Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on TK2051 STEREO 50W (8Ω) CLASS-T™ DIGITAL AUDIO AMPLIFIER DRIVER USING DIGITAL POWER PROCESSING (DPP™) TECHNOLOGY Technical Information Revision 1.1 – August 2002 GENERAL DESCRIPTION The TK2051 (TC2000/TP2051 chipset) is a 50W continuous average power per channel, Class-T Digital Audio Power Amplifier using Tripath’s proprietary Digital Power ProcessingTM technology. Class-T amplifiers offer both the audio fidelity of Class-AB and the power efficiency of Class-D amplifiers. APPLICATIONS 5.1-Channel DVD Mini/Micro Component Systems Home Theater Stereo applications (6Ω / 8Ω) Mono applications (4Ω) BENEFITS Single Supply Operation Very High Efficiency Wide Dynamic Range Compact layout 1 FEATURES Class-T Architecture High Output power 35W @ 6Ω, < 1% THD+N 50W @ 8Ω, < 3% THD+N 117W @ 4Ω, < 10.0% THD+N (paralleled outputs) Audiophile Quality Sound 0.007% THD+N @ 30W 8Ω 0.005% THD+N @ 70W 4Ω (paralleled outputs) High Efficiency 92% @ 60W 8Ω 85% @ 46W 6Ω 89% @ 117W 4Ω (paralleled outputs) Dynamic Range >100 dB TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on A B S O L U T E M A X I M U M R A T I N G S – T C 2 0 0 0 (Note 1) Value UNITS V5 SYMBOL 5V Power Supply PARAMETER 6 V Vlogic Input Logic Level V5+0.3V V TA Operating Free-air Temperature Range -40 to 85 °C TSTORE Storage Temperature Range -55 to 150 °C TJMAX Maximum Junction Temperature 150 °C ESDHB ESD Susceptibility – Human Body Model (Note 2), all pins 2000 V Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. See the table below for Operating Conditions. Note 2: Human body model, 100pF discharged through a 1.5KΩ resistor. A B S O L U T E M A X I M U M R A T I N G S – T P 2 0 5 1 (Note 1) Value UNITS VCC SYMBOL Power Supply PARAMETER 40 V Vlogic Input Logic Level 5.5 V TA Operating Free-air Temperature Range TSTORE Storage Temperature Range TJMAX Maximum Junction Temperature ESDHB ESD Susceptibility – Human Body Model (Note 2), all pins 0 to 70 °C -40 to 150 °C 150 °C 2000 V O P E R A T I N G C O N D I T I O N S – T C 2 0 0 0 (Note 1) MIN. TYP. MAX. V5 SYMBOL Supply Voltage PARAMETER 4.5 5 5.5 VHI Logic Input High V5-1.0 VLO Logic Input Low TA Operating Temperature Range -40 UNITS V V 25 1 V 85 °C O P E R A T I N G C O N D I T I O N S – T P 2 0 5 1 (Note 1) SYMBOL PARAMETER VCC Power Supply VHI Logic Input High VLO Logic Input Low TA Operating Temperature Range MIN. TYP. MAX. UNITS 36 V 10 Ibias/10 + 500mV 0 V Ibias/5 + 1V V 70 °C 25 THERMAL CHARACTERISTICS TC2000 SYMBOL PARAMETER Junction-to-ambient Thermal Resistance (still air) θJA Value UNITS 80 °C/W Value UNITS 2.5 °C/W TP2051 SYMBOL PARAMETER Junction-to-case Thermal Resistance θJC 2 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on ELECTRICAL CHARACTERISTICS – TC2000 SYMBOL PARAMETER MIN. TYP. MAX. UNITS I5 Supply Current 60 mA fsw Switching Frequency 650 kHz VIN Input Sensitivity VOUTHI High Output Voltage VOUTLO Low Output Voltage RIN Input Impedance 0 1.5 V5-0.5 100 Input DC Bias V V mV 2 kΩ 2.5 V ELECTRICAL CHARACTERISTICS – TP2051 TA = 25 °C. See Application/Test Circuit. Unless otherwise noted, the supply voltage is VCC = 28V. SYMBOL VIH PARAMETER Quiescent Current (No load, Mute = 0V) Mute Supply Current (No load, Mute = 5V) High-level input voltage (MUTE) CONDITIONS VCC = +28V V5 = 5V VCC = +31V V5 = 5V IIH = See Mute Control Section VIL Low-level input voltage (MUTE) IIL = See Mute Control Section ISC Short circuit current limit VCC = +30V, T=25 C Iq IMUTE o MIN. TYP. 125 27 28 7 MAX. 1.0 V 5 6.5 A 60 3.5 3.5 UNITS mA mA mA mA V PERFORMANCE CHARACTERISTICS – TK2051 TA = 25 °C. Unless otherwise noted, VCC = 30V, f=1kHz, and the measurement bandwidth is 20kHz. SYMBOL POUT PARAMETER Output Power (Continuous Average/Channel) (Note 13) THD + N Total Harmonic Distortion Plus Noise IHF-IM IHF Intermodulation Distortion SNR Signal-to-Noise Ratio CS Channel Separation AV Amplifier Gain AVERROR Channel to Channel Gain Error η Power Efficiency eN Output Noise Voltage 3 CONDITIONS VCC = +30V, RL = 8Ω THD+N < 0.01% THD+N < 3.0% THD+N < 10.0% VCC = +23.5V, RL = 6Ω THD+N < 0.05% THD+N < 5.0% THD+N < 10.0% VCC = +30V, RL = 4Ω (par. output) THD+N < 0.01% THD+N < 10% POUT = 40W/Channel, RL = 8Ω VCC = +30V POUT = 30W/Channel, RL = 6Ω VCC = +23.5V 19kHz, 20kHz, 1:1 (IHF), RL = 8Ω POUT = 30W/Channel A-Weighted 0dB = 50W/Channel, RL = 8Ω 0dB = 10W, RL = 8Ω, f=1kHz