LM4808LDBD

LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 LM4808 Low Voltage High Power Audio Power Amplifier Check for Samples: LM4808 FEATURES DESCRIPTION • The LM4808 is a dual audio power amplifier capable of delivering 105mW per channel of continuous average power into a 16Ω load with 0.1% (THD+N) from a 5V power supply. 1 2 • • • • WSON, VSSOP, and SOIC Surface Mount Packaging Switch On/Off Click Suppression Excellent Power Supply Ripple Rejection Unity-Gain Stable Minimum External Components APPLICATIONS • • • Headphone Amplifier Personal Computers Portable Electronic Devices Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components using surface mount packaging. Since the LM4808 does not require bootstrap capacitors or snubber networks, it is optimally suited for low-power portable systems. The unity-gain stable LM4808 can be configured by external gain-setting resistors. KEY SPECIFICATIONS • • • THD+N at 1kHz at 105mW Continuous Average Output Power Into 16Ω 0.1 % (typ) THD+N at 1kHz at 70mW Continuous Average Output Power Into 32Ω 0.1 % (typ) Output Power at 0.1% THD+N at 1kHz Into 32Ω 70 mW (typ) 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 © 2000–2013, Texas Instruments Incorporated LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com Typical Application *Refer to the APPLICATION INFORMATION section for information concerning proper selection of the input and output coupling capacitors. Figure 1. Typical Audio Amplifier Application Circuit Connection Diagram Figure 2. Top View WSON Package See Package Number NGL0008B Figure 3. Top View SOIC & VSSOP Package See Package Number D0008A, DGK0008A 2 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 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. ABSOLUTE MAXIMUM RATINGS (1) (2) Supply Voltage 6.0V −65°C to +150°C Storage Temperature −0.3V to VDD + 0.3V Input Voltage Power Dissipation (3) Internally limited ESD Susceptibility (4) 3500V ESD Susceptibility (5) 250V Junction Temperature Soldering Information 150°C (6) Small Outline Package Thermal Resistance Vapor Phase (60 seconds) 215°C Infrared (15 seconds) 220°C θJC (VSSOP) 56°C/W θJA (VSSOP) 210°C/W θJC (SOIC) 35°C/W θJA (SOIC) 170°C/W θJC (WSON) (1) (2) (3) (4) (5) (6) (7) (8) 15°C/W θJA (WSON) 117°C/W (7) θJA (WSON) 150°C/W (8) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. 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 P DMAX = (TJMAX − TA) / θJA. For the LM4808, TJMAX = 150°C, and the typical junctionto-ambient thermal resistance, when board mounted, is 210°C/W for package DGK0008A and 170°C/W for package D0008A. Human body model, 100 pF discharged through a 1.5 kΩ resistor. Machine Model, 220 pF–240 pF discharged through all pins. See http://www.ti.com for other methods of soldering surface mount devices. The given θJA is for an LM4808 packaged in an NGL0008B with the Exposed-DAP soldered to a printed circuit board copper pad with an area equivalent to that of the Exposed-DAP itself. The given θJA is for an LM4808 packaged in an NGL0008B with the Exposed-DAP not soldered to any printed circuit board copper. OPERATING RATINGS TMIN ≤ TA ≤ TMAX Temperature Range −40°C ≤ T A ≤ 85°C 2.0V ≤ VDD ≤ 5.5V Supply Voltage ELECTRICAL CHARACTERISTICS (1) (2) The following specifications apply for VDD = 5V unless otherwise specified, limits apply to TA = 25°C. Symbol Parameter Conditions LM4808 Typ VDD Supply Voltage IDD Supply Current (1) (2) (3) (4) VIN = 0V, IO = 0A (3) 1.2 Limit (4) Units (Limits) 2.0 V (min) 5.5 V (max) 3.0 mA (max) 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. Tested 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 © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 3 LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com ELECTRICAL CHARACTERISTICS (1) (2) (continued) The following specifications apply for VDD = 5V unless otherwise specified, limits apply to TA = 25°C. Symbol Parameter Conditions LM4808 Typ (3) Limit (4) Units (Limits) Ptot Total Power Dissipation VIN = 0V, IO = 0A 6 16.5 mW (max) VOS Input Offset Voltage VIN = 0V 10 50 mV (max) Ibias Input Bias Current VCM Common Mode Voltage GV Open-Loop Voltage Gain RL = 5kΩ Io Max Output Current THD+N < 0.1 % RO Output Resistance 10 pA 0 V 4.3 V 67 dB 70 mA 0.1 Ω RL = 32Ω, 0.1% THD+N, Min .3 RL = 32Ω, 0.1% THD+N, Max 4.7 VO Output Swing V PSRR Power Supply Rejection Ratio Cb = 1.0µF, Vripple = 100mVPP, f = 100Hz 