Datasheet TDA8920CTH (NXP) - 8

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NXP Semiconductors TDA8920C 2
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110 W class-D power amplifier 8.2 Pulse-width modulation frequency
The amplifier output signal is a PWM signal with a typical carrier frequency of between 250 kHz and 450 kHz. A 2nd-order LC demodulation filter on the output is used to convert the PWM signal into an analog audio signal. The carrier frequency is determined by an external resistor, ROSC, connected between pins OSC and VSSA. The optimal carrier frequency setting is between 250 kHz and 450 kHz. The carrier frequency is set to 345 kHz by connecting an external 30 kΩ resistor between pins OSC and VSSA. See Table 9 on page 14 for more details. If two or more class-D amplifiers are used in the same audio application, it is recommended that an external clock circuit be used with all devices (see Section 13.4). This will ensure that they operate at the same switching frequency, thus avoiding beat tones (if the switching frequencies are different, audible interference known as ‘beat tones’ can be generated)
8.3 Protection
The following protection circuits are incorporated into the TDA8920C:
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Thermal protection:
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Thermal FoldBack (TFB)
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OverTemperature Protection (OTP)
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OverCurrent Protection (OCP)
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Window Protection (WP)
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Supply voltage protection:
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UnderVoltage Protection (UVP)
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OverVoltage Protection (OVP)
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UnBalance Protection (UBP) How the device reacts to a fault conditions depends on which protection circuit has been activated.
8.3.1 Thermal protection
The TDA8920C employes an advanced thermal protection strategy. A TFB function gradually reduces the output power within a defined temperature range. If the temperature continues to rise, OTP is activated to shut down the device completely.
8.3.1.1 Thermal FoldBack (TFB)
If the junction temperature (Tj) exceeds the thermal foldback activation threshold, the gain is gradually reduced. This reduces the output signal amplitude and the power dissipation, eventually stabilizing the temperature. TFB is specified at the thermal foldback activation temperature Tact(th_fold) where the closed-loop voltage gain is reduced by 6 dB. The TFB range is: Tact(th_fold) − 5 °C < Tact(th_fold) < Tact(th_prot) The value of Tact(th_fold) for the TDA8920C is approximately 153 °C; see Table 8 for more details. TDA8920C_2 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 02 — 11 June 2009 8 of 39
Document Outline 1. General description 2. Features 3. Applications 4. Quick reference data 5. Ordering information 6. Block diagram 7. Pinning information 7.1 Pinning 7.2 Pin description 8. Functional description 8.1 General 8.2 Pulse-width modulation frequency 8.3 Protection 8.3.1 Thermal protection 8.3.1.1 Thermal FoldBack (TFB) 8.3.1.2 OverTemperature Protection (OTP) 8.3.2 OverCurrent Protection (OCP) 8.3.3 Window Protection (WP) 8.3.4 Supply voltage protection 8.4 Differential audio inputs 9. Limiting values 10. Thermal characteristics 11. Static characteristics 12. Dynamic characteristics 12.1 Switching characteristics 12.2 Stereo SE configuration characteristics 12.3 Mono BTL application characteristics 13. Application information 13.1 Mono BTL application 13.2 Pin MODE 13.3 Estimating the output power 13.3.1 Single-Ended (SE) 13.3.2 Bridge-Tied Load (BTL) 13.4 External clock 13.5 Heatsink requirements 13.6 Pumping effects 13.7 Application schematic 13.8 Curves measured in reference design 14. Package outline 15. Soldering of SMD packages 15.1 Introduction to soldering 15.2 Wave and reflow soldering 15.3 Wave soldering 15.4 Reflow soldering 16. Soldering of through-hole mount packages 16.1 Introduction to soldering through-hole mount packages 16.2 Soldering by dipping or by solder wave 16.3 Manual soldering 16.4 Package related soldering information 17. Revision history 18. Legal information 18.1 Data sheet status 18.2 Definitions 18.3 Disclaimers 18.4 Trademarks 19. Contact information 20. Contents