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Application Report

Passing CISPR-25 Radiated and Conduction
Emissions Using the TPS65033x-Q1

Gerard CopelandPower Products
ABSTRACTThis application report provides a summary of the CISPR-25 Conducted and Radiated Emissions test results
using the TPS650330-Q1 Power Management Integrated Circuit (PMIC) for automotive camera applications.
This device is capable of passing CISPR-25 and other automotive electromagnetic-compatibility (EMC) test
specifications. Similar results can be achieved using other devices in the TPS65033x-Q1 family. Due to anadvanced spread spectrum clocking (SSC) feature, these devices can pass EMC tests without needing a fullyoptimized layout, allowing for more flexible component placement and routing as required by the cameraapplication.

Table of Contents
1 Introduction.............................................................................................................................................................................22 Spread Spectrum.................................................................................................................................................................... 2
3 Schematics and Printed Circuit Board (PCB) Description..................................................................................................34 Design Considerations...........................................................................................................................................................65 Summary................................................................................................................................................................................. 8
6 Conducted and Radiated Emission Average and Peak Plots.............................................................................................97 References............................................................................................................................................................................ 13
8 Revision History................................................................................................................................................................... 14

List of Figures
Figure 2-1. Spread Bands of Harmonics in Modulated Square Signals 2 .................................................................................. 2Figure 2-2. TPS650330-Q1 SSC Conducted Emission Comparison...........................................................................................3Figure 3-1. CISPR-25 EMC Test Setup....................................................................................................................................... 3Figure 3-2. DUT Schematics........................................................................................................................................................4Figure 3-3. Printed Circuit Board Top Layer................................................................................................................................ 6Figure 3-4. Printed Circuit Board Layer 2 (Ground Plane)...........................................................................................................6Figure 3-5. Printed Circuit Board Layer 3.................................................................................................................................... 6Figure 3-6. Printed Circuit Board Layer 4.................................................................................................................................... 6Figure 3-7. Printed Circuit Board Layer 5 (Ground Plane)...........................................................................................................6Figure 3-8. Printed Circuit Board Layer 6.................................................................................................................................... 6Figure 3-9. Printed Circuit Board Layer 7 (Ground Plane)...........................................................................................................6Figure 3-10. Printed Circuit Board Bottom Layer.........................................................................................................................6Figure 4-1. Bottom Layer (PMIC Layer)- Zoom........................................................................................................................... 7Figure 4-2. Top Layer - Zoom...................................................................................................................................................... 8Figure 6-1. Conducted Emissions 0.15 MHz to 108 MHz............................................................................................................9Figure 6-2. Radiated Emissions - Rod Antenna 0.15 MHz to 30 MHz.......................................................................................10Figure 6-3. Radiated Emissions - Bicon Horizontal Antenna 30 MHz to 200 MHz.................................................................... 10Figure 6-4. Radiated Emissions - Bicon Vertical Antenna 30 MHz to 200 MHz.........................................................................11Figure 6-5. Radiated Emissions - Logarithmic Horizontal Antenna 200 MHz to 1000 MHz.......................................................11Figure 6-6. Radiated Emissions - Logarithmic Vertical Antenna 200 MHz to 1000 MHz...........................................................12

List of Tables
Table 3-1. Bill of Materials............................................................................................................................................................4SLVAEN0A – APRIL 2020 – REVISED OCTOBER 2020
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Trademarks

Table 5-1. Emissions Test Operating Conditions......................................................................................................................... 8Trademarks
All other trademarks are the property of their respective owners.

1 Introduction
This application report illustrates the EMI/EMC performance of the TPS650330-Q1 and relevant circuits in
automotive applications using example schematics and layout design. With this example, the TPS650330-Q1
and associated components pass the CISPR-25 1 conducted emission in the 0.15 MHz to 108 MHz frequency
range, and radiated emission in the 0.15 MHz to 1000 MHz frequency range.

2 Spread Spectrum
The TPS650330-Q1, TPS650331-Q1, TPS650332-Q1, and TPS650333-Q1 are a family of PMICs for camera
applications. Each device includes three step-down (buck) converters and one low dropout (LDO) regulator. The
three buck converters are capable of spread spectrum clocking (SSC), a feature that modulates the switchingfrequency of each converter to spread the power that can cause EMI. This internal modulation spreads theoperating frequency from 2.0 MHz to 2.5 MHz with a center frequency of 2.25 MHz and can be enabled or
disabled with a single register write through I2C communication.
The goal of spread spectrum architecture is to spread out emitted RF energy over a larger frequency range.
Spreading the operating frequency of the buck converters results in a more continuous power spectra that islower in peak amplitude, as shown in Figure 2-1. This peak reduction is possible because the time integral of thecurve (the EMI energy emitted by the circuit) remains constant whether spread spectrum is enabled or disabled.

