ELM412 Datasheet(数据表) 4 Page - ELM Electronics

来自 : html.alldatasheetcn.com/html-p 发布时间：2021-03-25

zoom inzoom out 4 pageElm Electronics – Circuits for the Hobbyist http://www.elmelectronics.com/ Example ApplicationELM412Output Waveforms4 of 4ELM412DSBOperation of the ELM412 is straightforward,requiring little explanation. Typically the resonantfrequency of the piezo element is determined, andpins 2, 3 and 4 are connected for this frequency. Inthe circuit of Figure 3, the frequency has been set for2400Hz. A single bit from a control circuit is thenused to turn the buzzer on and off.The 2.2KΩ resistor shown in the circuit servestwo purposes. One is to provide a current limit for theELM412 as it tries to rapidly change the piezovoltage (the piezo is like a large capacitor), and theother is to simply limit the output loudness.The only other detail in Figure 3 is the customary0.01µF capacitor for supply decoupling. It’s alwaysgood practice to add one, although it’s often notessential.Control Bit from theMicroprocessor(1=on, 0=off)0.01µF+5V12348765PiezoElement2.2KΩFigure 3.Out1EnableOut2Out1 - Out2The output waveforms are generated as long asthe enable input remains high. When brought low,the current cycle completes before the outputceases.Figure 2.