从TPS5450的手册来看,只要改变Vsense脚的反馈电压即可改变输出电压,但传统的电阻分压方式无法满足多种电压输出场合的应用。网上资料显示可以通过数字电位器或PWM方式控制反馈电压,但资料不够完整。请问,TI有没有这样成熟的应用案例可供参考?
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从TPS5450的手册来看,只要改变Vsense脚的反馈电压即可改变输出电压,但传统的电阻分压方式无法满足多种电压输出场合的应用。网上资料显示可以通过数字电位器或PWM方式控制反馈电压,但资料不够完整。请问,TI有没有这样成熟的应用案例可供参考?
在arduino的论坛上看到有用MCU I/O口来控制的:
With the port configured as an input, the resistor is in effect not present (provided the Arduino is powered up). With the port set to an output and LOW, the resistor is in parallel with the lower resistor in the feedback circuit, so the output voltage is increased. With the port set to an output and HIGH, a positive bias is inserted into the feedback input, so the output voltage is reduced.
原理上好像也可以,应用在TPS5450上应该也可以吧,但是输出直接电阻分压进入cpu的管脚会不会对cpu管脚有影响啊?
Hi
通过DA输出,接一个二极管(反向电压保护),然后通过一个电阻接到FB脚,这样DA的输出就可以影响到原来分压电阻给到FB的电压,即可以达到调整输出电压的目的。
噢,对了,D1后面还要加个电阻,对不对?如果是这样,假设pwm给出的模拟电压是Ui,那么输出应该怎么计算呢?TPS5450的参考电压Vref=1.221V