LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 LM4804 BoomerTM Audio Power Amplifier SerieLow Voltage High Power Audio Power Amplifier Check for Samples: LM4804 FEATURES DESCRIPTION * The LM4804 integrates a Boost Converter with an Audio Power Amplifier to drive voice coil speakers in portable applications. When powered by a 3V supply, it is capable of creating 1.8W power dissipation in an 8 bridge-tied-load (BTL) with less than 1% THD+N. 1 23 * * * * * * Pop & Click Circuitry Eliminates Noise During Turn-On and Turn-Off Transitions Low, 2A (Max) Shutdown Current Low, 11mA (Typ) Quiescent Current (VDD = 4.2V, RL = 8) 1.8W Mono BTL Output, RL = 8, VDD = 3V Short Circuit Protection Unity-Gain Stable External Gain Configuration Capability Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. The LM4804 does not require bootstrap capacitors, or snubber circuits. Therefore it is ideally suited for portable applications requiring high output voltage and minimal size. APPLICATIONS * * The LM4804 features a micro-power shutdown mode. Additionally, the LM4804 features an internal thermal shutdown protection mechanism. Cellphone PDA The LM4804 contains advanced pop & click circuitry that eliminates output transients which would otherwise occur during power or shutdown cycles. KEY SPECIFICATIONS * * * Quiescent Power Supply Current (VDD = 4.2V, RL = 8), 11mA (Typ) BTL Output Power (RL = 8, 2% THD+N, VDD = 3V), 1.8W (Typ) Shutdown Current, 2A (Max) The LM4804 is unity-gain stable. Its closed-loop gain is determined by the value of external, user selected resistors. FB FREQ SD1 GND2 NC NC GND3 Connection Diagram 28 27 26 25 24 23 22 NC 1 21 NC NC 2 20 NC GND1 3 19 BYPASS NC 4 18 SD2 NC 8 9 10 11 12 13 14 NC 15 VO2 7 V1 NC SW VO1 NC 16 NC 17 6 IN- 5 IN+ VDD BOOT Figure 1. LM4804LQ (5x5) Top View See Package Number NJB0028A 1 2 3 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. Boomer is a trademark of Texas Instruments. All other 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 (c) 2005-2013, Texas Instruments Incorporated LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com Typical Application D1 L1 4.7 PH Cs1 4.7 PF Bat VDD R3 150k C3 4.7 pF 3 25 26 S/D 27 Cf1 470 pF 5 7 VDD SW GND1 V1 = VFB (1 + R1/R2) FB Co 100 PF R1 301k 28 R2 78.7k GND2 S/D1 BOOT 6 FREQ 10 PH 0.1 PF 18 19 Cb 1.0 PF 9 V1 S/D2 Bypass GND3 +IN VO2 12 22 Cs2 4.7 PF 14 8: 20k Audio In 0.1 PF Ci 8 -IN VO1 11 Ri Rf 200k Figure 2. Typical LM4804 Audio Amplifier Application Circuit 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. 2 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 Absolute Maximum Ratings (1) (2) (3) Supply Voltage (VDD) 6.5V Supply Voltage (V1) 6.5V -65C to +150C Storage Temperature -0.3V to VDD + 0.3V Input Voltage (4) Internally limited ESD Susceptibility (5) 2000V ESD Susceptibility (6) 200V Power Dissipation Junction Temperature 125C JA (WQFN) Thermal Resistance 59C/W See AN-1187 'Leadless Leadframe Packaging (WQFN)'. (1) (2) (3) (4) (5) (6) All voltages are measured with respect to the GND 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 specify 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. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and specifications. The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX, JA, and the ambient temperature, TA. The maximum allowable power dissipation is PDMAX = (TJMAX - TA) / JA or the given in Absolute Maximum Ratings, whichever is lower. Human body model, 100pF discharged through a 1.5k resistor. Machine Model, 220pF - 240pF discharged through all pins. Operating Ratings TMIN TA TMAX Temperature Range -40C TA +85C 3V VDD 5V Supply Voltage (VDD) 2.7V V1 6.1V Supply Voltage (V1) Electrical Characteristics VDD = 4.2V (1) (2) The following specifications apply for VDD = 4.2V, V1 = 6.0V, AV-BTL = 20dB, RL = 8, fIN = 1kHz, CB = 1.0F, R1 = 301k, R2 = 78.7k unless otherwise specified. Limits apply for TA = 25C. See Figure 2 Symbol Parameter Conditions LM4804 Typical (3) Limit (4) (5) Units (Limits) IDD Quiescent Power Supply Current VIN = 0, RLOAD = 11 22 mA (max) ISD Shutdown Current VSHUTDOWN = GND (6) (7) 0.1 2 A (max) VSDIH Shutdown Voltage Input High SD1 SD2 0.7VDD 1.4 V (min) VSDIL Shutdown Voltage Input Low SD1 SD2 0.15VDD 0.4 V (max) TWU Wake-up Time CB = 1.0F VOS Output Offset Voltage TSD Thermal Shutdown Temperature POUT Output Power (1) (2) (3) (4) (5) (6) (7) 70 4 THD = 2% (max) 1.9 msec (max) 40 mV (max) 125 C (min) 1.7 W (min) All voltages are measured with respect to the GND 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 specify 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 25C and represent the parametric norm. Limits are specified to Texas Instruments' AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are ensured by design, test, or statistical analysis. Shutdown current is measured in a normal room environment. The Shutdown pin should be driven as close as possible to Vin for minimum shutdown current. Shutdown current is measured with components R1 and R2 removed. Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 3 LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com Electrical Characteristics VDD = 4.2V(1)(2) (continued) The following specifications apply for VDD = 4.2V, V1 = 6.0V, AV-BTL = 20dB, RL = 8, fIN = 1kHz, CB = 1.0F, R1 = 301k, R2 = 78.7k unless otherwise specified. Limits apply for TA = 25C. See Figure 2 Symbol Parameter Conditions THD+N Total Harmomic Distortion + Noise POUT = 1.5W OS Output Noise A-Weighted Filter, VIN = 0V, Input Referred PSRR Power Supply Rejection Ratio VRIPPLE = 200mVp-p f = 217Hz f = 1kHz VFB 4 Feedback Pin Reference Voltage LM4804 Typical (3) Limit (4) (5) 0.13 0.5 22 Submit Documentation Feedback % V 72 67 1.24 Units (Limits) dB (min) 1.2772 1.2028 V (max) V (min) Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 Electrical Characteristics VDD = 3.0V (1) (2) The following specifications apply for VDD = 3.0V, V1 = 6.0V, AV-BTL = 20dB, RL = 8, fIN = 1kHz, CB = 1.0F, R1 = 301k, R2 = 78.7k unless otherwise specified. Limits apply for TA = 25C. Symbol Parameter Conditions LM4804 Typical (3) Limit (4) (5) Units (Limits) IDD Quiescent Power Supply Current VDD = 3.2V, VIN = 0, RLOAD = 19 33 mA (max) ISD Shutdown Current VSHUTDOWN = GND (6) (7) 0.1 2 A (max) VSDIH Shutdown Voltage Input High SD1 SD2 0.7VDD 1.4 V (min) VSDIL Shutdown Voltage Input Low SD1 SD2 0.15VDD 0.4 V (max) TWU Wake-up Time CB = 1.0F VOS Output Offset Voltage TSD Thermal Shutdown Temperature POUT Output Power THD = 2% (max) THD+N Total Harmomic Distortion + Noise POUT = 1.5W OS Output Noise A-Weighted Filter, VIN = 0V, Input Referred PSRR Power Supply Rejection Ratio VRIPPLE = 200mVp-p f = 217Hz f = 1kHz VFB (1) (2) (3) (4) (5) (6) (7) (8) Feedback Pin Reference Voltage 70 3 See (8) msec (max) 40 mV (max) 125 C (min)) 1.8 1.65 W (min) 0.15 0.5 % 30 V 73 66 dB (min) 1.24 1.2772 1.2028 V (max) V (min) All voltages are measured with respect to the GND 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 specify 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 25C and represent the parametric norm. Limits are specified to Texas Instruments' AOQL (Average Outgoing Quality Level). Datasheet min/max specification limits are ensured by design, test, or statistical analysis. Shutdown current is measured in a normal room environment. The Shutdown pin should be driven as close as possible to Vin for minimum shutdown current. Shutdown current is measured with components R1 and R2 removed. Feedback pin reference voltage is measured with the Audio Amplifier disconnected from the Boost converter (the Boost converter is unloaded). Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 5 LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics THD+N vs Frequency VDD = 4.2V, RL = 8, POUT = 1.5W THD+N vs Frequency VDD = 3.0V, RL = 8, POUT = 1.5W 60 20 20 5 10 2 5 THD+N (%) THD + N (%) 10 1 0.5 0.2 2 1 0.5 0.2 0.1 0.1 0.05 0.05 0.02 0.02 0.01 20 0.01 20 50 100 200 500 1k 2k 5k 10k 20k FREQUENCY (Hz) 5k 10k 20k FREQUENCY (Hz) Figure 3. 