UNISONIC TECHNOLOGIES CO., LTD LM4811 Preliminary CMOS IC DUAL 105mW HEADPHONE AMPLIFIER WITH DIGITAL VOLUME CONTROL AND SHUTDOWN MODE DESCRIPTION The UTC LM4811 is a dual audio power amplifier with digital volume control and shutdown mode function. It is featured in unity-gain stability. The digital volume control sets the amplifier’s gain from +12dB to -33dB in 16 discrete steps using a two-wire interface. The shutdown mode is externally controlled, active-high and micropower consumption. An internal thermal shutdown protection circuit is contained in the device. Operating on a 5V power supply, it can drive 16Ω load at 105mW per channel of continuous average power with 0.1% (THD+N). This device is mainly used to provide customers with higher quality output power but less required external components. The UTC LM4811 reduces the use of bootstrap capacitors or snubber networks that make making it ideal for low-power portable systems applications. The UTC LM4811 is generally applied in cellular phones, MP3, CD, DVD players, PDA’s and other portable electronics. FEATURES * Digital volume control range: +12dB~ -33dB * "Click and Pop" suppression circuitry * Saving the use of bootstrap capacitors * Low shutdown current ORDERING INFORMATION Ordering Number Lead Free LM4811L-SM2-R Halogen Free LM4811G-SM2-R www.unisonic.com.tw Copyright © 2011 Unisonic Technologies Co., Ltd Package Packing MSOP-10 Tape Reel 1 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC PIN CONFIGURATION Top View VOUT1 1 VIN1 2 9 VOUT2 Bypass 3 8 VIN2 CLOCK 4 7 SHUTDOWN GND 5 6 UP/DN 10 VDD MSOP-10 PIN DESCRIPTION PIN NO. 1 2 3 4 5 6 PIN NAME VOUT1 VIN1 Bypass CLOCK GND UP/DN 7 SHUTDOWN 8 9 10 VIN2 VOUT2 VDD DESCRIPTION Channel 1 output Channel 1 audio input Connect to internal voltage divider for middle supply bias External clock input for the volume control Ground Volume UP/DOWN control Shutdown mode control input, high active, place LM4811 into shutdown mode, when held high Channel 2 audio input Channel 2 output Supply voltage UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 2 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC BLOCK DIAGRAM VDD 10 VIN1 2 VDD Shutdown 7 BIAS 50kΩ 1 VOUT1 + 20kΩ Bypass 3 50kΩ + 9 VOUT2 - 20kΩ VIN2 8 UP/DN 6 Clock 4 Digital Volume Control 5 GND UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 3 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC ABSOLUTE MAXIMUM RATING (TC = 25°C, unless otherwise specified) PARAMETER SYMBOL RATINGS UNIT Supply Voltage VCC 6.0 V Junction Temperature TJ 150 ℃ Storage Temperature TSTG -65~ +150 ℃ Notes: 1. Absolute maximum ratings are those values beyond which the device could be permanently damaged. Absolute maximum ratings are stress ratings only and functional device operation is not implied. THERMAL DATA PARAMETER Junction to Ambient Junction to Case RATINGS 194 52 UNIT °C/W °C/W SYMBOL VCC TA RATINGS 2.0 ~ 5.5 -40 ~ 85 UNIT V °C OPERATING RATINGS PARAMETER Supply Voltage Operating Temperature SYMBOL θJA θJC ELECTRICAL CHARACTERISTICS (TA=25°C, unless otherwise specified) (Note 4, 5) For VDD=5V PARAMETER Supply Voltage Supply Current Shutdown Current Output Offset Voltage Output Power Total Harmonic Distortion Channel Separation Power Supply Rejection Ratio Input Voltage (Clock, UP/DN, Shutdown) High Low Digital Volume Range Digital Volume Stepsize Stepsize Error Channel-to-Channel Volume Tracking Error Shutdown Attenuation SYMBOL TEST CONDITIONS VDD IDD VIN=0V, IO=0A ISD VIN=0V VOS VIN=0V RL=16Ω PO THD+N=0.1%, f=1kHz RL=32Ω THD+N PO=50mW, RL=32Ω, f=20Hz~20kHz Crosstalk RL=32Ω, f=1kHz, PO=70mW CB=1.0μF,VRIPPLE=100mVPP, PSRR f=217Hz VIH VIL Input referred minimum gain Input referred maximum gain All 16 discrete steps All 16 discrete steps TYP 1.3 0.3 4.0 105 70 0.3 100 MAX 5.5 3.0 50 60 UNIT V mA μA mV mW mW % dB dB -33 +12 3.0 ±0.3 V V dB dB dB dB All gain settings from -33dB ~ +12dB 0.15 dB Shutdown mode active -100 dB UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw MIN 2.0 1.4 0.4 4 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC ELECTRICAL CHARACTERISTICS(Cont.) For VDD=3.3V PARAMETER Supply Current Shutdown Current Output Offset Voltage Output Power Total Harmonic Distortion Power Supply Rejection Ratio Input Voltage High (Clock, UP/DN, Shutdown) Low Digital Volume Range Digital Volume Stepsize Stepsize Error Channel-to-Channel Volume Tracking Error Shutdown Attenuation For VDD=2.6V PARAMETER Supply Current Shutdown Current Output Offset Voltage Output Power Total Harmonic Distortion Power Supply Rejection Ratio Input Voltage High (Clock, UP/DN, Shutdown) Low Digital Volume Range SYMBOL TEST CONDITIONS IDD VIN=0V, IO=0A ISD VIN=0V VOS VIN=0V RL=16Ω