The secret of the longevity of the wireless earbud charging case is that it consumes only 1.6% of power per month

I believe everyone is familiar with Air Pods. The first generation of products was launched in 2016. Its exquisite shape and user-friendly experience are eye-catching. In March this year, its latest generation of products was launched, mainly updating the chip , which can speed up the connection time, support voice activation of Siri, and reduce game delay. The power consumption of the earphones has been reduced to a certain extent, and the usage time is 5 hours, but the talk time has increased to 3 hours, which is 50% higher than the first generation. The charging case can also choose a wireless charging style.

Due to the extremely small size of wireless earbuds, only very small lithium-ion batteries can be placed inside the earbuds, and the capacity of such batteries is usually less than 50mAH. In addition, the strict size requirements make it impossible to integrate the traditional micro-USB charging port inside the wireless earbuds. Instead, two simple metal plates are used as the input interface for earbud charging.

Due to the limited battery capacity of earphones, most manufacturers will provide a dedicated charging box as standard to extend the use time of earbuds. Due to the size limitation, the capacity of the charging box is generally within 1000mAH, which can support charging two 50mAH wireless earbuds for more than 5 times.

The yellow frame is the TI 87A6FP chip (picture from iFixit)

The new wireless earbuds are charged by the battery in their carrying case, a unique design that requires small-size solutions and efficient components. In addition, as market demand increases, businesses will be more motivated to launch products with the same functions but lower prices. TI has a complete ultra-low power reference design TIDA-050007 to meet the above needs. The design includes a charging case battery and boost converter powered by USB input.

More products with the same functions but lower prices are already on the market

The reference design provides a complete power solution from the charging box to the earbuds. TIDA-050007 includes two innovative designs to extend the use time of the charging box while reducing the PCB board size of the charging box and earbuds.

System Block Diagram of the TIDA-050007 Reference Design

First of all, the overall standby power consumption is only 18µA, which is lower than the static power consumption of almost all single chips on the market (such as charging chips, boost chips, and LDO).

This is due to the fact that this reference design uses TI's industry-leading ultra-low power MSP430 MCU (<1µA quiescent current), charging chip BQ25100A (75nA quiescent current), boost chip TPS61099 (800nA quiescent current) and LDOTPS7A05 (1µA quiescent current).

PCB photo of TIDA-050007

Such low standby power consumption can make the static consumption of the charging box less than 1.6% of the battery capacity per month (taking 800mAH battery capacity as an example). Most charging boxes on the market have static consumption of more than 10%. If this type of charging box is not used or forgotten for half a year, the internal lithium battery is basically permanently damaged. The charging box based on the TIDA-050007 reference design can effectively protect the battery because this static loss is even lower than the self-discharge loss of some lithium batteries.

TIDA-050007 Reference Design Features

• 18µA ultra-low standby current

• The charging box can provide up to 1.5A fast charging current

• Supports pass-through mode when input is higher than output.

• Charging efficiency exceeds 85%

• Small size solution

• Supports earbud charging current down to 1mA

In summary, TIDA-050007 greatly extends the charging times of the charging box and is extremely suitable for portable audio/medical devices . Don't hesitate, download the design document now and start designing your own charging box!

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