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Low power design - USB Bus powered Tuner based MPEG2 encoder



The client is a major supplier of PC based tuner products. The client required a low power USB based MPEG2 tuner. The hardware should be capable of encoding a cable TV video input in to MPEG2 and then send the same to USB. The hardware shall be bus powered.


The client was not ready to go for self powered USB and was interested only in bus powered USB. Also there was a need to optimize between video quality of the tuner with the power available and surge current of USB.


The following approach was taken to implement
  • Reduced usage of capacitors particularly decaps.
  • Selection of low power consumption components was critical. Every component was selected to operate at low power. For eg. the SDRAM, the buffers, flash and finally the processor all operate at 1.8V.
  • Choosing the processor was a tough one. An ARM processor with a USB high speed client was chosen, since it can operate at 150mA at 1.8V.
  • Initially client was favouring a MPEG4 but since e-con systems has already ported MPEG2 on to this processor successfully, MPEG2 was the chosen codec.
  • e-con systems developed the USB isochronous driver for Video streaming and a direct show filter and a single D1 frame was displayed on the PC display.