ST25DVxxx V_EH输出电压被限制为大约

亲爱的马可，
首先，感谢您考虑使用ST25DVxxx。
您的测量实际上是正确的。
V_EH输出确实不受管制，但内部受限。
V_EH输出直接取决于AC0 / AC1天线线圈上施加的电压。
如果RF场功率很强，天线线圈上的电压可以上升到高值（远大于10V）。
为了保护标签免受AC0 / AC1上的那些高电压的影响，有一个内部钳位机制将该电压限制为标签可以支持的值。由于V_EH输出电压直接取决于AC0 / AC1电压，因此也受此钳位值的限制。
这就是为什么你看到3.4V左右的限制（钳位实际上并不完美，RF场功率值非常高，V_EH电压可能升至4V以上）的原因。
您可以在图3和图4的应用笔记AN4913中看到，V_EH电压限制在3V和4V之间。这是由于钳位。当RF场功率高于6A / m时，钳位使电压稍微上升，V_EH> 4V。
希望这能回答你的问题。
最好的祝福。



以下为原文




Dear Marco,
First, thank you for considering the ST25DVxxx.
Your measurement is actually correct.
The V_EH output is indeed not regulated, but is internally limited.
The V_EH output directly depends on the the voltage applied on the AC0/AC1 antenna coils.
Voltage on the antenna coil can rise up to high values (much more than 10V) if RF field power is strong.
In order to protect the tag from those high voltage on AC0/AC1, there is a internal clamp mechanism which limits this voltage to values that the tag can support. As V_EH output voltage directly depends on AC0/AC1 voltage, it is also limited by this clamping value.
This is the reason why you see a limitation around 3.4V (the clamp is actually not perfect and with very high RF filed power values, it is possible for the V_EH voltage to rise above 4V).
You can see in the application note AN4913 in figures 3 and 4 that the V_EH voltage is limited to values between 3V and 4V. This is due to the clamp. When the RF field power is above 6A/m, the clamp let the voltage rise a little bit and you can have V_EH>4V.
Hope this answers your question.
Best regards.