Synchronous boost dc-dc converter circuit in fixed on-time mode

Abstract

The invention discloses a synchronous step-up DC-DC converter circuit with a fixed on-time mode, including a fixed TON generating circuit, a current sampling unit, a diode D1 and a diode D2, and a fixed TON generating circuit, which is generated by a pulse width modulation comparator PWM The result VPWM is compared with the clock signal generated by the clock control signal VREF, which is used to control the drive signal VDH for generating the synchronous power transistor Q1 and the main switch transistor Q2; the current sampling unit is used to sample the drain voltage of the synchronous power transistor Q1 The voltage difference between VOUT and the source switching node voltage VSW, and the voltage signal VLOAD of the sampling current is sent to the pulse width modulation comparator PWM. The present invention adopts the fixed TON mode, and when the load changes, it can make feedback at the fastest speed and respond to the change of the output, effectively improving the response speed of the loop; it adopts the valley current TON mode, which does not require resonance The wave compensation circuit has the advantages of simplified loop control and high reliability.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits and relates to an analog integrated circuit, in particular to a synchronous step-up DC-DC converter circuit in a fixed conduction time mode. Background technique [0002] With the rapid development of semiconductor technology and the continuous expansion of application fields, booster circuits are widely used in daily life. Traditional boost circuits generally use voltage mode control, in which there is only one voltage feedback path, and pulse width modulation is accomplished by comparing the voltage error signal with a constant harmonic waveform. Not only does current limiting have to be performed separately, but any change in voltage or load must be sensed as a change in output voltage and then corrected by a feedback loop, resulting in a slow response. The voltage-mode output filter adds two poles to the control loop, so designing the error amplifier for compensation requires atte...

AI Technical Summary

Problems solved by technology

Compensation is further complicated by the fact that loop gain changes with input voltage

[0003] Now some also use current mode control. Current mode control is a control method with a fixed clock on and peak current off. Although it improves the shortcoming of slow voltage mode response, there is still an error between peak current and average current that is difficult to correct. , prone to sub-harmonic oscillation, poor interactive adjustment performance for multiple output power supplies, etc.

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