89 dB Crosstalk Channel Separation RL = 32Ω 75 dB f = 1 kHz THD+N Total Harmonic Distortion + Noise RL = 16Ω, VO =3.5VPP (at 0 dB) 0.05 % 66 dB RL = 32Ω, VO =3.5VPP (at 0 dB) 0.05 % 66 dB SNR Signal-to-Noise Ratio VO = 3.5Vpp (at 0 dB) 105 dB fG Unity Gain Frequency Open Loop, RL = 5kΩ 5.5 MHz THD+N = 0.1%, f = 1 kHz Po Output Power CI Input Capacitance CL Load Capacitance SR Slew Rate RL = 16Ω 105 RL = 32Ω 70 mW THD+N = 10%, f = 1 kHz RL = 16Ω 150 mW RL = 32Ω 90 mW 3 pF 200 Unity Gain Inverting ELECTRICAL CHARACTERISTICS mW 60 pF 3 V/µs (1) (2) The following specifications apply for VDD = 3.3V unless otherwise specified, limits apply to TA = 25°C. Symbol Parameter Conditions Conditions Typ IDD Supply Current VIN = 0V, IO = 0A VOS Input Offset Voltage VIN = 0V (1) (2) (3) (4) 4 (3) Limit (4) Units (Limits) 1.0 mA (max) 7 mV (max) 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. Tested 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 © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 ELECTRICAL CHARACTERISTICS (1) (2) (continued) The following specifications apply for VDD = 3.3V unless otherwise specified, limits apply to TA = 25°C. Symbol Parameter Conditions Conditions (3) Typ Limit (4) Units (Limits) THD+N = 0.1%, f = 1 kHz Po Output Power RL = 16Ω 40 mW RL = 32Ω 28 mW RL = 16Ω 56 mW RL = 32Ω 38 mW THD+N = 10%, f = 1 kHz ELECTRICAL CHARACTERISTICS (1) (2) The following specifications apply for VDD = 2.6V unless otherwise specified, limits apply to TA = 25°C. Symbol Parameter Conditions Conditions Typ IDD Supply Current VIN = 0V, IO = 0A VOS Input Offset Voltage VIN = 0V (3) Limit (4) Units (Limits) 0.9 mA (max) 5 mV (max) RL = 16Ω 20 mW RL = 32Ω 16 mW RL = 16Ω 31 mW RL = 32Ω 22 mW THD+N = 0.1%, f = 1 kHz Po (1) (2) (3) (4) Output Power THD+N = 10%, f = 1 kHz 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. Tested limits are specified to AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are specified by design, test, or statistical analysis. EXTERNAL COMPONENTS DESCRIPTION (Figure 1) Components Functional Description 1. Ri The inverting input resistance, along with Rf, set the closed-loop gain. Ri, along with Ci, form a high pass filter with fc = 1/(2πRiCi). 2. Ci The input coupling capacitor blocks DC voltage at the amplifier's input terminals. Ci, along with Ri, create a highpass filter with fC = 1/(2πRiCi). Refer to the section, SELECTING PROPER EXTERNAL COMPONENTS, for an explanation of determining the value of Ci. 3. Rf The feedback resistance, along with Ri, set closed-loop gain. 4. CS This is the supply bypass capacitor. It provides power supply filtering. Refer to the APPLICATION INFORMATION section for proper placement and selection of the supply bypass capacitor. 5. CB This is the half-supply bypass pin capacitor. It provides half-supply filtering. Refer to the section, SELECTING PROPER EXTERNAL COMPONENTS, for information concerning proper placement and selection of CB. 6. CO This is the output coupling capacitor. It blocks the DC voltage at the amplifier's output and forms a high pass filter with RL at fO = 1/(2πRLCO) 7. RB This is the resistor which forms a voltage divider that provides 1/2 VDD to the non-inverting input of the amplifier. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 5 LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS 6 THD+N vs Frequency THD+N vs Frequency Figure 4. Figure 5. THD+N vs Frequency THD+N vs Frequency Figure 6. Figure 7. THD+N vs Frequency THD+N vs Frequency Figure 8. Figure 9. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) THD+N vs Frequency THD+N vs Frequency Figure 10. Figure 11. THD+N vs Frequency THD+N vs Frequency Figure 12. Figure 13. THD+N vs Output Power THD+N vs Output Power Figure 14. Figure 15. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 7 LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) 8 THD+N vs Output Power THD+N vs Output Power Figure 16. Figure 17. THD+N vs Output Power THD+N vs Output Power Figure 18. Figure 19. THD+N vs Output Power THD+N vs Output Power Figure 20. Figure 21. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) THD+N vs Output Power Output Power vs Load Resistance Figure 22. Figure 23. Output Power vs Load Resistance Output Power vs Load Resistance Figure 24. Figure 25. Output Power vs Supply Voltage Output Power vs Power Supply Figure 26. Figure 27. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 9 LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) 10 Output Power vs Power Supply Clipping Voltage vs Supply Voltage Figure 28. Figure 29. Power Dissipation vs Output Power Power Dissipation vs Output Power Figure 30. Figure 31. Power Dissipation vs Output Power Channel Separation Figure 32. Figure 33. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Channel Separation Noise Floor Figure 34. Figure 35. Power Supply Rejection Ratio Frequency Response Figure 36. Figure 37. Open Loop Frequency Response Open Loop Frequency Response Figure 38. Figure 39. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 11 LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) 12 Supply Current vs Supply Voltage Frequency Response vs Output Capacitor Size Figure 40. Figure 41. Frequency Response vs Output Capacitor Size Frequency Response vs Output Capacitor Size Figure 42. Figure 43. Typical Application Frequency Response Typical Application Frequency Response Figure 44. Figure 45. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 APPLICATION INFORMATION EXPOSED-DAP PACKAGE PCB MOUNTING CONSIDERATION The LM4808's exposed-dap (die attach paddle) package (LD) provides a low thermal resistance between the die and the PCB to which the part is mounted and soldered. This allows rapid heat transfer from the die to the surrounding PCB copper traces, ground plane, and surrounding air. The LD package should have its DAP soldered to a copper pad on the PCB. The DAP's PCB copper pad may be connected to a large plane of continuous unbroken copper. This plane forms a thermal mass, heat sink, and radiation area. However, since the LM4808 is designed for headphone applications, connecting a copper plane to the DAP's PCB copper pad is not required. The LM4808's Power Dissipation vs Output Power Curve in the TYPICAL PERFORMANCE CHARACTERISTICS shows that the maximum power dissipated is just 45mW per amplifier with a 5V power supply and a 32Ω load. Further detailed and specific information concerning PCB layout, fabrication, and mounting an LD (WSON) package is available from Texas Instruments' Package Engineering Group under application note AN-1187 (literature number SNOA401). POWER DISSIPATION Power dissipation is a major concern when using any power amplifier and must be thoroughly understood to ensure a successful design. Equation 1 states the maximum power dissipation point for a single-ended amplifier operating at a given supply voltage and driving a specified output load. PDMAX = (VDD) 2 / (2π2RL) (1) Since the LM4808 has two operational amplifiers in one package, the maximum internal power dissipation point is twice that of the number which results from Equation 1. Even with the large internal power dissipation, the LM4808 does not require heat sinking over a large range of ambient temperature. From Equation 1, assuming a 5V power supply and a 32Ω load, the maximum power dissipation point is 40mW per amplifier. Thus the maximum package dissipation point is 80mW. The maximum power dissipation point obtained must not be greater than the power dissipation that results from Equation 2: PDMAX = (TJMAX − TA) / θJA where • • θJA = 210°C/W for package DGK0008A TJMAX = 150°C for the LM4808 (2) Depending on the ambient temperature, TA, of the system surroundings, Equation 2 can be used to find the maximum internal power dissipation supported by the IC packaging. If the result of Equation 1 is greater than that of Equation 2, then either the supply voltage must be decreased, the load impedance increased or TA reduced. For the typical application of a 5V power supply, with a 32Ω load, the maximum ambient temperature possible without violating the maximum junction temperature is approximately 133.2°C provided that device operation is around the maximum power dissipation point. Power dissipation is a function of output power and thus, if typical operation is not around the maximum power dissipation point, the ambient temperature may be increased accordingly. Refer to the TYPICAL PERFORMANCE CHARACTERISTICS curves for power dissipation information for lower output powers. POWER SUPPLY BYPASSING As with any power amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. Applications that employ a 5V regulator typically use a 10µF in parallel with a 0.1µF filter capacitors to stabilize the regulator's output, reduce noise on the supply line, and improve the supply's transient response. However, their