Datasheet

ManualsBrandsSTMICROELECTRONICS ManualsLinear ICsLinear IC - Audio amplifier 2-channel (stereo) Class D PowerSSO 36

March 2011 Doc ID 13541 Rev 5 1/37

TDA7491LP

2 x 5-watt dual BTL class-D audio amplifier

Features

■ 5 W + 5 W continuous output power:

= 8 Ω, THD = 10% at V

= 9 V

■ 5 W + 5 W continuous output power:

= 4 Ω, THD = 10% at V

= 6.6 V

■ Wide range single supply operation (5 V - 14 V)

■ High efficiency (η = 90%)

■ Four selectable, fixed gain settings of

nominally 20 dB, 26 dB, 30 dB and 32 dB

■ Differential inputs minimize common-mode

noise

■ Filterless operation

■ No ‘pop’ at turn-on/off

■ Standby and mute features

■ Short-circuit protection

■ Thermal overload protection

■ Externally synchronizable

Description

The TDA7491LP is a dual BTL class-D audio

amplifier with single power supply designed for

LCD TVs and monitors.

Thanks to the high efficiency and

exposed-pad-down (EPD) package no separate

heatsink is required.

Furthermore, the filterless operation allows a

reduction in the external component count.

The TDA7491LP is pin-to-pin compatible with the

TDA7491P and TDA7491HV.

PowerSSO-36 with

exposed pad down

Table 1. Device summary

Order code Operating temperature Package Packaging

TDA7491LP -40 to 85 °C PowerSSO-36 EPD Tube

TDA7491LP13TR -40 to 85 °C PowerSSO-36 EPD Tape and reel

www.st.com

Summary of content (37 pages)