PO THD+N=0.1%, f=1kHz RL=32Ω THD+N PO=25mW, RL=32Ω, f=20Hz~20kHz CB=1.0μF,VRIPPLE=100mVPP, PSRR f=217Hz VIH VIL Input referred minimum gain Input referred maximum gain All 16 discrete steps All 16 discrete steps MIN TYP 1.1 0.3 4.0 40 28 0.5 UNIT mA μA mV mW mW % 60 dB -33 +12 3.0 ±0.3 V V dB dB dB dB All gain settings from -33dB ~ +12dB 0.15 dB Shutdown mode active -100 dB SYMBOL TEST CONDITIONS IDD VIN=0V, IO=0A ISD VIN=0V VOS VIN=0V RL=16Ω PO THD+N=0.1%, f=1kHz RL=32Ω THD+N PO=15mW, RL=32Ω, f=20Hz~20kHz CB=1.0μF,VRIPPLE=100mVPP, PSRR f=217Hz VIH VIL Input referred minimum gain Input referred maximum gain All 16 discrete steps All 16 discrete steps 1.4 0.4 MIN TYP 1.0 0.3 4.0 20 16 0.6 UNISONIC TECHNOLOGIES CO., LTD MAX 60 0.4 -33 +12 3.0 ±0.3 UNIT mA μA mV mW mW % dB 1.4 Digital Volume Stepsize Stepsize Error Channel-to-Channel Volume All gain settings from -33dB ~ +12dB 0.15 Tracking Error Shutdown Attenuation Shutdown mode active -75 Notes: 4. Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. 5. All voltages are measured with respect to the ground pin, unless otherwise specified. www.unisonic.com.tw MAX V V dB dB dB dB dB dB 5 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC APPLICATION INFORMATION DIGITAL VOLUME CONTROL The UTC LM4811 is dual audio power amplifier with digital volume control and shutdown mode function. The CLOCK pin is drived by an external clock. It’ s gain is controlled by the signals applied to the CLOCK and UP/DN inputs. The audio power amplifier’s gain is fixed by the signals, which are applied to the CLOCK and UP/DN inputs. The gain is controlled by the logic voltage level applied to the UP/DN pin at each rising edge of the clock signal. At each rising edge of the clock signal, when a logic high voltage level is applying to the UP/DN pin, 3dB is increased, in verse when a logic low voltage is applying to the UP/DN pin, 3dB is decreased on the contrary. For both the CLOCK and UP/DN inputs, the trigger point is 1.4V (MIN.) for a logic high level, and 0.4V (MAX.) for a logic low level. The UTC LM4811 contains16 discrete gain settings varying from +12dB (MAX.) to -33dB (MIN.), amplifier’s gain is set to a default value of 0dB during power on condition. However, when coming out of shutdown mode, the UTC LM4811 will revert back to its previous gain setting. In order to avoid undesired state changes during transitions between VIL and VIH, the UTC LM4811’s CLOCK and UP/DN pins should be debounced. This will ensure correct operation of the digital volume control. A microcontroller or microprocessor output is expected to drive the CLOCK and UP/DN pins. 1 UP/DN 0 1 CLOCK 0 VOLUME Default Up Up Down Down Figure 2. Timing Diagram POWER SUPPLY BYPASSING To obtain low noise performance and high power supply rejection, proper supply bypassing is essentially needed for any power amplifier. Capacitor on both the bypass and power supply pins should be placed closely as possible. Bypass capacitor value is also critical as it directly affects the device’s half-supply voltage stability and PSRR. The stability and supply rejection increase as the bypass capacitor’s value increases. In the typical applications, employing a 5V regulator with 10μF and a 0.1μF bypass capacitors which aid in supply stability. This, however, is not saving the need for bypassing the supply nodes of the UTC LM4811. The issue of selecting bypass capacitors, especially CB, is thus dependent upon desired low frequency PSRR, click and pop performance, system cost, and size constraints. SHUTDOWN FUNCTION The UTC LM4811 contains a bias circuitry shutdown to reduce power consumption while not is use. By applying a logic high to the SHUTDOWN pin, the shutdown function is active. For a logic high level, the trigger point is 1.4V (MIN.), and 0.4V (MAX.) for a logic low. For a better shutdown performance, it is best to switch between ground and VDD. By switching the SHUTDOWN pin to VDD, the UTC LM4811 supply current draw will be minimized in idle mode. Whereas the device will be disabled with shutdown voltages less than VDD, the idle current may be greater than 0.3μA (TYP.). In either case, the SHUTDOWN pin should be tied to a fixed voltage to avoid undesired state changes. In many applications, a microcontroller or microprocessor output is used to control the shutdown circuitry. This provides a quick, smooth shutdown transition. Another solution is to use a single-pole, single-throw switch in conjunction with an external pull-up resistor. When the switch is closed, the SHUTDOWN pin is connected to ground and enables the amplifier. If the switch is open, the external pull-up resistor, RPU, will disable the UTC LM4811. This scheme guarantees that the SHUTDOWN pin will not float, thus preventing undesired state changes. