APA4838 Stereo 2.8W Audio Power Amplifier with DC Volume Control and Selectable Gain Features • • General Description The APA4838 is a monolithic integrated circuit , which provides DC volume control , and a stereo bridged audio power amplifiers capable of producing 2.8W (2.3W) into 3Ω with less than 10% (1.0%) THD+N. APA4838 includes a DC volume control , stereo bridge-tied and single-ended audio power amplifiers , stereo docking outputs , and a selectable gain control , that makes it optimally fittable for notebook PC , multimedia monitors , and other portable applications. The attenuator range of the volume control in APA4838 is from 0dB (DC_Vol=0.8VDD) to –78dB (DC_Vol=0V) with 31 steps. Both of the depop circuitry and the thermal shutdown protection circuitry are integrated in APA4838 , that reduces pops and clicks noise during power up or shutdown mode operation , and protects the chip from being destroyed by over temperature failure. To simplify the audio system design , APA4838 combines a stereo bridgetied loads (BTL) mode for speaker drive and a stereo single-end (SE) mode for headphone drive into a single chip , where both modes are easily switched by the HP Sense input control pin signal. Besides the low supply current design to increase the efficiency of the amplifiers , APA4838 also features a shutdown function which keeps the supply current only 0.7µA (typ). Operating Voltage : 4.5V to 5V Stereo switchable bridged/single-ended power amplifiers • DC Volume Control Interface , 0dB to –78dB with precision scale • • • Supply Current , IDD = 15mA at Stereo BTL Low Shutdown Current , IDD = 0.7µA Bridge-Tied Load (BTL) or Single-Ended-(SE) Modes Operation • • Output Power at 1% THD+N , VDD=5V – 2.3W/Ch (typ) into a 3 Ω Load – 2.0W/Ch (typ) into a 4 Ω Load – 1.2W/Ch (typ) into a 8 Ω Load Output Power at 10% THD+N , VDD=5V – 2.8W/Ch (typ) into a 3 Ω Load – 2.3W/Ch (typ) into a 4 Ω Load – 1.5W/Ch (typ) into a 8Ω Load • Single-ended mode at 1.0% THD+N – 95mW/Ch (typ) into 32Ω Load • • Depop Circuitry Integrated Pin Description Thermal shutdown protection and over current protection circuitry • • • High supply voltage ripple rejection 1 28 Right O ut + Shutdown 2 27 V DD G ain Select 3 26 Right O ut - 28-pin TSSOP-P (with enhanced thermal pad) M ode 4 25 power package available M ute VDD 5 24 Right G ain 2 Right G ain 1 6 23 GN D DC V ol 7 22 BY PA SS GN D 8 21 HP Sense Right Dock 9 20 GN D Right In 10 19 Beep In 11 18 Left G ain 1 Left G ain 2 GN D PC99 Compliant Applications • • • Notebook and Desktop Computers Multimedia Monitors Left In 12 17 Left O ut - Left Dock 13 16 V DD GN D 14 15 Left O ut + Portable Applications ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and advise customers to obtain the latest version of relevant information to verify before placing orders. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 1 www.anpec.com.tw APA4838 Ordering and Marking Information APA4838 P ackage C ode R : T S S O P -P Tem p. R ange I : -4 0 to 8 5 ° C H a n d lin g C o d e TU : Tube H a n d lin g C o d e T em p. R an g e P ac ka ge C od e A P A 4838 XXXXX A P A 4838 R : TR : Tape & R eel X X X X X - D a te C o d e Block Diagram 20KΩ Mode Control Mute HP Sense Left Gain2 Mode 20KΩ Left Gain1 Gain Select 10KΩ DC_Vol 20KΩ 10KΩ Left Dock 0.33µF Beep Detect 0.33µF Right In Bias Volume Control 31 steps + Beep In 20KΩ 20KΩ + Left Out Bias + Right Audio Input 20KΩ Left In + - 200KΩ 20KΩ + - Left Audio Input 200KΩ - Left Out + - 20KΩ 0.068µF Right Dock 20KΩ 20KΩ + Right Out 20KΩ - Right Out Shutdown GND + VDD Power Management 10KΩ 10KΩ 20KΩ Right Gain2 0.068µF Click and Pop Suppression Circuitry Right Gain1 Bypass 20KΩ Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 2 20KΩ www.anpec.com.tw APA4838 Absolute Maximum Ratings (Over operating free-air temperature range unless otherwise noted.) Symbol VDD VIN TA TJ TSTG TS VESD PD Parameter Rating Supply Voltage -0.3 to 6 Input Voltage Range, HP sense, Shutdown, -0.3 to VDD+0.3 Mute, Mode, Gain Select Operating Ambient Temperature Range -40 to 85 Maximum Junction Temperature Internally Limited*1 Storage Temperature Range -65 to +150 Soldering Temperature,10 seconds 260 Electrostatic Discharge -2000 to 2000*2 Power Dissipation Internally Limited Unit V V °C °C °C °C V W Note: 1.APA4838 integrated internal thermal shutdown protection when junction temperature ramp up to 150°C 2.Human body model: C=100pF, R=1500Ω, 3 positives pulse plus 3 negative pulses 3.Machine model: C=200pF, L=0.5µF, 3 positive pulses plus 3 negative pulses Recommended Operating Conditions Supply Voltage, VDD High level threshold voltage, VIH Low level threshold voltage, VIL Min. Max. Unit 4.5 5.5 V Shutdown, Mute, Mode, Gain Select 2 HP Sense Shutdown, Mute, Mode, Gain Select 4 V 1.0 HP Sense 3 Common mode input voltage, VICM VDD-1.0 V V Thermal Characteristics Symbol Parameter R THJA Thermal Resistance from Junction to Ambient in Free Air TSSOP-P* Value Unit 45 K/W * 5 in2 printed circuit board with 2oz trace and copper pad through 9 25mil diameter vias. The thermal pad on the TSSOP_P package with solder on the printed circuit board. