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Class-D Audio Amplifier Rev AN10436 TDA8932B/33(B) Class-D audio amplifier Rev. 01 — 12 December 2007 Application note Document information Info Content Keywords Class-D amplifier, High efficiency, Switch mode amplifier, Flat TV. Abstract This application note describes a stereo Switched Mode Amplifier (SMA) for audio, based on either the TDA8932B or TDA8933(B) Class-D audio amplifier device of NXP Semiconductors, which has been designed for Flat TV applications. The TDA8932B device is the high-power version that delivers an output power of 2 × 10 WRMS to 2 × 25 WRMS in a Single Ended (SE) configuration or 10 WRMS to 50 WRMS in a Bridge Tied Load (BTL) configuration. The TDA8933(B) device is the low-power version that delivers an output power of 2 × 5 WRMS to 2 × 15 WRMS in a SE configuration or 10 WRMS to 30 WRMS in a BTL configuration. This high efficiency SMA device has been designed to operate without a heat sink and has the flexibility to operate from either an asymmetrical supply or a symmetrical supply with a wide range (10 V to 36 V or ±5Vto±18 V). The TDA8932B/33(B) device utilizes two advanced features, the Thermal Foldback (TF) and the cycle-by-cycle current limiting to avoid audio holes (interruptions) during normal operation. In addition, the TDA8932B/33(B) utilizes integrated Half Supply Voltage (HVP) buffers to simplify the design for an asymmetrical supply in the SE configuration. Control logic is integrated for a pop free transition between on/off. A SLEEP mode is incorporated to comply with the power saving regulations. An application designed around the TDA8932B/33(B) device is very robust because of the internal protection features, such as a number of voltage protections, OverCurrent Protection (OCP) and OverTemperature Protection (OTP). NXP Semiconductors AN10436 TDA8932B/33(B) Class-D audio amplifier Revision history Rev Date Description 01.00 20071212 First release Contact information For additional information, please visit: http://www.nxp.com For sales office addresses, please send an email to: [email protected] AN10436_1 © NXP B.V. 2007. All rights reserved. Application note Rev. 01 — 12 December 2007 2 of 55 NXP Semiconductors AN10436 TDA8932B/33(B) Class-D audio amplifier 1. Introduction This application note describes a reference design of a Switched Mode Amplifier (SMA) for audio, based on the TDA8932B or TDA8933(B) device of NXP Semiconductors operating from an asymmetrical supply. The TDA8932B device and the TDA8933(B) device are pin-to-pin compatible and can be used in either a stereo SE configuration or a mono BTL configuration. The TDA8932B is the high-power version and the TDA8933(B) is the low-power version. Together they cover a wide power range per channel of 5 WRMS to 50 WRMS. The two versions are available in the SO32 package (TDA8932BT, TDA8933T) and the HTSSOP32 package (TDA8932BTW, TDA8933BTW). The TDA8932B/33(B) Class-D amplifier is intended for: • Flat TV application • Flat panel monitors • Multimedia systems, docking stations • Wireless speakers • Microsystems Distinctive features • High efficiency Class-D audio amplifier due to a low RDSon in SE configuration. • Operates