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Philips TDA1562Q Application Note

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AN<nnnnn>
Applying the TDA1562Q Class H amplifier
Rev. 01.02 — 05 May 2006
Document information
Info
Content
Keywords
Car Audio Amplifier, Class H, High power, High efficiency
Abstract
This document contains application information for the TDA1562Q class
H amplifier.
Application note

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  • Page 1 Applying the TDA1562Q Class H amplifier Rev. 01.02 — 05 May 2006 Application note Document information Info Content Keywords Car Audio Amplifier, Class H, High power, High efficiency Abstract This document contains application information for the TDA1562Q class H amplifier.
  • Page 2 Second revision Contact information For additional information, please visit: http://www.semiconductors.philips.com For sales office addresses, please send an email to: sales.addresses@www.semiconductors.philips.com <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 2 of 62...

  • Page 3: Introduction

    1. Introduction 1.1 Amplifier description The TDA1562Q is a mono BTL amplifier, capable of delivering 70W into a 4 Ω load at a supply voltage of 14.4 V, without the need to use an external DC-DC converter to achieve a higher supply voltage. The high output power is achieved by means of a Class H circuit, which enables the amplifier to almost double its supply voltage at moments when more than 20W output power is needed.
  • Page 4 For proper operation at low frequencies it is therefore necessary that large lifter capacitors are used. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 5 14.4V and a THD of 10% will be 70W. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 5 of 62...

  • Page 6: Block Diagram

    AN<nnnnn> Philips Semiconductors TDA1562Q application note 1.3 Block diagram Fig 3. Block diagram of the TDA1562 <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 6 of 62...

  • Page 7: Pinning

    Positive terminal of lift electrolytic capacitor 2 Internal reference voltage Negative terminal of lift electrolytic capacitor 2 STAT Status I/O SGND Signal ground <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 7 of 62...

  • Page 8: Quick Reference Data

    AN<nnnnn> Philips Semiconductors TDA1562Q application note 1.5 Quick reference data <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 8 of 62...

  • Page 9: Features And Diagnostics

    The fast mute may cause a plop-like sound when it is engaged at a high output level, but in some situations a fast mute is required. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...

  • Page 10: The Diagnostic Pin

    When the diagnostic output is high, a load has been detected. When it is low, no load has been detected. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 10 of 62...
  • Page 11 When the status I/O pin is used as an input pin, the device can be forced into class H operation, class AB operation or fast mute. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 12 Finally, when there is a short across the load (between the two outputs), the diagnostic pin will go low for 20ms, and then up for 50µs as long as the short circuit is present. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 13 Just before the thermal protection becomes active, at a case temperature of 145°C, the diagnostic pin will go low indicating a too high temperature. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...

  • Page 14: Differential Inputs

    TDA1562Q application note Fig 6. Temperature diagnostics 2.4 Differential inputs The TDA1562Q has differential (symmetrical) inputs. A symmetrical input has the advantage that common mode interference that is picked up in the input lines is effectively suppressed. Especially in an automotive application where there is much interference by external sources, the suppression of noise is very important.
  • Page 15 Floating Pull down to 0V rapidly During engine starts, the Supply voltage may drop to values below 5V. The TDA1562Q is equipped with a so-called “Low Vp Mute circuit” which will mute the amplifier when the supply voltage drops to values below 7V, the amplifier will be automatically muted.

  • Page 16: Protections And Overstress Conditions

    4. Protections and overstress conditions Apart from the thermal protection circuitry which is mentioned in paragraph 2.3, the TDA1562Q is also equipped with short circuit protections. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
  • Page 17 In extreme conditions (continuous clipping signal), the charging and/or lifting circuits may overheat after prolonged operation. A number of other conditions that are known to have caused damage to the TDA1562Q are: 1. Driving the amplifier into thermal protection while the device is forced into class H mode by means of the status I/O pin.