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 3 www.anpec.com.tw APA4838 Electrical Characteristics Electrical Characteristics for Entire IC The following specifications apply for VDD= 5V unless otherwise noted. Limits apply for TA= 25°C Symbol VDD IDD ISD Parameter Supply Voltage Quiescent Power Supply Current Shutdown Current Test Conditions APA4838 Typ. Max. 5.5 Min. 4.5 Unit V VIN=0V, IO=0A 15 25 mA VPIN 2= VDD 0.7 2.0 µA Electrical Characteristics for Volume Attenuators The following specifications apply for VDD= 5V. Limits apply for TA= 25°C Symbol Parameter CRANGE Attenuator Range AM Mute Attenuation Test Conditions Gain with VPIN 7=5V Attenuation with VPIN 7=0V VPIN 5=5V, Bridged Mode VPIN 5=5V, Single-Ended Mode APA4838 Typ. Max. ±0.5 -65 -78 -70 -70 Min. Unit dB dB Electrical Characteristics for BTL Mode Operation The following specifications apply for VDD= 5V unless otherwise noted. Limits apply for TA= 25°C Symbol VOS PO THD+N PSRR XTALK SNR VN Parameter Test Conditions Output Offset Voltage Output Power VIN=0V THD=1%, f=1kHz RL=3Ω RL=4Ω RL=8Ω THD=10%, f=1kHz RL=8Ω Total Harmonic Distortion + Noise AVD=2, f=1kHz RL=4Ω , PO =1.5W RL=8Ω , PO=1W VRIPPLE=100mVRms CB=2.2µF, Power Supply Rejection Ratio RL=8Ω, f=1kHz CB=2.2µF, f=1kHz, RL=8Ω Channel Separation VDD=5V, PO =1.1W, RL=8Ω,A-Wtd Signal-to-Noise Ratio Filter RL=8Ω,A-Wtd Filter Output Noise Voltage Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 4 APA4838 Typ. 5 2.3 2.0 1.2 Unit mV W 1.5 0.07 0.07 % 70 dB 90 dB 95 dB 30 µV www.anpec.com.tw APA4838 Electrical Characteristics (Cont.) Electrical Characteristics for SE Mode Operation (Cont.) The following specifications apply for VDD= 5V unless otherwise noted. Limits apply for TA= 25°C Symbol VOS PO THD+N PSRR XTALK SNR VN Parameter Test Conditions Output Offset Voltage Output Power VIN=0V THD=1%, THD=10%, f=1kHz, RL=32Ω f=1kHz, RL=32Ω Total Harmonic Distortion AV= 1 , VOUT=1VRMS, RL=10kΩ, f=1kHz plus Noise PO =75mW, RL=32Ω, AV= 1, f=1kHz Power Supply Rejection VRIPPLE=100mVRMS , f=120Hz, CB=2.2µF Ratio Channel Separation CB=2.2µF, RL=8Ω , f=1kHz Signal-to-Noise Ratio PO =75mW, RL=32Ω, A-Wtd Filter Output Noise Voltage RL=32Ω, A-Wtd Filter APA4838 Typ. 5 95 110 mW 0.05 % 0.07 % 52 dB 90 102 20 dB dB µV Unit mV Pin Description Pin I/O Description Name GND No 1, 8, 14, 20, 23 Shutdown 2 I Shutdown mode control signal input, place entire IC in shutdown mode when held high, Idd=0.7uA Gain Select 3 I Gain select input pin, logic high will switch the amplifier to external gain mode, and logic low will switch to internal unity gain. Mode 4 I Mode select input pin, fixed gain when logic L and gain adjustable mode when logic H. Mute 5 I Mute control input pin, active H. VDD 6, 16, 27 Ground connection for circuitry. Supply voltage input pin DC_Vol 7 I Volume control function input pin. Right Dock 9 O Right docking output pin Right In 10 I Right channel audio input pin Beep In 11 I Beep signal input pin Left In 12 I Left channel audio input pin Left Dock 13 O Right docking output pin Left Out + 15 O Left channel positive output pin Left Out - 17 O Left channel negative output pin Left Gain 2 18 Connect pin 2 of the external gain setting resistor for left channel Left Gain 1 19 Connect pin 1 of the external gain setting resistor for left channel HP Sense 21 I Headphone sense control pin Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 5 www.anpec.com.tw APA4838 Pin Description (Cont.) Pin I/O Description Name Bypass No 22 Bypass pin Right Gain 1 24 Connect pin 1 of the external gain setting resistor for right channel Right Gain 2 25 Connect pin 2 of the external gain setting resistor for right channel Right Out - 26 O Right channel negative output pin Right Out + 28 O Right channel positive output pin Truth Table for Logic Inputs Mute Gain HP Mode Select Sense Gain Mode of Power Amplifier DC Vol. Control BTL Output SE Output 0 0 0 0 Unity Gain Setting Fixed Level Vol. Fixed - 0 0 0 1 Unity Gain Setting Fixed Level Muted Vol. Fixed 0 0 1 0 Unity Gain Setting Adjustable Vol. Adjustable - 0 0 1 1 Unity Gain Setting Adjustable Muted Vol. Adjustable 0 1 0 0 External Gain Setting Fixed Level Vol. Fixed - 0 1 0 1 External Gain Setting Fixed Level Muted Vol. Fixed 0 1 1 0 External Gain Setting Adjustable Vol. Adjustable - 0 1 1 1 External Gain Setting Adjustable Muted Vol. Adjustable 1 X X X - - Muted Muted Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 6 www.anpec.com.tw APA4838 Typical Application Circuit VDD VDD 1 µF R_var DC Vol Control VDD 100KΩ HP Sense Internal gain select 3 7 19 18 100KΩ 21 5 Mute Mode 4 10KΩ 13 - Left Out 20KΩ 12 + 0.33µ F 200KΩ Right In 20KΩ + 0.33µ F 20KΩ Beep Detect Bias 10 Right Dock 17 20KΩ + 11 Beep In Right Audio Input + - 200KΩ Left In + - 20KΩ Volume Control 31 steps 9 0.1µ F 0.1µ F 20KΩ Power Management Pin Ring + Left Out To HP sense Circuit + Right Out Tip Sleeve 10KΩ - Right Out 26 + 220µ F - 0.1µ F Bypass 22 28 + GND 15 Control Pin Headphone Jack 6,16,27 1,8,14,20,23 + 220µ F 1KΩ 20KΩ Bias 20KΩ VDD 0.068µ F 10KΩ + Left Dock 20KΩ Mode Control + - To Control Pin on Headphone Jack Left Audio Input 20KΩ 20KΩ 10KΩ Click and Pop Suppression Circuitry 1KΩ 20KΩ 0.068µ F 2.2µ F 2 24 25 Shutdown 20KΩ Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 7 20KΩ www.anpec.com.tw APA4838 Application Information Volume Control Table Gain (dB) Voltage Range (% of Vdd) Voltage Range (Vdd=5V) Low High Recommended Low High Recommended 0 77.5% 100.00% 100.000% 3.875 5.000 5.000 -1 75.0% 78.5% 76.875% 