likebattery  

For portable power applications, in order to take full advantage of advanced battery laptop battery technology, small size, the energy density advantages, they must discharge the entire battery voltage range to achieve high efficiency. This is required 3.3V lithium-ion battery-powered bus system as a design challenge. Although the standard buck converter in the 4.2 ~ 3.0V Li-ion batteries such as low output voltages down to 1.8V with high conversion efficiency when compared to the standard boost converter that will convert to lithium-ion battery such as a higher output voltage of 5V when they have a high conversion efficiency, but these two converters are commonly used 3.3V bus voltage is not generated the best solution. SEPIC and traditional buck can take advantage of full battery capacity, but with low efficiency, high cost, circuit boards and components for larger wait a few shortcomings. Using three kinds of configurations TPS6300x can solve these problems. TPS63000 adjustable output range is 1.2 ~ 5.5V. TPS63001 and TPS63002 fixed output voltages, respectively 3.3V and 5.0V. These products are available in a small 10-pin QFN (DRC) PA3331U-1BRS package.

TI TPS63001 has the least number of components, circuit board area is small, low cost and other characteristics, and can be highly efficient lithium-ion battery input voltage is converted to 3.3V bus voltage. A single 3x3-mm QFN package, in addition to integrated boost and buck two kinds of functions, including switching FET, compensation and protection functions. Only three external components can be guaranteed: the input and output capacitors and inductors. The peak efficiency of the converter is 96% (as shown in Figure 1), peak output current of 800mA, the current is sufficient for most portable load. A wide input voltage range (1.8 ~ 5.5V) able to cope with many of the common power supply, such as double or three alkaline batteries and NiMH batteries or 3.3V and 5V bus.

Figure: TPS63001 Efficiency Plan (voltage 1.8 ~ 5.5V, 320mA load (VOUT = 3.3V)).

Figure 2 for a single typical PA3098U-1BRS lithium-ion battery-powered 3.3V power supply. As the switching frequency of 1.5MHz, so you can use the small 2.2μH inductor and the 0603 volume of small ceramic input and output capacitors. Coupled with high efficiency, low external parts count of the overall solution size down to 6x6 mm (shown in Figure 3).

Figure 2: Typical Application Circuit.

Advanced Control topology to maximize efficiency

TPS6300x as shown in Figure 4 using the standard H-bridge buck-boost power stage, also includes the connection with a single inductor buck and boost switching FET configuration. TPS6300x proprietary modulator design, a time switch in which two FET, such a control mechanism significantly reduces unnecessary switching losses, with the standard buck-mode FET four different continuous simultaneous switching. TPS6300x the buck or boost mode buck than the traditional model of work more efficient, further reducing PA3084U-1BRS power loss.

Figure 3:6 x6 mm board space, the typical layout.

When the lithium-ion battery discharge to less than 3.3V, the buck-buck-mode converter to be changed from the boost mode. In the conversion point, many buck-control mechanisms will appear reduced efficiency, power supply jitter, or the output voltage unstable situation. TPS6300x may, if necessary buck and boost modes to seamlessly switch-by-pulse mode, which can be provided within the boost and buck constant PWM switching, but not between the two modes produce superimposed or dead time .

Figure 4: The power part of the chart.

Other Features

TPS6300x also includes other integrated features, easy to enhance the user experience in portable applications, such as very low quiescent current (less than 50μA), by the user to select the power-saving mode at light load conditions to maintain and highly efficient user-selectable PA3399U-1BRS power-saving ( PS) mode, and help to minimize system noise of the external synchronization.

Average current mode control topology can buck and boost modes to provide fast transient response and low output ripple. In the input and load range, the output voltage regulator tolerance of ± 1%. With internal compensation for the 10 to 22μF output capacitor external 2.2 ~ 4.7μH inductor is optimized.

Short circuit protection reverse current protection played a role, when the output voltage is reduced to 3%, the maximum output current limit from 1.7A down to 800mA. This reduces the output of the device under overload power. Overload can resume normal work after removal. Advantage of this approach is the ability to super-capacitors and other types of large output capacitor to charge.

PS mode even in less than 300mA even under light loads maintaining high efficiency. PS mode, the switching time can only guarantee the output voltage rise to slightly higher than the output voltage set point, then stops switching until the output voltage down to set point again below. This "first open and then off" switch mode high efficiency under light PA3395U-1BRS loads.

Other Applications

TPS6300x also in the current regulation mode to drive white LED (WLED), that is to replace the output WLED circuit using resistor divider networks. The typical forward voltage drop because of WLED is 4.2 ~ 3.5V, in the majority of power supply topologies using lithium-ion battery has a problem, because of its power supply will need to buck and boost output voltage. Function of the pressure rise and fall TPS6300x solves this problem, can easily blow torch or flash applications, providing PA3250U-1BRS 500mA current.

This summary

TPS6300x is the lithium-ion battery voltage is converted to 3.3V bus voltage is an ideal solution. That it is competent, high efficiency, circuit board size, low cost, buck and boost modes seamless conversion feature is to help design engineers to complete high-performance, rapid design of an ideal choice.