DSD: Delta Sigma Demodulator

DSD: Delta SigmaDemodulatorXMC™ microcontrollersSeptember 2016

Agenda

Overview

Key feature: adjustable CIC filter

Key feature: parallel auxiliary CIC filter with boundaries

Key feature: resolver support

System integration

Application examples

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3

4

5

6

Copyright © Infineon Technologies AG 2016. All rights reserved. 2

Agenda

Overview




System integration


1

2

3

4

5

6


Highlights

XMC™4000 provides four delta sigmademodulator channels and one carriergenerator.

It is tailored to demodulate a bitstream

from an external delta sigma modulator.

This can be used for isolated current/voltagemeasurement and for sensor interfaces.

DSDDelta Sigma Demodulator

› External sigma delta modulator can beconnected directly to XMC™ without ASIC

› Simultaneous overcurrent/voltagedetection with programmable boundaryinterrupt

› Resolver excitation and feedback readingwith full hardware support saving externalASIC

› Adjustable CIC filter

› Parallel auxiliary CIC filter withboundaries

› Resolver support

Customer benefitsKey feature

Main Filter

Fast Filter

Integrator

Comperator

Pin

Pin

Pin

Pin

CarrierGenerator

Rectify

4 DSD Channel

1 Carrier Generator


Agenda

Overview




System integration


1

2

3

4

5

6


DSDAdjustable CIC filter (1/2)

› Each DSD channel supports 4 types of CIC filters:

– CIC, CIC², CIC³, CIC F

› The decimation factor can be selected independent from other channels:

– 4 to 256

Configurable filter

Filter type:

Decimation:

COMB1-3, F

4-256

Clock rate: 3.75–60 MHz@120MHz CPUOn- chip hardware

Off- chip hardware

Legend:

DSDDSMSensor CPU

Analoginput

clock

Bit stream

Multiplebit value


DSDAdjustable CIC filter (2/2)

*1

6,4

3,2

1112,8

6,4

13

25,6

12,815

Responsetime[μs]

Update Time[μs]

Maximumoutput[Bit]

Decimation factor comparison

D: 32 D: 64 D: 128

*2

*1: Sample frequency 10 Mhz, decimation factor: 32*2: Sample frequency 10 MHz, filter type: CIC³

3,2

6,4

9,6

6,66

11

16

11,1

CIC CIC² CIC³ CIC F

Filter comparison

Responsetime[μs]

Maximum output[Bit]

Response time

Response time


Agenda

Overview




System integration


1

2

3

4

5

6


DSDParallel auxiliary filter with boundaries

› Each DSD channel has an auxiliary CIC filter

– 4 filter types can be selected (CIC, CIC², CIC³, CIC F)

– Decimation factor between 4 to 32

– Hardware boundary check with interrupt to reduce CPU load

9Copyright © Infineon Technologies AG 2016. All rights reserved.

Main filter

Fast filter Comperator

Currentanalysis

Interruptovercurrent

reaction

DSM

Main filter

Legend:

On- chip hardware

Off- chip hardware

Software

Advantages

COMB3Filter type:

Decimation:

Response time:

Update time:

Maximum output:

64

9.6 µs

3.2 µs

16-bit

Fast filter

COMB2Filter type:

Decimation:

Maximum output: 9-bit

16

Response time:

Update time:

3.2 µs

1.6 µs

Agenda

Overview




System integration


1

2

3

4

5

6


DSDResolver support (1/6)

› Hardware for resolver support

– Carrier generator

– Rectify (part of DSD channel)

– Integration (part of DSD channel)


Carriergenerator

DSDchannel

DSDchannel

Amplifier

Legend:

DSMAngle

calculation

On- chip hardware

Off- chip hardware

Software

Isola

tion

Primary coil

Cosine coil

Sine coil

DSDResolver support (2/6) – carrier generator

› Carrier generator

– Hardware generated waveform without CPU load

– Waveform: sine, triangle and rectangle

– Output frequency between 3,7 kHz and 58,6 kHz *

– Signed signal for rectification


* Peripheral clock 120 MHz

Carrier generator

Waveform:

