[问答]

ST95HF晶体规格有问题

问答对人有帮助，内容完整，我也想知道答案 0 嗨，我们正在使用ST95 HF NFC收发器和XRCGB27M120F3M00R0 27.12 MHz晶振。到目前为止，我们制造了大约30个模块，并且一切运行良好。但是，我们计划在不久的将来（10k +）更大的系列，所以我们希望确保一切都能在整个操作范围内正常工作。目前，我们对晶体规格有疑虑。在数据表（第59页）中指出，当ESR等于30欧姆的晶体时，额定负载电容应为6pF，并且使用的负载电容应为10至20 pF范围。如果晶体ESR大5倍（150欧姆），这是否意味着额定负载电容也应该更大（以及多少）以保持与嵌入式振荡器的兼容性？我们使用的是提到的150欧姆ESR和6pF负载电容的晶体。我们期望大约5 pF的杂散电容（包括引脚和PCB杂散电容），因此我们使用6.8pF负载电容。这也可能是一个问题，因为它们的范围不是10到20 pF吗？如果数据表指定了振荡器跨导，那也可能有用...... 以上来自于谷歌翻译以下为原文 Hi, we are using ST95 HF NFC transceiver with XRCGB27M120F3M00R0 27.12 MHz crystal. So far, we manuufactured about 30 modules and all works well. However, we are planning a bit larger series in a close future (10k+) so we would like to be sure everything will work fine in whole operating range. Currently, we have concerns regarding a crystal specification. In datasheet (p 59) it is stated that with a crystal of ESR equal to 30 ohms, rated load capacitance should be 6pF, and also that used load capacitors should be in 10 to 20 pF range. If a crystal ESR is 5 times larger (150 ohms), does that mean that rated load capacitance should also be larger (and how much) in order to keep compatibility with embedded oscillator? We are using mentioned crystal that has 150 ohms ESR and load capacitance of 6pF. We are expecting about 5 pF of stray capacitance (including pin and PCB stray capacitance), so we are using 6.8pF load capacitors. Could this also be a problem, since they are not in 10 to 20 pF range? If datasheet had specified oscillator transconductance, that could be also helpful... 0
2019-7-17 06:13:38　　评论淘帖0 邀请回答您可以邀请以下用户，快速回答问题 × wang21cj 该类别下有 44 个回答。邀请回答新星之火12138 该类别下有 41 个回答。邀请回答 chm5 该类别下有 39 个回答。邀请回答 hgimtk 该类别下有 33 个回答。邀请回答 HengDu 该类别下有 30 个回答。邀请回答 jghgfdssas 该类别下有 28 个回答。邀请回答 hwp0415229 该类别下有 28 个回答。邀请回答可口可甜该类别下有 26 个回答。邀请回答 kingnet6688 该类别下有 26 个回答。邀请回答颜刚YanG 该类别下有 26 个回答。邀请回答 zyh34997 该类别下有 25 个回答。邀请回答柱子图宁该类别下有 25 个回答。邀请回答 jenny042 该类别下有 25 个回答。邀请回答 kingnet9999 该类别下有 25 个回答。邀请回答 andyfly7 该类别下有 25 个回答。邀请回答麻酱该类别下有 25 个回答。邀请回答哈哈神神该类别下有 24 个回答。邀请回答成长的小师弟该类别下有 24 个回答。邀请回答 gXDhn 该类别下有 24 个回答。邀请回答 jiangwenwen 该类别下有 24 个回答。邀请回答举报邝计嘉相关推荐 • 如何在读取对等NFC设备后使ST95HF RF场不关闭 1573 • ST95HF错误代码 2290 • 如何在两个st95hf设备之间实现简单的数据传输 2288 • 为什么ST95HF会出现错误代码？ 1279 • 如何实现ST95HF / STM32L071点对点连接？ 3316 • ST95HF开发Peer to Peer连接应该使用什么协议？ 1003 • ST95HF错误代码：0x87 0x01 0x90 1155 • MISO上的ST95HF没有任何活动 1537 • 用于HF RFID阅读器的简单设计需要考虑以下因素 1214 • 为什么Zrx调谐ST95HF要调整到低于7V？ 1211 1个回答

答案对人有帮助，有参考价值 0 亲爱的托比亚斯，我猜你的6.8pF电容是合适的，非常接近建议的10pF 您可以通过尽可能短的跟踪来改善杂散电容，然后您可以将电容增加到接近10pF。（杂散电容可以假设在2到5 pF的范围内），越小越好增加负载电容。目的是使负载电容尽可能接近晶体C1 有关信息，负载电容的大值会增加频率稳定性，但可能会导致振荡器启动问题。也许选择温度系数较低的电容，如NP0或C0G类型。在CR95HF板上使用NDK晶体参考NX2520SA-27.12M，ESR max = 60欧姆，负载电容= 8pF。 2个10pF的电容连接到Murata的接地参考GRM1885C1H100KA01D（C0G）。问候以上来自于谷歌翻译以下为原文 Dear Tobias, I guess that your 6.8pF capacitors are suitable and quite close to the 10pF recommended You can perhaps improve your stray capacitor by keeping trace as short as possible, you will be able then to increase the capacitor close to 10pF.( Stray capacitance can be assumed to be in the range of 2 to 5 pF) the smaller is the best to increase the loading capacitors. Purpose is to have as close as possible load capacitance equal to crystal Cl For information large value of load capacitance will increase frequency stability but may cause oscillator start-up problems. Perhaps select capacitors with a low temperature coefficient such as NP0 or C0G types. On the CR95HF board a NDK crystal ref NX2520SA-27.12M is used the ESR max= 60 ohms and load capacitance= 8pF. 2 capacitors of 10pF are connected to ground ref GRM1885C1H100KA01D (C0G) from Murata. Regards

2019-7-17 06:26:56 评论举报刘峰