User Guide
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Revision 1.1
2021-03-21
EVAL-M3-302F User Guide
iMOTION™ Modular Application Design Kit
Hardware description of EVAL-M3-302F
6.2.3
PFC current feedback configuration
Figure 19 depicts IPFC- 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 19
The PFC current feedback circuit for EVAL-M3-302F evaluation board
Based on the principle of Kirchhoff's voltage law,
𝑉
4
≈ 𝑉
3
≈
(
𝑉
𝐷𝐷
+ 𝐼
𝑠ℎ
∗ 𝑅
𝑠ℎ
)
∗
𝑅
18
𝑅
17
+ 𝑅
18
− 𝐼
𝑠ℎ
∗ 𝑅
𝑠ℎ
=
𝑅
18
𝑅
17
+ 𝑅
18
𝑉
𝐷𝐷
−
𝑅
17
𝑅
17
+ 𝑅
18
𝑅
𝑠ℎ
∗ 𝐼
𝑠ℎ
𝐶𝑢𝑟𝑟𝑒𝑛𝑡 𝑖𝑛𝑝𝑢𝑡 =
𝑅
17
𝑅
17
+ 𝑅
18
𝑅
𝑠ℎ
=
12
13
𝑅
𝑠ℎ
Based on this calculation, and the R
sh
in EVAL-M3-CM615PN is 30 m
Ω
, the current input for the MADK
combination of EVAL-M3-302F and EVAL-M3-CM615PN is 27.69 mV/A. Please use the same procedure to
calculate the current input for other combinations of MADK boards, and enter it into MCEWizard.
Figure 20
The PFCTRIPREF circuit on the EVAL-M3-302F evaluation board
The PFC’s overcurrent protection circuit is shown in Figure 19 and Figure 20.
