Ultra-low power high-speed current sampling circuit

Abstract

An ultra-low power high-speed current sampling circuit belongs to the technical field of power management circuits. The current sampling circuit comprises a sampling module and an auxiliary clamping module, wherein the sampling module comprises an operational amplifier and a first NMOS transistor, the gate of the first NMOS transistor is connected to the gate of a power tube, the drain thereof is connected to the drain of the power tube and connected to the power supply voltage, and the source thereof is connected to the negative input terminal of the operational amplifier; the positive input terminal of the operational amplifier is connected to the source of the power tube, and the voltage of the output terminal of the operational amplifier returns to the negative input terminal of the operational amplifier through a feedback loop; the auxiliary clamp module sets upper and lower limits for the output voltage of the operational amplifier, the voltage clamp is used to accelerate the transient process from the disabled state to the enabled state, and an ultra-low power current sampling circuit with fast response speed is realized combined with the wide bandwidth. The invention also proposes an operational amplifier with a wide bandwidth to further accelerate the transient response of the current sampling circuit.

Description

technical field [0001] The invention belongs to the technical field of power management circuits, and in particular relates to a high-speed current sampling circuit with ultra-low power consumption. Background technique [0002] In the field of power management circuits, the current sampling circuit is a very important part. For switching power supplies, how to accurately and real-time collect the current information on the inductor for system control has become a key technology. The current sampling circuit judges whether the system is in an overcurrent state by sampling the inductor current information, which can prevent damage to the switching power supply in the event of overcurrent or short circuit. Secondly, current sampling, as a necessary technology in the current mode control mode, can control the stability of the loop and improve the response speed of the loop. Improving the accuracy and speed of current sampling and reducing the delay of sampling modules to ensu...

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Problems solved by technology

However, in this implementation method, the time constant of the RC branch is closely related to the inductance, capacitance, and resistance parameters in actual situations, so it is difficult to match the time constants of the two branches, and this method is lacking in integration

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