  • Page 18: Application Description

    “on” condition the lifter capacitors will be charged, and the risk of this condition occurring is minimal. When a very inductive load is connected to the TDA1562Q and the device is driven with a signal containing a high amount of high frequency components (>3kHz) the risk exists that the protection circuits of the device will be activated when the input level exceeds 1.2Vrms.
  • Page 19 AB BTL amplifier with a symmetrical input. In this paragraph, the different components in the application will be discussed. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 20 B: 220nF input capacitors C: 470nF input capacitors Fig 8. Low frequency roll off with different values of input capacitors <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 20 of 62...
  • Page 21 Choosing a smaller value than 100nF could lead to oscillations in the supply lines. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 21 of 62...
  • Page 22 ESR will increase and the capacitance will decrease, but for applications where extremely low operating temperatures (below <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...

  • Page 23: Dimensioning Of The Class H Application

    The purpose of these capacitors is to filter out any HF interference coming into the amplifier. The TDA1562Q is very sensitive to capacitive loads to ground, so a small capacitor from one of the outputs to ground could cause instability.
  • Page 24 The measurements were taken at a supply voltage of 14.4V, with a 4Ω load , a signal frequency of 30Hz and lift capacitors of 10000µF. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 25 I charge IClift I audio (fig 2b) Fig 12. Charge current, output signal and lift capacitor voltage at Po=40W, f=30Hz <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 25 of 62...
  • Page 26 (fig 2b) Fig 14. Charge current, output signal and lift capacitor voltage while lift capacitor is fully discharged, f=30Hz <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 26 of 62...
  • Page 27 This may eventually result in damage to the amplifiers. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 27 of 62...

  • Page 28: Minimum Load Impedance

    TDA1562Q application note 5.3 Minimum load impedance Philips strongly advises against load impedances lower than 4Ω because the output stage was designed for 4Ω loads. The maximum repetitive output current for which the TDA1562 output stage is designed is 8A. To ensure that no damage can be caused by too high output currents the maximum output current protection activates at an output current of 7.5A.

  • Page 29: Used Components

    When the amplifier is mainly used for driving a subwoofer, increasing the size of the lift capacitors is strongly advised. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 29 of 62...

  • Page 30: Pcb Lay Out

    The following figures show the PCB lay-out of the application PCB of the TDA 1562Q. a. PCB components top view b. PCB copper top view Fig 15. Top view of the TDA1562Q PCB <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved.
  • Page 31 Philips Semiconductors TDA1562Q application note a. Bottom side component view b. Bottom side copper layer Fig 16. Bottom view of the TDA1562Q PCB (as seen from above). <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...

  • Page 32: Thermal Behavior

    5.7 Thermal behavior 5.7.1 Power dissipation In order to calculate a suitable heatsink for the TDA1562Q it is necessary to know the power dissipation in the amplifier. Usually, the power dissipation of an amplifier is determined by driving the amplifier to a certain output power, and then measuring the total power delivered by the power supply.

  • Page 33: Power Dissipation Curves

    33W. For the TDA1562Q the situation is different. Up to output power levels of 11W the amplifier behaves like a single channel BTL amplifier, driving a 4 Ω load at a supply voltage of 14.4V.
  • Page 34 (fig.19). When we draw a line down from the point where the power dissipation in the class AB amplifier is 17.5W to the curve of the TDA1562Q, we see that at that output level the power dissipation of the TDA1562Q is only 9.3W. this means that the heatsink for the TDA1562Q can be considerably smaller than that of the normal class AB amplifier.

  • Page 35: Heatsink Calculation

    (Rth c-hs) to be 0.1K/W (thermal compound used). When we assume that the maximum ambient temperature will be 65°C we can calculate the thermal resistance for the external heatsinks for the TDA1562Q and for the class AB amplifier.
  • Page 36 = 4.25 K/W − − There is a difference of 1.65 K/W between the heatsink the TDA1562Q needs and the heatsink the class AB amplifier needs. Although 1.65 K/W does not seem to be a big difference, it usually means a considerable increase in heatsink size, as is illustrated in figure 21.

