1 M
:
1 M
:
LPF
AIN_0P
AIN_0GND
4.096V
AVDD = 5V
ADS8688
16 bit
ADC
C
0
R
0P
R
0M
Mu
lti
p
le
x
e
r
FPGA
SITARA
DDR
U
SB
Simple Capture Card
x
x
x
x
x
AD
S86
88
Ph
ase
Co
mp
ens
atio
n
GU
I
AGND
PGA
1 M
:
1 M
:
LPF
AIN_7P
AIN_7GND
C
7
R
7P
R
7M
PGA
Typical 50Hz
Sinewave from CT/PT
Balanced RC Filter
on Each Input
Angle (
)
¨
r1
¨
ri
(i = 1 to 7)
Ref. Input, V
R
Ch1 Input, V
1
Ch i Input, V
i
(i = 1 to 7)
¨
= Measured Phase Diff.
between channels
SBAS582C – JULY 2014 – REVISED APRIL 2015
9 Application and Implementation
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.
9.1 Application Information
The ADS8684 and ADS8688 devices are fully-integrated data acquisition systems based on a 16-bit SAR ADC.
The devices include an integrated analog front-end for each input channel and an integrated precision reference
with a buffer. As such, this device family does not require any additional external circuits for driving the reference
or analog input pins of the ADC.
9.2 Typical Applications
9.2.1 Phase-Compensated, 8-Channel, Multiplexed Data Acquisition System for Power Automation
Figure 95. 8-Channel, Multiplexed Data Acquisition System for Power Automation
9.2.1.1 Design Requirements
In modern power grids, accurately measuring the electrical parameters of the various areas of the power grid is
extremely critical. This measurement helps determine the operating status and running quality of the grid. Such
accurate measurements also help diagnose potential problems with the power network so that these problems
can be resolved quickly without having any significant service impact. The key electrical parameters include
amplitude, frequency, and phase, which are important for calculating the power factor, power quality, and other
parameters of the power system.
52
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