10 50 100 200 500 1k 2k Figure 4. THD+N vs Output Power VDD = 4.2V, RL = 8, f = 1kHz 10 THD+N vs Output Power VDD = 3.0V, RL = 8 5 5 2 THD+N (%) THD+N (%) 2 1 0.5 1 0.5 0.2 0.1 0.05 0.2 0.02 0.1 10m 20m 50m 100m 200m 500m 1 0.01 10m 20m 50m 100m 200m 500m 1 2 3 6 90 Figure 6. PSRR vs Frequency VDD = 3V, Input Referred PSRR vs Frequency VDD = 4.2V, Input Referred 80 70 60 50 40 20 50 100 200 500 1k 2k 2 3 OUTPUT POWER (W) Figure 5. POWER SUPPLY REJECTION RATIO (dB) POWER SUPPLY REJECTION RATIO (dB) OUTPUT POWER (W) 5k 10k 20k 90 80 70 60 50 40 20 50 100 200 500 1k 2k FREQUENCY (Hz) FREQUENCY (Hz) Figure 7. Figure 8. Submit Documentation Feedback 5k 10k 20k Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 Typical Performance Characteristics (continued) 25 Power Supply Current vs Power Supply Voltage RL = 8 Power Supply Current vs Output Power 1600 POWER SUPPLY CURRENT (mA) POWER SUPPLY CURRENT (mA) THD+N = 10% 20 15 10 5 0 2.6 2.8 3 3.2 3.4 3.6 3.8 4 1400 THD+N = 1% 1200 1000 VDD = 3.0V 800 VDD = 3.6V 600 400 VDD = 4.2V 200 0 4.2 0 0.5 1 Figure 9. Output Power vs Power Supply Voltage RL = 8 3.50 THD+N = 10% OUTPUT POWER (W) 2 THD+N = 1% 1.5 1 0.5 0 2.6 2.8 3 3.2 3.4 3.6 3.8 4 3.00 RL = 4: 2.50 2.00 THD+N = 1% 1.50 THD+N = 10% 1.00 RL = 8: 0.50 0.00 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.2 POWER SUPPLY VOLTAGE (V) LOAD DISSIPATION (W) Figure 11. Figure 12. VFB vs Temperature 1.2365 95.0 10mA 1.236 1.2355 85.0 V FB (V) Efficiency (%) 90.0 80.0 75.0 600mA V DD = 3.3V 1.235 1.2345 1.234 70.0 60.0 1.8 2.5 Amplifier Circuit Dissipation vs Load Dissipation Efficiency vs VIN VOUT = 5.0V 65.0 2 Figure 10. AMPLIFIER CIRCUIT DISSIPATION (W) 2.5 1.5 OUTPUT POWER (W) POWER SUPPLY VOLTAGE (V) 1.2335 300mA 1.233 2.1 2.4 2.7 3.0 3.3 3.6 3.9 4.2 4.5 Vin 1.2325 -40 -25 -10 5 20 35 50 65 80 TEMPERATURE (C) Figure 13. Figure 14. Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 7 LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Frequency vs VIN 300k 1.5 150 1 0.5 1.100 1.00 0 0.90 0 0 1.2 1.20 0 Start-Up Voltage Frequency (Mhz) 225k 75k Maximum Start Up Voltage vs Temperature 1.30 0 2 1.7 2.2 2.7 3.2 3.7 0.800 -50 4.2 0 50 Vin (V) Temperatur e Figure 15. Figure 16. Typical RDS(ON) vs Temperature Typical Current Limit vs Temperature 0.300 100 3.000 2.900 0.250 Current Limit 2.800 Rds on 0.200 0.150 2A 0.100 1A 2.700 2.600 2.500 2.400 2.300 2.200 0.050 2.100 0.000 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 Temperature (C) Figure 17. 8 2.000 - - - 0 10 20 30 40 50 60 70 80 40 30 20 10 Temperature (C) Figure 18. Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 APPLICATION INFORMATION BRIDGE CONFIGURATION EXPLANATION Audio Amplifier portion of the LM4804 has two operational amplifiers internally, allowing for a few different amplifier configurations. The first amplifier's gain is externally configurable, while the second amplifier is internally fixed in a unity-gain, inverting configuration. The closed-loop gain of the first amplifier is set by selecting the ratio of Rf to Ri while the second amplifier's gain is fixed by the two internal 20k resistors. Figure 2 shows that the output of amplifier one serves as the input to amplifier two which results in both amplifiers producing signals identical in magnitude, but out of phase by 180. Consequently, the differential gain for the IC is AVD = 2 *(Rf/Ri) (1) By driving the load differentially through outputs Vo1 and Vo2, an amplifier configuration commonly referred to as "bridged mode" is established. Bridged mode operation is different from the classical single-ended amplifier configuration where one side of the load is connected to ground. A bridge amplifier design has a few distinct advantages over the single-ended configuration, as it provides differential drive to the load, thus doubling output swing for a specified supply voltage. Four times the output power is possible as compared to a single-ended amplifier under the same conditions. This increase in attainable output power assumes that the amplifier is not current limited or clipped. In order to choose an amplifier's closedloop gain without causing excessive clipping, please refer to the Audio Power Amplifier Design section. A bridge configuration also creates a second advantage over single-ended amplifiers. Since the differential outputs, Vo1 and Vo2, are biased at half-supply, no net DC voltage exists across the load. This eliminates the need for an output coupling capacitor which is required in a single supply, single-ended amplifier configuration. Without