3.3 V
Gate Driver
5.0 V
AMC1204
AVDD DVDD
AINP DOUT
AINN CLKIN
AGND DGND
3.3 V
Gate Driver
5.0 V
AMC1204
AVDD DVDD
AINP DOUT
AINN CLKIN
AGND DGND
3.3 V
5.0 V
AMC1204
AVDD DVDD
AINP DOUT
AINN CLKIN
AGND DGND
3.3 V
TMS320F2837x
SD-D1
SD-C1
SD-D2
SD-C2
SD-D3
SD-C3
SD-D4
SD-C4
Figure 48. AMC1204 in a Frequency Inverter Application
8.2.1.1 Design Requirements
Figure 48 shows a diagram of the AMC1204 in a typical frequency inverter. When the inverter stage is part of a
motor drive system, measurement of the motor phase current is done via the shunt resistors (R_SHUNT).
Depending on the system design, either all three or only two phase currents are sensed.
In this example, an additional AMC1204 is used for isolated sensing of the DC link voltage. This high DC link
voltage is reduced using a high-impedance resistive divider before being sensed by the AMC1204 across a
smaller resistor. It is important to consider that the value of the resistor in the voltage divider can potentially
degrade the performance of the measurement. Such phenomenon is described in the Isolated Voltage Sensing
section.
8.2.1.2 Detailed Design Procedure
For modulator output bit-stream filtering, TI recommends a device from TI's TMS320F28x7x family of MCUs. This
family supports up to eight channels of dedicated hardwired filter structures that significantly simplify system level
design by offering two filtering paths per channel: one providing high accuracy results for the control loop and
one fast response path for overcurrent detection.
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