User Guide
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Revision 1.0
2020-05-22
EVAL-M3-302F User Guide
iMOTION™ Modular Application Design Kit
Hardware description of EVAL-M3-302F
The current input value is a product of the shunt resistance in milliohms and gain of external current sense
amplifier as shown in Figure 12.
Figure 12
Current shunt feedback and sample timing
Figure 13 depicts IU+ current feedback sensing circuity on EVAL-M3-302F evaluation board. Please note that the
default external amplification gain is less than 1 for current sense in this evaluation board.
Figure 13
The current feedback section on the EVAL-M3-302F evaluation board
Based on the principle of Kirchhoff's voltage law,
𝑉
2
≈ 𝑉
1
≈
(
𝑉
𝐷𝐷
− 𝐼
𝑠ℎ
∗ 𝑅
𝑠ℎ
)
∗
𝑅
23
𝑅
22
+ 𝑅
23
+ 𝐼
𝑠ℎ
∗ 𝑅
𝑠ℎ
=
𝑅
23
𝑅
22
+ 𝑅
23
𝑉
𝐷𝐷
+
𝑅
22
𝑅
22
+ 𝑅
23
𝑅
𝑠ℎ
∗ 𝐼
𝑠ℎ
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑖𝑛𝑝𝑢𝑡 =
𝑅
22
𝑅
22
+ 𝑅
23
𝑅
𝑠ℎ
=
5
6
𝑅
𝑠ℎ
Based on this calculation, and the R
sh
in EVAL-M3-CM615PN is 30 mΩ, the current input for the MADK
combination of EVAL-M3-302F and EVAL-M3-CM615PN is 25 mV/A. Please use same procedure to calculate the
current input for other combinations of MADK boards and enter it into MCEWizard.