an output coupling capacitor, the half-supply bias across the load would result in both increased internal IC power dissipation and also possible loudspeaker damage. AMPLIFIER POWER DISSIPATION Power dissipation is a major concern when designing a successful amplifier, whether the amplifier is bridged or single-ended. A direct consequence of the increased power delivered to the load by a bridge amplifier is an increase in internal power dissipation. Since the amplifier portion of the LM4804 has two operational amplifiers, the maximum internal power dissipation is 4 times that of a single-ended amplifier. The maximum power dissipation for a given BTL application can be derived from Equation 2. PDMAX(AMP) = 4(VDD)2 / (22RL) (2) BOOST CONVERTER POWER DISSIPATION At higher duty cycles, the increased ON time of the FET means the maximum output current will be determined by power dissipation within the LM2731 FET switch. The switch power dissipation from ON-state conduction is calculated by Equation 3. PDMAX(SWITCH) = DC x IIND(AVE)2 x RDS(ON) (3) There will be some switching losses as well, so some derating needs to be applied when calculating IC power dissipation. TOTAL POWER DISSIPATION The total power dissipation for the LM4804 can be calculated by adding Equation 2 and Equation 3 together to establish Equation 4: PDMAX(TOTAL) = [4*(VDD)2/22RL]+[DCxIIND(AVE)2xRDS(ON)] (4) The result from Equation 4 must not be greater than the power dissipation that results from Equation 5: PDMAX = (TJMAX - TA) / JA (5) For package LQA28A, JA = 59C/W. TJMAX = 125C for the LM4804. Depending on the ambient temperature, TA, of the system surroundings, Equation 5 can be used to find the maximum internal power dissipation supported by the IC packaging. If the result of Equation 4 is greater than that of Equation 5, then either the supply voltage must be increased, the load impedance increased or TA reduced. For the typical application of a 3V power supply, with V1 set to 6.0V and 8 load, the maximum ambient temperature possible without violating the Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 9 LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com maximum junction temperature is approximately TBDC provided that device operation is around the maximum power dissipation point. Thus, for typical applications, power dissipation is not an issue. 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 levels. EXPOSED-DAP PACKAGE PCB MOUNTING CONSIDERATIONS The LM4804'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. Further detailed and specific information concerning PCB layout, fabrication, and mounting an LD (WQFN) package is available from Texas Instruments' Package Engineering Group under application note AN1187. SHUTDOWN FUNCTION In many applications, a microcontroller or microprocessor output is used to control the shutdown circuitry to provide a quick, smooth transition into shutdown. Another solution is to use a single-pole, single-throw switch, in conjunction with an external pull-up resistor to drive both shutdown pins simultaneously. When the switch is closed, the shutdown pin is connected to ground which disables the amplifier. If the switch is open, then the external pull-up resistor to VDD will enable the LM4804. This scheme ensures that the shutdown pins will not float thus preventing unwanted state changes. EXTERNAL COMPONENT SELECTION Proper selection of external components in applications using integrated power amplifiers, and switching DC-DC converters, is critical to optimize device and system performance. Consideration to component values must be used to maximize overall system quality. The best capacitors for use with the switching converter portion of the LM4804 are multi-layer ceramic capacitors. They have the lowest ESR (equivalent series resistance) and highest resonance frequency which makes them optimum for use with high frequency switching converters. When selecting a ceramic capacitor, only X5R and X7R dielectric types should be used. Other types such as Z5U and Y5F have such severe loss of capacitance due to effects of temperature variation and applied voltage, they may provide as little as 20% of rated capacitance in