Philips UM10155 User Manual

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UM10155

Discrete Class D High Power Audio Ampliﬁer

Rev. 02 — 5 September 2006 User manual

Document information

Info Content Keywords Class D Audio Ampliﬁer, Universal Class D, UcD, PWM Audio Ampliﬁer,

High Power Audio.

Abstract This user manual describes the operating instructions and the most

important background information of the Philips Semiconductor Discrete Class D High Power Audio Ampliﬁer Demonstrator Board. With proper heatsinking of the Power MOSFETs and a well dimensioned powersupply, the PWM ampliﬁer is capable of supplying 200 W of high quality audio power into a 4 Ω loudspeaker.

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Philips Semiconductors

Revision history

Rev Date Description

02 20060905 corrected 01 20060801 initial version

UM10155

Discrete Class D High Power Audio Ampliﬁer

Figure 9.

Contact information

For additional information, please visit: http://www.semiconductors.philips.com For sales ofﬁce addresses, please send an email to: [email protected]

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Philips Semiconductors

1. Introduction

The Universal Class D (UcD) version 1.00 demonstrator board implements a 200 W true RMS (into a 4 Ω load) high quality audio power ampliﬁer on a very compact printed-circuit board. The ampliﬁer is built-up of discrete components only, and makes use of Philips patent WO 03/090343.

UM10155

Discrete Class D High Power Audio Ampliﬁer

001aaf148

Fig 1. General view

The demonstrator board is intended to illustrate the capability of Philips PowerMOSFETs in discrete high-end PWM audio ampliﬁer applications. The board is self-contained and only requires a simple (non-stabilized) dual power supply, an audio source (e.g. function generator,CD player) and a loudspeaker to demonstrate its capabilities. For evaluation at high output power a provision is made to attach an appropriate heatsink to the MOSFETs on the board.

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2. Circuit diagram

Philips Semiconductors

R29

10 Ω

47 kΩ

100 nF

R2 1 kΩ

C3 100 nF

BC857

BF821 Q1

560 Ω

47 kΩ

4.7 nF

J3 J4

J1 J2

BF820

BC847

R8 220 Ω

Q4 BF721

47 Ω

1PS76SB10

R7 220 Ω

47 Ω

R9 330 Ω

BF820

BC847

BF821

R13

2.2 kΩ

R12 22 kΩ

C4 220 pF

R14

5.6 MΩ

R10 220 Ω

R28

10 Ω

R15

3.9 MΩ

R27

8.2 kΩ

R11 1 kΩ

Q15

D6 BAS321

BF720

D5 PDZ12B

R16

4.7 kΩ

D8 PDZ12B

BAS321

C5 100 µF

C7 100 µF

C6 100 nF

C8 100 nF

R18 390 Ω

1PS76SB10

R17 390 Ω

D10

1PS76SB10

Q10 BC857

Q9 BC857

R20

27 Ω

R19

27 Ω

D11

BAS316

R8 1 kΩ

D12

BAS316

R21 1 kΩ

PHP18NQ11T

Q12 PBSS5140T

PHP18NQ11T

Q11 PBSS5140T

Q14

Q13

R26

0.05 Ω

R25

0.05 Ω

R24 10 Ω

28 µH

R23 10 Ω

C9 100 pF

C10 100 pF

C12 100 nF

C13 100 nF

C11 22 µF

C14 22 µF

C16 100 nF

C15 680 nF

C18 100 nF

C17 1000 µF

C19 1000 µF

001aaf149

J10

J11

Discrete Class D High Power Audio Ampliﬁer

Fig 2. Circuit diagram

UM10155

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Philips Semiconductors

Table 1. Connections

Connector Function Remarks

J1 audio in - signal use together with J2 J2 audio in - ground use together with J1 J3 ampliﬁer enable whenconnected to ground (J4)

J4 ground use together with J3 J5 positive supply voltage 30 V to 45 V (no need for a

J6 positive current sense can optionally be used in an

J7 power supply ground 0 V J8 negative current sense can optionally be used in an

J9 negative supply voltage −30 V to −45 V (no need for a

J10 loudspeaker output use together with J11 J11 loudspeaker ground use together with J10

UM10155

Discrete Class D High Power Audio Ampliﬁer

the ampliﬁer is enabled

stabilized power supply)

overcurrent protection scheme

stabilized power supply)

3. Printed-circuit board layout

001aaf150

Fig 3. Top copper layout Fig 4. Bottom copper layout

001aaf151

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Philips Semiconductors

UM10155

Discrete Class D High Power Audio Ampliﬁer

PHILIPS class D amp.