B = 2 × fm × (1 + mf ) = 2 × ( Dfc + fm )Bh = 2 × fm × (1 + mf × h )Figure 2-1. Spread Bands of Harmonics in Modulated Square Signals 2
Figure 2-2 compares the conducted emission performance with SSC enabled and disabled using theTPS650330-Q1 and the example layout discussed in this application report.

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Schematics and Printed Circuit Board (PCB) Description

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SSC Disabled
SSC Enabled
5040dB (PV)3020100-10-200.1

110100Frequency (MHz)

200D001

Figure 2-2. TPS650330-Q1 SSC Conducted Emission Comparison

3 Schematics and Printed Circuit Board (PCB) Description
This layout is derived from a compact camera module reference design. All non-power components have been
removed from the original design, and the remaining power solution was tested according to the CISPR-25
automotive specification. A power over coax (POC) filter is included on both ends of the harness (FPD-Link coaxcable) to replicate the expected EMI in a typical automotive camera application. The schematic and layout for thePOC filter on the receiver side are taken from the Automotive Camera PMIC Power Supply Reference Design
with Power Over Coax Filter reference design. The schematic and layout for the POC filter on the DUT-side isshown in Figure 3-2. As intended for a camera module reference design, the layout balances the tradeoffs
between PCB area and EMI performance. For example, some components for the low-voltage buck converters
are located on the layer opposite of the PMIC to minimize the total area occupied by the power solution. These
are less critical for EMI performance compared to the mid-voltage buck converter.

Figure 3-1. CISPR-25 EMC Test Setup

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Schematics and Printed Circuit Board (PCB) Description

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3.1 Schematics

Figure 3-2. DUT Schematics
Table 3-1. Bill of Materials

4ITEM

DESIGNATORQUANTITY

PART NUMBER

MANUFACTURER

DESCRIPTION

1!PCB1

1TIDA-020006

AnyPrinted Circuit Board

2C11CGA4J1X7R1E475M TDK Corporation
125AC

CAP, CERM, 4.7 µF,
25 V, ±20%, X7R,0805

3C21C1005X7R1E104K05 TDK Corporation
0BB

CAP, CERM, 0.1 µF,
25 V, ±10%, X7R,0402

4C3, C6

2

GRM21BZ71E106KE MuRata
15L

CAP, CERM, 10 µF,
25 V, ±10%, X7R,0805

5C41

GRM155R71E104KE MuRata
14D

CAP, CERM, 0.1 µF,
25 V, ±10%, X7R,0402

6C5, C8, C9 ,C44, C54 5

GRM188Z71A106MA MuRata
73DCAP, CERM, 10 µF,
10 V, ±20%, X7R,0603

7C40

CGA2B3X7R1H104M TDK050BB

CAP, CERM, 0.1 µF,
50 V, ±20%, X7R,
AEC-Q200 Grade 1,0402

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Schematics and Printed Circuit Board (PCB) Description

Table 3-1. Bill of Materials (continued)
ITEM

DESIGNATORQUANTITY

PART NUMBER

MANUFACTURER

DESCRIPTION

8C53, C56, C57, C584885012206026

Wurth Elektronik

CAP, CERM, 1 µF, 10V, ±10%, X7R, 0603

9H11CMT821

SunexLens holder, M12x0.5,11.2, centered

10J1159S10H-40ML5-Z

RosenbergerConnector, HF, 50 Ω,TH

11L11

TFM201610ALMA1R TDK
5MTAA

Inductor, Shielded,
Metal Composite, 1.5μH, 2.3 A, 0.11 Ω,
AEC-Q200 Grade 0,SMD

12L2, L3, L4

3

BLM18HE152SN1D

MuRataFerrite Bead, 1500 Ωat 100 MHz, 0.5 A,0603

13L51

LQH3NPZ100MJRL

MuRataInductor, Wirewound,Ferrite, 10 μH, 0.81A, 0.288 Ω, AECQ200 Grade 1, SMD

14L7, L82

TFM201610ALMA1R TDK0MTAA

Inductor, Shielded,Metal Composite, 1μH, 3.1 A, 0.06 Ω,
AEC-Q200 Grade 0,SMD

15R11

CRCW06034K02FKE Vishay-Dale
ARES, 4.02 k, 1%, 0.1W, 0603

16

R41

RC0603FR-0710KLRES, 10.0 k, 1%, 0.1W, 0603

17U1

1

TPS650330QRGEQ1 Texas Instruments

Automotive Camera
PMIC, RGE0024K(VQFN-24)

18

FID1, FID2, FID3,FID40N/A

N/A

Fiducial mark. Thereis nothing to buy ormount.

