Datasheet

Current Measurement
Current Shunt Measurement
Floating
PowerSupply
Gate
Drive
Circuit
Gate
Drive
Circuit
R
1
R
27W
2
D
5.1V
1
C
0.1 Fm
1
HV+
R
SENSE
Power
Supply
HV-
C
0.1 F
2
m
M0
V +
IN
V -
IN
M1
V
DD
MCLK
MDAT
GND
ADS1203 ISO721
V
CC1
IN
V
CC1
GND1
V
CC2
GND2
OUT
GND2
5.0V
0.1 Fm
BVDD CVDD DVDD
INx
CLK
32MHz
GNDAGND
AMC1210
AMC1210
SBAS372D – APRIL 2006 – REVISED MAY 2009 .............................................................................................................................................................. www.ti.com
The AMC1210 can also serve as a stand-alone digital filter for modulator signals coming from current-shunt
measurements. Performing the digital filtering in the AMC1210 frees resources in the microcontroller or DSP
from having to perform the constant processing required to ensure nonstop monitoring of the motor currents. For
example, a common application may require both real-time monitoring of motor over-current situations as well as
constant high-resolution data to monitor motor speed. A single filter module in the AMC1210 can perform both
high-resolution data filtering as well as provide a fast response, programmable over-current interrupt flag.
Current shunt measurements require a small differential signal range ( < 1V) and high voltage isolation. This
configuration can be incorporated with the AMC1210 with a delta-sigma modulator on the shunt side and a digital
isolation device providing common-mode voltage isolation; see Figure 26 .
Figure 26. Application Diagram — Isolated Current Measurement
The AMC1210 offers two different ways of current measurement from a modulator. For stable currents, using the
modulator along with the Sinc
3
filter offers up to 18.9 effective bits of resolution at an OSR = 256 at a modulator
rate of 10MHz.
For unstable currents, the integrator can be used in place of (or in combination with) the digital filter to give an
average filter value. When used with the time measurement unit, the integrator provides additional filtering
(averaging). This averaging is achieved by using the timer in Mode 2 and the integrator in Sample-and-Hold
Mode. On a rising edge of the selected Sample-and-Hold signal, both the integrator and the timer store their
current values, reset and begin again. These values, once read from their respective registers, are used to
calculate the average value by simply dividing the integrator value by the timer value. Figure 27 illustrates this
functionality.
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Product Folder Link(s): AMC1210