POUT = 10W/Channel, RL = 8Ω, See Application / Test Circuit POUT = 10W/Channel, RL = 8Ω See Application / Test Circuit POUT = 60W/Channel, RL = 8Ω POUT = 45W/Channel, RL = 6Ω A-Weighted, input AC grounded MIN. TYP. MAX. UNITS 30 50 60 W W W 30 40 45 W W W 75 117 0.03 W W % 0.03 % 0.05 % 103 dB 95 dB 15 V/V 0.5 92 85 135 dB % % µV TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on TC2000 AUDIO SIGNAL PROCESSOR PIN DESCRIPTIONS Pin 1 2, 6 3 4, 7 5 8 9, 12 10, 11 13 14 15 16 Function FDBKP2, FDBKP1 DCMP FDBKN2, FDBKN1 VPWR HMUTE Y1, Y2 Y1B, Y2B NC OCD2 REF OCD1 17 18 19 20 21 22, 27 VnnSense OVRLDB VppSense AGND V5 Oaout1, Oaout2 23, 28 Inv1, Inv2 24 25, 26 Description Bandgap reference times two (typically 2.5VDC). Used to set the common mode voltage for the input op amps. This pin is not capable of driving external circuitry. Positive switching feedback. Internal mode selection. This pin must be grounded for proper device operation. Negative switching feedback. Test pin. Must be left floating. Logic output. A logic high indicates both amplifiers are muted, due to the mute pin state, or a “fault”. Non-inverted switching modulator outputs. Inverted switching modulator outputs. No connect Over Current Detect. Internal reference voltage; approximately 1.2 VDC. Over Current Detect. This pin must be grounded for proper device operation. Negative power stage over/under supply voltage sense resistor tie point. A logic low output indicates the input signal has overloaded the amplifier. Positive power stage over/under supply voltage sense resistor tie point. Ground 5 Volt power supply input. Input stage output pins. Single-ended inputs. Inputs are a “virtual” ground of an inverting opamp with approximately 2.4VDC bias. When set to logic high, both amplifiers are muted and in idle mode. When low (grounded), both amplifiers are fully operational. If left floating, the device stays in the mute mode. Ground if not used. Break-before-make timing control to prevent shoot-through in the output FETs. BIASCAP MUTE BBM0, BBM1 TC2000 AUDIO SIGNAL PROCESSOR PINOUT 4 BIASCAP 1 28 INv2 FDBKP2 2 27 OAout2 DCMP 3 26 BBM0 FDBKN2 4 25 BBM1 VPWR 5 24 MUTE FDBKP1 6 23 INv1 FDBKN1 7 22 OAout1 HMUTE 8 21 V5 Y1 9 20 AGND Y1B 10 19 VppSENSE Y2B 11 18 OVRLDB Y2 12 17 VnnSENSE NC 13 16 OCD1 OCD2 14 15 REF TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on TP2051 POWER STAGE PIN DESCRIPTIONS Pin 1 35,36 15 12 7 4 14 13 6 5 16,17 10,11 8,9 2,3 29 30 31 32 21,22 33,34 25 26 27 24 28 19 23 18 20 Function GND-SUB VccSign Vcc1A Vcc1B Vcc2A Vcc2B GND1A GND1B GND2A GND2B OUT1A OUT1B OUT2A OUT2B IN1A IN1B IN2A IN2B Vdd Vss PWRDN TRI-STATE FAULT CONFIG TH-WAR GND-clean IBIAS NC GND-Reg Description Substrate ground Signal positive supply Positive supply Positive supply Positive supply Positive supply Negative supply Negative supply Negative supply Negative supply Output half bridge 1A Output half bridge 1B Output half bridge 2A Output half bridge 2B Input of half bridge 1A Input of half bridge 1B Input of half bridge 2A Input of half bridge 2B 5V regulator referenced to ground 5V regulator referenced to Vcc Stand-by pin Hi-Z pin Fault output Config input Thermal warning output Logic ground Logic high voltage Not connected Ground for Vdd regulator TP2051 POWER STAGE PINOUT (Top view with heat slug down) 5 GNDSUB 1 36 VCCSIGN OUT2B 2 35 VCCSIGN OUT2B 3 34 VSS VCC2B 4 33 VSS GND2B 5 32 IN2B GND2A 6 31 IN2A VCC2A 7 30 IN1B OUT2A 8 29 IN1A OUT2A 9 28 TH_WAR OUT1B 10 27 FAULT OUT1B 11 26 TRISTATE VCC1B 12 25 PWRDN GND1B 13 24 CONFIG GND1A 14 23 IBIAS VCC1A 15 22 VDD OUT1A 16 21 VDD OUT1A 17 20 GNDREG NC 18 19 GNDCLEAN TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on APPLICATION / TEST DIAGRAMS Inputs and TC2000 RREF 8.2K 15 16 17 V5 R53 11K 1 20 R54 22K COF .1u;50V 3 1 19 ROFA 500K ROFB 5K RCA_RT_ANG J9 ROFA 500K CI 2.2u;10V 1 2 ROFB 5K RF 20K 22 RCA_RT_ANG J10 1 2 JUMPER 24 25 COF .1u;50V 26 ROFA 500K RF 20K 27 28 + Y2B OVRLDB Y1B VHI Y1 GND FDBKN1 V5 13 12 Y2 11 Y2B 10 Y1B 9 Y1 8 HMUTE RFBC 14K;1% 7 RFBB 1.0K;1% VP1 CFB 470p;50V IN1 FDBKP1 MUTE RFBC 14K;1% 6 RFBB 1.0K;1% BBM2 V5 OUT1B CFB 470p;50V BBM1 VPWR VP2 FDBKN2 IN2 5 RFBC 14K;1% 4 RI 20K CI 2.2u;10V OUT1A V5 1 2 IN2 ROFA 500K 3 Y2 14 TC2000 JP 1 2 VLO RI 20K V5 1 NC HMUTE 23 + OCD0 V5 21 2 IN1 18 OCD1 REF RFBB 1.0K;1% V5 OUT2A CFB 390p;50V 2 + CS .1u;50V CS 100u;16V DCMP FDBKP2 BIASCAP 3 RFBC 