presence does not eliminate the need for a local 0.1µF supply bypass capacitor, CS, connected between the LM4808's supply pins and ground. Keep the length of leads and traces that connect capacitors between the LM4808's power supply pin and ground as short as possible. Connecting a 1.0µF capacitor, CB, between the IN A(+) / IN B(+) node and ground improves the internal bias voltage's stability and improves the amplifier's PSRR. The PSRR improvements increase as the bypass pin capacitor value increases. Too large, however, increases the amplifier's turn-on time. The selection of bypass capacitor values, especially CB, depends on desired PSRR requirements, click and pop performance (as explained in the section, SELECTING PROPER EXTERNAL COMPONENTS), system cost, and size constraints. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 13 LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com SELECTING PROPER EXTERNAL COMPONENTS Optimizing the LM4808's performance requires properly selecting external components. Though the LM4808 operates well when using external components with wide tolerances, best performance is achieved by optimizing component values. The LM4808 is unity-gain stable, giving a designer maximum design flexibility. The gain should be set to no more than a given application requires. This allows the amplifier to achieve minimum THD+N and maximum signal-tonoise ratio. These parameters are compromised as the closed-loop gain increases. However, low gain demands input signals with greater voltage swings to achieve maximum output power. Fortunately, many signal sources such as audio CODECs have outputs of 1VRMS (2.83VP-P). Please refer to the AUDIO POWER AMPLIFIER DESIGN section for more information on selecting the proper gain. Input and Output Capacitor Value Selection Amplifying the lowest audio frequencies requires high value input and output coupling capacitors (CI and CO in Figure 1). A high value capacitor can be expensive and may compromise space efficiency in portable designs. In many cases, however, the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 150Hz. Applications using speakers with this limited frequency response reap little improvement by using high value input and output capacitors. Besides affecting system cost and size, Ci has an effect on the LM4808's click and pop performance. The magnitude of the pop is directly proportional to the input capacitor's size. Thus, pops can be minimized by selecting an input capacitor value that is no higher than necessary to meet the desired −3dB frequency. As shown in Figure 1, the input resistor, RI and the input capacitor, CI, produce a −3dB high pass filter cutoff frequency that is found using Equation 3. In addition, the output load RL, and the output capacitor CO, produce a -3db high pass filter cutoff frequency defined by Equation 4. fI-3db=1/2πRICI fO-3db=1/2πRLCO (3) (4) Also, careful consideration must be taken in selecting a certain type of capacitor to be used in the system. Different types of capacitors (tantalum, electrolytic, ceramic) have unique performance characteristics and may affect overall system performance. Bypass Capacitor Value Besides minimizing the input capacitor size, careful consideration should be paid to the value of the bypass capacitor, CB. Since CB determines how fast the LM4808 settles to quiescent operation, its value is critical when minimizing turn-on pops. The slower the LM4808's outputs ramp to their quiescent DC voltage (nominally 1/2 VDD), the smaller the turn-on pop. Choosing CB equal to 1.0µF or larger, will minimize turn-on pops. As discussed above, choosing Ci no larger than necessary for the desired bandwidth helps minimize clicks and pops. 14 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 AUDIO POWER AMPLIFIER DESIGN Design a Dual 70mW/32Ω Audio Amplifier Given: Power Output 70mW Load Impedance 32Ω Input Level 1Vrms (max) Input Impedance 20kΩ Bandwidth 100Hz–20kHz ± 0.50dB The design begins by specifying the minimum supply voltage necessary to obtain the specified output power. One way to find the minimum supply voltage is to use the Output Power vs Supply Voltage curve in the TYPICAL PERFORMANCE CHARACTERISTICS section. Another way, using Equation 5, is to calculate the peak output voltage necessary to achieve the desired output power for a given load impedance. To account for the amplifier's dropout voltage, two additional