  • Page 37: Typical Waveforms

    The result of this is that the sinewave output signal will expand upwards. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 37 of 62...
  • Page 38 It is visible that the tops of the sine waves are becoming slightly “sharper” and it is also visible that the bottom part of the sinewaves starts “flattening” <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 39 <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 39 of 62...
  • Page 40 Philips Semiconductors TDA1562Q application note OUT 1 Vload OUT 2 Fig 26. Waveforms during clipping at low frequencies (40Hz) <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 40 of 62...
  • Page 41 Since there are two output stages, there are two lift capacitors, each taking care of one half of the sine wave. This is illustrated in figure 28. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 42 4A and the current drawn from the lift capacitor increases too. The lift capacitor is still capable of storing enough energy to sustain the signal during the complete sinewave. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 42 of 62...
  • Page 43 Fig 30. Current waveform during lifting (Po=40W @ f=1kHz) I charge I audio Clift + Clift - Fig 31. Current waveform during clipping (Po=55W @ f=1kHz) <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 43 of 62...
  • Page 44 “draining” the lift capacitors is much greater than at high frequencies. Also, the charge circuitry is stressed much harder when low frequency signals are amplified. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 44 of 62...

  • Page 45: Measurement Curves

    1kHz and 10kHz. The “bump” at 10W output powers shows the level at which the lifting circuitry becomes active. The notch in the 100Hz and 1kHz curves is caused by internal circuitry. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 45 of 62...
  • Page 46 Since these are constant numbers, the THD+noise ratio decreases as the output power increases. Above 10W, artifacts from the lifter circuitry are responsible for increased THD numbers. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 46 of 62...
  • Page 47 Pout vs Vp f=1kHz Rl=4ohms Clift=8200uF/16V Vp(V) A: THD=10% B: THD=0.5% Fig 35. Pout vs. Vp at constant THD levels <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 47 of 62...
  • Page 48 Philips Semiconductors TDA1562Q application note SVRR(dB) SVRR vs Freq Vp=14.4V Rload=4ohms Rin=0 Vripple=2Vp-p F(kHz) Fig 36. Supply voltage ripple rejection <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 48 of 62...

  • Page 49: Driving A Dual Voice Coil Speaker

    Vsupply Clift SPEAKER Parasitic Vpulse Pgnd Fig 37. One output stage of the TDA1562 with negative pulse <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 49 of 62...
  • Page 50 The schottky diode will conduct most of the current during a negative voltage pulse. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 51 The yellow trace shows the current through the parasitic diode at 5A/division and the magenta trace shows the current through the schottky diode at 10A/division. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...

  • Page 52: Positive Voltage Pulses At The Outputs

    Under these conditions it was only possible to damage the device by applying a DC voltage higher than 25V to the output. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 53 Schottky diode between the negative terminal of the lift capacitor and the supply rail did give the desired results. The resulting circuit is shown in fig. 42. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 54 Finally, adding a 50mΩ resistor between the output and the diode gave some more improvement. The total circuitry needed for optimum reliability in dual voice coil applications is shown in fig.43. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 54 of 62...

  • Page 55: Protection Circuits

    THD and in the case of a full range application, very low THD can be heavily weighted. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 56 R2 sets the gain of the feedback loop and the steepness of the limiting knee. R4, R8, R9, R11 and C2 set up the DC bias and filtering for the Gate of Q1, the special Philips Semiconductor's FET. The FET is designed to be linear over a wide operating range and is used in tuners as the AM amplifier.

  • Page 57: Ovp Circuit

    A second TDA1562 can be connected by using another diode (D3). 8.4 Load detection for subwoofers with very large self inductance <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 57 of 62...
  • Page 58 After the TDA1562 is switched from standby to mute or on, the mode pin can be switched to mute to see if a load is present on the outputs. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...
  • Page 59 With this external circuit it has become possible now, to detect subwoofers with an inductance of about > 0.5mH (at 1 kHz) at room temperature and Vp=14.4V . <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...

  • Page 60: Conclusion

    Thanks to the high efficiency of the amplifier the heatsink needed for such an amplifier can be considerably smaller that that of a comparable class AB amplifier. <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006...

  • Page 61: Table Of Contents

    OVP circuit ............. 57 Load detection for subwoofers with very large self inductance..............57 Conclusion ............60 Contents............61 <12NC> © Koninklijke Philips Electronics N.V. 2004. All rights reserved. Application note Rev. 01.02 — 05 May 2006 61 of 62...
  • Page 62 AN<nnnnn> Philips Semiconductors TDA1562 application note © Koninklijke Philips Electronics N.V. 2004 All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.

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