14K;1% 2 OUT2B 1 C7 .1u;50V RFBB 1.0K;1% CFB 390p;50V TP2051 and Outputs VCC U2 V5 29 Y1 IN1A M3 O UT1A 23 IBIAS C12 .1u 24 R37 10K 25 O UT1A CO NFIG M2 G ND1A LO 15u 17 16 O UT1P C H BR .1u;50V 26 C SN (note 1) 330p;100V;NPO 1000p;50V & FAULT 30 .1u;100V VCC1B TH_W AR O U T1B IN1B M4 NC G ND1B R SN (note 1) 20;1/4W 12 M5 O UT1B 18 11 C H BR .1u;50V 22 M17 33 34 C30 .1u 36 20 Y2B VSS 32 19 1 1000p;50V CO .22u;50V O UT1N VCC M15 G ND2A REG ULATO RS 560u;50V LO 15u 8 9 O UT2P C H BR .1u;50V CO .22u;50V 6 C SN (note 1) 330p;100V;NPO C C ASE (note 2) 1000p;50V VSS CZ .22u;50V VCCSIG N VCC G NDREG VCC2B O UT2B M14 O UT2B G ND2B R SN (note 1) 20;1/4W 4 M16 G NDCLEAN G NDSUB SPEAKER CDM .1u;100V VCCSIG N IN2B + CS O UT2A 7 C31 .1u 35 C14 .1u O UT2A VDD VDD C C ASE (note 2) O UT1B VCC2A IN2A RZ 15;1W 13 TP2051 O UT2A 21 LO 15u 10 VCC 31 SPEAKER CDM LO G IC TRISTATE VCC 28 C C ASE (note 2) CZ .22u;50V C21 .1u Y2 CO .22u;50V 14 PRO TECTIO N 27 Y1B O UT1A 15 PW RDN C18 .1u R40 10K VCC1A 3 C H BR .1u;50V 2 LO 15u RZ 15;1W C C ASE (note 2) 1000p;50V CO .22u;50V O UT2N 5 O UT2B NOTE 1: C SN /R SN are optional locations, loaded only if required to reduce overshoot NOTE 2: C CASE (4 locations) represent bypass capacitors m ounted at the exit of the speaker cable from the cabinet. They are optional and are used for EM I supression. Lead lengths on these com ponents m ust be kept short to be effective. They are shown in this schem atic for reference. 6 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on APPLICATION / TEST DIAGRAMS FOR PARALLEL OPERATION Inputs and TC2000 RREF 8.2K 15 16 17 R53 11K 18 19 20 R54 22K OCD1 REF OCD0 NC VLO Y2 OVRLDB Y2B VHI Y1B Y1 GND HMUTE V5 21 22 23 FDBKN1 V5 ROFA 500K 2 JP 2 24 25 26 ROFA 500K RF 20K 27 1 28 + Y2B 10 9 8 HMUTE RFBD 40K 7 RFBD 40K IN1 FDBKP1 MUTE 6 BBM2 BBM1 VPWR VP2 FDBKN2 IN2 5 RFBC 14K;1% 4 RI 20K CI 2.2u;10V 2 Y2 11 V5 JUMPER COF .1u;50V 3 1 12 TC2000 1 1 RCA_RT_ANG J10 13 VP1 V5 ROFB 5K 14 V5 RFBB 1.0K;1% V5 OUT2A CFB 390p;50V 2 + CS .1u;50V CS 100u;16V DCMP FDBKP2 BIASCAP 3 RFBC 14K;1% 2 OUT2B 1 RFBB 1.0K;1% C7 .1u;50V CFB 390p;50V TP2051 and Outputs VCC U2 V5 29 VCC1A M3 IN1A OUT1A 23 IBIAS C12 .1u 24 R37 10K 25 O UT1A CONFIG G ND1A 17 16 CHBR .1u;50V 14 PWRDN C18 .1u R40 10K M2 15 PROTECTION 27 26 OUT2A LO 15u & FAULT LOG IC TRISTATE O UT2P C21 .1u VCC 28 30 Y2 VCC1B TH_WAR OU T1B OUT1B M4 18 NC 12 M5 IN1B G ND1B CO .22u;50V 11 C H BR .1u;50V C C AS E (note 2) 10 1000p;50V C SN (note1) 13 CZ .22u;50V 330p;100V;NPO TP2051 .1u;100V VCC 31 Y2B VCC2A IN2A M17 OUT2A 21 22 33 34 C30 .1u M15 VSS G ND2A REGULATORS 7 R SN (note1) RZ 15;1W 20;1/4W 8 9 C C AS E (note 2) 1000p;50V C H BR .1u;50V 6 CO .22u;50V VSS LO C31 .1u 15u 35 C14 .1u O UT2A VDD VDD SPEAKER CDM 36 20 32 19 1 OUT2N VCCSIG N VCCSIG N IN2B VCC2B 4 VCC M16 OUT2B GNDCLEAN GNDSUB OUT2B VCC GNDREG M14 O UT2B G ND2B 3 CHBR .1u;50V 2 5 CS + 560u;50V NOTE 1: C SN /R SN are optional locations, loaded only if required to reduce overshoot NO TE 2: C CASE (4 locations) represent bypass capacitors mounted at the exit of the speaker cable from the cabinet. They are optional and are used for EM I supression. Lead lengths on these com ponents must be kept short to be effective. They are shown in this schem atic for reference. 7 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on E X T E R N A L C O M P O N E N T S D E S C R I P T I O N (Refer to the Application/Test Circuit) Components RI RF CI RFBB RFBC CFB ROFB ROFA RREF CS CZ RZ LO CO CHBR CSN RSN CDM 8 Description Inverting input resistance to provide AC gain in conjunction with RF. This input is biased at the BIASCAP voltage (approximately 2.5VDC). Feedback resistor to set AC gain in conjunction with RI. Please refer to the Amplifier Gain paragraph, in the Application Information section. AC input coupling capacitor, which, in conjunction with RI, forms a high pass filter at fC = 1 (2πRICI ) . Feedback divider resistor connected to AGND. The value of this resistor depends on the supply voltage setting and helps set the TK2051 gain in conjunction with RI, RF, RFBA, and RFBC. Please see the Modulator Feedback Design paragraphs in the Application Information Section. Feedback resistor connected from either the OUT1A/OUT2A to FDBKP1/FDBKP2 or OUT1B/OUT2B to FDBKN1/FDBKN2. The value of this resistor depends on the supply voltage setting and helps set the TK2051 gain in conjunction with