assass123 发表于 2024-11-14 17:30
AI8051U-34K64-QFP48的高频抗干扰性能如何，请问在300M高频W级应用中用加屏蔽罩么 ...
如果附近有很强的射频信号，做好还是用铁罩屏蔽为好。高频干扰一般不会直接干扰到IC内部，都是干扰电源或输入信号导致异常。
晓飛飛 发表于 2024-11-14 17:15
搞音频还是建议上I2S接口的功放芯片，单片机直驱，成本低效果好
有好的型号推荐吗？要便宜，最好是立体声。看到一个型号单声道还要几元一片，成本高了。做产品成本也重要，如果价格太高，不如用几毛钱的I2S-DAC芯片加几毛钱的功放芯片。
好的，搭起实验环境测试一下。{:handshake:}
assass123 发表于 2024-11-14 16:31
另外，PWM做DAC的信号输出相位准么，如果4个脚输出低点的频率100KHZ相位差值90度，能实现么 ...
你是要做DFT分析么？
PWM输出滤波成正弦波，必然会有相位延迟，不同的频率会有不同的延迟。
比如做数字电桥，100KHz正弦波还要提供0度、90度相位差的鉴相信号，就要注意延时的问题，除非电路方案不要求严格的相位差。
那还是必须用DAC芯片了，谢谢{:handshake:}
对DFT
请问积分兑换的芯片，安装前还用125度烘烤8个小时么
assass123 发表于 2024-11-14 20:31
请问积分兑换的芯片，安装前还用125度烘烤8个小时么
批量生产时，如果非真空包装或开封超过1周（168小时），先进行125度烘烤8小时。
如果是几个样片，自己焊，不用考虑烘烤。
梁工 发表于 2024-11-14 16:17
可以使用追频方式，使用32768Hz晶振做参考，设置目标频率，自动追频，可以设置的频率误差0.5%之内。 ...
Does that have jitter of 0.5% as the IRC chases the nearest value to 32768*N?
Is the average of that jitter as good as the ppm of the 3268 ?
本帖最后由 jmg 于 2024-11-15 11:44 编辑
assass123 posted on 2024-11-14 15:50
A set of IO, is it a good idea to make an 8-bit DAC? Is it necessary to use a second-order active filter? Can LC multi-section filtering meet the specifications?
That depends on your distortion requirements.
Simple R2R DAC's have a high output impedance, so should drive into a virtual ground, high slewe rate OpAmp if you want to be fast.
Lower resistance helps speed, but that increases the errors due to port impedance.
You can try LC filters, what is your final load circuit this has to drive ?
You have mentioned 200kHz then 500kHz, what frequencies do you actually need , with what adjustment and distortion ?
If you can dedicate a complete small package (eg SOP16) to get the best performance sine output, and update that over UART.
Eg AI8H2K17U-45I-SOP16 + Bourns 4610X-R2R-103LF 10K/20k 10SIP Arrow : 50 $0.0946 + Good OpAmp would give you the most steps in a fixed kHz sine out.
A 1MHz OpAmp would be hopeless, if you are const constrained, maybe a SL9062 at 25MHz & 8V/us is good enough?
Addit: note if you want to use the Frequency locking to 32768Hz mentioned in #14, you need more than 16 pins as parts with CRE and XTAL are 20 pins and up.