A BUCK type DCDC output constant current detection control circuit and method

Abstract

The invention relates to the technical field of constant current detection and control, in particular to a BUCK type DCDC output constant current detection and control circuit and method, comprising an input voltage compensation network, an output voltage dividing network, an input current sampling network, a loop control circuit and a step-down type circuit. The input voltage compensation networkis connected with an output voltage dividing network, the output voltage dividing network and the input current sampling network are connected with a loop control circuit, the step-down type circuitis connected with an input current sampling network and a loop control circuit, As that input current is detect and the input voltage compensation network is introduced at the same time, the output constant current control is realized, the input voltage and the output voltage are compensated, the influence of the offset factors such as the inductance value, the sample-and-hold, the capacitance, the charge injection and the buffered operational amplifier and the like is not exist, the structure is simple, additional control logic and the sample-and-hold circuit are not provided, and the precision is high.

Description

technical field [0001] The invention relates to the technical field of constant current detection and control, and specifically discloses a BUCK type DCDC output constant current detection and control circuit and method. Background technique [0002] In the prior art, there are usually the following two methods for BUCK type DCDC output constant current detection and control: one is to use an off-chip series high-precision sampling resistor, and the voltage at both ends of the detection resistor is amplified and filtered to take the average Value, compare the average value with the reference voltage for the loop error to achieve constant current control, but this method needs to increase the high-precision sampling resistor, which increases the cost, and the off-chip sampling resistor will generate power consumption; second, no sampling resistor is required. By detecting the current flowing through the upper tube, the load compensation current is introduced at the same time,...

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Problems solved by technology

[0002] In the prior art, there are usually the following two methods for BUCK type DCDC output constant current detection and control: one is to use an off-chip series high-precision sampling resistor, and the voltage at both ends of the detection resistor is amplified and filtered to take the average Value, compare the average value with the reference voltage for the loop error to achieve constant current control, but this method needs to increase the high-precision sampling resistor, which increases the cost, and the off-chip sampling resistor will generate power consumption; second, no sampling resistor is required. By detecting the current flowing through the upper tube, the load compensation current is introduced at the same time, and then the feedback current signal is generated by the sample-and-hold circuit and the low-pass filter, and the load current feedback signal is simulated, and this value is compared with the reference voltage for the loop error to achieve constant current Control, the accuracy of this method is poor, affected by input voltage, inductance value, sample and hold, capacitance, charge injection and buffer op amp offset, etc.

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