RI, RF, RFBA, and RFBB. It should be noted that the resistor from OUT1/OUT2 to FBKOUT1/FBKOUT2 must have a power rating of greater than PDISS = VPP2 (2RFBC) . Please see the Modulator Feedback Design paragraphs in the Application Information Section. Feedback delay capacitor that both lowers the idle switching frequency and filters very high frequency noise from the feedback signal, which improves amplifier performance. The value of CFB should be offset between channel 1 and channel 2 so that the idle switching difference is greater than 40kHz. Please refer to the Application / Test Circuit. Potentiometer used to manually trim the DC offset on the output of the TK2051. Resistor that limits the manual DC offset trim range and allows for more precise adjustment. Bias resistor. Locate close to pin 15 and ground at pin 20. Supply decoupling for the power supply pins. For optimum performance, these components should be located close to the TC2000/TP2051 and returned to their respective ground as shown in the Application/Test Circuit. Zobel capacitor, which in conjunction with RZ, terminates the output filter at high frequencies. Use a high quality film capacitor capable of sustaining the ripple current caused by the switching outputs. Zobel resistor, which in conjunction with CZ, terminates the output filter at high frequencies. The combination of RZ and CZ minimizes peaking of the output filter under both no load conditions or with real world loads, including loudspeakers which usually exhibit a rising impedance with increasing frequency. The recommended power rating is 1 Watt. Output inductor, which in conjunction with CO, demodulates (filters) the switching waveform into an audio signal. Forms a second order filter with a cutoff frequency of f C = 1 ( 2 π L O C O ) and a quality factor of Q = R L C O L O C O . Output capacitor, which, in conjunction with LO, demodulates (filters) the switching waveform into an audio signal. Forms a second order low-pass filter with a cutoff frequency of f C = 1 ( 2 π L O C O ) and a quality factor of Q = R L C O L O C O . Use a high quality film capacitor capable of sustaining the ripple current caused by the switching outputs. Electrolytic capacitors should not be used. High-frequency bypass capacitor for VCC – GND on each supply pin. A 50V rating is required for this component. Optional snubber capacitor, which in conjunction with RSN, reduces overshoot on non-optimal layouts. Only required if switching output overshoot is above rated voltage of TP2501. Use low-dissipation type (NPO). Optional snubber resistor, which in conjunction with CSN, reduces overshoot on nonoptimal layouts. Only required if switching output overshoot is above rated voltage of TP2501. Required ¼ Watt rating. Differential mode capacitor. TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on TYPICAL PERFORMANCE CHARACTERISTICS THD+N vs Output Power THD+N vs Output Power 10 10 f = 1kHz RL= 6Ω VDD=23.5 V AES 17 Filter 5 5 2 1 1 0.5 0.5 THD+N (%) THD+N (%) 2 0.2 0.1 0.1 0.05 0.02 0.02 0.01 0.01 0.005 1 0.005 1 2 5 10 Output Power (W) 20 50 100 THD+N vs Frequency 1 2 5 0.5 0.05 THD+N (%) 0.1 0.05 0.02 0.01 0.005 0.005 0.002 0.002 BW = 22kHz 0.001 50 100 200 500 1k 2k 5k 10k 20k 0.0005 20 50 100 200 Frequency (Hz) 500 1k 2k 5k 10k 20k Frequency (Hz) Intermodulation Distortion +0 -30 100 Po = 10W/ch RL = 8Ω Vcc=30V BW = 22kHz 0.001 -20 50 0.02 0.01 -10 20 0.2 0.1 0.0005 20 10 Output Power (W) THD+N vs Frequency 1 Po = 10W/ch RL = 6Ω Vcc=23.5V 0.2 THD+N (%) 0.2 0.05 0.5 f = 1kHz RL= 8Ω VDD=30V AES 17 Filter 19kHz, 20kHz 1:1 Po = 16.6W/ch, 6 Ω 0dBr = 10.0Vrms Vcc=23.5V BW = 22Hz - 30kHz Intermodulation Distortion +0 -10 -20 -30 19kHz, 20kHz 1:1 Po = 12.5W/ch, 8 Ω 0dBr = 10.0Vrms Vcc=30V BW = 22Hz - 30kHz -40 Amplitude (dBr) Amplitude (dBr) -40 -50 -60 -70 -80 -90 -70 -80 -100 -110 -110 -120 -120 -130 -130 50 100 200 500 1k Frequency (Hz) 9 -60 -90 -100 -140 20 -50 2k 5k 10k 20k -140 20 50 100 200 500 1k 2k 5k Frequency (Hz) TK2051 – SB/1.0/8-02 10k 20k Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on T Y P I C A L P E R F O R M A N C E C H A R A C T E R I S T I C S (cont’d) Efficiency vs Output Power Efficiency vs Output Power 100 100 Vcc=23.5V RL = 6Ω AES 17 Filter THD+N < 10% 90 80 80 70 70 Efficiency (%) Efficiency (%) 90 Vcc=30V RL = 8Ω AES 17 Filter THD+N < 10% 60 50 40 60 50 40 30 30 20 20 10 10 0 0 0 5 10 15 20 25 