Description

The High Efficiency Portable Media Player (PMP) Docking Station reference design showcases Texas Instruments' PowerWise® power converters: battery charging circuitry: audio drivers and display interface. The reference design saves more power by initiating a power-saving mode when the PMP is unplugged from the wall power: automatically reducing the maximum brightness of the display as well as the output power of the audio drivers. See Figure 1 which shows the power management and audio segments of the reference design.The LM3658SD-A dual source: USB/AC Li chemistry charger IC receives a wall wart or USB input and converts either input into a source voltage: using the LM20124 synchronous buck regulator: powers the docking station as well as providing the charging current to an external Lithium-Ion back-up battery pack.The LM20124 provides the source voltage which biases both the audio and DS90UR241/124 serializer/deserializer (SERDES) segments of the video transport sections of the system. The LM4674 stereo Class D audio amplifier drives two 2W speakers. The LM2735Y Boost and SEPIC DC-DC Regulator boosts the 3.3VDC output to 5VDC: which supplies the bias voltage needed to charge the PMP device when docked in the docking station connector. Additionally: the wall wart also feeds an LM3478 Low-Side N-Channel Controller which boosts the voltage to 12VDC and provides power to the AVP-1280 video interface controller. The AVP-1280 converts the analog video output signal from the docking station into digital inputs for processing by the DS90UR241 serializer segment. Finally: the output of the DS90UR124 deserializer is taken and displayed by the Sharp LQ104S1DG21 TFT-LCD display: which is illuminated by an LED backlight with dimming capability.