Texas Instruments TPSF12C1EVM-FILTER User Manual page 6

Hardware
L
LISN
N
LISN
V = V – V
DM 1 2
V = V + V
CM 1 2
LISNs are
2
bonded to the
GND plane
PE
Figure 2-2. EMI Measurement Setup for a Single-Phase System
The AC/DC regulator has internal high-dv/dt switching nodes that can capacitively couple CM noise to the
chassis. As such, verifying the Y-capactiors in the EMI filter are closely referenced to the chassis is imperative,
as illustrated in Figure 2-2. The Y-capacitors can then return the CM noise current back to the noise source in
a tight conduction loop. Otherwise, the noise current can flow in the reference ground plane back to the LISNs,
rendering the EMI filter less effective.
Figure 2-3 shows the recommended setup to evaluate the performance of the TPSF12C1 with a power stage
connected.
AC Mains
L
Dual
C
X1
LISN
2.2 F
GND
N
C C
Y1
LISNs bonded
2.2 nF 2.2 nF
to the Ground
Reference
Plane for EMI
measurement
Chassis (PE)
Figure 2-3. EVM Setup Schematic for High-Voltage Testing with AC/DC Power Stage Connected
A two-phase interleaved boost PFC topology in
and is drawn for illustrative purposes. The setup is essentially agnostic to regulator topology.
6 Active EMI Filter Evaluation Module for Single-Phase AC Power Systems
EMI
receiver
V
1
i /2
CM
+
V
+
DM
–
V
i /2
2
CM
V
CM loop
CM
i
–
CM
Ground Reference Plane
Filter board EVM with AEF
L
CM1
C
2.2 mH X2
2.2 F
C C
C
SEN2 SEN1 INJ
Y2
680 pF 680 pF 4.7 nF
Chassis
(PE)
To enable the IC, leave EN open or
connect it to VDD using a jumper
S2 S1 INJ VDD
J1
C
U1
VDD
NC IGND
TPSF12C1
R
D1A
VDD INJ
R
NC NC
SENSE1A COMP2
C
G1
C
G2
SENSE1B
COMP1
R
G
SENSE2A REFGND
SENSE2B EN
Figure 2-3
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Chassis
DM loop area
i
DM
EMI
filter
i
DM
Y caps
V
tied to
chassis
GND
CM loop area
L
CM2
C
2.2 mH X3
2.2 F
C
C
Y3
Y4
2.2 nF
2.2 nF
Chassis (PE)
EN
C
D3 R
D3
C
D1
D1
D
1
C
D2
R
D2
represents a typical single-phase AC/DC regulator
AC/DC
V
switching
OUT+
regulator Load
V
OUT–
(EMI source)
The load may
SW
be floating or
tied to chassis
GND for safety
Chassis bonded
to the GND plane
Interleaved boost PFC
Chassis-referred VDD bias supply = 12 V
= AC/DC regulator
= Dual LISN for EMI measurement
= Single-phase AEF IC
= Y-rated sense and inject capacitors
= 6-pin header
SLVUCQ2A – JULY 2023 – REVISED JULY 2023
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