3.750 3.938 3.844 -2 72.5% 76.25% 74.375% 3.625 3.813 3.719 -3 70.0% 73.75% 71.875% 3.500 3.688 3.594 -4 67.5% 71.25% 69.375% 3.375 3.563 3.469 -5 65.0% 68.75% 66.875% 3.250 3.438 3.344 -6 62.5% 66.25% 64.375% 3.125 3.313 3.219 -8 60.0% 63.75% 61.875% 3.000 3.188 3.094 -10 57.5% 61.25% 59.375% 2.875 3.063 2.969 -12 55.0% 58.75% 56.875% 2.750 2.938 2.844 -14 52.5% 56.25% 54.375% 2.625 2.813 2.719 -16 50.0% 53.75% 51.875% 2.500 2.688 2.594 -18 47.5% 51.25% 49.375% 2.375 2.563 2.469 -20 45.0% 48.75% 46.875% 2.250 2.438 2.344 -22 42.5% 46.25% 44.375% 2.125 2.313 2.219 -24 40.0% 43.75% 41.875% 2.000 2.188 2.094 -26 37.5% 41.25% 39.375% 1.875 2.063 1.969 -28 35.0% 38.75% 36.875% 1.750 1.938 1.844 -30 32.5% 36.25% 34.375% 1.625 1.813 1.719 -32 30.0% 33.75% 31.875% 1.500 1.688 1.594 -34 27.5% 31.25% 29.375% 1.375 1.563 1.469 -36 25.0% 28.75% 26.875% 1.250 1.438 1.344 -38 22.5% 26.25% 24.675% 1.125 1.313 1.219 -40 20.0% 23.75% 21.875% 1.000 1.188 1.094 -42 17.5% 21.25% 19.375% 0.875 1.063 0.969 -44 15.0% 18.75% 16.875% 0.750 0.937 0.844 -46 12.5% 16.25% 14.375% 0.625 0.812 0.719 -48 10.0% 13.75% 11.875% 0.500 0.687 0.594 -50 7.5% 11.25% 9.375% 0.375 0.562 0.469 -52 5.0% 8.75% 6.875% 0.250 0.437 0.344 -78 0.0% 6.25% 0.000% 0.000 0.312 0.000 Copyright ANPEC Electronics Corp. Rev. A.1 - Feb., 2003 8 www.anpec.com.tw APA4838 Typical Characteristics THD+N vs. Frequency 10 VDD=5V RL=3Ω Po=1.8W BTL 1 THD+N (%) THD+N (%) 10 THD+N vs. Output Power Av=2 Av=4 Av=8 0.1 VDD=5V RL=3Ω Av=2 BTL 1 f=20KHz f=1KHz 0.1 f=20Hz 0.01 20 100 1k 0.01 10m 20k 100m Frequency (Hz) THD+N vs. Frequency THD+N vs. Output Power 10 VDD=5V RL=4Ω Po=1.5W BTL VDD=5V RL=4Ω Av=2 BTL 1 1 THD+N (%) THD+N (%) 3 Output Power (W) 10 0.1 1 Av=2 Av=4 Av=8 f=20KHz 0.1 f=1KHz f=20Hz 0.01 20 100 1k 0.01 100m 20k 1 3 Output Power (W) Frequency (Hz) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 500m 9 www.anpec.com.tw APA4838 Typical Characteristics (Cont.) THD+N vs. Frequency THD+N vs. Output Power 10 10 VDD=5V RL=8Ω Av=2 BTL 1 THD+N (%) THD+N (%) VDD=5V RL=8Ω Po=1.0W BTL Av=2 Av=4 Av=8 0.1 1 f=20KHz 0.1 f=1KHz f=20Hz 0.01 20 100 1k 0.01 10m 20k 100m Frequency (Hz) 2 Output Power (W) THD+N vs. Frequency THD+N vs. Output Power 10 10 VDD=5V RL=8Ω Po=250mW SE VDD=5V RL=8Ω Av=1 SE 1 THD+N (%) THD+N (%) 1 Av=1 Av=2 Av=4 0.1 1 f=20KHz 0.1 f=1KHz f=20Hz 0.01 20 100 1k 0.01 10m 20k 500m Output Power (W) Frequency (Hz) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 100m 10 www.anpec.com.tw APA4838 Typical Characteristics (Cont.) THD+N vs. Frequency THD+N vs. Output Power 10 10 VDD=5V RL=16Ω Av=1 SE 1 THD+N (%) THD+N (%) VDD=5V RL=16Ω Po=150mW SE Av=1 Av=2 Av=4 0.1 1 f=20KHz 0.1 f=20Hz f=1KHz 0.01 20 100 1k 0.01 10m 20k Frequency (Hz) 300m Output Power (W) THD+N vs. Frequency THD+N vs. Output Power 10 10 VDD=5V RL=32Ω Av=1 SE VDD=5V RL=32Ω Po=75mW SE 1 1 THD+N (%) THD+N (%) 100m Av=1 Av=2 Av=4 0.1 f=20Hz f=20KHz 0.1 f=1KHz 0.01 20 100 1k 0.01 10m 20k Frequency (Hz) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 50m 100m 200m Output Power (W) 11 www.anpec.com.tw APA4838 Typical Characteristics (Cont.) THD+N vs. Frequency THD+N vs. Output Swing 10 10 VDD=5V RL=10KΩ Av=1 SE 1 THD+N (%) THD+N (%) VDD=5V RL=10KΩ Vo=1VRMS SE Av=1 0.1 Av=2 1 0.1 f=20Hz f=20KHz Av=4 0.01 20 100 1k f=1KHz 0.01 100m 20k Crosstalk vs. Frequency Crosstalk vs. Frequency VDD=5V RL=32Ω -20 Po=75mW Av=2 SE VDD=5V RL=8Ω Po=1.0W Av=2 BTL -40 -60 -80 R-ch to L-ch -100 -40 -60 -80 R-ch to L-ch -100 L-ch to R-ch L-ch to R-ch -120 20 3 +0 Crosstalk (dB) Crosstalk (dB) -20 2 Output Swing (VRHS) Frequency (Hz) +0 500m 100 1k -120 20k 20 Frequency (Hz) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 100 1k 20k Frequency (Hz) 12 www.anpec.com.tw APA4838 Typical Characteristics (Cont.) Noise Floor vs. Frequency Noise Floor vs. Frequency 100 100 Noise Floor (µVRMS) Noise Floor (µVRMS) No Filter A-Weight 10 VDD=5V RL=8Ω Av=2 BTL 1 20 100 1k No Filter A-Weight 10 VDD=5V RL=32Ω Av=1 SE 1 20k 20 100 Frequency (Hz) 1k 20k Frequency (Hz) Supply Current vs. Supply Voltage Power Dissipation vs. Output Power 25 2 Power Dissipation (W) Supply Current (mA) 1 .8 20 15 BTL 10 SE 5 RL=3Ω 1 .6 1 .4 1 .2 RL=4Ω 1 0 .8 0 .6 RL=8Ω 0 .4 VDD=5V Av=2 BTL 0 .2 No Load 0 0 1 1 .5 2 2 .5 3 3 .5 4 4 .5 5 5 .5 0 1 1 .5 2 2 .5 Output Power (W) Supply Voltage (V) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 0 .5 13 www.anpec.com.tw APA4838 Typical Characteristics (Cont.) Power Dissipation vs. Output Power Gain vs. Voltage, 5V, SE 0 .2 5 4 0 -4 -1 2 Output Gain (dB) Power Dissipation (W) -8 0 .2 RL=8Ω 0 .1 5 RL=16Ω 0 .1 RL=32Ω 0 .0 5 -1 6 -2 0 -2 4 -2 8 -3 2 -3 6 -4 0 -4 4 -4 8 -5 2 -5 6 -6 0 VDD=5V Av=2 SE -6 4 VDD=5V AV=1 SE -6 8 -7 2 -7 6 0 -8 0 0 0 .0 5 0 .1 0 .1 5 0 .2 0 .2 5 0 .3 0 .3 5 0 .4 0 0 .5 Output Power (W) 1 .5 2 2 .5 3 3 .5 4 4 .5 5 DC Vol Input Voltage (V) Output Power vs. Supply Voltage Output Power vs. Supply Voltage 160 2 .2 5 2 140 Output Power (mW) Output Power (W) 1 1 .5 THD+N=10% 1 THD+N=1% 0 .5 RL=8Ω Av=2 BTL 120 100 THD+N=10% 80 60 THD+N=1% 40 RL=32Ω Av=1 SE 20 0 0 2 .5 3 3 .5 4 4 .5 5 5 .5 2 .5 3 .5 4 4 .5 5 5 .5 Supply Voltage (V) Supply Voltage (V) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 3 14 www.anpec.com.tw APA4838 Typical Characteristics (Cont.) Output Power vs. Load Resistance Output Power vs. Load Resistance 3 800 