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TDA7491LP 2 x 5-watt dual BTL class-D audio amplifier Features ■ 5 W + 5 W continuous output power: RL = 8 Ω, THD = 10% at VCC = 9 V ■ 5 W + 5 W continuous output power: RL = 4 Ω, THD = 10% at VCC = 6.
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Contents TDA7491LP Contents 1 Device block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3 4 5 2.1 Pin out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.2 Pin list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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TDA7491LP 7 Contents Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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List of tables TDA7491LP List of tables Table 1. Table 2. Table 3. Table 4. Table 5. Table 6. Table 7. Table 8. Table 9. Table 10. 4/37 Device summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Pin description list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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TDA7491LP List of figures List of figures Figure 1. Figure 2. Figure 3. Figure 4. Figure 5. Figure 6. Figure 7. Figure 8. Figure 9. Figure 10. Figure 11. Figure 12. Figure 13. Figure 14. Figure 15. Figure 16. Figure 17. Figure 18. Figure 19. Figure 20. Figure 21. Figure 22. Figure 23. Figure 24. Figure 25. Figure 26. Figure 27. Figure 28. Figure 29. Figure 30. Figure 31. Figure 32. Figure 33. Figure 34. Figure 35. Figure 36. Figure 37. Figure 38. Internal block diagram (one channel only) . . . . . . . .
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Device block diagram 1 TDA7491LP Device block diagram Figure 1 shows the block diagram of one of the two identical channels of the TDA7491LP. Figure 1.
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TDA7491LP Pin description 2 Pin description 2.1 Pin out Figure 2.
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Pin description 2.2 TDA7491LP Pin list Table 2.
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TDA7491LP Electrical specifications 3 Electrical specifications 3.1 Absolute maximum ratings Table 3. Absolute maximum ratings Symbol 3.2 Parameter Value Unit VCC DC supply voltage 18 V VI Voltage limits for input pins STBY, MUTE, INNA, INPA, INNB, INPB, GAIN0, GAIN1 -0.3 to 3.6 V Top Operating temperature -40 to 85 °C Tj Operating junction temperature -40 to 150 °C Tstg Storage temperature -40 to 150 °C Thermal data Refer also to Section 5.
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Electrical specifications 3.3 TDA7491LP Electrical specifications Unless otherwise stated, the results in Table 5 below are given for the conditions: VCC = 9 V, RL (load) = 8Ω, ROSC = R3 = 39 kΩ, C8 = 100 nF, f = 1 kHz, GV = 20 dB, and Tamb = 25 °C. Table 5.
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TDA7491LP Electrical specifications Table 5. Symbol Electrical specifications (continued) Parameter Condition Min Typ Max Unit SVRR Supply voltage rejection ratio fr = 100 Hz, Vr = 1 Vpp, CSVR = 10 µF - 50 - dB Tr, Tf Rise and fall times - - 40 - ns fSW Switching frequency Internal oscillator, master mode 290 320 350 kHz fSWR Switching frequency range (1) 250 - 400 kHz VinH Digital input high (H) 2.3 - - VinL Digital input low (L) - - 0.
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Characterization curves 4 TDA7491LP Characterization curves The following characterization curves were made using the TDA7491LP demo board. The LC filter for the 4-Ω load uses components of 15 µH and 470 nF and that for the 8-Ω load uses 33 µH and 220 nF. 4.1 With 4-Ω load at VCC = 6.6 V Figure 3. Output power vs. supply voltage 6 Test Condition : Vcc = 5~6.
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TDA7491LP Characterization curves Figure 5. THD vs. output power (100 Hz) THD(%) Test Condition: Vcc =6.6V, RL= 4 ohm, Rosc =39kΩ, Cosc =100nF, f =100Hz, Gv =30dB, Tamb =25°C Specification Limit: Typical: Po =5W @ THD =10% Po per Channel (W) Figure 6. THD vs. frequency THD(%) Test Condition: Vcc =6.6V, RL= 4 ohm, Rosc =39kΩ, Cosc =100nF, f =1kHz, Gv =30dB, Po =1W Tamb =25°C Specification Limit: Typical: THD<0.
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Characterization curves Figure 7. TDA7491LP Frequency response Amplitude (dB) Test Condition: Vcc =6.6V, RL= 4 ohm, Rosc =39kΩ, Cosc =100nF, f =1kHz, Gv =30dB, Po =1W Tamb =25°C Cin = 1uF Specification Limit: Max: +/-3dB @20Hz to 20kHz Frequency (Hz) Figure 8. Crosstalk vs. frequency Crosstalk (dB) Test Condition: Vcc =6.
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TDA7491LP Characterization curves Figure 9. FFT (0 dB) FFT (dB) FFT (0 dB) Test Condition: Vcc =6.6V, RL= 4 ohm, Rosc =39kΩ, Cosc =100nF, f = 1kHz, Gv =30dB, Po =1W Tamb =25°C Specification Limit: Typical: >60dB for the harmonic frequency Frequency (Hz) Figure 10. FFT (-60 dB) FFT (dB) FFT (-60 dB) Test Condition: Vcc =6.
