2W Stereo Class-D Audio Power Amplifier BA20373 Data Sheet Rev.1.0, 2006.05.19 Biforst Technology Inc. BA20373 ____ 2W Stereo Class-D Audio Power Amplifier 2W Stereo Class-D Audio Power Amplifier BA20373 GENERAL DESCRIPTION The BA20373 is a 5V class-D amplifier from Biforst Technology. BA20373 provides dc volume control, lower supply current, high efficiency & few external components for driving speaker directly. BA20373 also integrates Anti-Pop, Output Short & Over-Heat Protection Circuitry to increase device reliability. The functionality makes this device ideal for LCD projectors, LCD monitors, powered speakers & other applications that demand more battery life. FEATURE 2W Per Channel Into 3-Ω Speakers (THD+N = 10%@5.6V) Operation Voltage From 3.3 To 5.5V DC Volume Control From –27dB to 20dB Low Shutdown Control : <10μA Low Noise Floor, -80dBV Maximum Efficiency into 3-Ω, 77% Maximum Efficiency into 8-Ω, 87% PSRR, -71dB Filter Free PWM Output Technology without LC Output Filter Integrated Anti-Pop Circuitry Integrated Output Short Protection Circuitry Integrated Over-Heat Protection Circuitry Provide DC Volume Control Shipping in Die Form APPLICATION LCD Monitors Powered Speakers Cellular Phones PDA Portable DVD/CD Players USB Audio Battery Powered Application _________________________________________________________________________________________________ Biforst Technology, Inc., reserves the right to change product or specifications without notice. Page 2 of 8 BA20373 ____ 2W Stereo Class-D Audio Power Amplifier PAD ASSIGNMENTS, PAD LIST & DESCRIPTION 3 4 46 47 48 VSS VSS LINP VDD VDD BA20373 1 2 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 VSS VSS VDD VDD RINP RINN C_BYPASS SHUTDOWN_B VSS VSS VSS VSS VSS OSC_C VOLUME OSC_R LINN 28 27 30 29 VSS VSS VSS VSS PAD ASSIGNMENTS 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 VSS VSS ROUT_N ROUT_N ROUT_N ROUT_P ROUT_P ROUT_P VDD VDD VDD VDD VDD VDD LOUT_P LOUT_P LOUT_P 9 8 7 LOUT_N LOUT_N LOUT_N 6 5 VSS VSS PAD LIST & DESCRIPTION Pad No. Pad Type X Y I/O Pad Function 1 176.48 46.50 2 274.48 46.50 1254.47 80.85 4 1354.47 80.85 5 1930.25 83.85 6 1930.25 183.85 7 1930.25 304.20 1930.25 409.20 Left channel negative output 9 1930.25 514.20 10 1930.25 619.20 1930.25 724.20 Left channel positive output 12 1930.25 829.20 13 1930.25 949.55 3 VSS 8 11 14 LOUT_N LOUT_P VDD Power Output Output Power 5V Ground 1930.25 1049.55 5V Power Input 15 1930.25 1149.55 16 1930.25 1597.45 17 18 VDD Power 1930.25 1697.45 5V Power Input 1930.25 1797.45 _________________________________________________________________________________________________ Biforst Technology, Inc., reserves the right to change product or specifications without notice. Page 3 of 8 BA20373 Pad No. Pad Type X 2W Stereo Class-D Audio Power Amplifier Y ROUT_P Output 1930.25 2022.80 Right channel positive output 21 1930.25 2127.80 22 1930.25 2232.80 23 ROUT_N Output 1930.25 2337.80 Right channel negative output 24 1930.25 2442.80 25 1930.25 2563.15 26 1930.25 2663.15 1354.47 2666.15 27 28 I/O Pad Function 1930.25 1917.80 19 20 ____ VSS Power 1254.47 2666.15 29 274.48 2699.70 30 176.48 2699.70 5V Ground 46.50 2437.45 31 VDD Power 5V Power Input 46.50 2339.45 32 33 RINP Input 46.50 2241.45 Right channel positive differential audio input 34 RINN Input 46.50 2143.45 Right channel negative differential audio input 35 C_BYPASS Input 36 SHUTDOWN_B Input Connect a 10-uF capacitor from C_BYPASS to ground for internal 46.50 2045.45 bias reference Shut down control for CS3006, Logic low is placed on this terminal for shut down mode, Logic high is placed on this terminal for normal operation (Recommend Connect 100K Ohm To VDD & Connect 1uF 46.50 1947.45 To Ground In Application Circuit) 37 46.50 1849.45 38 46.50 1751.45 39 VSS Power 46.50 1653.45 5V Ground 40 46.50 1081.95 41 46.50 Input 983.95 A capacitor connected to this terminal sets the oscillation