version 1.00

J3 J4

international patent

WO 03/090343

001aaf152

Fig 5. Component layout Fig 6. Top silk-screen

4. Speciﬁcations

Table 2. Speciﬁcations

Symbol Parameter Conditions Value

η efﬁciency P THD+N total harmonic

S/N signal-to-noise ratio > 120 dB f

PWM

offset

supply voltage equal positive and negative

supply voltages

output power VP= ±45 V; RL=4Ω;

appropriate heatsink needed

= 100 W; RL=4Ω >92%

= 10 W; frequency range

distortion-plus-noise

from 20 Hz to 20 kHz

PWM frequency idle ~ 400 kHz offset voltage DC value < 50 mV

C11

Q14

Q13

C14

C17

C19

C15

J10 J11 J7

J8 J9

001aaf153

±30 V to ±45 V

200 W (RMS)

< 0.03 %

4.1 Pop-less/click-less start-up and shutdown

A provision has been added to the circuit to provide pop-less/click-less start-up and shutdown. To make use of the start-up facility, make sure that the supply power (pins J5 and J9) is applied prior to enabling the ampliﬁer (connecting J3 to J4). Tobeneﬁt from the pop-less shutdown feature, disable the ampliﬁer (disconnect J3 and J4) prior to removing the supply power.

4.2 Overcurrent protection

A provision has been added to the circuit to monitor the current ﬂowing through the Power MOSFETs (Q13 and Q14). The voltage appearing between pins J5 and J6 is proportional to the current in MOSFET Q14 (ratio: 50 mV/A) and the voltage between J8 and J9 is proportional to the current in MOSFET Q13 (ratio: 50 mV/A). With the use of an external

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Philips Semiconductors

circuit these two signals may be used to disable the ampliﬁer (disconnect J3 and J4) in case of an overcurrent situation. Similarly the J3-J4 pin combination can be used to disable the ampliﬁer in case of other fault conditions.

4.3 Important notice

The ‘High Power Class D Audio Ampliﬁer Demonstrator Board’ is meant to demonstrate the capabilities of the speciﬁc Class D Ampliﬁer design and its semiconductor components. No provisions for short-circuit and overcurrent protection were made on the demonstrator board itself. Neither was an operating temperature compensation feature implemented on the board. The circuit on the board is reduced to its essentials.

In this implementation the ‘High Power Class D Audio Ampliﬁer Demonstrator Board’ is not intended to be used for long term operation or under extreme temperature conditions when delivering substantial output power.

5. Wiring diagram and powering-up

UM10155

Discrete Class D High Power Audio Ampliﬁer

J3 J4 J1

signal

ground

Audio input: J1 is signal; J2 is ground Initially, leave J6 and J8 unconnected; J7 and J11 are at the same (ground) potential

Fig 7. Wiring diagram

PHILIPS class D amp.

version 1.00

international patent

WO 03/090343

Q13

C11

C14

Q14

J5 J6

C17

10 mF 30 V to 45 V

C15

C19

J10 J11 J7

J8 J9

10 mF 30 V to 45 V

4 Ω to 8 Ω

001aaf154

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Philips Semiconductors

6. Adding external features

6.1 Electronic enabling/disabling of the ampliﬁer

UM10155

Discrete Class D High Power Audio Ampliﬁer

PHILIPS class D amp.

version 1.00

international patent

WO 03/090343

enable

signal

J3 J4 J1 J2

Enable signal: (HIGH = enable) (LOW = disable)

Fig 8. Enabling/disabling of the ampliﬁer

Electronic enabling/disabling can be used for:

C11

Q14

Q13

C14

C17

C19

001aaf155

C15

J10 J11 J7

J8 J9

• Implementing pop-less and click-less start-up and shut-down

• Shutting down the ampliﬁer in case of a failure condition

(short-circuit/overcurrent/over-temperature)

The transistor in the enabling/disabling circuit must be low current, 60 V type (such as BC846) and the resistor must limit the base current of the transistor to approximately 1 mA (in case of logic level driving, that would mean R = 4.7 kΩ).

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Philips Semiconductors

6.2 Short-circuit and overcurrent protection

UM10155

Discrete Class D High Power Audio Ampliﬁer

Q14

J5 J6

C17

C15

C19

J10 J11 J7

J8 J9

PHILIPS class D amp.

J3 J4 J1 J2

version 1.00

international patent

WO 03/090343

Q13

C11

C14

Fig 9. Short-circuit and overcurrent protection

The ‘Short-circuit and overcurrent protection’ circuit must be used together with the ‘Electronic enabling/disabling’ circuit.

The output pins of IC1 and IC2 produce a HIGH logic level pulse when overcurrent is detected in either the low side MOSFET (Q13 on the Demonstrator Board) and high side MOSFET (Q14 on the Demonstrator Board) respectively. The two signals are combined through the IC3 OR-gate. The resulting signal must be processed in the ‘µP or other logic’ block. One of the simplest solutions would be a latch circuit, which on a high pulse forces the output go low. This causes the ‘Electronic enabling/disabling circuit’ to disable the ampliﬁer. Through manual intervention and/or after a certain while, the latch should be reset to a HIGH logic level, which in turn re-enables the ampliﬁer.

