Switch charging control circuit

Abstract

The invention discloses a switch charging control circuit, belonging to the switch charging control circuit. The switch charging control circuit comprises a peak value current detection circuit which is used for detecting the peak value charging current flowing through a switch tube, a charging current setting resistor, a comparator which is used for generating an output switching off signal to switch off the switch tube, a fixed switching off time generation circuit which is used for outputting a conduction signal to conduct the switch tube after fixed switching off time of each cycle, an output driving circuit which is used for driving the switch and synchronously rectifying and a battery fully charging determination circuit which is used for outputting a switching off signal to switch off the output after the battery is fully charged. The switch charging control circuit disclosed by the invention works according to the modes, does not need the complicated error amplification device, the oscillator and the gradient compensating circuit, greatly reduces the difficulty and design cost of the control circuit, eliminates the power resistor and increases the charging power while reducing the system cost.

Description

technical field [0001] The invention belongs to the technical field of switch charging control circuits, in particular to a switch charging control circuit. Background technique [0002] With the popularity of portable devices and the increase in power consumption, in order to prolong the standby and use time of the device, the battery equipped with the device is also getting larger and larger, and with the increasing popularity of large-capacity mobile power supplies, these require a larger Charge the device with a high charging current to speed up the charging speed and reduce the charging time, which promotes the increasing popularity of the switch charging method. [0003] figure 1 It is a schematic diagram of a traditional switch charging control circuit. The charging current is set by the resistor RS1. RS1 is on the path of the charging current, which will generate a large resistance loss, so RS1 needs a high-cost power resistor, which will not only reduce the system....

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Problems solved by technology

[0003] figure 1 It is a schematic diagram of a traditional switch charging control circuit. The charging current is set by the resistor RS1. RS1 is on the path of the charging current, which will generate a large resistance loss, so RS1 needs a high-cost power resistor, which will not only reduce the system. Working efficiency , and increase the system cost; at the same time, because the traditional switching charging control circuit works in a fixed-frequency PWM mode, the control circuit needs an error amplifier, an oscillator, and a slope compensation circuit, which not only increases the difficulty of design but also increases the complexity of the control circuit. design cost

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