Datasheet

Filter
Module2
ControlModule
Signal
Generator
Interrupt
Unit
Register
Map
Interface
Module
ADS1205
ADS1205
AMC1210
M0
M1
INT
Resolver
ACK
IN1
CLK1
PWM1
PWM2
CLK
IN2
CLK2
IN4
CLK4
AD0
AD7
ALE
CS
RST
RD
WR
AMC1203
Current
Shunt
Resistor
Input
Control
SincFilter/
Integrator
Time
Measurement
Comparator
Filter
FilterModule1
IN3
CLK3
Current
Shunt
Resistor
AMC1203
Filter
Module3
Filter
Module4
AMC1203
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SBAS427C FEBRUARY 2008 REVISED JUNE 2011
GENERAL DESCRIPTION
The AMC1203 is a single-channel, 2nd-order, CMOS, suitable application-specific device, such as the
delta-sigma modulator, designed for medium- to AMC1210, a four-channel digital sinc-filter. Figure 23
high-resolution A/D conversions from dc to 39kHz shows two AMC1203s and one ADS1205
with an oversampling ratio (OSR) of 256. The isolated (dual-channel, non-isolated modulator) connected to
output of the converter (MDAT) provides a stream of an AMC1210, building the entire analog front-end of a
digital ones and zeros. The time average of this serial resolver-based motor-control application. For detailed
output is proportional to the analog input voltage. information on the ADS1205 and AMC1210, please
visit our home page at www.ti.com.
The modulator shifts the quantization noise to high
frequencies; therefore, a low-pass digital filter should The overall performance (speed and accuracy)
be used at the output of the device to increase the depends on the selection of an appropriate OSR and
overall performance. This filter is also used to convert filter type. A higher OSR results in higher accuracy
from the 1-bit data stream at a high sampling rate into while operating at lower refresh rate. Alternatively, a
a higher-bit data word at a lower rate (decimation). A lower OSR results in lower accuracy, but provides
digital signal processor (DSP), microcontroller (μC) or data at a higher refresh rate. This system allows
field programmable gate array (FPGA) can be used flexibility with the digital filter design and is capable of
to implement the filter. Another option is using a A/D conversion results that have a dynamic range
exceeding 95dB with OSR = 256.
Figure 23. Example of a Resolver-Based Motor-Control Application
Copyright © 20082011, Texas Instruments Incorporated 13