30 35 40 45 50 55 60 0 5 10 15 20 Output Power (W) RL = 8Ω -10 0dBr = 8.95V V S = 30V -20 BW = 22Hz - 20kHz(AES17) -30 -30 A -50 -60 d B r -70 A -70 45 50 55 60 -60 -80 -80 -90 -90 -100 -100 -110 -110 -120 40 -40 -40 -50 35 Channel Separation versus Frequency +0 RL = 6 Ω -10 0dBr = 7.75V VS = 23.5V -20 BW = 22Hz - 20kHz(AES17) d B r 30 Output Power (W) Channel Separation versus Frequency +0 25 30 50 100 200 500 1k 2k 5k -120 10k 20k Hz 30 50 100 200 500 1k 2k 5k 10k 20k Hz Efficiency vs Output Power (paralleled outputs) THD+N vs Output Power (paralleled outputs) 100 10 f=1kHz Vcc=30V RL = 4 AES 17 Filter 5 Vcc=30V RL = 4Ω AES 17 Filter THD+N < 10% 90 2 80 1 70 Efficiency (%) THD+N (%) 0.5 0.2 0.1 0.05 0.02 60 50 40 30 0.01 20 0.005 10 0.002 0 0.001 1 2 5 10 20 Output Power (W) 10 50 100 200 0 10 20 30 40 50 60 70 80 90 100 Output Power (W) TK2051 – SB/1.0/8-02 110 120 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on APPLICATION INFORMATION TK2051 Basic Amplifier Operation The TC2000 is a 5V CMOS signal processor that amplifies the audio input signal and converts the audio signal to a switching pattern. This switching pattern is spread spectrum with a typical idle switching frequency of about 700kHz. The switching patterns for the two channels are not synchronized and the idle switching frequencies should differ by at least 40kHz to avoid increasing the audio band noise floor. The idle frequency difference can be accomplished by offsetting the value of CFB for each channel. Typical values of CFB are 470pF for channel 1 and 390pF for channel 2. The TP2051 is a MOSFET output stage that level-shifts the signal processor’s 5V switching patterns to the power supply voltages and drives the power MOSFETs. The power MOSFETs are N-channel devices configured in full-bridges and are used to supply power to the output load. The outputs of the power MOSFETs must be low pass filtered to remove the high frequency switching pattern. A residual voltage from the switching pattern will remain on the speaker outputs when the recommended output LC filter is used, but this signal is outside of the audio band and will not affect audio performance. Circuit Board Layout The TK2051 is a power (high current) amplifier that operates at relatively high switching frequencies. The output of the amplifier switches between VPP and VNN at high speeds while driving large currents. This high-frequency digital signal is passed through an LC low-pass filter to recover the amplified audio signal. Since the amplifier must drive the inductive LC output filter and speaker loads, the amplifier outputs can be pulled above the supply voltage and below ground by the energy in the output inductance. To avoid subjecting the TK2051 to potentially damaging voltage stress, it is critical to have a good printed circuit board layout. It is recommended that Tripath’s layout and application circuit be used for all applications and only be deviated from after careful analysis of the effects of any changes. The following components are important to place near their associated TC2000/TP2051 pins and are ranked in order of layout importance, either for proper device operation or performance considerations. - The capacitors CHBR provide high frequency bypassing of the amplifier power supplies and will serve to reduce spikes across the supply rails. CHBR should be kept within 1/8” (3mm) of the VCC pins. Please note that the four VCC pins must be decoupled separately. In addition, the voltage rating for CHBR should be 50V as this capacitor is exposed to the full supply range. Similarly, capacitor CS (one place) should be located as close as possible to the VCC pins on TP2051. - CFB removes very high frequency components from the amplifier feedback signals and lowers the output switching frequency by delaying the feedback signals. In addition, the value of CFB is different for channel 1 and channel 2 to keep the average switching frequency difference greater than 40kHz. This minimizes in-band audio noise. - To minimize noise pickup and minimize THD+N, RFBC should be located as close to the TC2000 as possible. Make sure that the routing of the high voltage feedback lines is kept far away from the input op amps or significant noise coupling may occur. It is best to shield the high voltage feedback lines by using a ground plane around these traces as well as the input section. In general, to enable placement as close to the TC2000/TP2051, and minimize PCB parasitics, the capacitors listed above should be surface mount types. 