VDD=5V Av=2 BTL Output Power (mW) Output Power (W) 2.5 2 1.5 1 VDD=5V Av=1 SE 700 THD+N=10% 0.5 600 500 400 300 THD+N=10% 200 100 THD+N=1% THD+N=1% 0 0 4 8 16 24 32 40 48 56 4 8 64 Load Resistance (Ω) 40 48 56 64 PSRR vs. Frequency VDD=5V Vin=100mVRMS RL=8Ω Cbypass=2.2µF Av=2 BTL -40 Gain Adjustable -60 -80 -100 20 32 +0 Ripple Rejection Ratio (dB) Ripple Rejection Ratio (dB) -20 24 Load Resistance (Ω) PSRR vs. Frequency +0 6 16 Fixed Gain Mode 100 1k -40 Gain Adjustable -60 -80 Fixed Gain Mode -100 20 20k 100 1k 20k Frequency (Hz) Frequency (Hz) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 VDD=5V Vin=100mVRMS RL=8Ω -20 Cbypass=2.2µF Av=1 SE 15 www.anpec.com.tw APA4838 Typical Characteristics (Cont.) Gain vs. Frequency +12 Cf=0.22µF Gain (dB) +10 Cf=0.1µF +8 +6 Cf=0.068µF +4 VDD=5V RL=8Ω Av=2V/V BTL +2 -0 20 100 1k 20k Frequency (Hz) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 16 www.anpec.com.tw APA4838 Application Descriptions BTL Operation BTL Operation (Cont.) The APA4838 output stage (power amplifier) has two A BTL amplifier design has a few distinct advantages pairs of operational amplifiers internally, allowed for over the SE configuration, as it provides differential different amplifier configurations for each channel. drive to the load, thus doubling the output swing for a Gain 1 specified supply voltage. Gain 2 Four times the output power is possible as compared to a SE amplifier under the same conditions. A BTL -Out Volum e Control Am plifier output signal configuration, such as the one used in APA4838, also OP1 creates a second advantage over SE amplifiers. RL +Out Vbias Since the differential outputs, +Right Out, -Right Out, +Left Out, and -Left Out, are biased at half-supply, no need DC voltage exists across the load. This elimi- OP2 nates the need for an output coupling capacitor which Figure 1: APA4838 power amplifier internal configuration (each channel) is required in a single supply, SE configuration. The power amplifier OP1 gain is setting by internal Single-Ended Operation unity-gain or external gain setting which is selected from Gain Select pin and the audio input signal come Consider the single-supply SE configuration shown from internal volume control block, while the second Application Circuit. A coupling capacitor is required amplifier OP2 is internally fixed in a unity-gain, in- to block the DC offset voltage from reaching the load. verting configuration. Figure 1 shows that the output These capacitors can be quite large (approximately of OP1 is connected to the input to OP2, which re- 33µF to 1000µF) so they tend to be expensive, oc- sults in the output signals of with both amplifiers with cupy valuable PCB area, and have the additional identical in magnitude, but out of phase 180°. drawback of limiting low-frequency performance of Consequently, the differential gain for each channel the system (refer to the Output Coupling Capacitor). is 2X (Gain of SE mode). The rules described still hold with the addition of the By driving the load differentially through outputs -Out following relationship: and +Out, an amplifier configuration commonly re- 1 ≤ 1 << 1 Cbypass x 125kΩ RiCi RLCC ferred to as bridged mode is established. BTL mode (1) operation is different from the classical single-ended SE amplifier configuration where one side of its load is connected to ground. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 17 www.anpec.com.tw APA4838 Application Descriptions (Cont.) Output SE/BTL Operation Output SE/BTL Operation (Cont.) The ability of the APA4838 to easily switch between In Figure 2, input HP Sense operates as follows: BTL and SE modes is one of its most important costs When the phonejack plug is inserted, the 1kΩ resis- saving features. This feature eliminates the require- tor is disconnected and the HP Sense input is pulled ment for an additional headphone amplifier in appli- high and enables the SE mode. cations where internal stereo speakers are driven in When this input goes high level, the +Out amplifier is BTL mode but external headphone or speakers must shutdown causing the speaker to mute. The -Out be accommodated. amplifier then drives through the output capacitor (CC) Internal to the APA4838, two separate amplifiers drive into the headphone jack. –Out and +Out for each channel (see Figure 1). The When there is no headphone plugged into the system, HP Sense input controls the operation of the follower the contact pin of the headphone jack is connected amplifier that drives +Left Out and +Right Out. from the signal pin, the voltage divider set up by re- • When HP Sense is held low, the OP2 is turn on and sistors 100kΩ and 1kΩ. Resistor 1kΩ then pulls low the APA4838 is in the BTL mode. the HP Sense pin, enabling the BTL function. •When HP Sense is held high, the OP2 is in a high Docking Output Signal output impedance state, which configures the APA4838 as SE driver from -Out. IDD is reduced by APA4835 internal first amplifier is used as audio sig- approximately one-half in SE mode. nal pre-amplfier and feedback resistor is connected Control of the HP Sense input can be a logic-level between Dock output pin and audio input pin. TTL source or a resistor divider network or the ste- However, the internal first amplifier’s closed-loop gain reo headphone jack with switch pin as shown in Ap- can be adjusted using external resistors. Use Equa- plication Circuit. tion 2 to determine the input and feedback resistor values for a desired gain. 1kΩ AV = - VDD 100kΩ Control Pin Ring RF Ri (2) The Dock output signal provides low distortion audio quality for light driving output. ex. active speaker, HP sense Tip monitors or audio/visual equipment. These two out- Sleeve puts can driving load of >1kΩ with rail-to-rail output Headphone Jack Figure 2: HP Sense input selection by phonejack and output coupling capacitor is required when using plug these outputs. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 18 www.anpec.com.tw APA4838 Application Descriptions (Cont.) Docking Output Signal (Cont.) Input Capacitor, Ci (Cont.) Typical values for the output coupling capacitors are This leakage current creates a DC offset voltage at 0.33µF to 1.0µF. If polarized coupling capacitors are the input to the amplifier that reduces useful used, connect their ’+’ terminals to the respective headroom, especially in high gain applications. For output pin. this reason a low-leakage tantalum or ceramic ca- The Right Dock and Left Dock channel outputs sig- pacitor is the best choice. When polarized capaci- nal are also used to driving internal volume control tors are used, the positive side of the capacitor should amplifier. face the amplifier input in most applications as the DC level there is held at VDD/2, which is likely higher Input Capacitor, Ci that the source DC level. Please note that it is impor- In the typical application an input capacitor, Ci, is re- tant to confirm the capacitor polarity in the application. quired to allow the amplifier to bias the input signal to Effective Bypass Capacitor, Cbypass the proper DC level for optimum operation. In this case, Ci and the minimum input impedance Ri form a As other power amplifiers, proper supply bypassing high-pass filter with the corner frequency determined is critical for low noise performance and high power in the follow equation: supply rejection. FC(highpass)= 1 2πRiCi The capacitors located on the bypass and power (3) supply pins should be as close to the device as The value of Ci is important to consider as it directly possible. The effect of a larger half supply bypass affects the low frequency performance of the circuit. capacitor will improve PSRR due to increased half- Consider the example where Ri is 100kΩ and the supply stability. Typical application employ a 5V regu- specification calls for a flat bass response down to lator with 1.0µF and a 0.1µF bypass as supply filtering. 40Hz. Equation is reconfigured as follow: This does not eliminate the need for bypassing the Ci= 1 2πRifC supply nodes of the APA4838. The selection of by- (4) pass capacitors, especially Cbypass, is thus depen- Consider to input resistance variation, the Ci is 0.04µF dent upon desired PSRR requirements, click and pop so one would likely choose a value in the range of performance. 0.1µF to 1.0µF. To avoid start-up pop noise occurred, the bypass A further consideration for this capacitor is the leak- voltage should rise slower than the input bias voltage age path from the input source through the input net- and the relationship shown in equation (5) should be work (Ri+Rf, Ci) to the load. maintained. 1 1 << Cbypass x 125kΩ RiCi Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 19 (5) www.anpec.com.tw APA4838 Application Descriptions (Cont.) Effective Bypass Capacitor, Cbypass (Cont.) Power Supply Decoupling, Cs The bypass capacitor is fed from a 125kΩ resistor The APA4838 is a high-performance CMOS audio inside the amplifier. Bypass capacitor, Cbypass, val- amplifier that requires adequate power supply ues of 3.3µF to 10µF ceramic or tantalum low-ESR decoupling to ensure the output total harmonic dis- capacitors are recommended for the best THD and tortion (THD) is as low as possible. Power supply noise performance. decoupling also prevents the oscillations causing by The bypass capacitance also effects to the start up long lead length between the amplifier and the time. It is determined in the following equation: speaker. The optimum decoupling is achieved by Tstart up = 5 x (Cbypass x 125kΩ) (6) using two different type capacitors that target on different type of noise on the power supply leads. For Output Coupling Capacitor, Cc higher frequency transients, spikes, or digital hash In the typical single-supply (SE) configuration, an on the line, a good low equivalent-series-resistance output coupling capacitor (Cc) is required to block (ESR) ceramic capacitor, typically 0.1µF placed as the DC bias at the output of the amplifier thus pre- close as possible to the device VDD lead works best. venting DC currents in the load. As with the input For filtering lower-frequency noise signals, a large coupling capacitor, the output coupling capacitor and aluminum electrolytic capacitor of 10µF or greater impedance of the load form a high-pass filter gov- placed near the audio power amplifier is erned by equation. recommended. FC(highpass)= 1 2πRLCC (7) Optimizing Depop Circuitry For example, a 330µF capacitor with an 8Ω speaker Circuitry has been included in the APA4838 to mini- would attenuate low frequencies below 60.6Hz. The mize the amount of popping noise at power-up and main disadvantage, from a performance standpoint, when coming out of shutdown mode. Popping oc- is the load impedance is typically small, which drives curs whenever a voltage step is applied to the the low-frequency corner higher degrading the bass speaker. In order to eliminate clicks and pops, all response. Large values of CC are required to pass capacitors must be fully discharged before turn-on. low frequencies into the load. Rapid on/off switching of the device or the shutdown function will cause the click and pop circuitry. The value of Ci will also affect turn-on pops. (Refer to Effective Bypass Capacitance) The bypass voltage rise up should be slower than input bias voltage. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 20 www.anpec.com.tw APA4838 Application Descriptions (Cont.) Optimizing Depop Circuitry (Cont.) Shutdown and Mute Function (Cont.) Although the bypass pin current source cannot be The trigger point between a logic high and logic low modified, the size of Cbypass can be changed to al- level is typically 2.0V. It is best to switch between ter the device turn-on time and the amount of clicks ground and the supply voltage VDD to provide maxi- and pops. By increasing the value of Cbypass, turn- mum device performance. on pop can be reduced. However, the tradeoff for By switching the Shutdown pin to high level, the am- using a larger bypass capacitor is to increase the turn- plifier enters a low-current state, IDD<1µA. APA4838 on time for this device. There is a linear relationship is in shutdown mode. On normal operating, Shut- between the size of Cbypass and the turn-on time. down pin pull to low level to keeping the IC out of the In a SE configuration, the output coupling capacitor, shutdown mode. The Shutdown pin should be tied CC, is of particular concern. This capacitor discharges to a definite voltage to avoid unwanted state changes. through the internal 10kΩ resistors. Depending on The APA4838 mutes the amplifier and DOCK out- the size of CC, the time constant can be relatively puts when VDD is applied to the Mute pin. Even while large. To reduce transients in SE mode, an external muted, the APA4838 will amplify a system alert (beep) 1kΩ resistor can be placed in parallel with the inter- signal whose magnitude satisfies the PCBEEP de- nal 10kΩ resistor. The tradeoff for using this resistor tect circuitry. Applying 0V to the Mute pin returns the is an increase in quiescent current. APA4838 to normal operation. Prevent unanticipated In the most cases, choosing a small value of Ci in the mute behavior by connecting the Mute pin to VDD or range of 0.33µF to 1µF, Cbypass being equal to 4. ground. Do not let the Mute pin float. 7µF and an external 1kΩ resistor should be placed in PCBEEP Detect Circuitry parallel with the internal 10kΩ resistor should produce a virtually clickless and popless turn-on. APA4838 integrates a PCBEEP detect circuit for note- A high gain amplifier intensifies the problem as the book and computer used. When Beep In signal is small delta in voltage is multiplied by the gain. So it greater than 1/2VDD, the PCBEEP mode is active. is advantageous to use low-gain configurations. APA4838 will force to BTL mode and the internal fixed gain mode. The Beep In signal becomes the ampli- Shutdown and Mute Function fier input signal and plays on the system speaker with- In order to reduce power consumption while not in out coupling capacitor. Use input resistor between use, the APA4838 contains a Shutdown pin to exter- stereo input pin and Beep In to attenuate Beep In nally turn off the amplifier bias circuitry. This shut- signal. These resistors are shown as 200kΩ devices down feature turns the amplifier off when a logic high in Application Circuit. Use higher value resistors to is placed on the Shutdown pin. reduce the gain applied to the beep signal. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 21 www.anpec.com.tw APA4838 Application Descriptions (Cont.) PCBEEP Detect Circuitry (Cont.) Internal and External Gain Selection (Cont.) If the amplifier in the mute mode, it will out of mute C LF Gain 1 APA4838’s shutdown mode must be deactivated before a system alert signal is applied to Beep In pin. R I2 Gain 2 mode whenever PCBEEP mode enable. The R F2 R LF The APA4838 will return to previous setting when it is out of PCBEEP mode. The Beep In pin should be -Out Volum e Control Am plifier output signal tied to a ground when not used to avoid unwanted OP1 state changes. Figure3: Bass Boost gain setting configuration Mode Function In some cases a designer may want to improve the The APA4838’s Mode function has 2 states controlled low frequency response of the bridged amplifier or by the voltage applied to the Mode pin. By applying incorporate a bass boost feature. Refer to the Figure, 0V to the Mode pin, forces the APA4838 to fixed gain a resistor, RLF, and a capacitor, CLF, in parallel, can amplifier and internal volume control block will be dis- be placed in series with the feedback resistor of the able and internal first amplifier output signal (Dock) bridged amplifier as seen in Figure. 