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 6 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC APPLICATION INFORMATION(Cont.) PROPER SELECTION OF EXTERNAL COMPONENTS In applications, selection of external components when using integrated power amplifiers is critical for optimum device and system performance. Moreover, the vales of external components are also important to consider as they directly affect the overall system quality. The UTC LM4811 is tolerant to a variety external component combinations. The UTC LM4811 is unity-gain stable, providing designers maximize system performance. Low gain settings maximize signal-to-noise performance and minimizes THD+N. Low gain configurations require large input signals to obtain a given output power. Input signals reach 1Vrms or higher are available from sources such as audio codecs. SELECTION OF INPUT AND OUTPUT CAPACITOR SIZE Another consideration is the closed loop bandwidth besides gain. To a large extent, the bandwidth is dicated by the choice of external components shown in Figure 1. Both the CI (input coupling capacitor) and the CO (output coupling capacitor) form first order high pass filters which limit low frequency response. The values of these capacitors should be based on the desired frequency response weighed against the following: Large value input and output capacitors are both expensive and space consuming for portable designs. Clearly a certain sized capacitor is needed to couple in low frequencies without severe attenuation. But in many cases the speakers used in portable systems, whether internal or external, have little ability to reproduce signals below 150Hz. Thus large input and output capacitors may not increase system performance. Moreover, for the system cost and size, click and pop performance is affected by the size of the CI (input coupling capacitor). 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 the pops are apt to be generated upon device enable. Reducing the value of input coupling capacitor can minimize the turn on pops, which is based on necessary low frequency response. The value of bypass capacitor should be taken into consideration besides minimizing the input and output capacitor values. For minimizing turn on pops, the bypass capacitor CB plays the most important role, since it determines how fast the UTC LM4811 turns on. The slower the UTC LM4811’s outputs ramp to their quiescent DC voltage (nominally 1/2 VDD ), the smaller the turn on pop. While the device will function properly, (no oscillations or motorboating), with CB equal to 1μF, the device will be much more susceptible to turn on clicks and pops. Thus, a value of CB equal to 1μF or larger is recommended in all but the most cost sensitive designs. In addition, the type of capacitors should be given enough consideration since different types of capacitors (tantalum, electrolytic, ceramic) have unique performance characteristics and may affect overall system performance. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 7 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC TYPICAL APPLICATION CIRCUIT VDD CS + 1μF CI 1μF + Audio Input VIN1 VDD RPU 100kΩ VDD Shutdown BIAS - 50kΩ + VOUT1 + CO 100μF 20kΩ Bypass CB + 1μF 50kΩ + - CI 1μF Audio Input + VOUT2 20kΩ + CO 100μF VIN2 UP/DN Clock VDD Digital Volume Control GND VDD RP 100Ω RPD 100Ω CP 0.1μF * 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 UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 8 of 9 QW-R502-560.a LM4811 Preliminary CMOS IC EXTERNAL COMPONENTS DESCRIPTION PIN NO. PIN NAME 1 CI 2 CS 3 CB 4 CO DESCRIPTION This is the input coupling capacitor. It blocks the DC voltage at, and couples the input signal to, the amplifier’s input terminals. C also creates a highpass filter with the internal input resistor, RI, at fC =1/(2πRICI). The minimum value of RI is 33kΩ. Refer to the section, Proper Selection of External Components, for an explanation of how to determine the value of CI. 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. This is the BYPASS pin capacitor. It provides half-supply filtering. Refer to the section, Proper Selection of External Components, for information concerning proper placement and selection of CB. This is the output coupling capacitor. It blocks the DC voltage at the amplifier’s output and it forms a high pass filter with RL at fO = 1/(2πRLCo ) UTC assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all UTC products described or contained herein. UTC products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. UNISONIC TECHNOLOGIES CO., LTD www.unisonic.com.tw 9 of 9 QW-R502-560.a