Technology to extend the service life of lithium-ion batteries

TPS6300x is an ideal solution for converting lithium-ion battery voltage to 3.3V bus voltage. It has the characteristics of high efficiency, small circuit board area, low cost, and seamless conversion from buck mode to boost mode, making it an ideal choice to help design engineers complete high-performance and fast design. For portable power applications, to fully utilize the advantages of small size and high energy density of advanced battery technology, it is necessary to achieve efficient operation over the entire battery discharge voltage range.

The TPS6300x can also drive white LEDs in current regulation mode, which replaces the output voltage divider network with a resistor in the WLED loop. Since the typical forward voltage drop of WLEDs is 4.2 to 3.5V, it is problematic to power them with lithium-ion batteries in most power topologies because the power supply needs to buck and boost its output voltage at the same time. The buck-boost function of the TPS6300x solves this problem well and can easily provide 500mA of current for lighting or flash applications. TI's TPS63001 has the characteristics of minimum number of parts, small board area, low cost, and can efficiently convert the input voltage of lithium-ion batteries to a 3.3V bus voltage. In addition to the buck and boost functions, the switch FET, compensation and protection functions are integrated in a 3x3 mm QFN package. Only three external components are required to ensure operation: input and output capacitors and inductors. Its current is sufficient to power most portable loads.

The TPS6300x includes both buck and boost switching FET configurations connected to a single inductor. Unlike the standard buck-boost mode, which switches four FETs simultaneously and continuously, the TPS6300x uses a proprietary modulator design to switch only two of the FETs at a time. This control mechanism significantly reduces unnecessary switching losses. The TPS6300x operates more efficiently in buck or boost mode than in conventional buck-boost mode, further reducing power losses. When the Li-ion battery discharges to and below 3.3V, the buck-boost converter must switch from buck mode to boost mode. At this transition point, many buck-boost control mechanisms experience reduced efficiency, power supply jitter, or output voltage instability. The TPS6300x seamlessly transitions between buck and boost modes on a pulse-by-pulse basis as needed, providing constant PWM switching in both the buck and boost ranges without overlap or dead time between the two modes.

The TPS6300x also includes other integrated features that enhance the experience in portable applications, such as very low quiescent current, user-selectable power-save modes that maintain high efficiency at light loads, and external synchronization to help minimize system noise. The average current mode control topology provides fast transient response and low output ripple in both buck and boost modes. Short-circuit protection acts as a foldback current limit, and the maximum output current limit is reduced from 1.7A to 800mA when the output voltage drops by 3%. This reduces the device power consumption during output overload conditions. Normal operation resumes after the overload is removed. The advantage of this approach is that large output capacitors such as supercapacitors can be charged. The PS mode feature maintains very high efficiency even at light loads below 300mA. In PS mode, the switching time is only sufficient to ensure that the output voltage rises slightly above the output voltage set point, and then stops switching until the output voltage drops below the set point again. This "on-then-off" switching mode provides very high efficiency at light loads.