Method and device for detecting abnormal current of circuit

Abstract

The invention discloses a method and a device for detecting an abnormal current of a circuit. The method comprises the following steps of: locating a specific position with abnormal current consumption by detecting an input current of an electronic product; adjusting the voltage of a precise power supply of the electronic product, observing the change situation of the current consumed by the product along with the input voltage, and quickly distinguishing that the abnormal current occurs in an LDO (Low Drop Output) circuit, a DC-DC switch power supply circuit or a direct battery-powered circuit. Furthermore, for a complex multipath LDO circuit, the current consumption on each path of the LDO circuit can be measured by an external power supply forced substitution method. The invention can simplify detection operations, shorten the detection time, reduce the analysis difficulty and increase the efficiency of detecting abnormal current in circuits and the detection success rate.

Description

technical field [0001] The invention relates to detection technology, in particular to a method and device for detecting abnormal current of a circuit. Background technique [0002] With the development of modern technology, portable electronic products such as mobile phones, MP3, game consoles, notebook computers, digital video recorders, digital video discs (DVD), set-top boxes (STB), portable instruments and multimedia personal assistants (PDA) are moving towards energy-saving and high-efficiency. , short, thin, and multifunctional, its structure is becoming more and more complex. Moreover, the circuits of portable electronic products are generally packaged in chips. In this way, when an abnormal current occurs in the circuit of the electronic product, it is very inconvenient to detect, analyze and determine the circuit where the abnormal current occurs, and the operation is complicated and cumbersome, and the detection efficiency is low. . [0003] Taking the QSC6055 c...

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Problems solved by technology

However, in practical applications, since the signal lines mostly run on the inner layer of the PCB, for example, in order to reduce interference to other circuits and prevent external circuits from interfering with their own circuits, the wiring of the power line passes through the inner layer of the PCB. There is almost no exposed wiring. When using the method of cutting PCB wiring to detect leakage current, it is necessary to cut several layers of PVB plates, and the wiring on the PCB is dense, and the general spacing does not exceed 0.1mm, which makes the operation complicated and takes a long time. The success rate Another detection method is to use the characteristics of the LDO circuit power supply filtered by the filter capacitor outside the chip and then provide it to the chip for internal use of the chip, and add a zero-ohm resistor for debugging to each circuit path to detect leakage current, but due to actual The output filter capacitor of the designed LDO circuit is as close as possible to the output PIN pin of the LDO circuit to reduce the parasitic inductance of the wiring; and connecting a zero-ohm resistor in series will make the wiring longer and increase the parasitic inductance; at the same time, the zero-ohm The resistor itself also has an internal resistance of about 50 milliohms, which increases the output impedance of the LDO circuit power supply, and also has the problems of complicated and cumbersome detection operations and low detection efficiency; in addition, there are as many as 10 to 20 Adding a zero-ohm resistor to each LDO circuit will also increase the placement area and BOM cost of the corresponding devices on the mobile phone motherboard with limited space

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