DESCRIPTION
The ZXCD50STEVAL evaluation board is based on the
ZXCD1000 Class D audio amplifier solution from Zetex.
This board allows the user to evaluate the high fidelity
audio performance offered by the Zetex solution, with
an output power up to 50W music power into 4⍀.
INTRODUCTION
The ZXCD50STEVAL is a 50W music power (4⍀load)
high performance class D amplifier. The circuitry
contains MOSFET devices and should therefore be
handled appropriately.
The board requires a single rail power supply of 13
volts minimum and 25 volts maximum. Voltages in
excess of 25 volts may cause permanent damage to the
board.
The heart of the solution is the ZXCD1000 class D
controller IC and the user should refer to the ZXCD1000
data sheet for further technical information. The circuit
features pop suppression and over current protection
as well as a mute facility.
FEATURES
•Stereo
•Class D architecture
•Single power supply
•Output power ( Vsupply = 25V)
50W music into 4⍀
25W music into 8⍀
•THD + N <0.5% @ 90% power
•>90% efficiency
•Flat frequency response 20Hz – 20 kHz
•Turn on / turn off pop suppression
•Over current protection
•Mute facility
•Noise floor –115dB
Note: The ZXCD50STEVAL is intended as an evaluation platform for Zetex
Class D solutions. Zetex accepts no liability for external equipment
connected to the ZXCD500STEVAL or any other form of consequential
damage or loss.
ZXCD50STEVAL
ISSUE 1 - JULY 2002
1
50W CLASS D AUDIO AMPLIFIER EVALUATION BOARD
CONNECTION AND OPERATION
The following PCB image shows the connections
required for correct operation of the ZXCD50STEVAL
board. Simple connector blocks are provided to enable
easy connection of the supply voltage, audio inputs
and speaker outputs.
Power connection
The ZXCD50STEVAL requires a single positive supply
voltage:
25V @ approximately 2.3A for 50W music into 4⍀
Note: 8⍀speakers can be used in this application. In this case a 25V bridge
supply will result in an output power of 25W music. If this is required then
C2/102 should be removed to maintain a flat frequency response.
The supply should not exceed 25V and must not be less
than 13V to ensure correct operation of the amplifier.
Ensure the correct polarity of the supply applied.
Audio input
The ZXCD50STEVAL requires a single ended audio
input per channel as follows:
The input impedance is 18k⍀.
Input signal amplitude required for full output power is
approximately 2.5V peak to peak.
Speaker connection
4⍀speakers may be connected to the board as shown.
The correct polarity connection of the speakers is
essential to avoid phasing errors.
Note: 8⍀speakers can be used in this application. If this is required then
C2/102 should be removed to maintain a flat frequency response.
Over current protection is provided on the board, which prevents
damage to the circuit with shorts from the speaker to ground or across the
speaker.
EVALUATION BOARD DESCRIPTION AND
OPERATION
The top copper , bottom copper and silk screen ID
overlay are shown in figure 1,2 and 3.
The ZXCD1000 is available in a 16-pin exposed pad
QSOP package. The exposed pad on the underside of
the package is soldered down to an area of copper on
the PCB, to function as a heatsink. To further assist heat
dissipation, the PCB has plated through vias
connecting to an area of copper on the underside of the
board.
The MOSFETS required on the board are Zetex ZXM64
series HDMOS parts. These SOT223 parts are required
to handle the power dissipation in the amplifier with a
50W music load.
The regulator transistors on the board are ZTX692B,
E-Line devices. These devices are required to supply
the 12V rail to the channels from the board input
voltage which is the 25V bridge supply.
The inductors in place on the board have been selected
for their excellent linearity and low losses. These
components ensure minimal distortion is introduced in
the recovered audio signal across the full power band.
The speaker is connected as a Bridge Tied Load (BTL).
This means that both sides of the speaker are driven
from the Output Bridge and therefore neither side of
the speaker connects to ground. This allows maximum
power to be delivered to the load, from a given supply
voltage.
ZXCD50STEVAL
ISSUE 1 - JULY 2002
2
Audio input
Channel A
Audio input
Channel B
Mute
Power connection
Speaker connection
Channel A
Speaker connection
Channel B
If it is wished to view or measure the signal across the
load, a floating monitor must be used - for example a
differential probe. Alternatively this may be achieved
with a two channel oscilloscope monitoring the
speaker A and speaker B outputs, and using the invert
and add functions. For diagnostic purposes, the
speaker outputs can be monitored single-ended with
respect to ground with an oscilloscope (or other
instrument) if desired. However any results obtained in
this manner, are not valid for assessing performance.