Outputfrequency:

3.7 – 58 kHz@120 MHz CPU

ResolverCarrier

generatorAmplifier

0° 90° 180°

0° 90° 180°

PWM

Signed signal

Cosinecoil

Primarycoil

Sinecoil

DSDResolver support (3/6) – rectifier

› Rectifier

– Hardware rectifier for carrier cancellation

– Hardware sign delay capture

– Adjustable sign delay compensation

0° 90° 180°

Rectify

Filteroutput:

Signsignal :

Rectifieroutput:

Main filter Integrator

Legend:

On- chip hardware

On- chip hardwarein fokus


DSDResolver support (4/6) – rectifier

› Sign delay compensation Angle calculation resolution

depending on integration result

With delay With delaycompensation

Resultsine coil

Anglecalculation

Timing carriergenerator

Carriergenerator

DSD

Amplifier

DSMAngle

calculationResolver

232

Timing DSD


DSDResolver support (5/6) – integrator

› Integrator

– Hardware integrator

– Adjustable integration window

– Continuous and trigger mode

3 half waves

Period

Half wave

time

resolution

Half wave

Period

3 half waves


DSDResolver support (6/6) – overview

› 1

› 2

› 3

Legend:1. Signal after COMB filter2. Signal after rectify3. Signal after integration


Agenda

Overview




System integration


1

2

3

4

5

6


DSDSystem integration

› Target applications

– Motor control

– Isolated current measurement

– Isolated voltage measurement

DSD is connected to GPIO, ERU, NVIC and DMA.

In many applications it is mandatory tosynchronize the carrier generator, the DSD andthe external DSM. Therefore the DSD hasimplemented the carrier generator and providesa clock via GPIO for the DSM.

The connection to the ERU enables a various oftrigger sources.

XMC™4400 XMC™4500XMC™4200

● ●XMC™4100

DSD

NVIC

DMA

ERU

Carriergenerator

GPIO

GPIO

GPIO


Agenda

Overview




System integration


1

2

3

4

5

6


Application exampleIsolated current measurement

In brief

In many high voltage applications an isolation isneeded. The DSD offers the possibility for an isolationof the XMC™ MCU against the high voltage.

All three currents aremeasured in phase witha DSM. The bits streamallows a cost-efficientdigital isolation. Themicrocontroller isisolated against thehigh voltage part. Alsoa benefit is the goodsignal to noise ratiobased on theoversampling.

OverviewIsolated

DSDchannel

CCU8

CCU8Bridge

DSDchannel

DSDchannel

DSM

Bri

dge

dri

ver

Isola

tion

Motorcontrol

Angle

calc

ula

tion

Legend:

On- chip hardware

Off- chip hardware

Software


Application exampleRotary angle detection via resolver

Overview

In brief

For a resolver analysis a data processing isnecessary. The XMC™ offers many of thesecalculation in hardware.

The angle coming as sineand cosine analog valuefrom resolver are multipliedby the carrier signal. TheXMC™ DSD provideshardware for carriercancelation and datacalibration.

In addition on high voltageboards the resolver has tobe isolated against the highvoltage. In this case theXMC™ is on the high voltageside and the resolver isisolated.


Isolated

CCU8

CCU8Bridge

Amplifier

Bridge

driver

Motorcontrol

Carriergenerator

DSDchannel

DSDchannel

DSM

ADC

Amplifier

Isola

tion

Legend:

On- chip hardware

Off- chip hardware

Software

Cosinecoil

Sine coil

Primarycoil

General information

› For latest updates, please refer to:

www.infineon.com/xmc4000

› For support:

http://www.infineonforums.com/forums/8-XMC-Forum


http://www.infineon.com/xmc1000

http://www.infineonforums.com/forums/8-XMC-Forum

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DSD: Delta Sigma Demodulator

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