Today, MPS Xiaobian is here to discuss a key power management strategy found in charging ICs: dynamic path management. This technique plays a crucial role in optimizing the performance of rechargeable devices by intelligently managing power flow between the input source, battery, and system load. Dynamic path management works by continuously monitoring the input power supply's capabilities and the current demand of the system. Based on this information, it dynamically adjusts the charging current to ensure that the device charges as quickly as possible while still maintaining stable system operation. This not only reduces charging time but also ensures that the system remains powered even under varying load conditions. One of the main benefits of this strategy is that it allows the system to start up immediately once an external power source is connected, even if the battery is deeply discharged. This is especially important in portable devices where users expect instant responsiveness upon plugging in the charger. In modern mobile devices, the charging IC serves as the central component responsible for managing power distribution. Depending on the configuration, the system can be powered either by the battery, the external power source, or both simultaneously. The charging IC must therefore have advanced power management features to handle these scenarios seamlessly. A common implementation of dynamic path management is the Narrow Voltage DC (NVDC) approach. As shown in Figure 1, the system load is directly connected to the system bus (VSYS). Power can come from either the battery through the Battery FET or from the input power via a front-end DC/DC converter. Figure 1 When no external power is connected, the Battery FET is fully turned on, allowing the battery to directly power the system. Once an input power source is detected, the system bus voltage is regulated by the DC/DC converter, and the battery is charged through the same FET. However, the system load always takes priority, so the charging IC will first allocate power to the system before using any remaining energy to charge the battery. Figure 2 During the charging process, if the total system load exceeds the capacity of the input power, the system voltage may drop. In such cases, the charging IC will reduce the charging current to prevent further voltage sag and maintain stable system operation. This helps avoid unexpected shutdowns and keeps the device running smoothly. If the input power is still insufficient after the charging current is reduced to zero, the system voltage may continue to drop until it falls below the battery voltage. At this point, the battery will take over and supply power to the system through the Battery FET, entering what is known as the battery replenishment mode. In this mode, both the input power and the battery contribute to powering the system, ensuring uninterrupted operation. Figure 3 When the battery is over-discharged and an external power source is connected, the charging IC will adjust the system bus voltage to the minimum acceptable level. If the system voltage drops below a certain threshold, the charging current will be reduced to protect the battery from excessive discharge. Additionally, when the battery is in a reverse discharge state, the IC controls the Battery FET to operate in the saturation region, preventing large inrush currents from damaging the battery. This smooth transition into and out of battery supplementation is often referred to as the ideal diode mode for FETs. Figure 4 In the ideal diode mode, the Battery FET behaves similarly to a diode due to its operation in the saturation region. When the system voltage is slightly lower than the battery voltage (e.g., 40mV), the charging IC adjusts the gate voltage of the Battery FET to maintain a specific voltage difference (e.g., 20mV, similar to a diode’s forward voltage drop). As the battery discharges more, the gate voltage increases, reducing the FET’s impedance to keep the voltage difference at the desired level. Conversely, if the discharge current decreases, the gate voltage is lowered to increase the FET’s impedance and maintain the design voltage difference. In summary, dynamic path management is a complex yet highly effective power management strategy. It offers several advantages: First, it enables the system to power up instantly when an external power source is connected, regardless of the battery’s state. Second, it allows flexible adjustment of the charging current, ensuring that the system’s power needs are always prioritized. Electric Cold Shrink Tubing Electric cold shrink tubing,Cold Shrink Tube,Cold Shrinkable tubing,Cold-shrink tube Mianyang Dongyao New Material Co. , https://www.mydyxc.com
