The main purpose of this article is to help design engineers in selecting the right battery management and charging IC and completing their proof of concept (PoC) phase. The resources provided include schematics, bill of material (BOM), design files, GUI interface software, etc
The lithium-ion (Li-ion) cell is one of the most common energy sources in today’s battery-driven world. Li-ion cells have good energy density and can be recharged. But they are very volatile and thus require specialised chargers to keep the battery and device safe.
The main purpose of this article is to help design engineers in selecting the right battery management and charging IC and completing their proof of concept (PoC) phase. The resources provided include schematics, bill of material (BOM), design files, GUI interface software, etc.
All the reference designs in the article can be used as independent cell chargers. Some of the designs are small enough to be integrated into a product as a sub-system for charging an in-built battery.
In this article, we will discuss the essential parameters of each of the Li-ion chargers. Table 1 lists the important parameters of all the charging reference designs.
|What is a Reference Design?
Wikipedia defines a reference design as a technical blueprint of a system that is intended for others to copy. The main purpose of the reference design is to support companies in the development of next-generation products using the latest technologies. The reference product is proof of the platform concept and is usually targeted for specific applications. It enables a fast track to market, thereby cutting costs and reducing risk in the customer’s integration project.
TIDA-00590 for fast charging with low thermal budget
The TI TIDA-00590 is a fast charger reference design module from Texas Instruments. It is capable of fast charging a single Li-ion cell with 5A charge current with low thermal budget. The circuit design has been tested by TI and uses the EVM GUI and getting started guide.
TIDA 00590 utilises two charging ICs marked as U1 and U2 in a dual IC configuration, which provides more than their 5A maximum charge current and distributes the heat loss across the board more efficiently. The charging IC bq25890/2 is a highly integrated 5A switch-mode battery charge management and system power path management device for single-cell Li-ion and Li-polymer batteries.
To achieve higher efficiency, the module offers a low impedance power path, which also reduces battery charging time while extending the battery life during discharging phase. The IC also integrates input current optimiser (ICO) and resistance compensation (IRCOMP) to deliver maximum charging power to the battery.
The module is over 90% efficient with a maximum efficiency of about 94%. The efficiency of the charger decreases as the charge current is increased.
This device supports various input sources, which include a standard USB host port, USB charging port, and USB compliant adjustable high voltage adaptor. Furthermore, it uses MaxCharge handshake using D+/D– pins and DSEL pin for USB switch control.
The device is compliant with USB 2.0 and USB 3.0 power specs with input current and voltage regulation. The charger features multiple safety features, including battery temperature negative thermistor monitoring, charging safety timer, overvoltage/overcurrent protections, undervoltage protection, and over-discharge protection.
The charger also employs a TS3USB221A, which is a high-bandwidth switch that requires a 3.3V supply. Since there are two charging ICs with a single USB I/O for the charger, both the power management ICs need to work in sync and need to transfer data simultaneously. Therefore, there’s a need for a USB hub or controllers.
The TS3USB221A solution can effectively expand the limited USB I/O by switching between multiple USB buses to interface them to a single USB hub or controller. The switch works as a multiplexer; it takes a single USB input and gives output to both the bq25890/2 charging ICs. To provide a 3.3V output to the TS3USB221A, an LDO LP2985AIM5-3.3/NOPB is used.