HIGH FIDELITY CLASS AUDIO AMPLIFIER SOLUTION DESCRIPTION ZXCD1000

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HIGH FIDELITY CLASS AUDIO AMPLIFIER SOLUTION DESCRIPTION ZXCD1000

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ZXCD1000
HIGH FIDELITY CLASS AUDIO AMPLIFIER SOLUTION
DESCRIPTION ZXCD1000 provides complete control modulation functions heart high efficiency high performance Class switching audio amplifier solution. combination with custom output magnetics (ZXFN1000) Zetex HDMOS MOSFET devices, ZXCD1000 provides high performance Class audio amplifier with inherent benefits Class ZXCD1000 solution uses proprietary circuitry magnetic technology realise true benefits Class without traditional drawback poor distortion performance. combination circuit design, magnetic component choice layout essential realising these benefits. ZXCD1000 reference designs give output powers with typical open loop feedback) distortions less than 0.2% over entire audio frequency range full output power. This gives extremely linear system. addition minimum amount feedback (10dB) further reduces distortion figures give typical 1kHz. From acoustic point view, even more important than figures above, that residual distortion almost totally free crossover artifacts. This allows ZXCD1000 used true hi-fi
applications. This lack crossover distortion, sets ZXCD1000 solutions quite apart from most other presently available cost solutions, which general suffer from severe crossover distortion problems. FEATURES efficiency drive capability Noise Floor -115dB solution Flat response 20Hz 20kHz High gate drive capability 2200pF) Very 0.1% typical full power full band solution) Complete absence crossover artifacts output available sync multi-channel applications Available eQSOP package
APPLICATIONS Automotive audio systems Home Theatre Multimedia Wireless speakers Portable audio woofer systems Public Address system
Distortion Power
open loop 1kHz.
Output Power
plot shows Distortion Power into load 1kHz. This plot clearly demonstrates unequalled performance Zetex solution. Typical distortion 0.05% seen with better than 0.15% 10W. Truly world class performance. ISSUE -MARCH 2001
ZXCD1000
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage with respect Power Dissipation Operating Temperature Range Storage Temperature Range -40°C 70°C -50°C 85°C
Stresses beyond those listed under "Absolute Maximum Ratings" cause permanent damage device. These stress ratings only, functional operation device these other conditions beyond those indicated operational sections specifications implied. Exposure absolute maximum conditions extended periods affect device reliability.
ELECTRICAL CHARACTERISTICS TEST CONDITIONS (unless otherwise stated) 16V, 25°C
SYMBOL
PARAMETER
Operating Voltage Range Operating Quiescent Current
CONDITIONS
330pF 330pF load load Load Capacitance 2200pF Decoupling Decoupling 5.23 8.32 1.35k 1.35k 2.95 2.95 0.89
LIMITS
+/-25
UNITS
osc(tol) OutA/B OutA/B Drive 5V5tol 9VA/Btol Audio Triangle Audio Triangle
Switching Frequency Frequency Tolerance level output voltage High level output voltage Output Drive Capability (OUT Rise/Fall) Internal Rail Tolerance Internal Rail Tolerance Input Impedence Input Impedence Bias Level Bias Level Amplitude
8.75 1.8k 1.8k 1.05 5.77 9.18 2.3k 2.3k 3.25 3.25
Ohms Ohms
ISSUE MARCH 2001
ZXCD1000
number
Name
Audio Triangle Dist Triangle Audio Gnd2
Description
Audio Input Channel Triangle Input Channel Triangle Output connection External timing capacitor node switching frequency) Triangle Output (for slave ZXCD1000 stereo application) Triangle Input Channel Audio Input Channel Small Signal Channel Output drive external Bridge MOSFETs Power (for Output Drivers) Internal Supply Rail (Decouple with Cap) Input Supply (Max 18V) Internal Supply Rail (Decouple with Cap). Channel Output drive external Bridge MOSFETs Internal Supply Rail (Decouple with Cap)
Audio Triangle Dist Cosc Triangle Audio
Gnd2
Figure Connection Diagram
ISSUE -MARCH 2001
ZXCD1000
ZXCD1000 Class controller
functional block diagram ZXCD1000 shown Figure chip series regulators drop external supply (12V-18V) approximate (9VA/9VB) 5.5V (5V5) supplies required internal circuitry. triangular waveform generated chip brought OscA OscB outputs. frequency this ~200kHz) external capacitor (Cosc) chip resistor. triangular waveform must externally coupled back into ZXCD1000 TriangleA TriangleB inputs.
