ATA-120

ATA-120 20W Class D Single Channel Audio Amplifier • • • • • • • • • • • • FEATURES HIGH OUTPUT POWER CAPABILITY SINGLE SUPPLY (+7.5V to +24V) THD+N < 0.05% @ 1W, 8Ω HIGH EFFICIENCY, > 90% @ 4Ω, 20W LOW QUIESCENT CURRENT, 13mA LOW NOISE (190µV typ.) POP ELIMINATION AT STARTUP AND SHUTDOWN BUILT-IN THERMAL PROTECTION INTEGRATED SHORT CIRCUIT PROTECTION 180mΩ MOSFET SWITCHES MUTE / STANDBY MODE SMALL SMD PACKAGE IS BOTH LEAD-FREE (Pb) AND GREEN 1.0 GENERAL DESCRIPTION The ATA-120 Class-D Audio Amplifier is a fully integrated monolithic audio amplifier that can provide audio power up to 20 watts @ 10% THD into a 4Ω speaker. The ATA-120 incorporates a single ended output structure with built-in short circuit and overtemperature protection. This low noise, high performance device delivers the excellent audio quality of a class A/B amplifier while still achieving class-D efficiency greater than 90%. ORDERING INFORMATION: Part Number * ATA-120 EB-120 Package Temperature SOIC8 -40°C to + 85°C Evaluation Board for the ATA-120 APPLICATIONS • • • • • TELEVISIONS HOME AUDIO MINI-SYSTEMS FLAT PANEL MONITORS MULTIMEDIA SPEAKERS SURROUND SOUND DVD SYSTEMS IN_P - BOOST VDD IN_N + FET DRIVE REGULATOR, CONTROL & PROTECTION FET DRIVE ENABLE POUT AGND PGND Figure 1 - Block Diagram This is preliminary information on a new product. Specifications are subject to change without notice. 129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc DRN: PRELIMINARY Page 1 of 13 ATA-120 Absolute Maximum Ratings [Note 1] SYMBOL PARAMETER VDD VBOOST VENABLE VOUT VIN_P VIN_N Supply Voltage Bootstrap Voltage Enable Voltage Output Switch Positive Input Negative Input Analog GND to Power GND Junction Temperature Lead Temperature Storage Temperature MIN VOUT-0.3 -0.3 -1 -1 -1 -0.3 TYP MAX 26 VOUT+6.5 6.0 VDD+1 VDD+1 VDD+1 0.3 UNIT V V V V V V V Tj TLEADS TS -65 150 260 150 °C °C °C Note 1 – Operation above maximum ratings may damage the device. 1.1 VDD TA Recommended Operating Conditions [Note 2] PARAMETER Supply Voltage Operating Temperature SYMBOL MIN 7.5 -40 TYP MAX 24 85 UNIT V °C Note 2 - Performance not guaranteed beyond recommended operating conditions. 1.2 θJ-A θJ-C Thermal Characteristics PARAMETER Thermal Resistance, Junction to Ambient Thermal Resistance, Junction to Case [Note 3] SYMBOL MIN TYP 105 50 MAX UNIT °C/W °C/W Note 3 – Solder pins directly to large copper surface areas to improve device cooling. 1.3 ISTBY IQ Electrical Characteristics [Note 4] PARAMETER Standby Current Quiescent Current Output MOSFET on Resistance Short Circuit Current IN_P, IN_N Input Common Mode Voltage Range IN_P, IN_N Input Current Enable Threshold Voltage Enable Input Current Thermal Shutdown Trip Point Thermal Shutdown Hysteresis Rising signal voltage Falling signal voltage VENABLE = 5V TJ Rising SYMBOL Supply Current CONDITION VENABLE = 0 MIN TYP 130 13 0.18 5 VDD 2 1 1.4 1.2 1 150 30 MAX UNIT µA mA Ω A Output Drivers RDS-ON ISC Sourcing and Sinking Sourcing and Sinking 3 0 Inputs VIN IIN VENABLE IENABLE TSD TSD-HYS VDD-1.5 5 2.0 V µA V µA °C °C 0.4 Thermal Shutdown Note 4 – Performance based on circuit in Figure 3, VDD = 24V, VENABLE = 5V, TA = 25°C This is preliminary information on a new product. Specifications are subject to change without notice. 129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc DRN: PRELIMINARY Page 2 of 13 ATA-120 1.4 POUT THD+N η BW DNR SNR PSR Typical Operating Characteristics [Note 5] PARAMETER Power Output Total Harmonic Distortion Plus Noise Efficiency Maximum Power Bandwidth Dynamic Range Signal to Noise Ratio Noise Floor Power Supply Rejection SYMBOL CONDITION THD+N = 10%, 4Ω Load THD+N = 10%, 8Ω Load POUT = 1 W, 4Ω Load POUT = 1 W, 8Ω Load POUT = 20 W, 4Ω Load POUT = 10 W, 8Ω Load A-Weighted A-Weighted, relative to 15W A-Weighted MIN TYP 20 10 0.1 0.05 90 93 20 91 92 190 47 MAX UNIT W W % % % % KHz dB dB µV dB Note 5 – Performance based on circuit of Figure 3, VDD = 24V, VENABLE = 5V, f = 1 KHz, TA = 25°C 2.0 PIN DESCRIPTION Pin No. 1 2 3 4 5 Pin Name IN_P IN_N AGND ENABLE BOOST Pin Function Amplifier Positive Input. IN_P is the positive side of the differential input to the amplifier. Use a resistive voltage divider to set the voltage at IN_P to VDD/2. See Figure 3. Amplifier Negative Input. IN_N is the negative side of the differential input to the amplifier. Drive the input signal and close the feedback loop at IN_N. See Figure 3. Analog Ground. Signal input ground. Connect AGND to PGND at one single point. Enable Input. Set ENABLE high to turn-on the amplifier; set it low to turn it off. High-Side MOSFET Bootstrap Input. A capacitor from BOOST to POUT supplies the gate drive current to the high-side of the MOSFET. Connect a 0.47µF capacitor from POUT to BOOST. Place a 6.2V zener diode from BOOST to POUT to prevent overstressing the internal circuitry. Power Supply Input. VDD is the drain of the high-side MOSFET switch and supplies the power to both the output stage and the ATA-120 internal control circuitry. In addition to the main bulk capacitor, bypass VDD to PGND with a 1µF X7R capacitor placed close to the IC’s VDD (pin 6) and PGND (pin 8). Switched Power Output. POUT is the output of the ATA-120. Connect the L-C filter between POUT and the output blocking capacitor. See Figure 3. Power Ground. Power stage ground. Connect PGND to AGND at one single point. 