LM4674TLBD

LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 LM4674 Filterless 2.5W Stereo Class D Audio Power Amplifier Check for Samples: LM4674 FEATURES DESCRIPTION • • • • • • • • • The LM4674 is a single supply, high efficiency, 2.5W/channel, filterless switching audio amplifier. A low noise PWM architecture eliminates the output filter, reducing external component count, board area consumption, system cost, and simplifying design. 1 2 Output Short Circuit Protection Stereo Class D Operation No Output Filter Required Logic Selectable Gain Independent Shutdown Control Minimum External Components Click and Pop Suppression Micro-Power Shutdown Available in Space-Saving 2mm x 2mm x 0.6mm DSBGA, and 4mm x 4mm x 0.8mm WQFN Packages APPLICATIONS • • • Mobile Phones PDAs Laptops KEY SPECIFICATIONS • • • • • • Efficiency at 3.6V, 100mW into 8Ω: 80% (typ) Efficiency at 3.6V, 500mW into 8Ω: 85% (typ) Efficiency at 5V, 1W into 8Ω: 85% (typ) Quiescent Power Supply Current at 3.6V supply: 4mA Power Output at VDD = 5V, RL = 4Ω, THD ≤ 10%: 2.5 W (typ) Shutdown Current: 0.03μA (typ) The LM4674 is designed to meet the demands of mobile phones and other portable communication devices. Operating from a single 5V supply, the device is capable of delivering 2.5W/channel of continuous output power to a 4Ω load with less than 10% THD+N. Flexible power supply requirements allow operation from 2.4V to 5.5V. The LM4674 features high efficiency compared to conventional Class AB amplifiers. When driving an 8Ω speaker from a 3.6V supply, the device features 85% efficiency at PO = 500mW. Four gain options are pin selectable through the G0 and G1 pins. Output short circuit protection prevents the device from being damaged during fault conditions. Superior click and pop suppression eliminates audible transients on power-up/down and during shutdown. Independent left/right shutdown control maximizes power savings in mixed mono/stereo applications. 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2005–2013, Texas Instruments Incorporated LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com TYPICAL APPLICATION 2.4V to 5.5V CS2 CS1 VDD AUDIO INPUT PVDD Ci INR+ OUTRA GAIN/ MODULATOR Ci H-BRIDGE INR- OUTRB SDR G0 OSCILLATOR G1 SDL AUDIO INPUT Ci INL+ OUTLA GAIN/ MODULATOR Ci H-BRIDGE INL- OUTLB GND PGND Ci = 1 μF CS1 = 1 μF CS2 = 0.1 μF Figure 1. Typical Audio Amplifier Application Circuit EXTERNAL COMPONENTS DESCRIPTION (Figure 1) Components 2 Functional Description 1. CS Supply bypass capacitor which provides power supply filtering. Refer to the AUDIO AMPLIFIER INPUT CAPACITOR SELECTION section for information concerning proper placement and selection of the supply bypass capacitor. 2. Ci Input AC coupling capacitor which blocks the DC voltage at the amplifier's input terminals. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 G1 GND OUTRA G0 INL- INR- INR+ A B C D SDR SDL 12 11 10 9 OUTRB 13 8 OUTLB OUTRA 14 7 OUTLA VDD 15 6 PVDD G0 16 5 G1 VDD INL+ PGND OUTRB Figure 2. DSBGA (Top View) See YZR0016 Package 1 2 3 4 INL+ 1 PVDD SDR PGND INL- 2 OUTLA SDL INR- 3 OUTLB INR+ 4 GND CONNECTION DIAGRAM Figure 3. WQFN (Top View) See RGH0016A Package Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 3 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com PIN DESCRIPTION BUMP PIN NAME FUNCTION A1 A2 4 INL+ Non-inverting left channel input 6 PVDD Power VDD A3 7 OUTLA Left channel output A A4 8 OUTLB Left channel output B B1 3 INL- Inverting left channel input B2 5 G1 Gain setting input 1 B3 10 SDR Right channel shutdown input B4 9 SDL Left channel shutdown input C1 2 INR- Inverting right channel input C2 16 G0 Gain setting input 0 C3 12 GND Ground