voltages, based on the Dropout Voltage vs Supply Voltage in the TYPICAL PERFORMANCE CHARACTERISTICS curves, must be added to the result obtained by Equation 5. For a singleended application, the result is Equation 6. (5) (6) VDD ≥ (2VOPEAK + (VODTOP + VODBOT)) The Output Power vs Supply Voltage graph for a 32Ω load indicates a minimum supply voltage of 4.8V. This is easily met by the commonly used 5V supply voltage. The additional voltage creates the benefit of headroom, allowing the LM4808 to produce peak output power in excess of 70mW without clipping or other audible distortion. The choice of supply voltage must also not create a situation that violates maximum power dissipation as explained above in the POWER DISSIPATION section. Remember that the maximum power dissipation point from Equation 1 must be multiplied by two since there are two independent amplifiers inside the package. Once the power dissipation equations have been addressed, the required gain can be determined from Equation 7. (7) Thus, a minimum gain of 1.497 allows the LM4808 to reach full output swing and maintain low noise and THD+N perfromance. For this example, let AV=1.5. The amplifiers overall gain is set using the input (Ri ) and feedback (Rf ) resistors. With the desired input impedance set at 20kΩ, the feedback resistor is found using Equation 8. AV = Rf/Ri (8) The value of Rf is 30kΩ. The last step in this design is setting the amplifier's −3db frequency bandwidth. To achieve the desired ±0.25dB pass band magnitude variation limit, the low frequency response must extend to at lease one−fifth the lower bandwidth limit and the high frequency response must extend to at least five times the upper bandwidth limit. The gain variation for both response limits is 0.17dB, well within the ±0.25dB desired limit. The results are an fL = 100Hz/5 = 20Hz (9) and a fH = 20kHz∗5 = 100kHz (10) As stated in the EXTERNAL COMPONENTS DESCRIPTION section, both Ri in conjunction with Ci, and Co with RL, create first order highpass filters. Thus to obtain the desired low frequency response of 100Hz within ±0.5dB, both poles must be taken into consideration. The combination of two single order filters at the same frequency forms a second order response. This results in a signal which is down 0.34dB at five times away from the single order filter −3dB point. Thus, a frequency of 20Hz is used in the following equations to ensure that the response is better than 0.5dB down at 100Hz. Ci ≥ 1 / (2π * 20 kΩ * 20 Hz) = 0.397µF; use 0.39µF. Co ≥ 1 / (2π * 32Ω * 20 Hz) = 249µF; use 330µF. Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 15 LM4808 SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 www.ti.com The high frequency pole is determined by the product of the desired high frequency pole, fH, and the closed-loop gain, AV. With a closed-loop gain of 1.5 and fH = 100kHz, the resulting GBWP = 150kHz which is much smaller than the LM4808's GBWP of 900kHz. This figure displays that if a designer has a need to design an amplifier with a higher gain, the LM4808 can still be used without running into bandwidth limitations. Demonstration Board Layout Figure 46. Recommended SO PC Board Layout: Top Silkscreen Figure 47. Recommended LD PC Board Layout: Top Silkscreen Figure 48. Recommended SOIC PC Board Layout: Top Layer Figure 49. Recommended LD PC Board Layout: Top Layer Figure 50. Recommended SOIC PC Board Layout: Bottom Layer Figure 51. Recommended LD PC Board Layout: Bottom Layer 16 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 LM4808 www.ti.com SNAS051D – FEBRUARY 2000 – REVISED MAY 2013 REVISION HISTORY Changes from Revision C (May 2013) to Revision D • Page Changed layout of National Data Sheet to TI format .......................................................................................................... 16 Submit Documentation Feedback Copyright © 2000–2013, Texas Instruments Incorporated Product Folder Links: LM4808 17 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) LM4808M/NOPB ACTIVE SOIC D 8 95 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM48 08M LM4808MM/NOPB ACTIVE VSSOP DGK 8 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 G08 LM4808MMX/NOPB ACTIVE VSSOP DGK 8 3500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 G08 LM4808MX/NOPB ACTIVE SOIC D 8 2500 RoHS & Green SN Level-1-260C-UNLIM -40 to 85 LM48 08M (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