Triangle
coupling ensures symmetrical operation resulting minimal system offsets. TriangleA connected inputs comparator TriangleB connected inputs second comparator. other inputs these comparators connected AudioA AudioB inputs, which anti-phase signals externally derived from audio input. triangular wave order higher frequency than audio input (max 20kHz). outputs comparators toggle every time TriangleA/B (relatively slow) AudioA/B signals cross.
Triangle
Cosc
Dist
Oscillator Ramp
Generator
Buffers
Audio Audio
Internal
PreDriver Comp PreDriver Comp
Driver
Driver
Internal
Figure Functional Block Diagram
Gnd2
ISSUE MARCH 2001
ZXCD1000
Comparator Audio
Audio
Triangle
Triangle
Comparator (Duty Cycle 50%)
Figure
Triangle Audio
Figure
Triangle Audio
Comparator (Duty Cycle 75%)
Comparator (Duty Cycle 25%)
Figure
Figure
Figures 3a,3b,3c audio input Pulse Width Modulates comparator output.
With audio input signal applied, AudioA/B inputs biased mid-point triangular wave, duty cycle output comparators nominally 50%. AudioA/B signal ascends towards peak level, crossing points with (higher frequency) triangular wave also ascend. comparator monitoring these signals exhibits corresponding increase output duty cycle. Similarly, AudioA/B signal descends, duty cycle correspondingly reduced. Thus audio input Pulse Width Modulates comparator outputs. This principle illustrated Figures comparator outputs buffered used drive OutA OutB outputs. These turn drive speaker
load (with audio information contained signal) chip output bridge single stage filter network. ramp amplitude approximately AudioA, AudioB, TriangleA TriangleB inputs internally biased voltage approximately VCC/5. point level OscA OscB triangular outputs around triangular wave Cosc traverses between about 2.7Vand 3.8V dist exhibits roughly square wave from about 1.4V (The above voltages vary practice included guidance only).
ISSUE -MARCH 2001
ZXCD1000
ZXM64P03X
68µF 100n
ZXFN1000 NE5532
AUDIO INPUT 22µF
100n
100n 22µF 100µF
20uH
100n
100R 22µF
ZXM64N03X
ZXCD1000
Audio Triangle OscA Dist Cosc OscB Triangle Audio Gnd2
470n 470n
470n
INPUT
SPEAKER
****
270pF
100n 22µF 100µF
ZXM64P03X **** SPEAKER
NE5532
22µF
100n
ZXFN1000
20uH
22µF
100n
100n
ZXM64N03X
470n
470n
470n
78L12
ISSUE MARCH 2001
2200µF
100µF
100n
100n
22µF
optional components
Figure Zetex Class Mono Open Loop Solution
ZXCD1000
Class Mono Open Loop (Bridge Tied Load BTL) Solution Circuit Description
Proprietary circuit design high quality magnetics necessary yield high performance specified. Deviation from Zetex recommended solution could significantly degrade performance. speaker connected Bridge Tied Load (BTL). This means that both sides speaker driven from output bridge therefore neither side speaker connects ground. This allows maximum power delivered load, from given supply voltage. supply voltage this solution nominally 16V. schematic diagram solution shown Figure audio input coupled applied simple pass filter phase splitter built around NE5532 dual op-amp. these op-amps configured voltage follower other inverting amplifier. This produces phase inverted signals application ZXCD1000. op-amp outputs coupled into ZXCD1000 Audio Audio inputs simple pass filters (R16/C8 R15/C9). op-amps biased level approximately R12. Pulse Width Modulated (PWM) outputs, OutA OutB, which contain audio information, coupled restored before driving Zetex ZXM64P03X ZXM64N03X PMOS NMOS output bridge FET's. coupling C17, C18, C20. restoration provided D2(A1a)/R4, D1(A4a)/R2 D3(A1a)/R6, D4(A4a)/R9 components. This technique allows output stage supply voltage higher than high level OutA OutB outputs (approximately 8.5V), whilst still supplying almost full output voltage swing gates bridge FET's (thereby ensuring good turn on). This exploited yield higher power solutions with higher supply voltages this discussed later. resistor/diode combinations (R5/D2(A16), R3/D1(A46), R7/D3(A16) R8/D4(A46)) series with bridge gates, assist controlling switching bridge FET's. This