C4 11 PGND Power Ground D1 1 INR+ Non-inverting right channel input D2 15 VDD Power Supply D3 14 OUTRA Right channel output A D4 13 OUTRB Right channel output B These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 4 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 ABSOLUTE MAXIMUM RATINGS (1) (2) Supply Voltage (1) 6.0V −65°C to +150°C Storage Temperature Input Voltage –0.3V to VDD +0.3V Power Dissipation (3) Internally Limited ESD Susceptibility, all other pins (4) 2000V ESD Susceptibility (5) 200V Junction Temperature (TJMAX) Thermal Resistance (1) (2) (3) (4) (5) 150°C θJA (DSBGA) 45.7°C/W θJA (WQFN) 38.9°C/W All voltages are measured with respect to the ground pin, unless otherwise specified. Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, θJA, and the ambient temperature, TA. The maximum allowable power dissipation is PDMAX = (TJMAX – TA)/ θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM4674 see power derating currents for more information. Human body model, 100pF discharged through a 1.5kΩ resistor. Machine Model, 220pF–240pF discharged through all pins. OPERATING RATINGS (1) (2) Temperature Range (TMIN ≤ TA ≤ TMAX) −40°C ≤ TA ≤ 85°C 2.4V ≤ VDD ≤ 5.5V Supply Voltage (1) (2) All voltages are measured with respect to the ground pin, unless otherwise specified. Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. ELECTRICAL CHARACTERISTICS VDD = 3.6V (1) (2) The following specifications apply for AV = 6dB, RL = 15µH + 8Ω + 15µH, f = 1kHz unless otherwise specified. Limits apply for TA = 25°C. Symbol VOS Parameter Differential Output Offset Voltage IDD Quiescent Power Supply Current Conditions LM4674 Typical (3) Limit (4) (5) Units (Limits) VIN = 0, VDD = 2.4V to 5.0V 5 mV VIN = 0, RL = ∞, Both channels active, VDD = 3.6V 4 6 mA VIN = 0, RL = ∞, Both channels active, VDD = 5V 5 7.5 mA ISD Shutdown Current 1 μA VSDIH Shutdown Voltage Input High 1.4 V (min) VSDIL Shutdown Voltage Input Low 0.4 V (max) TWU Wake Up Time (1) (2) (3) (4) (5) V SDR = V SDL = GND V SDR/SDL = 0.4V 0.03 0.5 ms All voltages are measured with respect to the ground pin, unless otherwise specified. Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, but do not ensure specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which ensure specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not ensured for parameters where no limit is given, however, the typical value is a good indication of device performance. Typicals are measured at 25°C and represent the parametric norm. Limits are specified to AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are specified by design, test, or statistical analysis. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 5 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com ELECTRICAL CHARACTERISTICS VDD = 3.6V(1)(2) (continued) The following specifications apply for AV = 6dB, RL = 15µH + 8Ω + 15µH, f = 1kHz unless otherwise specified. Limits apply for TA = 25°C. Symbol AV RIN Gain Input Resistance LM4674 Typical (3) Limit (4) (5) Units (Limits) G0, G1 = GND RL = ∞ 6 6 ± 0.5 dB G0 = VDD, G1 = GND RL = ∞ 12 12 ± 0.5 dB G0 = GND, G1 = VDD RL = ∞ 18 18 ± 0.5 dB G0, G1 = VDD RL = ∞ 24 24 ± 0.5 dB Parameter Conditions AV = 6dB 28 kΩ AV = 12dB 18.75 kΩ AV = 18dB 11.25 kΩ AV = 24dB 6.25 kΩ VDD = 5V 2.5 W VDD = 3.6V 1.2 W VDD = 2.5V 0.530 W RL = 15μH + 4Ω + 15μH, THD ≤ 10% f = 1kHz, 22kHz BW RL = 15μH + 8Ω + 15μH, THD ≤ 10% f = 1kHz, 22kHz BW PO Output Power VDD = 5V 1.5 VDD = 3.6V 0.78 W VDD = 2.5V 0.350 W 1.9 W VDD = 3.6V 1 W VDD = 2.5V 0.430 W VDD = 5V 1.25 W VDD = 3.6V 0.63 W VDD = 2.5V 0.285 W PO = 500mW, f = 1kHz, RL = 8Ω 0.07 % PO = 300mW, f = 1kHz, RL = 8Ω 0.05 % VRIPPLE = 200mVP-P