from a wide voltage range 10 V to 36 V (asymmetrical) or ±5 V to ±18 V (symmetrical). • Maximum power capability: – TDA8932B is 2 × 30 WRMS short time output power in 4 Ω SE without heat sink. – TDA8933(B) is 2 × 20 WRMS short time output power in 8 Ω SE without heat sink. • Cycle-by-cycle current limiting to avoid interruption during normal operation. • Unique Thermal Foldback (TF) to avoid interruption during normal operation. • Integrated Half Supply Voltage (HVP) buffers for reference and SE output capacitance (asymmetrical supply). • Internal logic for pop free power supply on/off cycling. • Low standby current in SLEEP mode for power saving regulations. Protection features • Window Protection (WP) • UnderVoltage Protection (UVP) • OverVoltage Protection (OVP) • UnBalance Protection (UBP) • OverCurrent Protection (OCP) • OverTemperature Protection (OTP) • ESD protection These features enable an engineer to design a high performance, reliable and cost effective SMA with only a small number of external components. AN10436_1 © NXP B.V. 2007. All rights reserved. Application note Rev. 01 — 12 December 2007 3 of 55 NXP Semiconductors AN10436 TDA8932B/33(B) Class-D audio amplifier 1.1 Block diagram OSCREF OSCIO VDDA 10 31 8 28 BOOT1 OSCILLATOR 29 2 V IN1P DRIVER DDP1 HIGH 27 VSSD PWM OUT1 MODULATOR CTRL DRIVER 26 V LOW SSP1 3 IN1N 21 12 MANAGER BOOT2 INREF 20 15 V IN2P DRIVER DDP2 HIGH 22 PWM OUT2 MODULATOR CTRL DRIVER 23 V LOW SSP2 14 IN2N PROTECTIONS: OVP, OCP, OTP, VDDA UVP, TF, WP 25 STABILIZER 11 V STAB1 4 DIAG VSSP1 VDDA 24 STABILIZER 11 V STAB2 7 CGND VSSP2 6 18 POWERUP REGULATOR 5 V DREF VSSD MODE 5 ENGAGE 11 VDDA HVPREF 30 HVP1 V 13 TDA8932B SSA 19 TEST HVP2 HALF SUPPLY VOLTAGE 9 1, 16, 17, 32 001aaf597 VSSA VSSD(HW) Fig 1. Block diagram 1.2 Fixed frequency pulse width modulated Class-D concept The TDA8932B/33(B) device is a closed loop fixed frequency pulse width modulated Class-D amplifier with two differential analog inputs, each driving an independent power stage (see Figure 2). The power stage consists out of a low side and a high side N-channel MOSFET. AN10436_1 © NXP B.V. 2007. All rights reserved. Application note Rev. 01 — 12 December 2007 4 of 55 NXP Semiconductors AN10436 TDA8932B/33(B) Class-D audio amplifier The TDA8932B/33(B) can be configured for use in either SE or BTL. The major benefits of an SE configuration compared to a BTL configuration are cost and efficiency. This is because: • Only one pair of power switches is required for each channel. • Only one LP filter (inductor and film capacitor) is required for each channel. • Only two power stages for stereo in one package, therefore no heat sink required. TDA8932B/33(B) PWM IN1P 2 27 OUT1 LP 3 FILTER CSE IN1N PWM IN2N 14 22 OUT2 15 LP FILTER C IN2P SE 010aaa000 Fig 2. TDA8932B/33(B) in SE configuration An internal feedback network has a fixed closed loop gain of 30 dB in the SE configuration (36 dB in the BTL configuration). The Pulse Width Modulation (PWM) output signal has a oscillator frequency that is fixed by either: • An internal oscillator when configured as master. • An external oscillator when configured as slave. The pulse width will be modulated according to the input signal. Section 3 describes the complete application design of the TDA8932B/33(B) and includes the dimensioning of the LP output filter. 1.3 Typical application circuits (simplified) 1.3.1 Asymmetrical supply stereo SE configuration The simplified application circuit of the TDA8932B/33(B) device when operated from an asymmetrical supply (single supply) can be seen in Figure 3. The TDA8932B/33(B) incorporates three integrated half supply voltage buffers to simplify the design for an asymmetrical supply in SE configuration. One buffer is for the reference decoupling capacitor (CHVPREF) on HVPREF (pin 11) and two other buffers are for the two AC-couple capacitors (CSE) in series with the speaker. AN10436_1 © NXP B.V. 2007. All rights reserved. Application note Rev. 01 — 12 December 2007 5 of 55 NXP Semiconductors AN10436 TDA8932B/33(B) Class-D audio amplifier VP Rvdda VP VPA 10 Ω Cvdda Cvddp 100 nF 220 μF (35 V) GND VSSD(HW) VSSD(HW) 1 32 Cin Cvssp IN1P OSCIO 100 nF + 2 31 HVP1 Cin 470 nF IN1N HVP1 − 3 30 Cvddp Csn 470 nF DIAG VDDP1 100 nF 470 pF 4 29 VP Rsn ENGAGE BOOT1 Ω MUTE control 5 28 (1) 10 Cbo Cen POWERUP OUT1 15 nF Llc 470 nF 6 27 CGND VSSP1 SLEEP control 7 26 VDDA STAB1 HVP1 Cosc U1 VPA 8 25 Clc Cse VSSA TDA8932B/ STAB2 100 nF 9 33(B) 24 Cstab Rosc OSCREF VSSP2 100 nF 10 23 39 kΩ HVPREF OUT2 Llc 11 22 Cbo Chvpref Chvp (1) INREF BOOT2 15 nF Rsn 47 μF (25 V) 100 nF 12 21 10 Ω Cinref TEST VDDP2 HVP2 100 nF Csn 13 20 VP Clc Cse Cin Cvddp 470 pF IN2N HVP2 + 14 19 100 nF Cin 470 nF IN2P DREF − 15 18 HVP2 Cdref 470 nF V CHVP SSD(HW) VSSD(HW) 100 nF 100 nF 16 17 010aaa418 (1) The TDA8933T device requires a 1 MΩ resistor in parallel with the bootstrap capacitor Cbo. TDA8932BT, TDA8932BTW and TDA8933BTW devices do not require a 1 MΩ resistor. Fig 3. Simplified SE application TDA8932B/33(B) (asymmetrical supply) 1.3.2 Symmetrical supply stereo SE configuration The TDA8932B/33(B) can operate also from a symmetrical supply (see Figure 4). The three half supply voltage buffers are disabled. HVPREF (Pin 11), HVP1 (pin 30) and HVP2 (pin 19) should be connected to ground when supplied from a symmetrical supply. AN10436_1 © NXP B.V. 2007. All rights reserved. Application note Rev. 01 — 12 December 2007 6 of 55 NXP Semiconductors AN10436 TDA8932B/33(B) Class-D audio amplifier VDD Rvdda VDD VDDA 10 Ω Cvdda Cvddp μ 100 nF 220 F (25 V) GND Cvssa Cvssp μ 100 nF 220 F Rvssa (25 V) VSS VSSA 10 Ω VSS VSSD(HW) VSSD(HW) VSS VSSA 1 32 VSSA Cin Cvssp IN1P OSCIO + 2 31 100 nF Cin 470 nF IN1N HVP1 − 3 30 Cvddp Csn 100 nF 470 pF 470 nF DIAG VDDP1 4 29 VDD Rsn ENGAGE BOOT1 10 Ω MUTE control 5 28 (1) Cbo Cen POWERUP OUT1 15 nF Llc 470 nF 6 27 CGND VSSP1 SLEEP control 7 26 VSS Clc VDDA STAB1 Cosc VDDA 8 U1 25 VSSA TDA8932B/ STAB2 100 nF VSSA 9 24 33(B) Cstab Rosc OSCREF VSSP2 100 nF VSSA 10 23 VSS 39 kΩ HVPREF OUT2 Llc 11 22 Cbo INREF BOOT2 15 nF 21 Clc 12 (1) Rsn Cinref TEST VDDP2 10 Ω 100 nF VSSA 13 20 VDD Cin IN2N HVP2 Cvddp Csn + 14 19 100 nF 470 pF Cin 470 nF IN2P DREF − Cvssp 15 18 Cdref 100 nF 470 nF VSSD(HW) VSSD(HW) 100 nF VSSA 16 17 VSSA VSS 010aaa419 (1) The TDA8933T device requires a 1 MΩ resistor in parallel with the bootstrap capacitor Cbo.
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