Charger 8 Click is an intelligent Li-Ion battery charger, system power manager, and a battery fuel gauge Click board™. As a system power distributor, it can supply up to 2A to a connected load. By utilizing an externally connected power supply, it can charge a single-cell Li-Po/Li-Ion battery. A dedicated power management IC with the optimized smart power control allows very efficient management of the available power. An additional battery fuel gauge IC with proprietary battery aging prediction algorithm and time-to-empty / time-to-full estimation, offers the complete diagnostic related to the battery charging process.

Charger 8 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

Equipped with the intelligent power management and battery fuel gauge ICs, this Click board™ is the complete power solution for many embedded and consumer applications that rely on the efficient power ORing and an advanced battery charging functionality. Charger 8 Click can be used as a part of the power supply and distribution system in many applications: different kinds of handheld appliances, portable media players, portable audio players, and other general-purpose battery-operated electronic devices.

Charger 8 Click is based on two different ICs: It uses the MAX8903B, an integrated single cell Li-Ion/Li-Po battery charger for USB and external power, as well as the MAX17201, a stand-alone battery fuel gauge with SHA-256 authentication, both ICs from Analog Devices.

The MAX8903B is labeled as U1, and it provides the majority of functions for this Click board™. Its basic task is to provide power for the system load and charge a single-cell Li-Ion/Li-Po battery, connected at the standard 2.5mm pitch XS battery connector, labeled as BAT. When the USB input is used as a primary power source, the MAX8903B will try to maintain the system current by utilizing the connected battery or the external power supply unit (PSU) at the VIN input. On the other hand, it will try to redirect all the unused power to the battery charging section in cases when the system requires lower current levels. With the help of the Smart Power Selector™ technology, it will always choose the best path in order to utilize the limited power resources in the most efficient way.

The MAX8903B IC is designed with reliability in mind: the IC prevents draining the battery below the critical level, protects it from overheating (if thermistor is used), offers prequel charging (for deeply depleted batteries), features an overvoltage protection, charging status monitoring and so on. The Click board™ itself is equipped with a set of indicators used to monitor both charging process and power distribution.

• USB LED indicates that there is a valid voltage at the USB input. Instead to the USB connector, the USB power supply input pin of the MAX8903B is connected to the mikroBUS™ 5V power rail.
• CHARGE LED indicates the charge-in-progress status.
• FAULT LED indicates an error during charging process.

Besides the FAULT LED indicator, the FAULT pin of the MAX8903B is also routed to the mikroBUS™ INT pin, allowing an interrupt to be generated on the host MCU in case of a charging failure. This pin will be pulled to a LOW logic level when the charging timer expires while the charger is still in prequel mode (mode in which only 10% of charging current is applied to the battery, while it is deeply discharged), or while the battery stays in fast-charging mode.

DOK pin is routed to the mikroBUS™ AN pin, labeled as DOK. A logic LOW level on this pin indicates that there is a valid power supply at the DC power supply input pin of the MAX8903B. If there is a PSU connected to the VIN terminal, its voltage should stay within the valid range. The undervoltage/overvoltage protection will be activated if the internal voltage threshold is exceeded. The absolute maximum voltage rating of the MAX8903B is 20V.

USB Suspend (USUS) pin from the MAX8903B is routed to the mikroBUS™ PWM pin, and it is labeled as US. It is used to suspend the power source connected to the USB power supply input pin. With no external PSU connected, setting this pin to a HIGH logic level will disable the battery charger and the SYS output, allowing the USB SUSPEND mode.

The CEN pin is used to disable the charging circuitry. It is pulled to a LOW logic level by a resistor, and the MAX8903B should be controlling this pin internally for optimum performance. However, if battery charging is not wanted, it can be forced off by pulling this pin to a HIGH logic level. It is routed to the mikroBUS™ pin CS and labeled as EN.

The MAX17201 IC offers a battery gauge functionality, allowing to monitor the performance of the connected battery. It employs a proprietary ModelGauge™ m5 algorithm, which allows very accurate monitoring of all battery parameter, including the predicted aging time, remaining cycles and so on. It has a programmable ALERT function which is signaled over the ALTR1 pin, routed to the mikroBUS™ RST pin, labeled as ALT. The MAX17201 IC uses the I2C interface to communicate with the host MCU.

• Interface: GPIO, I²C
• Compatibility: mikroBUS™
• Dimensions: 42.9 x 25.4mm
• Input Voltage: 3.3V, 5V
• Input Voltage (at VIN terminal): Min. 4.6V, Typ. 5V, Max. 16V
• System output voltage (at VOUT terminal): Min. 4.265V, Max. 4.395V
• Charging Current (max current selectable by IOUT SEL): Min. 0.5A, Max. 1 (2)A

• Schematic
• MAX172xx Datasheet
• MAX8903A Datasheet
• mikroSDK
• GitHub