11 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on Some components are not sensitive to location but are very sensitive to layout and trace routing. - To maximize the damping factor and reduce distortion and noise, the modulator feedback connections should be routed directly to the pins of the output inductors, LO. - The modulator feedback resistors, RFBA and RFBB should all be grounded and attached to 5V together. These connections will serve to minimize common mode noise via the differential feedback. TK2051 Grounding Proper grounding techniques are required to maximize TK2051 functionality and performance. Parametric parameters such as THD+N, noise floor and cross talk can be adversely affected if proper grounding techniques are not implemented on the PCB layout. The following discussion highlights some recommendations about grounding both with respect to the TK2051 as well as general “audio system” design rules. The TK2051 is divided into two sections: the input section, and the output (high power) section. On the TK2051 evaluation board, the ground is also divided into distinct sections, one for the input and one for the output. To minimize ground loops and keep the audio noise floor as low as possible, the input and output ground must be only connected at a single point. Depending on the system design, the single point connection may be in the form of a ferrite bead or a PCB trace. Modulator Feedback Design The modulator converts the signal from the input stage to the high-voltage output signal. The optimum gain of the modulator is determined from the maximum allowable feedback level for the modulator and maximum supply voltage for the power stage. Depending on the maximum supply voltage, the feedback ratio will need to be adjusted to maximize performance. The values of RFBB and RFBC (see explanation below) define the gain of the modulator. Once these values are chosen, based on the maximum supply voltage, the gain of the modulator will be fixed even with as the supply voltage fluctuates due to current draw. For the best signal-to-noise ratio and lowest distortion, the maximum differential modulator feedback voltage should be approximately 4Vpp. This will keep the gain of the modulator as low as possible and still allow headroom so that the feedback signal does not clip the modulator feedback stage. The modulator feedback resistors are: RFBB = User specified; typically1kΩ V CC ∗ R FBB R FBC = 2V − R FBB TK2051 Amplifier Gain The gain of the TK2051 is the product of the input stage gain and the modulator gain. Please refer to the sections, Input Stage Design, and Modulator Feedback Design, for a complete explanation of how to determine the external component values. A VTK2051 = A VINPUTSTAG A VTK2051 ≈ 12 E * A V MODULATOR R F R FBC + R FBB RI R FBB TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on For example, using a TK2051 with the following external components, RI = 20kΩ RF = 20kΩ RFBB = 1kΩ RFBC = 14kΩ A VTK2051 ≈ 20k Ω 14k Ω + 1k Ω ) V = 15 20k Ω 1k Ω V Input Stage Design The TC2000 input stage is configured as an inverting amplifier, allowing the system designer flexibility in setting the input stage gain and frequency response. Figure 1 shows a typical application where the input stage is a constant gain inverting amplifier. The input stage gain should be set so that the maximum input signal level will drive the input stage output to 4Vpp. TC2000 OAOUT1 CI V5 RF RI INV1 INPUT1 + BIASCAP AGND V5 + INV2 CI - RF RI INPUT2 OAOUT2 AGND Figure 1: Input Stage The gain of the input stage, above the low frequency high pass filter point, is that of a simple inverting amplifier: It should be noted that the input amplifiers are biased at approximately 2.5VDC. Thus, the polarity of CI must be followed as shown in Figure 1 for a standard ground referenced input signal A VINPUTSTAG E =− RF RI Input Capacitor Selection CI can be calculated once a value for RI has been determined. CI and RI determine the input low frequency pole. Typically this pole is set below 10Hz. CI is calculated according to: CI = 1 2π f P R I where: RI = Input resistor value in ohms. fP = Input low frequency pole (typically 10Hz or below) 13 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on