design minimises shoot through currents whilst still achieving distortion characteristics system. purpose (ZXFN1000) inductors conjunction with output capacitors C23, C24, pass filter high frequency ISSUE -MARCH 2001 switching signal that comes from bridge. Thus lower frequency audio signal recovered available speakerA speakerB outputs across which speaker should connected. ZXFN1000 magnetics form integral part specially designed for, Zetex solution. optional components form Zobel network. applicability these depends upon application speaker characteristics. Suggested values 47nF ohms Efficiency following plots show measured efficiency Zetex solution various power levels into both loads. comparison, typical efficiency plotted class amplifier. They clearly demonstrate major efficiency benefits available from Zetex class solution.
ZXCD1000
Class Mono Open Loop (Bridge Tied Load BTL) Solution description Operation.
copper, bottom copper silk screen (top) shown Figures respectively, double sided implementation applications circuit Figure component listing given (Bill Materials) table. Gerber files this solution available from Zetex Plc. board operates from (nom.) supply which should applied underside supply decoupling capacitor C29. audio input speaker connections should made solder pads indicated Figure audio input should have maximum amplitude approximately pk-pk. diagnostic purposes, speaker outputs monitored single-endedly with respect ground with oscilloscope other instrument) desired. However remember that speaker connected Bridge Tied Load, therefore results obtained this manner, valid assessing performance. true performance depends upon some differential cancellation across speaker load. view differential output across speakerA speakerB, floating monitor must used i.e. neither side speaker should grounded! example, this achieved with channel oscilloscope monitoring speakerA speakerB outputs, using invert functions.
Figure Class Mono O.L. Bottom Copper (Actual Size) exposed underside ZXCD1000 eQSOP package should soldered down PCB. This conjunction with vias bottom copper areas, functions heat sink.
Speaker Outputs
Audio Input
Figure Class Mono O.L. Silk Screen (Actual Size) Plots typical performance solution shown included graphs. previously stated, very important feature Zetex solution that residual distortion almost totally free crossover artifacts. This lack crossover distortion sets ZXCD1000 solutions quite apart from most other presently available cost solutions, which general suffer from severe crossover distortion problems.
Figure Class Mono O.L. Copper (Actual Size)
ISSUE MARCH 2001
ZXCD1000
well known that this kind distortion particularly unpleasant listener. scope traces clearly show lack such artifacts with Zetex solution
Other Solutions Stereo, Closed Loop Higher Powers. STEREO
possible duplicate above solution give channel stereo solution. However oscillator frequencies locked together, beat occur which acoustically audible. This undesirable. stereo solution which avoids this problem achieved synchronising operating frequencies both ZXCD1000's class controller IC's, slaving device from other. This illustrated Figure
ZXCD1000
Audio Triangle Dist Gnd2
1.5k
MASTER
Cosc
ZETEX Class Solution. (10W into Note lack Crossover Artifacts
Triangle
1.5k
Audio
ZXCD1000
Audio Triangle Gnd2
Dist Cosc
SLAVE
Triangle Audio
Figure Frequency sync Stereo Apps. Here OscA master used drive both TriangleA TriangleB inputs master. OscB master used drive both TriangleA TriangleB inputs slave. order achieve increased drive capabilty required OscA/B outputs master, 1.5k pull down resistors added from these pins ground. slave oscillator disabled connecting (dist) ground. Great care must taken when linking triangle from master slave. pickup cause slicing errors result increased distortion. best connection method tracks, side side, from master slave. these tracks would triangle itself, other would direct local ground linking master pin9 ground slave ground.
