ANALOG DEVICES


Table 1. Charging Current with Step Charging and JEITA Cold


Too Cold (<0°C)


Step 2 Step 1 Step 0


No Charging No Charging No Charging


Room (0°C to 10°C)


0.19C 0.38C 0.75C


(10°C to 40°C)


0.25C 0.5C 1C


Table 2. Charging Voltage with Step Charging and JEITA Temperature


Too Cold (<0°C)


Step 2 Step 1 Step 0


No Charging No Charging No Charging


Table 3. Management of FET Logic PAREN 0 1 1 1 1


Cold (0°C to 10°C)


4.14V 4.1V


4.06V Room (10°C to 40°C) 4.2V


4.16V 4.12V


Warm (40°C to 45°C)


0.22C 0.44C 0.88C


Hot (45°C to 55°C)


0.15C 0.31C


0.625C


Too Hot (>55°C)


No Charging No Charging No Charging


Warm (40°C to 45°C)


4.18V 4.14V 4.1V


Hot (45°C to 55°C)


4.16V 4.12V 4.08V


Too Hot (>55°C)


No Charging No Charging No Charging


BLOCKDIS × 0 0 1 1


ALLOWCHGB × 0


1 (timeout) 0


1 (timeout)


CHG FET Normal Normal


Block Ready Normal


Block Ready


DIS FET Normal Normal Normal


Block Ready Normal


Conclusion


Moving charging and fuel gauge functionality from the host side to the battery pack allows individual control of each battery in a 1S2P configuration. Rather than requiring the host MCU to fully manage charging, a smart charger itself can manage its own output according to an optimal charging profile. Because management on the host side is limited to managing ALRT signals generated by the fuel gauge, systems can easily adapt to different battery packs.


A smart charger can also block charging and discharging when needed to prevent cross charging. This approach increases the flexibility of a typical fast charging system where battery mismatches are not considered. In addition to simplifying design and the overall charging process, OEMs can minimise power dissipation and ensure safe charging and discharging across a wide range of applications, all while improving the user experience with faster battery charging.


Analog Devices www.analog.com


Evaluating 1S2P Architectures Evaluating a simple charging system and testing its functionality can typically be done with an evaluation kit. These kits include all the necessary hardware and software applications, as well as graphical user interface (GUI)-based tools and APIs, to configure charging systems. However, complex systems that require multiple cells are correspondingly more complex to evaluate. Complex systems may have several devices that need to be characterised. Developers will need to write some software code to read the signals


Figure 8: To prevent cross charging, discharge on the higher voltage battery is blocked when the battery ΔV >400mV


generated from different system parts, analyse them, and take action. Consider a two Li+ cells in a parallel battery fast charging system using the MAX17330. As described in the data sheet, the MAX17330 can be used to charge and control two Li+ cells simultaneously. This system requires two MAX17330 ICs each managing one Li+ cell, and a buck converter (such as the MAX20743) with the capability to change its output voltage on-the-fly. A microcontroller is required to configure and manage battery charging as well as to handle communication between the two ICs.


JUNE 2023 | ELECTRONICS TODAY 19


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