19R2, R3, R50

CRM2512FX-1R00ELF

Bourns

RES, 1.00, 1%, 2 W,
6.3x3.1 mm

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Schematics and Printed Circuit Board (PCB) Description

3.2 Board Layout

Figure 3-3. Printed Circuit Board Top Layer

Figure 3-4. Printed Circuit Board Layer 2 (GroundPlane)

Figure 3-5. Printed Circuit Board Layer 3

Figure 3-6. Printed Circuit Board Layer 4

Figure 3-7. Printed Circuit Board Layer 5 (GroundPlane)

Figure 3-8. Printed Circuit Board Layer 6

Figure 3-9. Printed Circuit Board Layer 7 (GroundPlane)

Figure 3-10. Printed Circuit Board Bottom Layer

4 Design Considerations
Automotive camera modules are typically as small as possible to support placement in remote regions of thevehicle. A designer may need to sacrifice some layout best practices in terms of conducted and radiatedemissions in order to meet stringent size constraints. The SSC feature of the TPS650330-Q1 allows for a suboptimal layout while still passing CISPR-25 emissions testing specifications.
Design considerations for this layout to reduce emissions include:
1. Minimize the loop area between the buck converter input capacitors and the thermal pad of the PMIC.
Smaller decoupling capacitors are placed closer to the device pins.
2. Minimize the loop area between the input capacitor, output inductor, and output capacitor of each buckconverter.

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3. The mid-voltage buck converter (Buck 1) has the highest priority for external component placement on thePCB.
4. The input capacitors for the low-voltage buck converters (Buck 2 and Buck 3) have the next highest
placement priority.
5. External components for the less EMI critical converter can be placed on the opposite side. In this case theless critical converter is Buck 2 because it has a higher output voltage (1.8 V).
6. Incorporate multiple solid ground planes with low impedance connections to the ground pours on the external
component layers.

Figure 4-1. Bottom Layer (PMIC Layer)- Zoom

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Summary

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Figure 4-2. Top Layer - Zoom

5 Summary
The TPS65033x-Q1 device family passes the CISPR25 Class-5 Conducted and Radiated Emissions required forautomotive applications. Passing results can be achieved using the integrated SSC feature combined with thedesign and layout considerations described in Section 3 and Section 4. The operating conditions are given inTable 5-1.
Table 5-1. Emissions Test Operating Conditions
REGULATOROUTPUT VOLTAGE (V)OUTPUT CURRENT (mA)

Buck 1

3.3770

Buck 21.8600

Buck 31.1600LDO

2.9150(1)(1)

The output current for Buck 1 is comprised of the input currents for Buck 2, Buck 3, and the LDO. There is no additional loading on the3.3 V rail.

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Conducted and Radiated Emission Average and Peak Plots

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6 Conducted and Radiated Emission Average and Peak Plots
Red Trace - PK
Blue Trace - AVG

Figure 6-1. Conducted Emissions 0.15 MHz to 108 MHz

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9Conducted and Radiated Emission Average and Peak Plots

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Figure 6-2. Radiated Emissions - Rod Antenna 0.15 MHz to 30 MHz

Figure 6-3. Radiated Emissions - Bicon Horizontal Antenna 30 MHz to 200 MHz

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Conducted and Radiated Emission Average and Peak Plots

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Figure 6-4. Radiated Emissions - Bicon Vertical Antenna 30 MHz to 200 MHz

Figure 6-5. Radiated Emissions - Logarithmic Horizontal Antenna 200 MHz to 1000 MHz

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Conducted and Radiated Emission Average and Peak Plots

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Figure 6-6. Radiated Emissions - Logarithmic Vertical Antenna 200 MHz to 1000 MHz

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References

7 References
1. CISPR, CISPR 25:2016, fourth edition (or EN 55025:2017), “Vehicles, boats and internal combustion engines– Radio disturbance characteristics – Limits and methods of measurement for the protection of on-board
receivers,” October 27, 2016.
2. "EMI Reduction in Switched Power Converters Using Frequency Modulation Techniques," in IEEE
TRANSACTIONS ON ELECTROMAGNETIC COMPATIBILITY, VOL. 4, NO. 3, AUGUST 2005, pp 569-576
by Josep Balcells, Alfonso Santolaria, Antonio Orlandi, David González, Javier Gago.

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Revision History

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8 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision * (April 2020) to Revision A (October 2020)
Page• Updated the numbering format for tables, figures, and cross-references throughout the document..................2• Updated Schematics and Printed Circuit Board (PCB) Description section....................................................... 3• Updated the Conducted and Radiated Emission Average and Peak Plots section............................................914Passing CISPR-25 Radiated and Conduction Emissions Using theSLVAEN0A – APRIL 2020 – REVISED OCTOBER 2020
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