A current sampling circuit

Abstract

The invention belongs to the technical field of integrated circuits, and in particular relates to a current sampling circuit. Including sampling and timing control module, uncompensated error amplifier EA module and output stage, the input terminal of sampling and timing control module is connected with inductor current I L , its two output terminals are respectively connected to the non-inverting input terminal and inverting input terminal of the error amplifier EA module without compensation; the input terminal of the output stage is connected to the output terminal of the error amplifier EA module without compensation, and its output terminal outputs the sampling current Isense. In the present invention, the error amplifier EA module without compensation does not need a compensation circuit while ensuring sufficient gain, so that the gain-bandwidth product GBW of the error amplifier EA can be increased to more than 10M; through the timing control network of the sampling and timing control module, the switching signal is suppressed. Glitch, thereby reducing the influence of the PMW signal and the LX point signal on the input terminal of the uncompensated error amplifier EA and the final sampling output current.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a current sampling circuit. Background technique [0002] Due to its high efficiency and high stability, the switching power supply has an irreplaceable role in the application field of electronic technology. The effective detection of the inductor current can not only realize the circuit loop control, but also play the role of overcurrent protection for the circuit. , so accurate and fast current detection is very critical. [0003] The traditional current sampling circuit structure such as figure 1 As shown, through a mirror tube M_mirror proportional to the size of the power tube M_power, the high-gain uncompensated error amplifier EA is used to clamp the drains of the power tube M_power and the mirror tube M_mirror, so that the current passing through the mirror tube M_mirror is proportional shrinking inductor current. [0004] However, this inducto...

AI Technical Summary

Problems solved by technology

[0004] However, this inductor current sampling circuit requires the error amplifier EA to have a high gain for sampling accuracy, and based on stability considerations, a compensation network is required, so that the gain-bandwidth product GBW of the error amplifier EA is relatively small, which reduces the current detection speed; Moreover, when the switching frequency of the switching power supply continues to increase, the glitch caused by the switching signal at the input of the error amplifier EA will have a serious impact on the obtained sampling current

Images