Electromagnetic immunity design of smart power high side ...

(1) Infineon Technologies AG, 9500 Villach, Austria(2) Infineon Technologies AG, 85579 Neubiberg, Germany

EMCCompo 2009 7th International Workshop on Electromagnetic Compatibilityof Integrated Circuits

Toulouse, November 17th-19th 2009

Electromagnetic Immunity Design of Smart Power High Side Switches

Paolo Del Croce(1) , Bernd Deutschmann(2)

EMCCompo 2009Toulouse, 17th-19th November, 2009 Paolo del Croce, Bernd Deutschmann, 2009Paolo del Croce, Bernd Deutschmann, 2009--0909--16 16

Page 2

Overview

PROFETTM+ high side switches in Automotive

Electromagnetic immunity issues of high side switches

Setup for immunity measurement and simulation

A simple impedance control circuit to improve the immunity by design

Simulation and Measurement results


Page 3

PROFETTM+ Switches in Automotive

The continued increase of electric and electronic systems in modern cars leads to growing electromagnetic noise.

Integrated circuits often turn out to the source of interferenceproblems

Airbag

Electric Mirrors

Power Door

Power Seat

Window Lift

Lighting

SteeringEngine ControlBrake System

Electrical SunroofRelay replacementFuse replacement


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PROFET TM + Switches

Product description and block diagram

PROFET TM + switches combine power MOSFET (switch) and logic functionalitiesfor control, level conversion, protection and diagnostic in one single package.

In order to improve immunity, we have to know what is inside the package and which might be the main contributors to susceptibility problems.


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RF-interference - high side switch

RF interference

RFI problem description – Switch ON

ON


Page 6


RF interference

RFI problem description – Switch OFF

OFF


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RFI problem description – Signal at Vbat

V

t

Vbat

If the supply voltage goes below Vbat min. the full functionality can not be guaranteed anymore. If the supply voltage goes further below GND, substrate junctions get forward biased.

Vbat min.


Page 8

Impedance Control Concept

The voltage signal at Vbat mainly depends on the impedance that is present between Vbat and Gnd pin.

In order to keep the voltage swing at Vbat above Vbat minan “impedance reduction circuit” was integrated into the IC right between the Vbat and the GND pin.

This impedance reduction circuit should provide an undisturbed operation of the switch for a direct power injection of 37dBm over the frequency range from 1MHz to 110MHz.


Page 9

DPI measurement setup according to IEC 62132-4

Setup for EMI Measurement


Page 10

DPI simulation setup according to IEC 62132-4

Setup for EMI Simulation


Page 11

Impedance Reduction Circuit

Circuit topology

56789

101112131415

1 10 100 1000Frequency (MHz)

Impe

danc

e (O

hm)

Circuit impedance over frequency


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1.5MHz, 37dBm DPI simulation

Simulated Circuit Performance

Simulation test-bench Simulation results (Vbat, IGND)


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Simulated Product Behavior

1.5MHz, 37dBm DPI simulation

Simulation test-bench Simulation results (Vbat, IGND)


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Comparison Simulation vs. Measurement

Simulated Vbat during DPI Measured Vbat during DPI

1.5MHz, 37dBm DPI


Page 15

Effects on Load Isolation Performance

Simulated load monitoring voltage with and without impedance reduction circuit


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Immunity Test Results

Assessment of product robustness to DPI in off state

0

5

10

15

20

25

30

35

40

1 10 100 1000

f / MHz

dBm

OFF-Mode

max. test level

Device:Load:O-Mode:Coupling Point:Monitoring:Modulation:

IC under test3.3ΩOFFVbatOutCW


Page 17

Conclusion

An optimization methodology based on pin impedance control has been proposed and applied in the development of PROFET TM + switch products.

Simulation and measurement results have been compared to validate the approach.

Effectiveness of the methodology in the low frequency range has been confirmed.

Electromagnetic immunity design of smart power high side ...

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