MAX865 High-efficiency Charge Pump Converts 5V to 3.3V

In portable products, LDO is often used to convert the 5V main power supply to 3.3V. LDO has the characteristics of low cost, small size, low quiescent current and easy implementation, but its conversion efficiency is very low, generally 67% in this application. An alternative solution is to use a step-down switching regulator, the conversion efficiency can reach 90% typical, but it requires an external inductor, occupies a large circuit board size, and is relatively expensive. Another solution is to use a charge pump, which makes up for the shortcomings of LDO and switching power supply, and has the characteristics of low cost, small size, easy implementation, and high conversion efficiency. Usually, the charge pump circuit can provide +2VIN, +1VIN, -1VIN, but when converting +5V to 3.3V, the output-to-input voltage ratio is 2/3, and this result can be achieved by combining charge pump circuits with outputs of 2VIN and -1VIN respectively. MAX865 is a dual charge pump chip. By grounding its V-, 2/3VIN can be obtained from the GND terminal. The conversion efficiency is as high as 95%, the typical quiescent current is 37μA, and the output load current is 0.1mA to 5mA. Since the structure adopts a fixed output/input ratio of 2/3, the input voltage must be a stable 5V. In addition, 4/3VIN output can be obtained from the V+ terminal.

[Attachment: MAX865 high-efficiency charge pump converts 5V voltage to 3.3V]