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Characterization curves TDA7491LP Figure 11. Power supply rejection ratio vs. frequency PSRR (dB) Test Condition : Vcc = 6.6V, RL = 4 ohm, Rosc =39kΩ, Cosc =100nF, Vin=0, Gv =30dB, Tamb =25°C Vr = 500mVrms Fr = 100Hz Frequency (Hz) Figure 12. Power dissipation and efficiency vs. output power Test Condition : 90 2 80 1. 8 Vcc = 6.6V, 1. 6 70 Gv =30dB, Tamb =25°C Efficiency (%) Rosc =39kΩ, Cosc =100nF, 1. 4 60 1. 2 50 1 40 0. 8 30 0. 6 20 0. 4 10 0.
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TDA7491LP Characterization curves Figure 13. Attenuation vs. voltage on pin MUTE Test Condition : RL = 4 ohm, Rosc =39kΩ, Cosc =100nF, f=1kHz, 0dB@f=1kHz, Po=1w, Gv =30dB, Tamb =25°C Attenuation (dB) Vcc = 6.6V, 5 0 -5 - 10 - 15 - 20 - 25 - 30 - 35 - 40 - 45 - 50 - 55 - 60 - 65 - 70 - 75 - 80 0 0. 5 1 1. 5 Vmute (V) 2 2. 5 3 3. 5 3 3. 5 Figure 14. Current consumption vs. voltage on pin STBY 0. 025 Test Condition : Vcc = 6.6V, 0.
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Characterization curves TDA7491LP Figure 15. Attenuation vs. voltage on pin STBY 10 0 Test Condition : RL = 4 ohm, Rosc =39kΩ, Cosc =100nF, f=1kHz, 0dB@f=1kHz, Po=1w, Gv =30dB, Tamb =25°C Attenuation (dB) Vcc = 6.6V, - 10 - 20 - 30 - 40 - 50 - 60 - 70 - 80 - 90 0 18/37 0. 5 1 Doc ID 13541 Rev 5 1. 5 2 Vstby (V) 2. 5 3 3.
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TDA7491LP With 8-Ω load at VCC = 9 V Figure 16. Output power vs. supply voltage Test Condition : Vcc = 5~9V, RL = 8 ohm, Rosc =39kΩ, Cosc =100nF, f =1kHz, Gv =30dB, Tamb =25°C Specification Limit: Typical: Vs =9V,Rl = 8 ohm Output power (W) 4.2 Characterization curves Po =5W @THD =10% Po =4W @THD =1% 6 5. 5 5 4. 5 4 3. 5 3 2. 5 2 1. 5 1 0. 5 0 THD =10% Rl =8 ohm f =1kHz THD =1% 5 6 7 8 9 Supply voltage (V) Figure 17. THD vs.
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Characterization curves TDA7491LP Figure 18. THD vs. output power (100 Hz) THD (%) 10 Test Condition: Vcc =9V, 5 2 RL= 8 ohm, Rosc =39kΩ, Cosc =100nF, f =100Hz, Gv =30dB, 1 0.5 0.2 Tamb =25°C 0.1 Specification Limit: Typical: Po =5W @ THD =10% 0.05 0.02 0.01 0.005 100m 200m 300m 400m 600m 800m 1 2 3 4 5 6 Output Power (W) Figure 19. THD vs. frequency THD (%) 1 Test Condition: Vcc =9V, 0.5 RL= 8 ohm, Rosc =39kΩ, Cosc =100nF, 0.2 f =1kHz, 0.1 Gv =30dB, Po =1W 0.05 Tamb =25°C 0.
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TDA7491LP Characterization curves Figure 20. Frequency response Ampl (dB) +2 Test Condition: Vcc =9V, +1 RL= 8 ohm, Rosc =39kΩ, Cosc =100nF, -0 f =1kHz, -1 Gv =30dB, Po =1W -2 Tamb =25°C -3 Specification Limit: Max: +/-3dB -4 @20Hz to 20kHz -5 10 20 50 100 200 500 1k 2k 5k 10k 30k Frequency (Hz) Figure 21. Crosstalk vs.
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Characterization curves TDA7491LP Figure 22. FFT (0 dB) FFT (0 dB) FFT (dB) +10 +0 Test Condition: -10 Vcc =9V, -20 RL= 8 ohm, -30 Rosc =39kΩ, Cosc =100nF, -40 -50 f = 1kHz, Gv =30dB, Po =1W Tamb =25°C -60 -70 -80 -90 -100 -110 Specification Limit: Typical: >60dB for the harmonic frequency -120 -130 -140 -150 20 50 100 200 500 1k 2k 5k 10k 20k 2k 5k 10k 20k Frequency (Hz) Figure 23.
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TDA7491LP Characterization curves Figure 24. Power supply rejection ratio vs. frequency Test Condition : Vcc = 9V, RL = 8 ohm, Rosc =39kΩ, Cosc =100nF, Ripple frequency=100Hz Vin=0, Ripple voltage=500mV Gv =30dB, Tamb =25°C Figure 25. Power dissipation and efficiency vs. output power 90 Vcc = 9V, 80 Rosc =39kΩ, Cosc =100nF, Vin=0, Gv =30dB, Tamb =25°C Efficiency (%) RL = 8 ohm, 2. 5 2 70 60 1. 5 50 40 1 Vcc=9V 30 Rload=8ohm 20 Gain=30dB 10 f=1kHz 0.
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Applications information TDA7491LP 5 Applications information 5.1 Applications circuit Figure 26. Applications circuit for class-D amplifier & Q) & Q) 6*1' & Q) & Q) 6*1' & Q) 68%B*1' 2873$ / ,13$ 2873$ X+ ,11$ - & & Q) Q) ',$* 39&&$ ',$* 6<1&/. 526& *$,1 6<1&/. - ,1 / ,1 / & ,1 5 Q) 5 - .
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TDA7491LP 5.2 Applications information Mode selection The three operating modes, defined below, of the TDA7491LP are set by the two inputs STBY (pin 20) and MUTE (pin 21) as shown in Table 6. ● Standby mode: all circuits are turned off, very low current consumption. ● Mute mode: inputs are connected to ground and the positive and negative PWM outputs are at 50% duty cycle. ● Play mode: the amplifiers are active.
