Application Skills of High Efficiency Boost Converter

The development of power circuits for portable electronic devices requires design engineers to extend battery life by maximizing power and reducing the power consumption of the entire system. This promotes the size of the device itself to become smaller, which is beneficial to the design of end products. High flexibility. One of the most important components of this design is the power management IC or DC/DC converter.

High-efficiency DC/DC converters are the foundation of all portable designs. Many portable electronic applications are designed to work with a single AA or AAA battery, which poses a challenge to the power supply design engineer. A constant 3.3V system output is generated from an input voltage of 850mV～1.5V. The synchronous boost DC/DC converter is required to work at a fixed switching frequency, with an on-chip compensation circuit, and requires miniature low-height inductors and ceramic capacitors. It is best to use a miniature IC package to reduce its total footprint in the device design.

A proven circuit design consisting of a thin SOT IC package and a small number of external components has realized a single cell to 3.3V/150mA converter with a 90% efficiency of only 7×9mm2 board area. When working under a single battery input (1.5V), a load current between 25mA and 80mA may achieve an efficiency of more than 90%. An external low-current Schottky diode (although not required) will maximize efficiency at higher output currents.

This circuit design integrates a high-efficiency DC/DC converter with a low gate electrode voltage internal switch with a rated resistance value of 0.35Ω(N) and a typical resistance value of 0.45Ω(P). In the entire operating temperature range, the switch current limit is generally 850mA, so that the output power of 0.66W and 2.5W can be achieved respectively when the new alkaline AA single-cell battery and two-cell battery are input.

Current mode control provides excellent input line and output load transient response. Slope compensation (which is necessary to prevent crossover harmonic instability when the duty cycle exceeds 50%) can be integrated into the converter to maintain the constant current limit threshold along with the circuit, regardless of the input voltage.

Main features

Two characteristics of advanced power management IC design will affect its efficiency: the integration of internal feedback mechanisms and the addition of power saving modes that can save energy during operation. The increased internal feedback loop compensation no longer requires external components, thereby reducing the total cost and simplifying the design process. By activating the power converter only when needed to keep the output voltage modulation within 1%, the power saving mode of operation improves the converter efficiency at light loads (ILOAD