The true performance depends upon some differential
cancellation across the speaker load.
The board requires an input signal of 2.5V peak to peak
nominal to yield the full output power. The input
impedance of the board is nominally 18k⍀. This may
attenuate the source voltage and may need to be
allowed for, depending on the output impedance of the
source.
The maximum supply voltage to the ZXCD50STEVAL
evaluation board is 25V nominal. A supply voltage of
25V will achieve 50W music into a 4⍀load.
ZXCD50STEVAL
ISSUE 1 - JULY 2002
3
Fig.1. Component Overlay
Fig.2. Top Copper Fig.3. Bottom Copper
ZXCD50STEVAL CIRCUIT DESCRIPTION.
Propriety circuit design and high quality magnetics are
necessary to yield the excellent THD performance of
the solution. At the heart of the circuit is the Zetex
ZXCD1000 class D audio IC.
The ZXCD50STEVAL circuit diagram is shown in figure
4. The board features two class D channels, one master
and one slave. These channels are essentially the same
other than the triangle synchronisation facilitated by
Q1 on the master channel.
Each audio channel consists of an input phase splitter,
the ZXCD1000, an output bridge to drive the load - via
L-C filters, and an over-current protection circuit. Each
channel also features its own dropper voltage
regulator.
The voltage regulator (Q5/105, ZD1/101 etc.) is
necessary to drop higher supply voltages (25V on the
bridge for 50W) to a level suitable for the ZXCD1000
and input phase splitter (12V on the board).
The input phase splitter per channel, built around the
NE5532 dual op amp, is necessary to drive the Audio A
and Audio B channels on each ZXCD1000.
Each channel phase splitter features a mute transistor
(Q11/111) which is controlled via the circuit built
around Q12. This circuit provides a mute function with
an active low input. The mute function reduces the
effective output signal by 54dB.
The Output Bridges are built around the Zetex
ZXM64P035G and ZXM64N035G PMOS and NMOS
SOT223 transistors.
The circuit built around Q10 facilitates a slow start for
the bridge supply voltage This circuit performs
anti-pop for the solution.
R20/120 are over current sense resistors. The circuit
built around these (Q2/102, Q3/103 etc) enables an
over-current protection for the solution. In fault
conditions the circuit disables the triangle modulation
waveform to the channel and thus disables the output
bridge. Protection is given for speaker shorts and
speaker to ground shorts.
The ZXCD1000 outputs drive Output Bridge MOSFET’s,
with the PWM signal, which subsequently drives the
load via L-C filters. The purpose of the filters is to low
pass filter the high frequency switching PWM signal
from the bridge. Thus the lower frequency audio signal
is recovered and is available at the speaker outputs.
ZXCD50STEVAL CIRCUIT PERFORMANCE
The graph shown in fig 5 indicates the typical THD
performance of the solution. THD is shown from zero
up to full power.
Distortion is sub 1% all the way up to full power,
typically at 1W 1kHz distortion is 0.1%.
ZXCD50STEVAL
ISSUE 1 - JULY 2002
4
WARNING - Appropriate safety precautions should be taken by
a competent person if the ZXCD100MOEVAL is to be connected
to any potentially hazardous equipment.
Figure 5.
Notes.