many typical applications. Always consult capacitor manufacturer's data curves before selecting a capacitor. High-quality ceramic capacitors can be obtained from Taiyo-Yuden, AVX, and Murata. POWER SUPPLY BYPASSING As with any amplifier, proper supply bypassing is critical for low noise performance and high power supply rejection. The capacitor location on both the bypass and power supply pins should be as close to the device as possible. SELECTING THE AUDIO AMPLIFIER'S INPUT CAPACITOR One of the major considerations is the closedloop bandwidth of the amplifier. To a large extent, the bandwidth is dictated by the choice of external components shown in Figure 2. The input coupling capacitor, Ci, forms a first order high pass filter which limits low frequency response. This value should be chosen based on needed frequency response for a few distinct reasons. Large input capacitors are both expensive and space hungry for portable designs. Clearly, a certain sized capacitor is needed to couple in low frequencies without severe attenuation. But ceramic speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 100Hz to 150Hz. Thus, using a large input capacitor may not increase actual system performance. 10 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 In addition to system cost and size, click and pop performance is effected by the size of the input coupling capacitor, Ci. A larger input coupling capacitor requires more charge to reach its quiescent DC voltage (nominally 1/2 VDD). This charge comes from the output via the feedback and is apt to create pops upon device enable. Thus, by minimizing the capacitor size based on necessary low frequency response, turn-on pops can be minimized. SELECTING THE AUDIO AMPLIFIER'S BYPASS CAPACITOR Besides minimizing the input capacitor size, careful consideration should be paid to the bypass capacitor value. Bypass capacitor, CB, is the most critical component to minimize turn-on pops since it determines how fast the amplifer turns on. The slower the amplifier's outputs ramp to their quiescent DC voltage (nominally 1/2 VDD), the smaller the turn-on pop. Choosing CB equal to 1.0F along with a small value of Ci (in the range of 0.039F to 0.39F), should produce a virtually clickless and popless shutdown function. While the device will function properly, (no oscillations or motorboating), with CB equal to 0.1F, the device will be much more susceptible to turn-on clicks and pops. Thus, a value of CB equal to 1.0F is recommended in all but the most cost sensitive designs. OPERATING PRINCIPLE The LM4804 includes step-up DC-DC voltage regulation for battery-powered and low-input voltage systems. It combines a step-up switching regulator, N-channel power MOSFET, built-in current limit, thermal limit, and voltage reference. The switching DC-DC regulator boosts an input voltage between .8V and 14V to a regulated output voltage between 1.24V and 14V. The LM4804 starts from a low 1.1V input and remains operational down to below .8V. This device is optimized for use in cellular phones and other applications requiring a small size, low profile, as well as low quiescent current for maximum battery life during stand-by and shutdown. Additional features include a built-in peak switch current limit, a high-efficiency gated-oscillator topology that offers an output of up to 2A at low output voltages, and thermal protection circuitry. Figure 19. Functional Diagram of the LM4804's Regulator Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 11 LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com GATED OSCILLATOR CONTROL SCHEME The on/off regulation mode of the LM4804, along with its ultra-low quiescent current, results in good efficiency over a very wide load range. The internal oscillator frequency can be programmed using an external resistor to be constant or vary with the battery voltage. Adding a capacitor to program the frequency allows the designer to adjust the duty cycle and optimize it for the application. Adding a resistor in addition to the capacitor allows the duty cycle to dynamically compensate for changes to the input/output voltage ratio. We call this a Ratio Adaptive Gated Oscillator circuit. Using