DC/DC circuit

Abstract

The invention discloses a DC / DC circuit, comprising a PWM controller, a current amplifier, a peak current comparator, an error amplifier, a main switch, a synchronous switch and also an operational amplifier. The non inverting input end of the operational amplifier is used for coupling with input voltage or voltage reference, or used for coupling with the input voltage and the voltage reference; the inverting input end of the operational amplifier is used for coupling with the voltage reference or ground, and the output end thereof is connected with the non inverting input end of the error amplifier. As a DC / DC basic structure is adopted, the operational amplifier leads the non inverting input end voltage of the error amplifier to follow the input voltage linearly, thus realizing the linear following relation between the output voltage and the input voltage. As the DC / DC basic structure is adopted, the circuit provided by the invention has the advantages of DC / DC to guarantee the high efficiency of the output of the voltage and great driving capacity.

Description

【Technical field】 [0001] The invention relates to a DC / DC circuit structure. 【Background technique】 [0002] There are mainly three types of voltage regulators in current portable power management IC products, namely: low-dropout linear regulators, non-isolated DC / DC converters and charge pumps. Among them, the low-dropout linear regulator can only be used for step-down. The advantages are small ripple, few peripheral components, and low cost, but it generates a lot of heat and low efficiency, especially in the case of large voltage drop and high current. Therefore, it is generally Applied to output current within 300mA, up to about 500mA. The DC / DC converter can realize step-up, step-down and buck-boost, and requires external magnetic components such as inductors. The application circuit is relatively complicated. Because it is a switch control mode, the ripple is large. The biggest advantage is high efficiency and can be adapted to Applications with high current requirem...

AI Technical Summary

Problems solved by technology

[0004] In order to realize the special application where the output voltage varies linearly with the input voltage, the following two schemes can be adopted considering the existing products in the market: 1. Use a charge pump to directly realize a certain step-up or step-down proportional relationship between the output voltage and the input voltage , but there are two defects in this scheme. One is that as mentioned above, it cannot provide a large current output (for example, more than 0.5A), and the other is that it is inconvenient to realize the output voltage V OUT with input voltage V IN Any proportional relationship, because the more special the ratio value, the more switch tubes are required inside the IC, especially in high current applications, which will result in a large switch tube area, and the charge pump is generally used as 1.5 times, 2 times or 3 times

2. Use a simple operational amplifier to realize V OUT with V IN A certain proportional relationship, but the driving capacity is limited, it cannot be used as a power supply device, and it can only realize step-down, and it is impossible to realize the step-up of the power supply

[0005] The DC / DC converter itself has the characteristics of high efficiency and high current, but the existing technology cannot make its output voltage and input voltage follow any linear relationship

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