6 VDD 7 8 POUT PGND This is preliminary information on a new product. Specifications are subject to change without notice. 129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc DRN: PRELIMINARY Page 3 of 13 ATA-120 3.0 Functional Description The ATA-120 is a single-ended Class-D audio amplifier that converts analog audio input signals into PWM pulses. The pulses drive an internal high current output stage and, when filtered through an external L-C filter, reproduce the input signal across the load. Because of the switching Class-D output stage, power dissipation in the amplifier is drastically reduced compared to Class A, Class B or Class A/B amplifiers while maintaining high fidelity and low distortion. The amplifier uses a differential input to the modulator. IN_P is the positive input and IN_N is the negative input. The common mode voltage of the input is set to half the DC power supply input voltage (VDD/2) through the resistive voltage divider formed by R2 and R5. The input capacitor C3 couples the AC input signal into the amplifier while blocking the DC component. The output driver stage uses two 180 mΩ N-channel MOSFETs to deliver the pulses to the L-C output filter which in turn drives the load. When the output switches low, the bootstrap capacitor, C9, which is located between POUT and BOOST, is charged from VDD through internal circuitry inside the ATA-120. The gate of the upper MOSFET is driven from this voltage (higher than VDD but clamped to safe levels by zener diode D2). 3.1 Pop Elimination The DC-blocking capacitor, C38, allows only AC current to pass to the output load (speaker). To insure that the amplifier properly passes low frequency signals, the time constant of C38*RLOAD needs to be long. Typically the C11 capacitor charges over a long time period and would normally result in turn-on and/or turn-off “pops”. The ATA-120, however, includes internal circuitry that eliminates the turn-on and turn-off pops associated with this charging of the AC coupling capacitor. 3.2 Short Circuit/Overload Protection The ATA-120 has internal overload and short circuit protection. The currents in both the high-side and low-side MOSFETs are internally measured and if the current exceeds the 5A (typical) short circuit current limit on either MOSFET, both MOSFETs are placed in an open condition. After the short circuit condition is removed, the ATA-120 restarts with the same power up sequence that is used for normal starting to prevent a pop from occurring. 3.3 Mute/Enable Function The ENABLE input is an active high enable control. To enable the device, drive ENABLE with a 2.0V or greater voltage. To disable the amplifier, drive it below 0.4V. While the device is disabled, the VDD operating current is less than 130µA and the output MOSFETs are turned off. The ATA-120 requires approximately 500ms from the time that ENABLE is asserted (driven high) to when the amplifier arrives at normal operation. This is preliminary information on a new product. Specifications are subject to change without notice. 129 Morgan Drive, Norwood, MA 02062 voice: (781) 551-9450 fax: (781) 440-9528 email: apogee@apogeeddx.com CONTROLLED DOCUMENT: P_903-000009_Rev14 ATA-120 Data Sheet.doc DRN: PRELIMINARY Page 4 of 13 ATA-120 4.0 Power Output Figure 2 shows the full-scale sine-wave output power as a function of Power Supply Voltage for 2, 3, 4, 6, and 8 Ohm loads. Output power is constrained for higher impedance loads by the maximum voltage limit of the ATA-120 and by the over-current protection limit for lower impedance loads. The minimum threshold for the overcurrent protection circuit is 3.0A (at 25 ºC) but the typical threshold is 5.0A. Solid lines depict typical output power capability of the ATA-120. Dashed lines depict the output power capability constrained to the minimum current specification of for the ATA-120. The output power curves assume proper thermal management of the power device’s internal dissipation. Since The IC’s thermal path is predominantly through the leadframe to the PC Board copper foil, a sufficient copper area must be connected to each lead in order to facilitate proper cooling. 24 22 20 10% THD Output Power (Watts) 18 16 14 12 10 8 6 4 2 0 7 8 9 10% THD Output Power vs Supply Voltage 3Ω 4Ω 2Ω 6Ω 8Ω 10 11 12 13 14 15 16 17 18 Power Supply Voltage (VDC) 19 20 21 22 23 24 LEGEND IOUT (min) = 3.0A IOUT (typ) = 5.0A RL=8Ω RL=6Ω RL=4Ω RL=3Ω RL=8Ω RL=6Ω RL=4Ω RL=3Ω Figure 2 – 10% THD Power Output vs. Power Supply Voltage RL=2Ω RL=2Ω Note 6 : Sine-wave output power (