in conjunction with OSC_C. For proper operation, connect a 220-pF 885.95 capacitor from OSC_C to ground DC volume control for setting the gain on the internal amplifier. The 787.95 dc voltage range is 0 to VDD A resistor connected to this terminal sets the oscillation in 689.95 conjunction with OSC_R. For proper operation, connect a 120-kΩ resistor from OSC_R to ground 42 OSC_C 43 VOLUME Input 46.50 44 OSC_R Input 46.50 45 LINN Input 46.50 591.95 Left channel negative differential audio input 46 LINP Input 46.50 493.95 Left channel positive differential audio input 47 VSS 46.50 395.95 46.50 297.95 46.50 Power 48 VSS 5V Ground _________________________________________________________________________________________________ Biforst Technology, Inc., reserves the right to change product or specifications without notice. Page 4 of 8 BA20373 ____ 2W Stereo Class-D Audio Power Amplifier FUNCTION DESCRIPTION Output Power Efficiency The output transistors of BA20373 act as switches. The amount of power dissipated in the speaker may be estimated by first considering the overall efficiency of the system. The on-resistance of the output transistors is considered to cause the dominant loss in the system, the on-resistance of output transistors is small that the power loss is small and the power efficiency is high. When BA20373 is with 8-ohm load, the power efficiency can be better than 87%. Shutdown Mode The BA20373 provides a shutdown mode to reduce supply current to the absolute minimum level during periods of non-use for battery-power conservation. The SHUTDOWN_B input pin should be held high during normal operation when the amplifier is in use. Pulling SHUTDOWN_B low causes the outputs to mute and the amplifier to enter a low-current state. SHUTDOWN_B should never be left unconnected because the amplifier state would be unpredictable. Recommend connecting SHUTDOWN_B pin with 100K Ohm To VDD & Connect 1uF To Ground. Differential Input The differential input stage of the amplifier cancels any noise that appears on both input lines of the channel. To use the BA20373 with a differential source, connect the positive lead of the audio source to the LINP/RINP input and the negative lead from the audio source to the LINN/RINN input. To use the BA20373 with a single-ended source, ac ground either input through a capacitor and apply the audio signal to the remaining input. In a single-ended input application, the un-used input should be ac-grounded at the audio source instead of at the device input for best noise performance. Single-end stereo input application circuit shows in Figure 1. It’s recommended LINN & RINN connect 1uF to ground. & Left/Right analog audio signal series connect 1uF to LINP & RINP. Left Channel Input 1uF 1uF Right Channel Input 1uF 1uF LINP LINN BA20373 RINP RINN Figure 1. Single-end stereo input application circuit Volume Control The VOLUME pin controls the volume of the BA20373. It is controlled with a dc voltage, which should not exceed VDD. Table 1 lists the voltage on the VOLUME pin and the corresponding gain. The volume control circuitry of the BA20373 is internally referenced to the VDD and 1V. Any _________________________________________________________________________________________________ Biforst Technology, Inc., reserves the right to change product or specifications without notice. Page 5 of 8 BA20373 ____ 2W Stereo Class-D Audio Power Amplifier common-mode noise between the VOLUME terminal and these terminals will be sensed by the volume control circuitry. If the noise exceeds the step size voltage, the gain will change. In order to minimize this effect, care must be taken to ensure the signal driving the VOLUME terminal is referenced to the VDD and 1V of the BA20373. DC volume application circuit shows in Figure 2. It’s recommended to connect 10K VR series to 2.2 K resister to ground or 50K VR series to 11 K resister to ground. VDD