Sine, fRIPPLE = 217Hz, Inputs AC GND, Ci = 1μF, input referred 75 dB VRIPPLE = 1VP-P Sine, fRIPPLE = 1kHz, Inputs AC GND, Ci = 1μF, input referred 75 dB 0.6 W RL = 15μH + 4Ω + 15μH, THD ≤ 1% f = 1kHz, 22kHz BW VDD = 5V RL = 15μH + 8Ω + 15μH, THD = 1% f = 1kHz, 22kHz BW THD+N PSRR Total Harmonic Distortion Power Supply Rejection Ratio CMRR Common Mode Rejection Ratio VRIPPLE = 1VP-P fRIPPLE = 217Hz 67 dB η Efficiency PO = 1W, f = 1kHz, RL = 8Ω, VDD = 5V 85 % Xtalk Crosstalk PO = 500mW, f = 1kHz 84 dB SNR Signal to Noise Ratio VDD = 5V, PO = 1W 96 dB εOS Output Noise Input referred, A-Weighted Filter 20 μV 6 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 BLOCK DIAGRAMS 2.4V to 5.5V PVDD VDD OSCILLATOR INL+ OUTLA PWM MODULATOR H-BRIDGE INL- OUTLB G0 G1 GAIN CONTROL CLICK/POP SUPPRESSION BIAS OUTRA INR+ PWM MODULATOR H-BRIDGE OUTRB INR- PGND GND SDR SDL Figure 4. Differential Input Configuration 2.4V to 5.5V PVDD VDD OSCILLATOR INL+ OUTLA PWM MODULATOR H-BRIDGE INL- OUTLB G0 G1 GAIN CONTROL CLICK/POP SUPPRESSION BIAS OUTRA INR+ PWM MODULATOR H-BRIDGE OUTRB INR- PGND GND SDR SDL Figure 5. Single-Ended Input Configuration Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 7 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS THD+N vs Output Power f = 1kHz, AV = 24dB, RL = 8Ω THD+N vs Output Power f = 1kHz, AV = 6dB, RL = 8Ω 100 100 10 10 VDD = 5V VDD = 3.6V THD+N (%) THD+N (%) VDD = 3.6V 1 VDD = 2.5V 1 VDD = 2.5V 0.1 0.01 0.001 VDD = 5V 0.1 0.01 0.1 1 0.01 0.001 10 OUTPUT POWER/CHANNEL (W) THD+N vs Output Power f= 1kHz, AV = 24dB, RL = 4Ω THD+N vs Output Power f = 1kHz, AV = 6dB, RL = 4Ω 100 10 VDD = 5V 1 VDD = 2.5V VDD = 5V VDD = 3.6V THD+N (%) VDD = 3.6V THD+N (%) 10 OUTPUT POWER/CHANNEL (W) 1 VDD = 2.5V 0.1 0.1 0.01 0.1 1 0.01 0.001 10 0.01 0.1 1 10 OUTPUT POWER/CHANNEL (W) OUTPUT POWER/CHANNEL (W) Figure 8. Figure 9. THD+N vs Frequency VDD = 2.5V, POUT = 100mW/ch, RL = 8Ω THD+N vs Frequency VDD = 3.6V, POUT = 250mW/ch, RL = 8Ω 100 100 10 10 THD+N (%) THD+N (%) 1 Figure 7. 10 1 0.1 0.01 0.001 10 8 0.1 Figure 6. 100 0.01 0.001 0.01 1 0.1 0.01 100 1000 10000 100000 0.001 10 100 1000 10000 FREQUENCY (Hz) FREQUENCY (Hz) Figure 10. Figure 11. Submit Documentation Feedback 100000 Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) THD+N vs Frequency VDD = 2.5V, POUT = 100mW/ch, RL = 4Ω 100 100 10 10 THD+N (%) THD+N (%) THD+N vs Frequency VDD = 5V, POUT = 375mW/ch, RL = 8Ω 1 0.1 0.01 0.1 0.01 0.001 10 100 1000 10000 0.001 10 100000 1000 10000 100000 FREQUENCY (Hz) Figure 12. Figure 13. THD+N vs Frequency VDD = 3.6V, POUT = 250mW/ch, RL = 4Ω THD+N vs Frequency VDD = 5V, POUT = 375mW/ch, RL = 4Ω 100 100 10 10 1 0.1 0.01 1 0.1 0.01 0.001 10 100 1000 10000 0.001 10 100000 100 1000 10000 100000 FREQUENCY (Hz) FREQUENCY (Hz) Figure 14. Figure 15. Efficiency vs Output Power/channel RL = 4Ω, f = 1kHz Efficiency vs Output Power/channel RL = 8Ω, f = 1kHz 100 100 90 90 VDD = 5V 80 70 60 50 VDD = 3.6V 40 30 VDD = 5V 80 EFFICIENCY (%) EFFICIENCY (%) 100 FREQUENCY (Hz) THD+N (%) THD+N (%) 1 V DD = 2.5V 70 60 VDD = 3.6V 50 40 V DD = 2.5V 30 20 20 10 10 0 0 0 500 1000 1500 2000 OUTPUT POWER (mW) 0 200 400 600 800 1000 1200 OUTPUT POWER (mW) Figure 16. Figure 17. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 9 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) Power Dissipation vs Output Power RL = 4Ω, f = 1kHz Power Dissipation vs Output Power RL = 8Ω, f = 1kHz 1000 400 VDD = 5V POWER DISSIPATION (mW) POWER DISSIPATION (mW) VDD = 5V VDD = 3.6V 750 V DD = 2.5V 500 250 300 VDD = 3.6V V DD = 2.5V 200 100 POUT = P OUTL + P OUTR 0 0 1000 2000 3000 POUT = P OUTL + P OUTR 0 4000 0 OUTPUT POWER (mW) 500 1000 1500 2000 2500 OUTPUT POWER (mW) Figure 18. Figure 19. Output Power/channel vs Supply Voltage RL = 4Ω, f = 1kHz Output Power/channel vs Supply Voltage RL = 8Ω, f = 1kHz 3000 2000 OUTPUT POWER (mW) OUTPUT POWER (mW) 2500 2000 THD+N = 10% 1500 THD+N = 1% 1000 1500 THD+N = 10% 1000 THD+N = 1% 500 500 0 2.5 3 3.5 4 4.5 5 5.5 SUPPLY VOLTAGE (V) 3 3.5 4 4.5 5 5.5 SUPPLY VOLTAGE (V) Figure 20. 