ZXCD50STEVAL
ISSUE 1 - JULY 2002
5
ZXCD50STEVAL
ISSUE 1 - JULY 2002
6
ZXCD50STEVAL
ISSUE 1 - JULY 2002
7
ZETEX CLASS D 50W STEREO DISTRIBUTOR BOARD BOM - REV1
PCB ID Value Case Specific Part Number Note
Manufacturer
Resistors:-
R1 100k 1% 0.1W SMD 0805 Generic
R2 11k 1% 0.1W SMD 0805 Generic
R3 390 1% 0.1W SMD 0805 Generic
R4 22k 1% 0.1W SMD 0805 Generic
R5 22k 1% 0.1W SMD 0805 Generic
R6 22k 1% 0.1W SMD 0805 Generic
R7 390 1% 0.1W SMD 0805 Generic
R8 5k6 1% 0.1W SMD 0805 Generic
R9 5k6 1% 0.1W SMD 0805 Generic
R10 1k5 1% 0.1W SMD 0805 Generic
R11 820 1% 0.1W SMD 0805 Generic
R12 47k 1% 0.1W SMD 0805 Generic
R13 56 1% 0.1W SMD 0805 Generic
R14 56 1% 0.1W SMD 0805 Generic
R15 47k 1% 0.1W SMD 0805 Generic
R16 47k 1% 0.1W SMD 0805 Generic
R17 56 1% 0.1W SMD 0805 Generic
R18 56 1% 0.1W SMD 0805 Generic
R19 47k 1% 0.1W SMD 0805 Generic
R20 0R01 1% 1W Open Air Welwyn OARS series
Farnell 327-4561
R21 390 1% 0.1W SMD 0805 Generic
R22 47k 1% 0.1W SMD 0805 Generic
R23 47k 1% 0.1W SMD 0805 Generic
R24 22k 1% 0.1W SMD 0805 Generic
R25 100k 1% 0.1W SMD 0805 Generic
R26 62k 1% 0.1W SMD 0805 Generic
R27 11k 1% 0.1W SMD 0805 Generic
R28 11k 1% 0.1W SMD 0805 Generic
R29 100k 1% 0.1W SMD 0805 Generic
R30 100k 1% 0.1W SMD 0805 Generic
R31 51k 1% 0.1W SMD 0805 Generic
R32 11k 1% 0.1W SMD 0805 Generic
R33 100k 1% 0.1W SMD 0805 Generic
R34 8k2 1% 0.1W SMD 0805 Generic
R35 3k9 1% 0.1W SMD 0805 Generic
R36 1k 1% 0.1W SMD 0805 Generic
R101 100k 1% 0.1W SMD 0805 Generic
R102 11k 1% 0.1W SMD 0805 Generic
R103 390 1% 0.1W SMD 0805 Generic
R104 22k 1% 0.1W SMD 0805 Generic
R105 22k 1% 0.1W SMD 0805 Generic
R106 22k 1% 0.1W SMD 0805 Generic
R107 390 1% 0.1W SMD 0805 Generic
R108 5k6 1% 0.1W SMD 0805 Generic
R109 5k6 1% 0.1W SMD 0805 Generic
R112 47k 1% 0.1W SMD 0805 Generic
R113 56 1% 0.1W SMD 0805 Generic
R114 56 1% 0.1W SMD 0805 Generic
R115 47k 1% 0.1W SMD 0805 Generic
R116 47k 1% 0.1W SMD 0805 Generic
R117 56 1% 0.1W SMD 0805 Generic
R118 56 1% 0.1W SMD 0805 Generic
R119 47k 1% 0.1W SMD 0805 Generic
R120 0R01 1% 1W Open Air OARS series
Farnell 327-4561
R121 390 1% 0.1W SMD 0805 Generic
R122 47k 1% 0.1W SMD 0805 Generic
ZXCD50STEVAL
ISSUE 1 - JULY 2002
8
ZETEX CLASS D 50W STEREO DISTRIBUTOR BOARD BOM - REV1
PCB ID Value Case Specific Part Number Note
Manufacturer
Resistors :-
R123 47k 1% 0.1W SMD 0805 Generic
R124 22k 1% 0.1W SMD 0805 Generic
R125 100k 1% 0.1W SMD 0805 Generic
R126 62k 1% 0.1W SMD 0805 Generic
R127 11k 1% 0.1W SMD 0805 Generic
R128 11k 1% 0.1W SMD 0805 Generic
R132 11k 1% 0.1W SMD 0805 Generic
RV1 10k 0.05W SMD 3mm Meggitt 3203 Series Cermet
preset pot trimer Farnell 107-133
RV101 10k 0.05W SMD 3mm Meggitt 3203 Series Cermet
preset pot trimer Farnell 107-133
Capacitors :-
C1 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16VElect x2mmP Farnell 301-7564
C2 1n 50V X7R SMD 0805 Generic
C3 47p 16V COG SMD 0805 Generic
C4 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C5 100n 50V X7R SMD 0805 Generic
C6 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C7 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C8 330p 16V COG/NPO SMD 0805 Generic
C9 47n 16V X7R SMD 0805 Generic
C10 47n 16V X7R SMD 0805 Generic
C11 6n8 16V X7R SMD 0805 Generic
C12 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C13 100n 50V X7R SMD 0805 Generic
C14 6n8 16V X7R SMD 0805 Generic
C15 100n 50V X7R SMD 0805 Generic
C16 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C17 100n 50V X7R SMD 0805 Generic
C18 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C19 100u ±20% 11mmHx6.3mmD Rubycon YXF series THC 105
16V Elect x2.5mmP Farnell 580--417
C20 1u 25V X7R SMD 1206 Generic
C21 1u 25V X7R SMD 1206 Generic
C22 1u 25V X7R SMD 1206 Generic
C23 1u 25V X7R SMD 1206 Generic
C24 470n 50V X7R SMD 1812 Generic
C25 1u 63V Polyester 5mm pitch Generic
C26 470n 50V X7R SMD 1812 Generic
C27 1u 63V Polyester 5mm pitch Generic
C28 100n 50V X7R SMD 0805 Generic
C29 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C30 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C31 100n 50V X7R SMD 0805
C32 100u ±20% 11.5mmHx8mmD Rubycon ZL series THC 105
50V Elect x3.5mmP Farnell 778-679
C33 220n 50V X7R SMD 0805 Generic
ZXCD50STEVAL
ISSUE 1 - JULY 2002
9
ZETEX CLASS D 50W STEREO DISTRIBUTOR BOARD BOM - REV1
PCB ID Value Case Specific Part Number Note
Manufacturer
Capacitors :-
C34 2200u ±20% 31.5mmHx16mmD Panasonic FC series THC 105
35V Elect x7.5mmP Farnell 303-6455
C35 100n 50V X7R SMD 0805 Generic
C36 220u ±20% 11.5mmHx8mmD Rubycon ZL series THC 105
25V Elect x3.5mmP Farnell 762-090
C37 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C101 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C102 1n 50V X7R SMD 0805 Generic
C103 47p 16V COG SMD 0805 Generic
C104 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C105 100n 50V X7R SMD 0805
C106 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C107 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C109 47n 16V X7R SMD 0805 Generic
C110 47n 16V X7R SMD 0805 Generic
C111 6n8 16V X7R SMD 0805 Generic
C112 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C113 100n 50V X7R SMD 0805 Generic
C114 6n8 16V X7R SMD 0805 Generic
C115 100n 50V X7R SMD 0805 Generic
C116 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C117 100n 50V X7R SMD 0805 Generic
C118 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C119 100u ±20% 11mmHx6.3mmD Rubycon YXF series THC105
16V Elect x2.5mmP Farnell 580-417
C120 1u 25V X7R SMD 1206 Generic
C121 1u 25V X7R SMD 1206 Generic
C122 1u 25V X7R SMD 1206 Generic
C123 1u 25V X7R SMD 1206 Generic
C124 470n 50V X7R SMD 1812 Generic
C125 1u 63V Polyester 5mm pitch Generic
C126 470n 50V X7R SMD 1812 Generic
C127 1u 63V Polyester 5mm pitch Generic
C128 100n 50V X7R SMD 0805 Generic
C129 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C130 22u ±20% 7mmHx5mmD Multicomp MCMHR Series THC 105
16V Elect x2mmP Farnell 301-7564
C131 100n 50V X7R SMD 0805
C132 100u ±20% 11.5mmHx8mmD Rubycon ZL series THC 105
50V Elect x3.5mmP Farnell 778-679
C133 220n 50V X7R SMD 0805
C134 2200u ±20% 31.5mmHx16mmD Panasonic FC series THC 105
35V Elect x7.5mmP Farnell 303-6455
C135 100n 50V X7R SMD 0805 Generic
ZXCD50STEVAL
ISSUE 1 - JULY 2002
10
ZETEX CLASS D 50W STEREO DISTRIBUTOR BOARD BOM - REV1
PCB ID Value Case Specific Part Number Note
Manufacturer
Integrated Circuits
U1 NE5532AD8 SMD SO8 Phillips
U2 ZXCD1000EQ16 QSOP16 Zetex
(Exposed Pad)
U101 NE5532AD8 SMD SO8 Phillips
U102 ZXCD1000EQ16 QSOP16 Zetex
(Exposed Pad)
Transistors
Q1 FMMT591A SMD SOT23 Zetex
Q2 FMMT591A SMD SOT23 Zetex
Q3 FMMT591A SMD SOT23 Zetex
Q4 ZVN3306F SMD SOT23 Zetex
Q5 ZTX692B E Line Zetex
Q6 ZXM64P035G SOT223 Zetex
Q7 ZXM64N035G SOT223 Zetex
Q8 ZXM64P035G SOT223 Zetex
Q9 ZXM64N035G SOT223 Zetex
Q10 ZXM64P035G SOT223 Zetex
Q11 FMMT491A SMD SOT23 Zetex
Q12 ZVN3306F SMD SOT23 Zetex
Q102 FMMT591A SMD SOT23 Zetex
Q103 FMMT591A SMD SOT23 Zetex
Q104 ZVN3306F SMD SOT23 Zetex
Q105 ZTX692B E Line Zetex
Q106 ZXM64P035G SOT223 Zetex
Q107 ZXM64N035G SOT223 Zetex
Q108 ZXM64P035G SOT223 Zetex
Q109 ZXM64N035G SOT223 Zetex
Q111 FMMT491A SMD SOT23 Zetex
Diodes