the correct RC components to adjust the oscillator allows the part to run with low ripple and high efficiency over a wide range of loads and input/output voltages. Figure 20. Typical Step-Up Regulator Waveforms PULSE FREQUENCY MODULATION (PFM) Pulse Frequency Modulation is typically accomplished by switching continuously until the voltage limit is reached and skipping cycles after that to just maintain it. This results in a somewhat hysteretic mode of operation. The coil stores more energy each cycle as the current ramps up to high levels. When the voltage limit is reached, the system usually overshoots to a higher voltage than required, due to the stored energy in the coil (see Figure 20). The system will also undershoot somewhat when it starts switching again because it has depleted all the stored energy in the coil and needs to store more energy to reach equilibrium with the load. Larger output capacitors and smaller inductors reduce the ripple in these situations. The frequency being filtered, however, is not the basic switching frequency. It is a lower frequency determined by the load, the input/output voltage and the circuit parameters. This mode of operation is useful in situations where the load variation is significant. Power managed computer systems, for instance, may vary from zero to full load while the system is on and this is usually the preferred regulation mode for such systems. CYCLE TO CYCLE PFM When the load doesn't vary over a wide range (like zero to full load), ratio adaptive circuit techniques can be used to achieve cycle to cycle PFM regulation and lower ripple (or smaller output capacitors). The key to success here is matching the duty cycle of the circuit closely to what is required by the input to output voltage ratio. This ratio then needs to be dynamically adjusted for input voltage changes (usually caused by batteries running down). The chosen ratio should allow most of the energy in each switching cycle to be delivered to the load and only a small amount to be stored. When the regulation limit is reached, the overshoot will be small and the system will settle at an equilibrium point where it adjusts the off time in each switching cycle to meet the current requirements of the load. The off time adjustment is done by exceeding the regulation limit during each switching cycle and waiting until the voltage drops below the limit again to start the next switching cycle. The current in the coil never goes to zero like it frequently does in the hysteretic operating mode of circuits with wide load variations or duty cycles that aren't matched to the input/output voltage ratio. Optimizing the duty cycle for a given set of input/output voltages conditions can be done by using the circuit values in the Application Notes. 12 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 LOW VOLTAGE START-UP The LM4804 can start-up from voltages as low as 1.1 volts. On start-up, the control circuitry switches the Nchannel MOSFET continuously until the output reaches 3 volts. After this output voltage is reached, the normal step-up regulator feedback and gated oscillator control scheme take over. Once the device is in regulation, it can operate down to below .8V input, since the internal power for the IC can be boot-strapped from the output using the Vdd pin. SHUT DOWN The LM4804 features a shutdown mode that reduces the quiescent current to less than a 2.5uA over temperature. This extends the life of the battery in battery powered applications. During shutdown, all feedback and control circuitry is turned off. The regulator's output voltage drops to one diode drop below the input voltage. Entry into the shutdown mode is controlled by the active-low logic input pin S/D1 (pin 26). When the logic input to this pin is pulled below 0.15VDD, the device goes into shutdown mode. The logic input to this pin should be above 0.7VDD for the device to work in normal step-up mode. SELECTING OUTPUT CAPACITOR (CO) FOR BOOST CONVERTER A single ceramic capacitor of value 4.7F to 10F will provide sufficient output capacitance for most applications. If larger amounts of capacitance are desired for improved line support and transient response, tantalum