SLYT842 june   2023 BQ25180 , BQ25620

 

  1.   1
  2. 1Introduction
  3. 2Maximizing shelf life
  4. 3Performing a watchdog reset
  5. 4Employing the full battery capacity
  6. 5Minimizing battery fatigue
  7. 6TI power path battery chargers
  8. 7Conclusion
  9. 8Related Websites

1 Introduction

With so many options for batteries and differing system requirements, it can be challenging to design the best battery charging integrated circuit (IC) to maximize battery lifetime and enable optimum system performance. The decision to choose a power path or non-power path battery charger can have a big impact on the functionality of your charging IC.

Figure 1 shows non-power path devices have one path for charging, in which the system and battery connect to the same node. This makes non-power path charging an effective option when you do not need to use the system and charge the battery at the same time, since you cannot control how much current is devoted to powering the system vs. charging the battery. Applications such as shavers or electric bikes are a good fit for non-power path chargers.

GUID-20230621-SS0I-XXPD-XGSC-01MGM4XSDGWZ-low.svg Figure 1 Non-power path and power path block diagrams.

Power path charging is a better option for products when both charging and use can occur simultaneously, since the integrated Q2 metal-oxide semiconductor field-effect transistor (MOSFET) in the battery allows you to customize the amount of current devoted to powering the system vs. charging the battery. This customization is also useful when a battery is deeply discharged. Because deeply discharged batteries are often charged with small currents, a power path device can independently regulate the system and battery current from the adapter to provide small current into the battery, ensuring that the system is still getting the required power to turn on.

When there is high demand for system current while charging the battery, the Q2 MOSFET can also turn on to combine power from the input and the battery to support the system load. This feature is known as supplement mode, where the device will pull current from the battery to supplement the current from the input in case the system is pulling more current than what the input can provide. A typical application that would benefit from power path charger features would be a smartphone.

The following sections show how power path topology improves system performance and battery life.