Test Results
15
SLVUBC9 – December 2017
Copyright © 2017, Texas Instruments Incorporated
TPS23523EVM-863 Evaluation Module
The INA226 measures the voltage on the V
BUS
pin, which is tied to V
IN
through a resistor divider.
illustrates a simplified diagram. Note that there is an 830-k
Ω
resistor that must be accounted for. For this
EVM, R
1
= 100 k
Ω
and R
2
= 5.49 k
Ω
. To compute V
IN, MEAS
from V
BUS, MEAS
measured, first compute R
BOT
and then compute the resistor divider ration as follows:
(1)
(2)
Figure 46. Effective Circuit for Voltage Monitoring
shows the current monitoring accuracy results. The VSNS was measured between TP19 and
TP7, which is before the RC filter going into the IC. The results show that the sense resistor is responsible
for the majority of the error and roughly equals 2%. Note that on this PCB, a simple two-terminal, 2-m
Ω
resistor was used. If greater accuracy is desired, 4-terminal resistors or higher-accuracy resistors can be
used. Note that the
IC + Other Error
sources are 0.5% at 1 A and down to 0.1% at 10 A.
Table 6. TPS23523 EVM, Measured Current Monitoring Accuracy
IIN,
ACT
VSNS, ACT (mV)
VSNS, MEAS (mV)
IIN, MEAS (A)
RSNS, ERROR
IC + Other Error
Total Error
1
2.035
2.025
1.0125
1.8%
-0.49%
1.25%
2
4.08
4.07
2.035
1.9%
-0.25%
1.65%
3
6.125
6.11
3.055
2.1%
-0.25%
1.83%%
4
8.17
8.153
4.0765
2.1%
-0.21%
1.91%
5
10.21
10.19
5.095
2.1%
-0.20%
1.90%
6
12.22
12.19
6.095
1.8%
-0.25%
1.58%
7
14.27
14.25
7.125
1.9%
-0.14%
1.79%
8
16.34
16.32
8.16
2.1%
-0.12%
2.00%
9
18.38
18.36
9.18
2.1%
-0.11%
2.00%
10
20.4
20.38
10.19
2.0%
-0.10%
13.22%
