Power tube circuit integrated with sampling resistor

Abstract

The invention relates to the technical field of power tube circuits, and discloses a power tube circuit integrated with a sampling resistor, which comprises an IC chip, wherein a main power tube and a secondary power tube are integrated on the IC chip, the main power tube and the secondary power tube are connected in parallel, and the main power tube is connected with a source electrode and a drain electrode in a top aluminum metal through laying mode. The secondary power tube is connected with a source electrode through aluminum metal and connected with a drain electrode through top aluminum metal in a through laying mode, an aluminum metal routing parasitic resistor is a sampling resistor, and the two ends of the metal routing resistor are resistor sampling ends. According to the invention, the sampling resistor is arranged in the chip, and the parasitic resistor on the wiring of the lower tube of the power tube is used as the sampling current resistor by utilizing the characteristics of the switching power supply power tube, so that the current can be accurately sampled, and the situation of current reversal can be coped with; on the basis of not adding additional elements and circuits, high-efficiency and wide-range accurate sampling which basically does not reduce loss is realized, and the cost is saved and the efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of power tube circuits, in particular to a power tube circuit integrated with a sampling resistor. Background technique [0002] In the existing switching power supply circuit, a variety of methods are used for current sampling, which are mainly divided into IC peripheral precise resistance sampling, built-in resistance sampling, and power tube voltage mirror sampling. [0003] Using the method of peripheral precision resistance sampling, it is necessary to use a precision sampling resistance outside the IC to obtain the current information and send it into the internal loop, which not only increases the number of external pins, but also increases the number of peripheral components, and has higher requirements for resistance. , the implementation cost is high; [0004] Using the built-in resistor sampling method, it is necessary to set the built-in lightly doped poly resistor as a sampling resistor to accu...

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Problems solved by technology

[0003] Using the method of peripheral precision resistance sampling, it is necessary to use a precision sampling resistance outside the IC to obtain the current information and send it into the internal loop, which not only increases the number of external pins, but also increases the number of peripheral components, and has higher requirements for resistance. , the implementation cost is high;

[0004] Using the built-in resistor sampling method, it is necessary to set the built-in lightly doped poly resistor as a sampling resistor to accurately sample the current without external resistors, reducing interference and improving efficiency, but the loss caused by the resistor and the interference generated by the resistor Still can't better improve work efficiency;

[0005] The inductor current is obtained by mirroring the voltage at both ends of the power tube. This method is widely used and has no resistance loss to improve the work efficiency. However, for the switching circuit, this method cannot accurately sample the reverse current. When the voltage of the switch terminal SW is too low When PGND, the sampling circuit cannot work normally. At the same time, the sampling ratio is affected by the power transistor Rds(on), so it cannot cope with the situation where VDD is adjustable.

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