10 0 2.5 Figure 21. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) PSRR vs Frequency VDD = 3.6V, VRIPPLE= 200mVP-P, RL = 8Ω Crosstalk vs Frequency VDD = 3.6V, VRIPPLE = 1VP-P, RL = 8Ω 0 0 -10 -10 -20 -20 -30 CROSSTALK (dB) PSRR (dB) -30 -40 -50 -60 -40 -50 -60 -70 -70 -80 -80 -90 -90 10 100 1000 10000 100000 -100 10 100 FREQUENCY (Hz) 100000 Figure 23. CMRR vs Frequency VDD = 3.6V, VCM = 1VP-P, RL = 8Ω Supply Current vs Supply Voltage RL = ∞ -10 7 SUPPLY CURRENT (mA) 8 -20 CMRR(dB) 10000 Figure 22. 0 -30 -40 -50 -60 -70 -80 10 1000 FREQUENCY (Hz) 6 5 4 3 2 1 100 1000 10000 100000 FREQUENCY (Hz) 0 2.5 3 3.5 4 4.5 5 5.5 SUPPLY VOLTAGE (V) Figure 24. Figure 25. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 11 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com APPLICATION INFORMATION GENERAL AMPLIFIER FUNCTION The LM4674 stereo Class D audio power amplifier features a filterless modulation scheme that reduces external component count, conserving board space and reducing system cost. The outputs of the device transition from VDD to GND with a 300kHz switching frequency. With no signal applied, the outputs for each channel switch with a 50% duty cycle, in phase, causing the two outputs to cancel. This cancellation results in no net voltage across the speaker, thus there is no current to the load in the idle state. With the input signal applied, the duty cycle (pulse width) of the LM4674 outputs changes. For increasing output voltage, the duty cycle of the A output increases, while the duty cycle of the B output decreases for each channel. For decreasing output voltages, the converse occurs. The difference between the two pulse widths yields the differential output voltage. DIFFERENTIAL AMPLIFIER EXPLANATION As logic supplies continue to shrink, system designers are increasingly turning to differential analog signal handling to preserve signal to noise ratios with restricted voltage signs. The LM4674 features two fully differential amplifiers. A differential amplifier amplifies the difference between the two input signals. Traditional audio power amplifiers have typically offered only single-ended inputs resulting in a 6dB reduction of SNR relative to differential inputs. The LM4674 also offers the possibility of DC input coupling which eliminates the input coupling capacitors. A major benefit of the fully differential amplifier is the improved common mode rejection ratio (CMRR) over single ended input amplifiers. The increased CMRR of the differential amplifier reduces sensitivity to ground offset related noise injection, especially important in noisy systems. POWER DISSIPATION AND EFFICIENCY The major benefit of a Class D amplifier is increased efficiency versus a class AB amplifier. The efficiency of the LM4674 is attributed to the region of operation of the transistors in the output stage. The Class D output stage acts as current steering switches, consuming negligible amounts of power compared to their Class AB counterparts. Most of the power loss associated with the output stage is due to the IR loss of the MOSFET onresistance (RDS(ON)), along with switching losses due to gate charge. SHUTDOWN FUNCTION The LM4674 features independent left and right channel shutdown controls, allowing each channel to be disabled independently. SDR controls the right channel, while