Mute Control When a logic high signal is supplied to MUTE, both amplifier channels are muted (both high- and lowside transistors are turned off). When a logic level low is supplied to MUTE, both amplifiers are fully operational. There is a delay of approximately 200 milliseconds between the de-assertion of MUTE and the un-muting of the TK2051. To ensure proper device operation, including minimization of turn on/off transients that can result in undesirable audio artifacts, Tripath recommends that the TK2051 device be muted prior to power up or power down of the 5V supply. The “sensing” of the V5 supply can be easily accomplished by using a “microcontroller supervisor” or equivalent to drive the TC2000 mute pin high when the V5 voltage is below 4.5V. This will ensure proper operation of the TK2051 input circuitry. A micro-controller supervisor such as the MCP101-450 from Microchip Corporation has been used by Tripath to implement clean power up/down operation. If turn-on and/or turn-off noise is still present with a TK2051 amplifier, the cause may be other circuitry external to the TK2051. While the TK2051 has circuitry to suppress turn-on and turn-off transients, the combination of power supply and other audio circuitry with the TK2051 in a particular application may exhibit audible transients. One solution that will completely eliminate turn-on and turn-off pops and clicks is to use a relay to connect/disconnect that amplifier from the speakers with the appropriate timing during power on/off. TK2051 Output Capability The TK2051 can drive two 8 Ohm loads with 45 Watts each at less than 0.05% THD+N. The maximum sustained amplifier output power will be determined by a number of factors including the TC2000/TP2051 junction temperatures, the load impedance and the power supply voltage. Tripath does not recommend driving loads below 6 Ohms single ended as the amplifier efficiency will be reduced and the amplifier will reach it’s current limit at relatively low power output levels. With the outputs connected in parallel, however, the TK2051 is capable of driving single channel loads down to 4 Ohms with very high power capability. In such applications, special consideration must be give to cooling of the TP2051 power device. Paralleled Outputs For stereo mode operation, the TK2051 is a dual full bridge. For parallel mode operation, the TK2051 can be configured as a single full bridge with double current capability by connecting the CONFIG pin to the Vdd pin of the TP2051. Please refer to the Applications/Test Diagram for Parallel Operation. Output Voltage Offset The TK2051 does not have internal compensation for DC offset. If offset is a consideration for the intended application, trimming of the input offset voltage will be required. Tripath has had success with both active and passive circuits for this purpose; please consult with the Tripath applications team for further information or review the EB-TK2051 datasheet for a full description of input trimming. Output Filter Design Tripath amplifiers generally have a higher switching frequency than PWM implementations, allowing the use of higher cutoff frequency filters and reducing the load dependent peaking/drooping in the 20kHz audio band. This is especially important for applications where the end customer may attach any speaker to the amplifier (as opposed to a system where speakers are shipped with the amplifier), since speakers are not purely resistive loads and the impedance they present changes over frequency and from speaker model to speaker model. An RC network, or “Zobel” (RZ, CZ) should be placed at the filter output to control the impedance “seen” by the TP2051 when not attached to a 14 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on speaker load. The TK2051 works well with a 2nd order, 80kHz LC filter with LO = 10uH and CO = 0.47uF and RZ = 10 Ohm/1W and CZ = 0.47uF. NOTE: Output inductor selection is a critical design step. The core material and geometry of the output filter inductor affects the TK2051 distortion levels, efficiency, power dissipation and EMI output. Minimum and Maximum Supply Voltage Operating Range The TK2051 can operate over a wide range of power supply voltages from +12V to +30V. In order to optimize operation for either the low or high range, the user must select the proper values for RFBB, and RFBC. Protection Circuits The TK2051 is protected