Portable electronic products such as mobile phones are integrating more and more multimedia functions, which has aroused great interest in adding stereo functions. This article describes a low-cost stereo switching solution based on the MA6335+MS6863 chipset from Maosheng, which is ideal for MP3 players, portable media players (PMPs), mobile phones, portable TVs, portable DVDs and more. Currently, portable devices such as 3G mobile phones or portable multimedia players can easily provide audio 3D effects through digital processing. With this device, stereo headphone listening can be embedded so that the left and right signals are available from the DAC or FM radio. Although the headphone power is approximately 10 mW over a 32 ohm load, the main horn can be easily used to generate and output up to 1 W of power for an 8 ohm load. Due to the need to provide a stereo solution instead of a conventional mono system, it is difficult to provide a highly efficient clean audio signal at these power levels. MOSA Electronics Corp.'s MS6335 digital/analog converter works with the MS6863 low distortion power amplifier for MP3 players, portable media players (PMPs), mobile phones, portable TVs, and Portable products such as portable DVDs offer a complete low-cost stereo switching solution with a functional diagram as shown in Figure 1. Figure 1. Function diagram of low-cost physical voice switching scheme based on MS6335+MS6863 MS6335 Digital/Analog Converter The MS6335 is a 16-bit digital/analog converter (DAC) with an integrated Class AB stereo headphone driver with an I2C SPI interface and volume control. The internal structure is shown in Figure 2. Its unique synchronous decoding technology combined with a precisely matched initial current source effectively eliminates zero-crossing to produce high quality audio. Figure 2. Internal structure of the MS6335 The MS6335 is manufactured in a CMOS process with a volume control range of 6dB to -39dB (1.5dB/step). The output voltage can be adjusted with an external resistor. It has excellent Power Supply rejection ratio (PSRR) and can reproduce high quality audio. Ideal for low power, small form factor portable applications. Typical application of the MS6335 in an FM-enabled MP3 player. See Figure 3. Figure 3. Application of the MS6335 in an FM-enabled MP3 player Figure 4. Internal structure of MS6863 MS6863 low distortion power amplifier The MS6863 is a low distortion power amplifier capable of driving a continuous average power of 2&TImes; a 2W dual 4 ohm BTL load, or a 2&TImes; 90mW stereo 32 ohm single-ended (SE) earphone. With the headphone detection pin, the MS6863 automatically switches between dual BTL and stereo SE modes. In most applications, this BTL configuration eliminates coupling capacitors at the output, making design simpler and more cost effective. The MS6863 is packaged in a TSSOP20 package. The gain can also be set by an external resistor. There is no POP noise when shutting down. The typical application circuit is shown in Figure 5. Figure 5. Typical application circuit for noiseless shutdown of MS6863 Program description The design consists of an MS6335 audio DAC and an MS6863 power amplifier. It has two inputs for stereo digital and analog signals and three outputs for stereo Line-Out, speaker and headphone. Figure 6 is a demo board based on the schematic of Figure 1. The demo board switches the source and output and can be used as a volume control. Figure 6. The human voice switching demonstration board consisting of the MS6335 audio DAC and the MS6863 power amplifier. The design is controlled by infrared and MCU, the MCU maintains the Standby state, and the initial state of MS6335 and MS6863 is Power down mode. Stereo digital sources come from digital signal processors (MP3 decoders, set-top boxes) and are available in either I2S or Normal format. Stereo analog signals come from signals such as FM. The stereo output can be connected to a 32 ohm or 16 ohm headphone, which can directly drive an 8 ohm or 4 ohm stereo speaker; the Line-out has no drive capability and requires a post-amplifier with drive capability. Metro Pcb Board,Pcb Board Slot,Metro Pcb Motherboard,Game Machine Pcb Guangzhou Ruihong Electronic Technology CO.,Ltd , https://www.callegame.com