capacitors can be used. Aluminum electrolytics with ultra low ESR such as Sanyo Oscon can be used, but are usually prohibitively expensive. Typical AI electrolytic capacitors are not suitable for switching frequencies above 500 kHz due to significant ringing and temperature rise due to self-heating from ripple current. An output capacitor with excessive ESR can also reduce phase margin and cause instability. In general, if electrolytics are used, it is recommended that they be paralleled with ceramic capacitors to reduce ringing, switching losses, and output voltage ripple. INTERNAL CURRENT LIMIT AND THERMAL PROTECTION An internal cycle-by-cycle current limit serves as a protection feature. This is set high enough (2.85A typical, approximately 4A maximum) so as not to come into effect during normal operating conditions. An internal thermal protection circuit disables the MOSFET power switch when the junction temperature (TJ) exceeds about 160C. The switch is re-enabled when TJ drops below approximately 135C. NON-LINEAR EFFECT The LM4804 takes advantage of a non-linear effect that allows for the duty cycle to be programmable. The C3 capacitor is used to dump charge on the FREQ pin in order to manipulate the duty cycle of the internal oscillator. The part is being tricked to behave in a certain manner, in the effort to make this Pulse Frequency Modulated (PFM) boost switching regulator behave as a Pulse Width Modulated (PWM) boost switching regulator. CHOOSING THE CORRECT C3 CAPACITOR The C3 capacitor allows for the duty cycle of the internal oscillator to be programmable. Choosing the correct C3 capacitor to get the appropriate duty cycle for a particular application circuit is a trial and error process. The nonlinear effect that C3 produces is dependent on the input voltage and output voltage values. The correct C3 capacitor for particular input and output voltage values cannot be calculated. Choosing the correct C3 capacitance is best done by trial and error, in conjunction with the checking of the inductor peak current to make sure your not too close to the current limit of the device. As the C3 capacitor value increases, so does the duty cycle. And conversely as the C3 capacitor value decreases, the duty cycle decreases. An incorrect choice of the C3 capacitor can result in the part prematurely tripping the current limit and/or double pulsing, which could lead to the output voltage not being stable. SETTING THE OUTPUT VOLTAGE The output voltage of the step-up regulator can be set by connecting a feedback resistive divider made of RF1 and RF2. The resistor values are selected as follows: R1 = R2[(VOUT/1.24) -1] (6) A value of 50k to 100k is suggested for R2. Then, R1 can be selected using Equation 6. Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 13 LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com VDD SUPPLY The Vdd supply must be between 3 to 5 volts for the LM4804. This voltage can be bootstrapped from a much lower input voltage by simply connecting the VDD pin to VOUT. In the event that the VDD supply voltage is not a low ripple voltage source (less than 200 millivolts), it may be advisable to use an RC filter to clean it up. Excessive ripple on VDD may reduce the efficiency. SETTING THE SWITCHING FREQUENCY The switching frequency of the oscillator is selected by choosing an external resistor (R3) connected between VIN and the FREQ pin. See the graph titled "Frequency vs VIN" in the Typical Performance Characteristics section of the data sheet for choosing the R3 value to achieve the desired switching frequency. A high switching frequency allows the use of very small surface mount inductors and capacitors and results in a very small solution size. A switching frequency between 300kHz and 2MHz is recommended. OUTPUT DIODE SELECTION A Schottky diode should be used for the output diode. The forward current rating of the diode should be higher than the peak input current, and the reverse voltage rating must be higher than the output voltage. Do not use ordinary rectifier diodes, since slow switching speeds and long recovery times cause the efficiency and the load regulation to suffer. Table 1 shows a list of the