Average current type buzzer driving circuit

Abstract

The invention discloses an average current type buzzer driving circuit. The average current type buzzer driving circuit comprises a loop control electronic switch, a follow current module, a low passfiltering module, a proportional link module, an error amplification module, a PWM comparator module, an oscillator, a sampling circuit and a logic and drive module; the sampling circuit samples the current on a series loop, and the sampling circuit outputs a sampling signal to a non-inverting input terminal of the PWM comparator module and the low pass filtering module; the low pass filtering module outputs the direct current component to the proportional link module, the proportional link module outputs a voltage signal to the error amplification module, and the error amplification module outputs an error amplification signal to an inverting input terminal of the PWM comparator module; and the output end of the PWM comparator module is connected to the reset end of the logic and drive module, the oscillator outputs a clock signal to the set end of the logic and drive module, the output end of the logic and drive module is connected to the control end of the loop control electronic switch. The sound pressure consistency of the average current type buzzer driving circuit is good.

Description

technical field [0001] The invention relates to an average current type buzzer driving circuit. Background technique [0002] The traditional electromagnetic buzzer driving circuit generally uses a triode and a transformer to form a self-excited oscillation circuit, such as figure 1 As shown, first, when the circuit is powered on, the base junction capacitance of the transistor Q1 is charged through the resistor R1. When the base junction capacitance voltage of the transistor Q1 reaches the turn-on threshold of the transistor Q1, the transistor Q1 is turned on, and the voltage source VCC The excitation inductance of the buzzer is charged through the triode Q1, and the upper positive and lower negative induced electromotive force is generated at the same-named end of the inductance L1 and L2. The transistor Q1 is in a saturated conduction state. When the current of the inductor L1 reaches the maximum value, the change of the magnetic flux is zero, the induced electromotive ...

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Problems solved by technology

However, the problem with this solution is that if the duty cycle is too small, the sound pressure of the buzzer will drop too much, and the sound pressure of the buzzer will also change too much under a wide input voltage.

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