SDL controls the left channel. Driving either low disables the corresponding channel. It is best to switch between ground and VDD for minimum current consumption while in shutdown. The LM4674 may be disabled with shutdown voltages in between GND and VDD, the idle current will be greater than the typical 0.03µA value. For logic levels between GND and VDD bypass SD_ with a 0.1μF capacitor. The LM4674 shutdown inputs have internal pulldown resistors. The purpose of these resistors is to eliminate any unwanted state changes when SD_ is floating. To minimize shutdown current, SD_ should be driven to GND or left floating. If SD_ is not driven to GND or floating, an increase in shutdown supply current will be noticed. SINGLE-ENDED AUDIO AMPLIFIER CONFIGURATION The LM4674 is compatible with single-ended sources. When configured for single-ended inputs, input capacitors must be used to block any DC component at the input of the device. Figure 5 shows the typical single-ended applications circuit. AUDIO AMPLIFIER POWER SUPPLY BYPASSING/FILTERING Proper power supply bypassing is critical for low noise performance and high PSRR. Place the supply bypass capacitor as close to the device as possible. Typical applications employ a voltage regulator with 10µF and 0.1µF bypass capacitors that increase supply stability. These capacitors do not eliminate the need for bypassing of the LM4674 supply pins. A 1µF capacitor is recommended. 12 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 AUDIO AMPLIFIER INPUT CAPACITOR SELECTION Input capacitors may be required for some applications, or when the audio source is single-ended. Input capacitors block the DC component of the audio signal, eliminating any conflict between the DC component of the audio source and the bias voltage of the LM4674. The input capacitors create a high-pass filter with the input resistance Ri. The -3dB point of the high pass filter is found using Equation (1) below. f = 1 / 2πRiCi (1) The values for Ri can be found in the EC table for each gain setting. The input capacitors can also be used to remove low frequency content from the audio signal. Small speakers cannot reproduce, and may even be damaged by low frequencies. High pass filtering the audio signal helps protect the speakers. When the LM4674 is using a single-ended source, power supply noise on the ground is seen as an input signal. Setting the high-pass filter point above the power supply noise frequencies, 217 Hz in a GSM phone, for example, filters out the noise such that it is not amplified and heard on the output. Capacitors with a tolerance of 10% or better are recommended for impedance matching and improved CMRR and PSRR. AUDIO AMPLIFIER GAIN SETTING The LM4674 features four internally configured gain settings. The device gain is selected through the two logic inputs, G0 and G1. The gain settings are as shown in the following table. LOGIC INPUT GAIN G1 G0 V/V dB 0 0 2 6 0 1 4 12 1 0 8 18 1 1 16 24 PCB LAYOUT GUIDELINES As output power increases, interconnect resistance (PCB traces and wires) between the amplifier, load and power supply create a voltage drop. The voltage loss due to the traces between the LM4674 and the load results in lower output power and decreased efficiency. Higher trace resistance between the supply and the LM4674 has the same effect as a poorly regulated supply, increasing ripple on the supply line, and reducing peak output power. The effects of residual trace resistance increases as output current increases due to higher output power, decreased load impedance or both. To maintain the highest output voltage swing and corresponding peak output power, the PCB traces that connect the output