VDD 50K VR Volume 10K VR Volume 2.2K 11K Figure 2. DC Volume Application Circuit Table 1. Typical DC Volume Control Voltage On Volume Pin 0.97 - 0.87 1.08 - 0.98 1.19 - 1.09 1.32 - 1.20 1.42 - 1.33 1.53 - 1.43 1.63 - 1.54 1.75 - 1.64 1.84 - 1.76 1.96 - 1.85 2.09 - 1.97 2.19 - 2.10 2.33 - 2.20 2.43 - 2.34 2.49 - 2.44 2.62 - 2.50 2.75 - 2.63 2.85 - 2.76 2.99 - 2.86 3.12 - 3.00 3.25 - 3.13 3.36 - 3.26 3.48 - 3.37 3.64 - 3.49 VDD - 3.65 Typical Gain Of Amplifier (dB) -27 -25 -23 -21 -19 -17 -15 -13 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 OSC_C & OSC_R Pin The switching frequency is determined using the values of the components connected to OSC_R and OSC_C _________________________________________________________________________________________________ Biforst Technology, Inc., reserves the right to change product or specifications without notice. Page 6 of 8 BA20373 ____ 2W Stereo Class-D Audio Power Amplifier The frequency may be varied from 200 kHz to 300 kHz by adjusting the values chosen for OSC_R and OSC_C. The recommended values are OSC_C = 220 pF, OSC_R= 120 kΩ for a switching frequency of 250 kHz. Over-Heat Protection Over-Heat protection on the BA20373 prevents damage to the device when the internal die temperature exceeds 125°C. Once the die temperature exceeds the thermal set point, the device enters the shutdown state and the outputs are disabled. The device will back to normal operation when die temperature is reduced without external system interaction. Output Short Protection The BA20373 has output short circuit protection circuitry on the outputs that prevents damage to the device during output-to-output short, output-to-GND short, and output-to-VDD short. BA20373 enters the shutdown state and the outputs are disabled when detects output short. The device will back to normal operation automatically after 2 ~ 3 minute. Anti-Pop A soft start capacitor must be added to the C_BYPASS pin. It recommends connecting a capacitor of 1uF from C_BYPASS pin to Ground. BA20373 provides fade-in function when power-on or SHUTDOWN_B input voltage level from 0V to VDD, and fade-out function when SHUTDOWN_B input voltage level from VDD to 0V. The pop noise can be eliminated by fade-in/fade-out function. Output Filter Application Note Design the BA20373 without the filter if the traces from amplifier to speaker are short (< 1 inch). Where the speaker is in the same enclosure as the amplifier is a typical application for class-D without a filter. Many applications require a ferrite bead filter. The ferrite filter reduces EMI around 30 MHz. When selecting a ferrite bead, choose one with high impedance at high frequencies, but low impedance at low frequencies. Use an LC output filter if there are low frequency (<1 MHz) EMI sensitive circuits and/or there are long wires from the amplifier to the speaker. 22uH OUTP 0.1uF 0.47uF 22uH 0.1uF OUTN Figure 3. Typical LC Output Filter _________________________________________________________________________________________________ Biforst Technology, Inc., reserves the right to change product or specifications without notice. Page 7 of 8 BA20373 ____ 2W Stereo Class-D Audio Power Amplifier BEAD (600R) OUTP 330pF 470pF BEAD (600R) 330pF OUTN Figure 4. Typical Ferrite Chip Bead Output Filter C_BYPASS Pin It’s recommended to connect a 10-uF capacitor from C_BYPASS pin to ground for internal bias reference & provide high power supply rejection ratio (PSRR). CONTACT INFORMATION Biforst Technology Inc. 8F-3, No.26, Tai Yuen St., Jubei City, Hsin-Chu, Taiwan, R.O.C. Tel: 886-3-552-6521; Fax: 886-3-552-6558; Email: [email protected] Version History Version Date 1.0 2006.05.19 Page Description First Release _________________________________________________________________________________________________ Biforst Technology, Inc., reserves the right to change product or specifications without notice. Page 8 of 8