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[问答] VDD小于Vmin?
156 VDD 处理器
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当PIC30F的VDD低于Vmin(最小工作电压)时会发生什么情况?这时处理器上的逻辑不再正常工作了吗?我的家庭参考手册和数据表不清楚。看来,处理器可以发送复位脉冲(SySRST)任何时间VDD低于POR电路阈值电压(1.85 V)。同样,处理器上的逻辑也会在1.85伏以上的电压下运行。这是真的吗?数据表列出了最小工作电压(Vmin)为2.5V。这是所有外围设备将工作的电压,而逻辑将一直工作到1.85伏,在这一点上复位脉冲被断言。我的DSPIC30F6012A应用是由汽车电池供电。过去,非微芯片,项目,我有一个问题,电压下降到低于电压的芯片设计操作(2.5V的30F6012A)。结果总是离奇的。处理器中的逻辑不能正确运行。基于这个原因,我一直在使用处理器上的“棕色”重置。现在,我的平台上有一个未被缓冲的继电器存在问题。它降低了我的VDD电压低于褐色输出电压,并导致我的处理器复位。如果我禁用棕色输出重置一切都运行良好。PIC30F家庭参考手册说,棕色输出重置仅适用于AC供电应用。DC应用应该使用低电压中断来触发处理器关闭,这是真的吗?由于DSPIC30F没有关闭功能,当电压降到Vmin以下时,什么可以让处理器不停地运行?

以上来自于百度翻译


      以下为原文

    What happens when a PIC30F’s VDD drops below Vmin (the minimum operating voltage)?  At that point will the logic on the processor no longer operate properly?

The Family Reference Manual and Data Sheet are not clear to me.  It looks like the processor may send a reset pulse (SYSRST) any time VDD falls below the POR Circuit Threshold Voltage (1.85V).  So too it sounds like the logic on the processor will operate at voltages above 1.85V.  Is that true?  The Data Sheet lists the minimum operating voltage (Vmin) as 2.5V.  Is that the voltage at which all the peripherals will operate while the logic will work all the way to 1.85V at which point a reset pulse is asserted?

My dsPIC30F6012A application is powered by a car battery.   On past, non-microchip, projects I’ve had a problem with voltages dropping below the voltage at which the chip is designed to operate (2.5V for the 30F6012A).  The results have always been bizarre.  The logic in the processor does not run correctly.  For that reason I’ve been using the Brown-Out Reset on my processor.

Now, I’m having a problem with an un-snubbed relay on my platform.  It’s drooping my VDD Voltage below the brown-out voltage and causing my processor to reset.  IF I disable the Brown-Out Reset everything runs fine.

The PIC30F Family Reference Manual says that the Brown-Out Reset is for AC Powered applications only.  DC Applications should use the Low Voltage Interrupt to trigger the processor to shut down gracefully.
Is that true?  Since the dsPIC30F does not have a shut-down feature what’s to keep the processor from running wildly when the voltage drops below Vmin?
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2019-4-22 14:52:22   评论 分享淘帖 邀请回答
5个回答
提供具有较大电源滤波电容的PIC。修改电源电路,防止快速滤波电容放电进入欠电压NETVORK,例如通过电压调节器本征二极管。并且不禁用BOR电路,也可能由于EMI而发生复位或故障,而不仅仅是由于电源电压下降。如果PIC引脚与外部网络的连接,对于任何PCB线,那么它们应该以某种方式被保护,应该被过滤。

以上来自于百度翻译


      以下为原文

    Provide the PIC with larger supply filtering capacitor. Modify supply circuit to prevent fast filter capacitor discharge into the undervoltaged netvork, for example through voltage regulator intrinsic diode. And do not disable the BOR circuit.
Also the reset or glitches may occur due to the EMI, not just due to the supply voltage sag. If PIC pins have a connections to the external networks, to any out of PCB wires then they should be protected somehow, shouldbe filtered.
2019-4-22 15:08:01 评论

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“如果我禁用棕色的重置,一切都运行良好。”多少单位?温度?VCC容限?老化?这是错误的,你知道这是错误的。你在找人告诉你忽略它吗?

以上来自于百度翻译


      以下为原文

    "If I disable the Brown-Out Reset everything runs fine."
on how many units?  
Temperature?
Vcc Tolerance?
Aging?
It is wrong, you know it is wrong.  Are you looking for someone to tell you to ignore it?
2019-4-22 15:23:09 评论

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谢谢大家!NKurzman,不,我正在找人告诉我当电压降到2.5伏以下时,处理器会做什么。逻辑引擎是否可以不可预知地开始处理,或者我的指令是否正确运行,即使外围设备不能工作,一直到1.85 V(POR电路阈值电压)。当电压降到1.85伏以下时,微控制器是否进入复位?每个数据表VPOR为我的芯片= VSS(0V)。这告诉我,当微控制器上升到0V以上时,POR(上电复位)开始,在微控制器上升到1.85 V之后继续TPOR+TPWRT秒。如果这是真的,它告诉我必须保持棕色输出使处理器在任何时间都处于复位状态。太低,无法正常运行逻辑引擎。这有道理吗?

以上来自于百度翻译


      以下为原文

    Thanks guys!

NKurzman, No, I'm looking for someone to tell me what the processor does when the voltage drops under 2.5 Volts.  Does the logic engine begin processing unpredictably or will my instructions actually run correctly, even if the peripherals won't work, all the way down to 1.85V (POR Circuit Threshold Voltage).  So too, does the micro controller go into reset when the voltage drops below 1.85V?

Per the data sheet VPOR for my chip = VSS (0V).  That tells me that POR (power on reset) starts when the micro controller rises above 0V and continues for TPOR +TPWRT Seconds after the micro controller rises above 1.85V.

If that's true it tells me that I HAVE TO keep the brown out enabled so that the processor will be in reset any time the voltage is too low to properly run the logic engine.  Does that make sense?
 
2019-4-22 15:32:29 评论

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如果您禁用BOR,并运行电源电压低于最低化的芯片,任何事情都可能发生,随机故障,错误的结果,错误的指令,处理器跳转到错误的功能?当BOR启动时,当电压太低时,芯片将处于复位状态。没有BOR,没有任何确定。问候,Mysil。

以上来自于百度翻译


      以下为原文

    If you disable BOR, and run the chip with supply voltage lower than sepcification minimum,
anything could happen, random malfunction, wrong results, wrong instructions, processor jumping to the  wrong function?
With BOR enabled, the chip will be in Reset when voltage is too low. 
Without BOR, there is nothing sure.
 
Regards,
   Mysil
2019-4-22 15:40:25 评论

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不要禁用棕色输出重置。将电源固定到PIC。第一步是将二极管与输入的12V串联,因此任何负尖峰不能释放您的滤波电容器。同时确保您有良好的接地连接。

以上来自于百度翻译


      以下为原文

    Don't disable the brown out reset.
Fix your power supply to the PIC.
First move would be to put a diode in series with the incoming 12V, so any negative spike cannot discharge your filter capacitor.
Also make sure you have a good ground connection.
 
2019-4-22 15:49:06 评论

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