Typical Class Solution. Note Large Crossover Artifacts
ISSUE -MARCH 2001
1N4148
ZXM64P03X 2200µF
ZXCD1000
1N4148
ZXFN1000
20uH
22µF Audio 1N4148 1N4148 Triangle OscA
BRIDGE
SPEAKER
1N4148
ZXM64N03X
3.9K
Cosc Gnd2 OscB Triangle
Dist
560R
LM358D
Audio 2.2nF
ZXCD1000
*****
330pF
LM358D
ZXM64P03X
560R 2.2nF
1N4148
3.9K
ZXFN1000
BRIDGE
*****
2.4K
10µF
1N4148
20µH
ZXM64N03X SPEAKER
1.6k 47µF
0.1u
220R
680pF 1N4148
RC4558D
2.7k
1.5k 3.9k
8.2k
430R
3.3µF
430R
AUDIO INPUT
1.5k
4.7k
47µF
RC4558D
ISSUE MARCH 2001
Figure Mono with Feedback
ZXCD1000
Class Mono Bridge Tied Load (BTL) Solution with Feedback Circuit Description
With addition feedback (hence closed loop solution) possible obtain even better performance. schematic diagram this shown Figure Again proprietary circuit special magnetic design necessary yield high performance deviation from this could significantly reduce performance. Much circuitry same described open loop solution. main differences being consequence using feedback circuitry. input feedback circuitry shown separately Figure described. audio input coupled applied op-amp (1/2 RC4558D) configured non-inverting amplifier with gain approximately 2.8. op-amp input tied level approximately VCC/2. Feedback applied differentially from bridge outputs other half RC4558D op-amp. portion single ended output from this op-amp subtracted from output non-inverting op-amp output above. Overall negative feedback applied polarity connection signals involved. audio signal from above circuitry applied phase splitter (see Figure done open loop solution. This built around other LM3580 dual op-amp. these op-amps configured voltage follower other inverting amplifier. This produces phase inverted signals application ZXCD1000 Audio Audio inputs respectively. output circuitry downstream ZXCD1000 described open loop solution, components slightly different (and have different numbering).
Higher Power Solutions
With some modifications applications solutions extended give even higher output powers. solution implemented with circuit very similar solution. main differences being supply voltage output magnetics. magnetics necessarily larger than required order handle higher load currents. operation supply voltage circuit nominally 25V. However maximum supply voltage ZXCD1000 class controller 20V, hence voltage dropper required. This could done, example, open loop solution described previously. addition, closed loop solution, slightly modified feedback resistor ratios required. ZXCD1000 class controller inherently capable driving even higher power solutions, with appropriate external circuitry. However stated above maximum supply voltage ZXCD1000 class controller higher supply voltages must therefore dropped. Also consideration must given ZXCD1000 output drive levels characteristics bridge MOSFET's. latter must sufficiently enhanced OutA OutB outputs ensure filter load network driven properly. gate drive ZXCD1000 chosen MOSFET then OUTA OUTB signal must buffered using appropriate MOSFET driver circuit. Additionally, suitable magnetics essential achieve good performance.
Package details
ZXCD1000 available eQSOP package. exposed underside package should soldered down area copper PCB, function heatsink. should have plated through vias underside board, again connecting area copper.
ISSUE -MARCH 2001
ZXCD1000
1.5k
Audio
3.3µF
RC4558D
1.5k
47µF
47µF
8.2k
4.7k 220R
FROM BRIDGE (via R41/C41) FROM BRIDGE (via R40/C40)
RC4558D
2.7k
680pF
3.9k
1.6k
Phase Splitter
Figure Feedback Input Circuitry.