against over-current, over / under-voltage and over-temperature conditions. Over-temperature Protection An over-temperature fault occurs if the junction temperature of the part exceeds approximately 165°C. The thermal hysteresis of the part is approximately 30°C, therefore the fault will automatically clear when the junction temperature drops below 135°C. HMUTE The HMUTE pin is a 5V logic output that indicates various fault conditions within the device. It is not normally used in product applications. OVRLDB The OVRLDB pin is a 5V logic output that is asserted just at the onset of clipping. When low, it indicates that the level of the input signal has overloaded the amplifier resulting in increased distortion at the output. The OVRLDB signal can be used to control a distortion indicator light or LED through a simple buffer circuit, as the OVRLDB cannot drive an LED directly. There is a 20K resistor on chip in series with the OVRLDB output. Performance Measurements of the TK2051 The TK2051 operates by generating a high frequency switching signal based on the audio input. This signal is sent through a low-pass filter (external to the Tripath amplifier) that recovers an amplified version of the audio input. The frequency of the switching pattern is spread spectrum in nature and typically varies between 100kHz and 1MHz, which is well above the 20Hz – 20kHz audio band. The pattern itself does not alter or distort the audio input signal, but it does introduce some inaudible components. The measurements of certain performance parameters, particularly noise related specifications such as THD+N, are significantly affected by the design of the low-pass filter used on the output as well as the bandwidth setting of the measurement instrument used. Unless the filter has a very sharp roll-off just beyond the audio band or the bandwidth of the measurement instrument is limited, some of the inaudible noise components introduced by the TK2051 amplifier switching pattern will degrade the measurement. One feature of the TK2051 is that it does not require large multi-pole filters to achieve excellent performance in listening tests, usually a more critical factor than performance measurements. Though using a multi-pole filter may remove high-frequency noise and improve THD+N type measurements (when they are made with wide-bandwidth measuring equipment), these same filters 15 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on degrade frequency response. The TK2051 Evaluation Board uses the Application/Test Circuit of this data sheet, which has a simple two-pole output filter and excellent performance in listening tests. Measurements in this data sheet were taken using this same circuit with a limited bandwidth setting in the measurement instrument. 16 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on PACKAGE INFORMATION – TC2000 17 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on Package Information – TP2051 18 TK2051 – SB/1.0/8-02 Tr i path Technol ogy, I nc. - Techni cal I nfor m ati on Tripath and Digital Power Processing are trademarks of Tripath Technology Inc. Other trademarks referenced in this document are owned by their respective companies. Tripath Technology Inc. reserves the right to make changes without further notice to any products herein to improve reliability, function or design. Tripath does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, nor the rights of others. TRIPATH’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN CONSENT OF THE PRESIDENT OF TRIPATH TECHNOLOGY INC. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in this labeling, can be reasonably expected to result in significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. For more information on Tripath products, visit our web site at: http://www.tripath.com Other useful documents concerning the TK2051 available on the Tripath website. EB-TK2051 Evaluation Board – TK2051 Evaluation Board Document RB-TK2051 Two Channel Reference board – RB-TK2051 Board Design Document RB-TK2051 Six Channel Board – Six-channel reference design using the TK2051 Contact Information TRIPATH TECHNOLOGY, INC 2560 Orchard Parkway, San Jose, CA 95131 408.750.3000 - P 408.750.3001 - F For more Sales Information, please visit us @ www.tripath.com/cont_s.htm For more Technical Information, please visit us @ www.tripath.com/data.htm 19 TK2051 – SB/1.0/8-02