Fast-charging continues to be a hot topic with consumers and engineers alike. With smartphones running more and more applications, the power needed for the application processor is increasing. Standard battery capacity has already doubled in the past two to three years, but batteries still take a long time to charge using traditional limited ~10W input power – too long for users who don’t have time to wait. Increasing the input power and optimizing high-voltage charging thus becomes attractive.
TI’s MaxCharge technology allows fast charging by increasing adapter output power and delivering that power to the battery with the highest efficiency possible to reduce charging time. The Fully Charged blog post, “MaxCharge technology ‒ faster charge with more mobility” describes the details of this faster, cooler and safer charging technology.
The bq25892 is the industry’s first 5A fast charger with MaxCharge technology. It is a highly integrated switch-mode battery charger with a system power path management integrated circuit (IC), designed for single-cell lithium-ion (Li-Ion) and Li-polymer batteries in a wide range of smartphones and other portable devices with universal serial bus (USB) or high-voltage adapters. The bq25890 and bq25895 have built-in algorithms to communicate with adapters in order to activate high-input voltage charging.
When designers start looking into implementing this type of technology, reference designs bridge the gap for getting designs to market faster. TI Design “1S 5A fast charger with MaxCharge technology for high-input voltage and adjustable USB OTG boost” was designed just for this purpose (Figure 1).
Figure 1: TI Design (TIDA-00538) evaluation board
The reference design package enables customers to quickly have access to the bq25892 evaluation module (EVM) schematic, layout (Figure 2), Gerber file, bill of materials (BOM), test data and reports, as well as software tools. It is also linked to other TI components that have been used to make the entire design easy to use and robust.
Figure 2: TI Design (TIDA-00538) evaluation board layout
There are two ways to implement MaxCharge technology, as shown in Figure 3. One method is to use a host processor to communicate with the AC adapter to complete the MaxCharge protocol handshake process and then control the MaxCharge device to handle the high-input voltage from the adapter. The other method is autonomous: The MaxCharge device completes the handshake process with the adapter directly and activates fast charging.
Figure 3: MaxCharge system diagram
Designers can use the TI Designs reference tool discussed above to create fast-charging designs with MaxCharge technology and achieve the highest efficiency and most flexible implementation.
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