diode manufacturers. WQFN PACKAGE DEVICES The LM4804 is offered in the 14 lead WQFN surface mount package to allow for increased power dissipation compared to the MSOP-8. For details of the thermal performance as well as mounting and soldering specifications, refer to Application Note AN-1187. RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT Figure 22 through Figure 27 show the recommended four-layer PC board layout that is optimized for the LQpackaged, 3V 1.7W LM4804 mono-BTL audio amplifier and its associated external components. This circuit is designed for use with an external 3V to 4.2V supply and speakers with 4 or higher impedance (8 nominal). The LM4804 circuit board is easy to use. Apply between 3V and 4.2V (equivalent to, respectfully, a discharged or a fully charged Li-ion or NMH battery) and ground to JP2's VDD and GND pins, respectively. Connect a speaker with an impedance of 4 or greater (8 nominal) between the board's VO1 (-) and VO2 (+) pins. An audio signal is applied to JP1 between the VIN (+) and GND (-) pins. The circuit board is configured for a gain of 20 or 26dB (VO2 -VO1 with respect to VIN). An inverting gain of -10 at VO1 is set by Rf (200k) versus Ri (20k). The extra gain of 2 is a product of the BTL output (VO2 - VO1). Gain can be modified by changing Rf's value with respect to Ri. Table 1. Suggested Manufacturers List Inductors Capacitors Diodes Coilcraft Tel: (800) 322-2645 Fax: (708) 639-1469 Sprague/ Vishay Tel: (207) 324-4140 Fax: (207) 324-7223 Motorola Tel: (800) 521-6274 Fax: (602) 244-6609 Coiltronics Tel: (407) 241-7876 Fax: (407) 241-9339 Kemet Tel: (864) 963-6300 Fax: (864) 963-6521 International Rectifier (IR) Tel: (310) 322-3331 Fax: (310) 322-3332 Pulse Engineering Tel: (619) 674-8100 Fax: (619) 674-8262 Nichicon Tel: (847) 843-7500 Fax: (847) 843-2798 General Semiconductor Tel: (516) 847-3222 Fax: (516) 847-3150 14 Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 D1 L1 4.7 PH Cs1 4.7 PF Bat C3 4.7 pF VDD R3 150k 3 25 26 S/D 27 Cf1 470 pF 5 7 VDD SW GND1 V1 = VFB (1 + R1/R2) FB Co 100 PF R1 301k 28 R2 78.7k GND2 S/D1 BOOT 6 FREQ 10 PH 0.1 PF 18 19 Cb 1.0 PF 9 V1 S/D2 Bypass GND3 +IN VO2 12 22 Cs2 4.7 PF 14 8: 20k Audio In 0.1 PF Ci 8 -IN VO1 11 Ri Rf 200k Figure 21. Demo Board Reference Schematic Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 15 LM4804 SNAS268C - MARCH 2005 - REVISED APRIL 2013 www.ti.com Demonstration Board Layout 16 Figure 22. Top Trace Layer Silkscreen Figure 23. Top Layer Silkscreen Figure 24. Top Trace Layer Figure 25. Upper Internal GND Layer Figure 26. Lower Internal VDD Layer Figure 27. Bottom Trace Layer with GND Plane Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 LM4804 www.ti.com SNAS268C - MARCH 2005 - REVISED APRIL 2013 Revision History Rev Date Description 1.0 6/14/05 Under SHUTDOWN (Apps section), changed EN to S/D1 and (pin- 2) into pin 26, then re-released D/S to the WEB. C 4/08/13 Changed layout of National Data Sheet to TI format. Submit Documentation Feedback Copyright (c) 2005-2013, Texas Instruments Incorporated Product Folder Links: LM4804 17 PACKAGE OPTION ADDENDUM www.ti.com 7-Nov-2016 PACKAGING INFORMATION Orderable Device Status (1) LM4804LQ/NOPB LIFEBUY Package Type Package Pins Package Drawing Qty WQFN NJB 28 1000 Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM Op Temp (C) Device Marking (4/5) L4804LQ (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) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. 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Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 7-Nov-2016 Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM4804LQ/NOPB Package Package Pins Type Drawing WQFN NJB 28 SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 1000 178.0 12.4 Pack Materials-Page 1 5.3 B0 (mm) K0 (mm) P1 (mm) 5.3 1.3 8.0 W Pin1 (mm) Quadrant 12.0 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 12-Aug-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM4804LQ/NOPB WQFN NJB 28 1000 210.0 185.0 35.0 Pack Materials-Page 2 MECHANICAL DATA NJB0028A LQA28A (REV B) www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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