LM358D
560R
AudioA input Phase Signal)
2.2nF
2.4k
10µF
3.9k
LM358D Audio Signal From Input Feedback Circuitry
560R
AudioB input (Inverted Signal)
2.2nF
3.9k
Figure Phase Splitter
ISSUE MARCH 2001
ZXCD1000
Typical performance graphs Zetex open loop solution shown here both loads. These graphs further demonstrate true high fidelity performance achieved Zetex solutions.
Output Power
f(Hz)
Power into 1kHz
distortion noise floor load)
f(Hz)
f(Hz)
Frequency response load)
distortion noise floor load)
ISSUE -MARCH 2001
ZXCD1000
Output Power
f(Hz)
Power into 1kHz
distortion noise floor load)
f(Hz)
f(Hz)
Frequency response load) Note roll off. This corrected using alternative values output filter components.
distortion noise floor load)
ISSUE MARCH 2001
ZXCD1000
B.O.M. Table Mono Open Loop Solution
Value
100R 22µF 22µF 270pF 22µF 68µF 100n 100n 100n 22µF 22µF 100µF 100n 100n 100n 100n 100n
Case
0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 0805 Tant Tant 0805 0805 0805 Tant 0805 0805 Tant 1206 0805 0805 Tant Tant std. 6.3mm 0805 0805 0805 0805 0805
Notes
Value
22µF 470n 470n 470n 470n 470n 470n 2200µF 100n 22µF 100µF 100n 100µF ZXCD1000 NE5532 78L12 ZXM64P03X ZXM64N03X ZXM64P03X ZXM64N03X BAV70 BAW56 BAW56 BAV70
Case
Tant 1812 1812 1812 1812 1812 1812 std. 12.5mm 1206 Tant std. 6.3mm 1206 std. 6.3mm TO92 MSOP MSOP MSOP MSOP SOT23 SOT23 SOT23 SOT23
Notes
A4-Common Cathode A1-Common Anode A1-Common Anode A4-Common Cathode
20µH (ZXFN1000) 20µH (ZXFN1000)
std. std.
Custom core Custom core
ISSUE -MARCH 2001
ZXCD1000
PACKAGE DIMENSIONS
EXPOSED
DETAIL
BOTTOM VIEW VIEW VIEW
.010 SEATING PLANE
DIMENSIONS INCHES MIN. NOM. MAX. .058 .061 .066 .001 .003 .005 .055 .058 .061 .012 .008 .010 .007 .189 .194 .196 .150 .154 .157 .025 .228 .236 .244 .010 .016 .013 .035 .025 .016 .005 .007 .002
SEATING PLANE
SIDE VIEW
Zetex part ordering information (per channel)
Device channel ZXCD1000EQ16 ZXFN1000 ZXM63N03X ZXM63P03X Description Class modulator Custom magnetics Channel MOSFET Channel MOSFET MSOP8 MSOP8 Package Suffix
Zetex plc. Fields Road, Chadderton, Oldham, OL9-8NP, United Kingdom. Telephone: (44)161 4422 (Sales), (44)161 4444 (General Enquiries) Fax: (44)161 4420 Zetex GmbH D-81673 Germany Telefon: (49) Fax: (49) Zetex Inc. Mall Drive, Unit Commack 11725 Telephone: (631) 543-7100 Fax: (631) 864-7630 Zetex (Asia) Ltd. 3701-04 Metroplaza, Tower Hing Fong Road, Kwai Fong, Hong Kong Telephone:(852) 26100 Fax: (852) 24250 These supported agents distributors major countries world-wide Zetex 2000 Internet:http://www.zetex.com
This publication issued provide outline information only which (unless agreed Company writing) used, applied reproduced purpose form part order contract regarded representation relating products services concerned. Company reserves right alter without notice specification, design, price conditions supply product service.
DETAIL
eQSOP16
ISSUE MARCH 2001

HIGH FIDELITY CLASS AUDIO AMPLIFIER SOLUTION DESCRIPTION ZXCD1000

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