A startup auxiliary power circuit

Abstract

The invention discloses a start accessory power supply circuit, including a voltage regulator circuit providing a reference voltage, a current circuit connected with the voltage regulator circuit, wherein the current circuit has an output port. The invention is characterized in that: the voltage regulator circuit includes at least two voltage regulator tubes connected mutually, and a controller is connected with at least one voltage regulator tube in parallel, the controller is possible to be in the short circuit condition or the open circuit condition. The controller is a switching tube, the control input terminal of the switching tube is connected to the guard signal output terminal of an outside circuit, and the output port of the switching tube is connected with the both ends of the voltage regulator tube in parallel. The invention uses two or above voltage regulator tubes in series connection to provide the reference voltage, controllers are connected with part of voltage regulator tubes in parallel, so that the reference voltage output value of the entire voltage regulator tubes circuit may be cut, when the outside module has the protection movement, the output voltage of the accessory power supply for starting will be reduced, the load current provided for starting the accessory power supply will be reduced, so as to reduce the primary device power loss and the heat dissipating capacity.

Description

technical field [0001] The invention relates to a power supply circuit, in particular to a startup auxiliary power supply circuit. Background technique [0002] In the DC-DC module power supply, the start-up auxiliary power supply is generally used to provide operating current for the control chip and peripheral circuits. Some control chips may have their own auxiliary power supply, but due to high power consumption, its application is limited. In order to save cost and space, the input voltage linear regulator circuit is directly used in the application of starting auxiliary power supply, which mainly works when the auxiliary power supply energy provided by the winding or chip is insufficient, such as the module starting stage and protection status and overcurrent and overvoltage. When the voltage is short-circuited, etc. Its circuit is shown in Figure 1, where the voltage regulator D1 provides the reference voltage. In practical applications, the operating voltage of the...

AI Technical Summary

Problems solved by technology

[0003] The defect of the above circuit is: when the module starts or is in the protection state, the auxiliary power supply is started to provide full load current, so the power consumption of the resistor and the triode is large, and the package required is large. The four resistors R1~R4 generally require 1206 packages, and the triode Q1 requires SOT89 or larger package

However, if increasing the device package can improve the heat dissipation capability and solve this problem, it will inevitably increase the size of the circuit board, which is not conducive to the miniaturization of the DC-DC module

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