High-precision low-side current limiting circuit
A technology for limiting circuit and terminal current, which is applied in the field of high-precision low-end current limiting circuit, can solve the problems of complex structure, low precision, high power consumption, etc., and achieve the effect of simplifying the circuit, reducing the chip area and avoiding power consumption
Inactive Publication Date: 2013-05-22
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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[0004] The present invention proposes a high-precision low-end current limiting circuit for the problems of excessive power consumption and low precision caused by the introduction of detection resistors in the current limiting circuit, or the complex structure caused by copying the current through mirroring.
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[0016] The present invention will be further elaborated below in conjunction with the accompanying drawings and specific embodiments.
[0017] A precision low-side current limit circuit, such as figure 1 As shown, it includes an NMOS transistor M1, two NLDMOS transistors NLD1 and NLD2, a synchronous rectifier POWER MOSFET, two constant current sources I1 and I2, and a comparator A1, where:
[0018] The drain and the gate of the NMOS transistor M1 are connected to the inverting input terminal of the comparator A1, and the source and the substrate are coupled to the ground point;
[0019] The drain of the first NLDMOS transistor NLD1 is connected to the positive input terminal of the comparator A1, the gate is used to receive the input signal LS_D, and the source and the substrate are coupled to the ground point;
[0020] The drain of the second NLDMOS transistor NLD2 is connected to the external node SW, the gate is used to receive the input signal LS_D, the source and the sub...
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The invention relates to a high-precision low-side current limiting circuit and belongs to the technical field of integrated circuits. The high-precision low-side current limiting circuit comprises an NMOS (N-channel metal oxide semiconductor) transistor M1, two NLD MOS (N-channel lateral double-diffused metal oxide semiconductor) transistors NLD1 and NLD2, a synchronous rectifier tube POWER MOSFET (power metal oxide semiconductor field-effect transistor), two constant current sources I1 and I2, and a comparator A1. Whether current of a third NLDMOS transistor exceeds a designed limit or not is determined by comparing voltage at positive and negative input ends of the comparator, intensity of input signals is controlled, and accordingly current limiting function of the circuit is realized. Devices in the circuit are few, so that chip area is reduced effectively. No extra resistor is added, the devices can be subjected to chip-on integration, and accordingly system integrity is improved. In addition, the circuit is insusceptible to external factors such as temperature and process, so that the high-precision low-side current limiting circuit is capable of limiting current of the synchronous rectifier tube precisely to allow the system precision to be higher, and is widely applicable to analog or digital-analog hybrid integrated circuits.
Description
technical field [0001] The invention belongs to the technical field of integrated circuits, and in particular relates to a high-precision low-end current limiting circuit. Background technique [0002] With the development of switching power supplies in the direction of high efficiency and low power consumption, many technologies have emerged to improve the conversion efficiency of converters. Among them, synchronous rectification technology uses power MOSFETs with low on-resistance to replace rectifier diodes, which greatly improves the conversion efficiency of converters. efficiency, but this technology brings new problems: under light load conditions, if the current of the synchronous rectifier is not limited, there will be current flowing from the drain of the synchronous rectifier to the ground, and a negative inductor current will appear. This will not only lead to excessive inductor current ripple, resulting in power loss; but also will generate a current flowing to t...
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IPC IPC(8): H02M1/32
Inventor 周泽坤程洁代高强石跃明鑫王卓张波
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA