Charging and data on a two-wire bus for portables


The interface, branded Pow:Com, supplies 5V at up to 150mA for charging and data at 1kbit/s.

AS3442 is aimed at the charger cradle (WL-CSP16 package). It includes:

  • Pow:Com interface to AS3447
  • I2C slave interface to communicate with host MCU
  • interrupt output to host MCU

AS3447 goes in the item to be charged (WL-CSP36 package). It includes:

  • Pow:Com interface to AS3442
  • I2C master interface to communicate with local sensors.
  • Five GPIOs
  • An interrupt input

Through its I2C interface, the host MCU in the charger can read and write the GPIOs at the earbud end, and an interrupt generated at the earbud end is transferred to the output pin at the charger end – as far as Electronics Weekly can determine as data sheets do not appear to be available yet and all the information here has been gleaned from a document sent to Electronics Weekly and what little is available on the AMS website.

“The MCU inside the charger cradle can request data from the earphone while the charging process is on-going and vice versa,” said AMS. “An interrupt signal line is available to detect status changes on GPIOs or if communication is interrupted. For instance, the earbud can request the battery information from the charger cradle and display it on a mobile app.”

The chips are available now in production volumes, or so AMS told Electronics Weekly, although the AMS website today indicates pre-production status for both the AS3447 and AS3442 and no stock of either.

An evaluation board is available, according to the firm, although there does not appear to be any mention of this on the website.

Functions such as auto-recharge, firmware update and automatic phone-earbud pairing are foreseen.

According to the AMS, it has won design-ins, in end-user products that will be on the shelves before Christmas.

Electronics Weekly has requested data sheets for the chips and the eval board.