1 Fc= 2πRLFCLF to power amplifier directly. When Mode pin goes to high level, which uses the internal DC controlled vol- (8) ume control is selected. This mode sets the amplifier’s The bridged-amplifier low frequency differential gain gain according to the DC voltage applied to the DC is: Vol control pin. Do not let the Mode pin float when it Fc= does not used. 2x(RF2+RLF) R12 (9) Internal and External Gain Selection Using the component values shown in Figure (RF2 = APA4838 provides external gain setting for base 20kΩ,RLF = 20kΩ, and CLF = 0.068µF), a first-order, - boost function or internal feedback gain setting which 6dB pole is created at 120Hz. Assuming R12 = 20kΩ, is decided by Gain Select control input. If Gain Se- the low frequency differential gain is 4. The input (Ci) lect pin goes high level, the gain setting will be de- and output (CO) capacitor values must be selected fined by Gain1 and Gain2 pin. When Gain Select pin for a low frequency response that covers the range tied to low level, APA4835 power amplifier gain set- of frequencies affected by the desired bass-boost ting as unit gain by internal resistor. operation. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 22 www.anpec.com.tw APA4838 Application Descriptions (Cont.) Internal and External Gain Selection (Cont.) BTL Amplifier Efficiency At low frequencies CLF is a virtual open circuit and at An easy-to-use equation to calculate efficiency starts high frequencies, its nearly zero ohm impedance out as being equal to the ratio of power from the power shorts RLF. The result is increased bridge-amplifier supply to the power delivered to the load. The fol- gain at low frequencies. The combination of RLF and lowing equations are the basis for calculating ampli- CLF form a -6dB corner frequency at fier efficiency. Efficiency = Volume Adjustable and Fixed Gain selection PO PSUP (10) Where : PO = VORMS x VORMS = VPxVP 2RL RL The APA4838 has an internal stereo volume control whose setting is a function of the DC voltage applied VORMS = to the DC Vol control pin. The APA4838 volume con- VP √2 (11) PSUP = VDD x IDDRMS = VDD x 2VP πRL trol consists of 31 steps that are individually selected (12) by a variable DC voltage level on the DC Vol control Efficiency of a BTL configuration : pin. The range of the steps, controlled by the DC PO VPxVP ) / (VDD x 2VP ) = πVP =( 2VDD PSUP 2RL πRL voltage, are from 0dB to -78dB. Each gain step cor- (13) responds to a specific input voltage range, as shown in table. To minimize the effect of noise on the volPo (W) Efficiency (%) IDD(A) VPP(V) PD (W) ume control pin, which can affect the selected gain level, hysteresis and internal clock delay are 0.2 26.67 0.15 2.00 0.55 implemented. The amount of hysteresis corresponds 0.50 41.67 0.24 2.83 0.7 1.00 58.82 0.34 4.00 0.7 1.3 68.42 0.38 4.47 0.6 to half of the step width, as shown in volume control graph. For highest accuracy, the voltage shown in the ’recommended voltage’ column of the table is used to **High peak voltages cause the THD to increase. select a desired gain. This recommended voltage is Table 1. Efficiency Vs Output Power in 5-V/8Ω BTL exactly halfway between the two nearest transitions. Systems The gain levels are 1dB/step from 0dB to -6dB, 2dB/ Table 1 calculates efficiencies for four different out- step from -6dB to -52dB, and the last step at -78dB put power levels when load is 8Ω. as mute mode. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 23 www.anpec.com.tw APA4838 Application Descriptions (Cont.) BTL Amplifier Efficiency (Cont.) Power Dissipation (Cont.) The efficiency of the amplifier is quite low for lower BTL mode : PD,MAX= power levels and rises sharply as power to the load 4VDD2 2π2RL (15) is increased resulting in a nearly flat internal power Since the APA4838 is a dual channel power amplifier, dissipation over the normal operating range. Note the maximum internal power dissipation is 2 times that the internal dissipation at full output power is less that both of equations depending on the mode of than in the half power range. Calculating the efficiency operation. Even with this substantial increase in power for a specific system is the key to proper power sup- dissipation, the APA4838 does not require extra ply design. For a stereo 1W audio system with 8Ω heatsink. The power dissipation from equation15, loads and a 5V supply, the maximum draw on the assuming a 5V-power supply and an 8Ω load, must power supply is almost 3W. not be greater than the power dissipation that results A final point to remember about linear amplifiers from the equation16: (either SE or BTL) is how to manipulate the terms in PD,MAX= the efficiency equation to utmost advantage when TJ,MAX - TA θJA (15) possible. Note that in equation, V DD is in the For TSSOP-28 package with and without thermal pad, denominator. This indicates that as VDD goes down, the thermal resistance (θJA) is equal to 45οC/W and efficiency goes up. In other words, use the efficiency 50οC/W, respectively. analysis to choose the correct supply voltage and Since the maximum junction temperature (TJ,MAX) of speaker impedance for the application. APA4838 is 150οC and the ambient temperature (TA) is defined by the power system design, the maximum Power Dissipation power dissipation which the IC package is able to Whether the power amplifier is operated in BTL or handle can be obtained from equation16. Once the SE modes, power dissipation is a major concern. In power dissipation is greater than the maximum limit equation14 states the maximum power dissipation (PD,MAX), either the supply voltage (V DD) must be point for a SE mode operating at a given supply volt- decreased, the load impedance (RL) must be in- age and driving a specified load. creased or the ambient temperature should be SE mode : PD,MAX= VDD 2 2π2RL reduced. (14) In BTL mode operation, the output voltage swing is doubled as in SE mode. Thus the maximum power dissipation point for a BTL mode operating at the same given conditions is 4 times as in SE mode. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 24 www.anpec.com.tw APA4838 Application Descriptions (Cont.) Thermal Pad Considerations The thermal pad must be connected to ground. The package with thermal pad of the APA4838 requires special attention on thermal design. If the thermal design issues are not properly addressed, the APA4838 4Ω will go into thermal shutdown when driving a 4Ω load. The thermal pad on the bottom of the APA4838 should be soldered down to a copper pad on the circuit board. Heat can be conducted away from the thermal pad through the copper plane to ambient. If the copper plane is not on the top surface of the circuit board, 8 to 10 vias of 13 mil or smaller in diameter should be used to thermally couple the thermal pad to the bottom plane. For good thermal conduction, the vias must be plated through and solder filled. The copper plane used to conduct heat away from the thermal pad should be as large as practical. If the ambient temperature is higher than 25°C, a larger copper plane or forced-air cooling will be required to keep the APA4838 junction temperature below the thermal shutdown temperature (150°C). In higher ambient temperature, higher airflow rate and/ or larger copper area will be required to keep the IC out of thermal shutdown. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 25 www.anpec.com.tw APA4838 Packaging Information TS S O P / TS S O P -P ( R eference JE D E C R egistration M O -153) e N 2x E/2 E1 1 2 3 E e/2 D A2 A ( 2) GAUGE PLANE A1 b D1 S EXPOSED THERMAL PAD ZONE E2 0.25 L 1 (L1) ( 3) BOTTOM VIEW (THERMALLY ENHANCED VARIATIONDS ONLY) D im A A1 A2 b D D1 e E E1 E2 L L1 R R1 S φ1 φ2 M illim eters Inches M in. M ax. 1.2 0.00 0.15 0.80 1.05 0.19 0.3 6.4 (N =20PIN ) 6.6 (N =20PIN ) 7.7 (N =24PIN ) 7.9 (N =24PIN ) 9.6 (N =28PIN ) 9.8 (N =28PIN ) 4.2 B S C (N =20P IN ) 4.7 B S C (N =24P IN ) 3.8 B S C (N =28P IN ) 0.65 B S C 6.40 B S C 4.30 4.50 3.0 B S C (N =20P IN ) 3.2 B S C (N =24P IN ) 2.8 B S C (N =28P IN ) 0.45 0.75 1.0 R E F 0.09 0.09 0.2 0° 8° 12° R E F Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 26 M in. M ax. 0.047 0.000 0.006 0.031 0.041 0.007 0.012 0.252 (N =20P IN ) 0.260 (N =20P IN ) 0.303 (N =24P IN ) 0.311 (N =24P IN ) 0.378 (N =28P IN ) 0.386 (N =28P IN ) 0.165 B S C (N =20P IN ) 0.188 B S C (N =24P IN ) 0.150 B S C (N =28P IN ) 0.026 B S C 0.252 BS C 0.169 0.177 0.118 B S C (N =20P IN ) 0.127 B S C (N =24P IN ) 0.110 B S C (N =28P IN ) 0.018 0.030 0.039R E F 0.004 0.004 0.008 0° 8° 12° R E F www.anpec.com.tw APA4838 Physical Specifications Terminal Material Lead Solderability Solder-Plated Copper (Solder Material : 90/10 or 63/37 SnPb) Meets EIA Specification RSI86-91, ANSI/J-STD-002 Category 3. Reflow Condition (IR/Convection or VPR Reflow) temperature Reference JEDEC Standard J-STD-020A APRIL 1999 Peak temperature 183°C Pre-heat temperature Time Classification Reflow Profiles Convection or IR/ Convection Average ramp-up rate(183°C to Peak) 3°C/second max. 120 seconds max Preheat temperature 125 ± 25°C) 60 – 150 seconds Temperature maintained above 183°C Time within 5°C of actual peak temperature 10 –20 seconds Peak temperature range 220 +5/-0°C or 235 +5/-0°C Ramp-down rate 6 °C /second max. 6 minutes max. Time 25°C to peak temperature VPR 10 °C /second max. 60 seconds 215-219°C or 235 +5/-0°C 10 °C /second max. Package Reflow Conditions pkg. thickness ≥ 2.5mm and all bgas Convection 220 +5/-0 °C VPR 215-219 °C IR/Convection 220 +5/-0 °C pkg. thickness < 2.5mm and pkg. volume ≥ 350 mm³ Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 27 pkg. thickness < 2.5mm and pkg. volume < 350mm³ Convection 235 +5/-0 °C VPR 235 +5/-0 °C IR/Convection 235 +5/-0 °C www.anpec.com.tw APA4838 Reliability test program Test item SOLDERABILITY HOLT PCT TST ESD Latch-Up Method MIL-STD-883D-2003 MIL-STD-883D-1005.7 JESD-22-B, A102 MIL-STD-883D-1011.9 MIL-STD-883D-3015.7 JESD 78 Description 245°C , 5 SEC 1000 Hrs Bias @ 125 °C 168 Hrs, 100 % RH , 121°C -65°C ~ 150°C, 200 Cycles VHBM > 2KV, VMM > 200V 10ms , Itr > 100mA Carrier Tape & Reel Dimensions t D P Po E P1 Bo F W Ko Ao D1 T2 J C A B T1 Application TSSOP- 28 A B C J T1 T2 W P E 330 ±1 100 ref 13 ±0.5 2 ±0.5 16.4 ±0.2 2 ±0.2 16 ±0.3 12 ±0.1 1.75±0.1 F D D1 Po P1 Ao Bo Ko t 7.5 ±0.1 1.5 +0.1 1.5 min 4.0 ±0.1 2.0 ±0.1 6.9 ±0.1 10.2 ±0.1 1.8 ±0.1 0.3±0.05 (mm) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 28 www.anpec.com.tw APA4838 Cover Tape Dimensions Application TSSOP- 28 Carrier Width 16 Cover Tape Width 21.3 Devices Per Reel 2000 Customer Service Anpec Electronics Corp. Head Office : 5F, No. 2 Li-Hsin Road, SBIP, Hsin-Chu, Taiwan, R.O.C. Tel : 886-3-5642000 Fax : 886-3-5642050 Taipei Branch : 7F, No. 137, Lane 235, Pac Chiao Rd., Hsin Tien City, Taipei Hsien, Taiwan, R. O. C. Tel : 886-2-89191368 Fax : 886-2-89191369 Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2003 29 www.anpec.com.tw