A buck converter with built-in overcurrent protection control circuit

Abstract

The invention discloses a step-down converter with a built-in overcurrent protection control circuit, and relates to the technical field of power supply management. The built-in overcurrent protection control circuit of the step-down converter includes an upper tube overcurrent comparator and a lower tube overcurrent comparator And the comparison control logic of the lower tube, the upper tube overcurrent comparator and the lower tube overcurrent comparator are used to compare the currents driving the upper tube and the lower tube with their respective thresholds, so that the currents of the upper tube and the drive can be monitored at the same time The current of the lower tube; the lower tube comparison control logic shields the upper tube open signal when the lower tube is driven to open and the current that drives the lower tube is detected to exceed the corresponding threshold, until the normal modulation is performed when the abnormality is resolved, so as to avoid short circuit or continuous overcurrent Because the minimum duty cycle of the driver upper tube is turned on, the continuous charging of the inductor makes the inductor current out of control and causes damage to the chip, and achieves better protection for the drive switch tube, meeting the requirements for functional safety and reliability in actual use. .

Description

technical field [0001] The invention relates to the technical field of power management, in particular to a step-down converter with a built-in overcurrent protection control circuit. Background technique [0002] In consumer electronics and automotive electronics, the energy of the power consumption terminal comes from the battery terminal, and the voltage range provided by the battery terminal is about 8-20V, while the power consumption terminal is usually LED lamp beads, sensor chips, interface chips and main control chips, etc. , These electronic components and chips of different specifications have different requirements for power supply, and the working voltage range is about 3~5V. Therefore, it is necessary to use BUCK (step-down converter) chips to reduce the voltage of the battery terminal to the rated working voltage of the power supply terminal. power it. [0003] But in automotive electronics, the output of the battery terminal is not a stable voltage, especiall...

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Problems solved by technology

[0005] But the above figure 1 The BUCK chip with the structure shown has the following problems in practical applications, which makes it unable to meet the security and reliability requirements of practical applications:

[0006] (1) The minimum on-time of driving the upper tube MN1 is the pulse width of the CLK_OS signal. When the output is short-circuited, MN1 will be turned off due to overcurrent, but when the next cycle comes, MN1 will still be turned on by CLK_OS to charge the inductor L1 , so that the DC current value on the inductor L1 will increase cycle by cycle, and eventually the switch tubes MN1 and MN2 will be damaged

[0007] (2) figure 1 This structure can protect the driving upper transistor MN1, but cannot protect the driving lower transistor MN2 in real time, thus increasing the risk of damage to MN2 due to instantaneous high current.

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