D1 BAV70 SMD SOT23 Zetex
D2 BAW56 SMD SOT23 Zetex
D3 BAV70 SMD SOT23 Zetex
D4 BAW56 SMD SOT23 Zetex
D5 BAV70 SMD SOT23 Zetex
D6 BAS16 SMD SOT23 Zetex
D101 BAV70 SMD SOT23 Zetex
D102 BAW56 SMD SOT23 Zetex
D103 BAV70 SMD SOT23 Zetex
D104 BAW56 SMD SOT23 Zetex
D105 BAV70 SMD SOT23 Zetex
ZD1 BZX84C13 SMD SOT23 13V Zener diode
ZD101 BZX84C13 SMD SOT23 13V Zener diode
Inductors :-
L1 20uH PG0036 Pulse
55-8810-20 Cambion
L2 20uH PG0036 Pulse
55-8810-20 Cambion
L101 20uH PG0036 Pulse
55-8810-20 Cambion
L102 20uH PG0036 Pulse
55-8810-20 Cambion
ZXCD50STEVAL
ISSUE 1 - JULY 2002
11
This publication is issued to provide outline information only which (unless agreed by the Company in writing)
may not be used, applied or reproduced for any purposes or form part of any order or contract or be regarded as
representation relating to the products or services concerned. The company reserves the right to alter without
notice the specification, design, price or conditions of supply of any product or service.
Some changes to earlier published data may have been made, data presented in this handbook supersedes all
previous specifications. The information contained in this publication has been carefully checked and is
considered to be accurate, but no responsibility is assumed for any inaccuracies.
Zetex makes no warranty, representation or guarantee regarding the suitability of the products and circuits in
this publication for any given purpose; nor does Zetex assume any liability arising from the use or application of
any these products or circuits and specifically disclaims any and all incidental damages.
Zetex products are specifically not authorised for use as critical components in life support devices or systems
without the express written approval of the Managing Director of Zetex plc. As used herein -
a. Life support devices or systems are devices or systems which
(1) are intended to implant into the body, or
(2) support or sustain life and whose failure to perform when properly used in accordance with instructions for
use provided in the labelling can be reasonable expected to result in significant injury to the user.
b. A critical component is any component on a life support device or system whose failure to perform can be
reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness.
E. & O.E.
“all rights reserved”
ZXCD50STEVAL
12
ISSUE 1 - JULY 2002
Europe
Zetex plc
Fields New Road
Chadderton
Oldham, OL9 8NP
United Kingdom
Telephone (44) 161 622 4422
Fax: (44) 161 622 4420
uk.sales@zetex.com
Zetex GmbH
Streitfeldstraße 19
D-81673 München
Germany
Telefon: (49) 89 45 49 49 0
Fax: (49) 89 45 49 49 49
europe.sales@zetex.com
Americas
Zetex Inc
700 Veterans Memorial Hwy
Hauppauge, NY11788
USA
Telephone: (631) 360 2222
Fax: (631) 360 8222
usa.sales@zetex.com
Asia Pacific
Zetex (Asia) Ltd
3701-04 Metroplaza, Tower 1
Hing Fong Road
Kwai Fong
Hong Kong
Telephone: (852) 26100 611
Fax: (852) 24250 494
asia.sales@zetex.com
These offices are supported by agents and distributors in major countries world-wide.
This publication is issued to provide outline information only which (unless agreed by the Company in writing) may not be used, applied or reproduced
for any purpose or form part of any order or contract or be regarded as a representation relating to the products or services concerned. The Company
reserves the right to alter without notice the specification, design, price or conditions of supply of any product or service.
For the latest product information, log on to www.zetex.com
© Zetex plc 2002
