AMC1203 Datasheet, PDF (13/23 Pages) Texas Instruments – 1-Bit, 10MHz, 2nd-Order, Isolated Delta-Sigma Modulator

AMC1203
www.ti.com
GENERAL DESCRIPTION
SBAS427 – FEBRUARY 2008
The AMC1203 is a single-channel, 2nd-order, CMOS,
delta-sigma modulator, designed for medium- to
high-resolution A/D conversions from dc to 39kHz
with an oversampling ratio (OSR) of 256. The isolated
output of the converter (MDAT) provides a stream of
digital ones and zeros. The time average of this serial
output is proportional to the analog input voltage.
The modulator shifts the quantization noise to high
frequencies; therefore, a low-pass digital filter should
be used at the output of the device to increase the
overall performance. This filter is also used to convert
from the 1-bit data stream at a high sampling rate into
a higher-bit data word at a lower rate (decimation). A
digital signal processor (DSP), microcontroller (µC) or
field programmable gate array (FPGA) can be used
to implement the filter. Another option is using a
suitable application-specific device, such as the
AMC1210, a four-channel digital sinc-filter. Figure 23
shows two AMC1203s and one ADS1205
(dual-channel, non-isolated modulator) connected to
an AMC1210, building the entire analog front-end of a
resolver-based motor-control application. For detailed
information on the ADS1205 and AMC1210, please
visit our home page at www.ti.com.
The overall performance (speed and accuracy)
depends on the selection of an appropriate OSR and
filter type. A higher OSR results in higher accuracy
while operating at lower refresh rate. Alternatively, a
lower OSR results in lower accuracy, but provides
data at a higher refresh rate. This system allows
flexibility with the digital filter design and is capable of
A/D conversion results that have a dynamic range
exceeding 95dB with OSR = 256.
Resolver
PWM1
PWM2
ADS1205
IN1
CLK1
IN2
ADS1205
Filter Module 1
Comparator
Filter
Input
Control
Sinc Filter/
Integrator
Time
Measurement
Current
Shunt
Resistor
CLK2
IN3
AMC1203 _CLK3
Current
Shunt
Resistor
AMC1203
IN4
CLK4
Filter
Module 2
Filter
Module 3
Filter
Module 4
Control Module
Signal
Generator
AMC1210
Interrupt
Unit
Register
Map
Interface
Module
CLK
RST
INT
ACK
CS
ALE
RD
WR
M0
M1
AD0
AD7
Figure 23. Example of a Resolver-Based Motor-Control Application
Copyright © 2008, Texas Instruments Incorporated
Product Folder Link(s): AMC1203
Submit Documentation Feedback
13