A detection circuit and method for full-inductance current waveform

Abstract

The invention discloses a detection circuit for a whole inductive current waveform and a method for detecting the whole inductive current waveform. The detecting circuit comprises a high side switch, a low side switch, an internet service provider (ISP) module, an information system network (ISN) module and a sampling resistance. The high side switch and the low side switch are connected between the input voltage and the ground in series. The end, connected with the low side switch in series, of the high side switch is used for connecting an inductance. A control end of the high side switch is used for connecting high side switch control signals. A control end of the low side switch is used for connecting low side switch control signals. Three ends of the ISP module are respectively connected with three ends of the high side switch. The fourth end of the ISP module is connected with one end of the sampling resistance. Three ends of the ISN module are respectively connected with three ends of the low side switch. The fourth end of the ISN module is connected with one end of the sampling resistance. The other end of the sampling resistance is connected with the ground. According to the detection circuit and the method, the whole inductive current waveform detection sampling can be achieved without utilizing a resistance or a transformer, a detection unit is integrated into the interior of a chip, and therefore circuit cost and design difficulty of terminal users are reduced.

Description

technical field [0001] The invention belongs to the field of current detection, and more specifically relates to a detection circuit and method for a full-inductance current waveform. Background technique [0002] The average current mode (average current mode) is a control method of switching power supplies (swith mode power supplies), which achieves the purpose of constant output current or voltage by controlling the average value of the inductor current. In order to obtain the average value of the inductor current, it is necessary to detect the full inductor current waveform, figure 1 shows a typical inductor current waveform; figure 2 It is a schematic diagram of a step-down (buck) switching power supply circuit. Using a resistor in series with an inductor, the full inductor current waveform signal is obtained by detecting the voltage at both ends of the resistor, and the PWM signal for controlling the switch is obtained after being processed by the control circuit (in...

AI Technical Summary

Problems solved by technology

Obviously, the method of using the sampling resistor will consume a certain amount of power. In order to reduce the consumption, it is necessary to use a smaller resistor. The resistor that is small and has certain requirements for the accuracy of the resistance value is not easy to integrate in the chip.

[0003] image 3 It is another method of detecting current. The transformer is used to detect the current of the high and low side switches respectively, and the detected current is added to the detection resistor to obtain a complete inductor current waveform signal. The disadvantage of this method is that a transformer is required and cannot be integrated on the chip. Internal, and the large volume of the transformer is not conducive to the miniaturization of the power module, and the use of the transformer will also bring additional problems such as core saturation

[0004] Because the peak current mode (peak current mode) is a common control mode, it needs to detect the peak value of the inductor current, so there are more used to detect the current of the high-side switch ( figure 2 Ip) of the mature circuit, but there is no document introduced integrated in the chip to detect the current of the low-side switch ( figure 2 In) method

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