R10

R2 C1

R11

IC2

IC1

R12

IC3

µP OR

OTHER

LOGIC to enabling/

disabling circuit

001aaf156

Table 3. Components

Component Value

R1, R4 270 Ω R2, R3 4.7 kΩ R5, R6, R7, R8, R9, R10, R11, R12 10 kΩ C1, C2 4.7 nF D1, D5 Philips PDZ10B D2, D3, D4, D6 Philips PDZ5.1B Q1 Philips BC846 Q2 Philips BC856 IC1, IC2 Fast operational ampliﬁer; feed with +12 V and

−12 V supplies

IC3 Philips HEF4071; feed with 5 V

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Philips Semiconductors

6.3 Sonic performance versus Efﬁciency trade-off

The dead-time that is allowed between Q13 and Q14 conduction determines the efﬁciency of the Demonstrator Board for a great deal; a long dead-time leads to better efﬁciency. On the other side,long dead-time also leads to worse sonic performance; it has important adverse consequences for e.g. THD.

Short dead-time causes quiescent current to go up, thus reducing efﬁciency and improving sonic performance. The higher quiescent current is the result of more cross-conduction of Q13 and Q14. So, most of the power that is lost in this way is dissipated in Q13 and Q14, which may heat-up excessively. This may cause thermally instable behavior of the MOSFETs. For that reason, the Demonstrator Board is shipped in low quiescent current mode – during initial evaluation the risk of damaging the MOSFETs through thermal runaway is thus reduced.

Nevertheless, by modifying one resistor value, the dead-time can be shortened and evaluation in enhanced sonic performance mode can take place. Changing R9 to a lower value decreases dead-time. It is left the responsibility of the experimenter to prevent thermal runaway, but assistance from Philips will be available through the local sales representatives.

UM10155

Discrete Class D High Power Audio Ampliﬁer

To reduce the risk of thermal runaway in the enhanced sonic performance mode, a thermal feedback loop can be implemented: the operating temperature of the MOSFETs can be fed-back to the dead-time control by changing the ﬁxed R9 value, mounting a PTC resistor on the heatsink of the MOSFETs and connecting the PTC in parallel with R9. Again, any changes are left the responsibility of the experimenter, but assistance from Philips will be available through the local sales representatives.

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Philips Semiconductors

7. Legal information

UM10155

Discrete Class D High Power Audio Ampliﬁer

7.1 Deﬁnitions

Draft — The document is a draft version only. The content is still under

internal review and subject to formal approval, which may result in modiﬁcations or additions. Philips Semiconductors does not give any representations or warranties as to the accuracy or completeness of information includedherein and shallhave noliabilityfor theconsequences of use of such information.

7.2 Disclaimers

General — Information in this document is believed to be accurate and

reliable. However, Philips Semiconductors does not give any representations or warranties, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information.

Right to make changes — Philips Semiconductors reserves the right to make changes to information published in this document, including without limitation speciﬁcations and product descriptions, at any time and without notice. This document supersedes and replaces all information supplied prior to the publication hereof.

Suitability for use — Philips Semiconductors products are not designed, authorized or warranted to be suitable for use in medical, military, aircraft, space or life support equipment, nor in applications where failure or

malfunction of a Philips Semiconductors product can reasonably be expected to result in personal injury, death or severe property or environmental damage. Philips Semiconductors accepts no liability for inclusion and/or use of Philips Semiconductors products in such equipment or applications and therefore such inclusion and/or use is at the customer’s own risk.

Applications — Applications that are described herein for any of these products are for illustrative purposes only. Philips Semiconductors makes no representation or warranty that such applications will be suitable for the speciﬁed use without further testing or modiﬁcation.

7.3 Patents

Notice is herewith given that the subject device uses one or more of the following patents and that each of these patents may have corresponding patents in other jurisdictions.

WO 03/090343 — owned by Koninklijke Philips Electronics N.V. (int. patent application)

7.4 Trademarks

Notice: All referenced brands, product names, service names and trademarks are the property of their respective owners.

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Philips Semiconductors

8. Contents

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 Circuit diagram. . . . . . . . . . . . . . . . . . . . . . . . . . 4

3 Printed-circuit board layout . . . . . . . . . . . . . . . 5

4 Speciﬁcations. . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.1 Pop-less/click-less start-up and shutdown . . . . 6

4.2 Overcurrent protection . . . . . . . . . . . . . . . . . . . 6

4.3 Important notice . . . . . . . . . . . . . . . . . . . . . . . . 7

5 Wiring diagram and powering-up. . . . . . . . . . . 7

6 Adding external features. . . . . . . . . . . . . . . . . . 8

6.1 Electronic enabling/disabling of the ampliﬁer . . 8

6.2 Short-circuit and overcurrent protection . . . . . . 9

6.3 Sonic performance versus Efﬁciency trade-off 10

7 Legal information. . . . . . . . . . . . . . . . . . . . . . . 11

7.1 Deﬁnitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7.2 Disclaimers . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7.3 Patents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

7.4 Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . 11

8 Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

UM10155

Discrete Class D High Power Audio Ampliﬁer

Please be aware that important notices concerning this document and the product(s) described herein, have been included in section ‘Legal information’.

For more information, please visit: http://www.semiconductors.philips.com. For sales office addresses, email to: [email protected].

Date of release: 5 September 2006

Document identifier: UM10155_2