pins to the load and the supply pins to the power supply should be as wide as possible to minimize trace resistance. The use of power and ground planes will give the best THD+N performance. In addition to reducing trace resistance, the use of power planes creates parasitic capacitors that help to filter the power supply line. The inductive nature of the transducer load can also result in overshoot on one or both edges, clamped by the parasitic diodes to GND and VDD in each case. From an EMI standpoint, this is an aggressive waveform that can radiate or conduct to other components in the system and cause interference. In is essential to keep the power and output traces short and well shielded if possible. Use of ground planes beads and micros-strip layout techniques are all useful in preventing unwanted interference. As the distance from the LM4674 and the speaker increases, the amount of EMI radiation increases due to the output wires or traces acting as antennas become more efficient with length. Ferrite chip inductors places close to the LM4674 outputs may be needed to reduce EMI radiation. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 13 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com LM4674TL DEMO BOARD SCHEMATIC U1 VDD D2 JP1 + VDD GND C11 10 PF C1 1 PF C3 POWER C4 JP2 C3 RIGHT INPUT C5 C6 LEFT INPUT C1 B1 C2 1 PF L1 INR+ OUTRA D3 1 mH INROUTRB JP9 C7 0.022 PF 1 2 D4 L2 INL+ Header 2 C8 0.022 PF JP10 R1 300 1 2 Right Output 1 mH A1 C2 B2 G0 G1 C4 INL- L4 1 PF VDD G0 GND VDD G1 GND PGND 1 PF INL+ INL- JP7 GND A2 1 PF JP3 VDD PVDD 1 PF INR+ INR- JP6 D1 VDD VDD JP4 B3 VDD VDD SDR SDR B4 JP5 VDD SDL VDD G0 OUTLA A3 1 mH OUTLB SDR JP8 C10 0.022 PF 1 2 G1 A4 L3 Header 2 C9 0.022 PF JP11 R2 300 1 2 Left Output 1 mH SDL LM4674TL SDL Figure 26. LM4674TL Demo Board Schematic LM4674TL DEMONSTRATION BOARD LAYOUT Figure 27. Layer 1 14 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 Figure 28. Layer 2 Figure 29. Layer 3 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 15 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com Figure 30. Layer 4 Figure 31. Top Silkscreen 16 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 Figure 32. Bottom Silkscreen LM4674SQ DEMO BOARD SCHEMATIC Figure 33. LM4674SQ Demo Board Schematic Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 17 LM4674 SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 www.ti.com LM4674SQ DEMONSTRATION BOARD LAYOUT Figure 34. Layer 1 Figure 35. Layer 2 Figure 36. Layer 3 18 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 LM4674 www.ti.com SNAS344E – DECEMBER 2005 – REVISED APRIL 2013 Figure 37. Top Silkscreen Figure 38. Bottom Layer REVISION TABLE Rev Date 1.0 12/16/06 Initial release. Description 1.1 05/17/06 Added the LLP package. 1.2 05/31/06 Added the LLP markings. 1.3 09/05/06 Added “No Load” in the Conditions on Av (3.6V table). 1.4 09/21/06 Edited graphics (26, 38, 60) and input some text edits. 1.5 09/27/06 Edited Figure 1 (page 2), TL and LLP pkg/marking drawings (page 3). Input text edits. 1.6 07/13/07 Added the TL and SQ demo boards and schematics diagrams. 1.7 10/30/07 Updated the SQ schematic diagram and replaced the demo boards. 1.8 07/02/08 Text edits (under SHUTDOWN FUNCTION). E 04/05/13 Changed layout of National Data Sheet to TI format. Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated Product Folder Links: LM4674 19 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) LM4674SQ/NOPB ACTIVE WQFN RGH 16 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 L4674SQ LM4674TLX/NOPB ACTIVE DSBGA YZR 16 3000 RoHS & Green SNAGCU Level-1-260C-UNLIM -40 to 85 GG2 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of