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Applications information 5.3 TDA7491LP Gain setting The gain of the TDA7491LP is set by the two inputs, GAIN0 (pin 30) and GAIN1 (pin 31). Internally, the gain is set by changing the feedback resistors of the amplifier. Table 7. Gain settings Voltage level on pin GAIN0 Voltage level on pin GAIN1 Nominal gain, Gv (dB) L(1) H(1) 20 L H 26 H L 30 H H 32 1. Refer to VinL and VinH in Table 5: Electrical specifications on page 10 for the drive levels for L and H 5.
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TDA7491LP 5.5 Applications information Internal and external clocks The clock of the class-D amplifier can be generated internally or can be driven by an external source. If two or more class-D amplifiers are used in the same system, it is recommended that all devices operate at the same clock frequency. This can be implemented by using one TDA7491LP as master clock, while the other devices are in slave mode, that is, externally clocked. The clock interconnect is via pin SYNCLK of each device.
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Applications information 5.6 TDA7491LP Modulation The output modulation scheme of the BTL is called unipolar pulse width modulation (PWM). The differential output voltages change between 0 V and +VCC and between 0 V and -VCC. This is in contrast to the traditional bipolar PWM outputs which change between +VCC and -VCC. An advantage of this scheme is that it effectively doubles the switching frequency of the differential output waveform on the load then reducing the current ripple accordingly.
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TDA7491LP 5.6.1 Applications information Reconstruction low-pass filter Standard applications use a low-pass filter before the speaker. The cut-off frequency should be higher than 22 kHz and much lower than the output switching frequency. It is necessary to choose the L-C component values depending on the loud speaker impedance. Some typical values, which give a cut-off frequency of 27 kHz, are shown in Figure 32 and Figure 33 below. Figure 32. Typical LC filter for an 8-Ω speaker Figure 33.
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Applications information TDA7491LP Emission tests have been performed with a 1-m length of twisted speaker wire with ferrite beads. Changing the type of the ferrite bead requires care due to factors such as its effectiveness in the EMC frequency range and impedance stability over the rated current range. An output snubber network further improves the emissions and this should be tuned according to the actual PCB, layout and component characteristics. Figure 34.
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TDA7491LP 5.7 Applications information Protection functions The TDA7491LP is fully protected against undervoltages, overcurrents and thermal overloads as explained here. Undervoltage protection (UVP) If the supply voltage drops below the value of VUVP given in Table 5: Electrical specifications on page 10 the undervoltage protection is activated which forces the outputs to the high-impedance state. When the supply voltage recovers the device restarts.
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Applications information 5.9 TDA7491LP Heatsink requirements Due to the high efficiency of the class-D amplifier a 2-layer PCB can easily provide the heatsinking capability for low to medium power outputs. Using such a PCB with a copper ground layer of 3 x 3 cm2 and 16 vias connecting it to the contact area for the exposed pad, a thermal resistance, junction to ambient (in natural air convection), of 24 °C/W can be achieved.
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TDA7491LP 5.10 Applications information Test board Figure 37.
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Package mechanical data 6 TDA7491LP Package mechanical data The TDA7491LP comes in a 36-pin PowerSSO package with exposed pad down (EPD). Figure 38 below shows the package outline and Table 9 gives the dimensions. Table 9. PowerSSO-36 EPD dimensions Dimensions in mm Dimensions in inches Symbol Min Typ Max Min Typ Max A 2.15 - 2.47 0.085 - 0.097 A2 2.15 - 2.40 0.085 - 0.094 a1 0.00 - 0.10 0.000 - 0.004 b 0.18 - 0.36 0.007 - 0.014 c 0.23 - 0.32 0.009 - 0.
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TDA7491LP Figure 38.
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Revision history 7 TDA7491LP Revision history Table 10. Document revision history Date Revision 02-Jul-2007 1 Initial release. 15-Oct-2008 2 Updated characterization curves. 3 Updated text concerning oscillator R and C in Section 3.
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TDA7491LP Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale.