运放在采用双电源供电时,该如何做好电源的滤波。一直搞不清如何选择滤波电容的容值大小,耐压值和电源电压的关系。
如下图中,我采用的是±15V给OPA4170供电,滤波电容采用的是10uF/25V(AVX钽电容)和0.1uF(TDK)组合滤波,但在测试的过程中,偶尔会有钽电容爆掉的情况发生,对系统的稳定存在很大的影响。对此,各位有什么好的建议?
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滤波电容瓷片电容,推荐使用NP0电容。温度稳定性好。其它电容CBB电容也不错。一般电解电容不用于滤波器。像钽电解电容,它不能接负向电压,如果电压反向一般很容易爆。下面是常见电容的比较,希望对你有帮助。
电容类型 | Capacitor types | Capacitance range | Accuracy | Temperature stability | Leakage | Typical Dielectric Absorption |
电解 | Electrolytic | 0.1 uF - ~1 F | Very poor | Very poor | Poor | high |
陶器 | Ceramic | 10 pF - 1 uF | Variable | Variable | Average | NPO <0.1% |
钽 | Tantalum | 0.1 uF - 500 uF | Poor | Poor | Poor | high |
云母 | Silver mica | 1 pF - 3000 pF | Good | Good | Good | >0.003% |
聚酯 | Polyester (Mylar) | 0.001 uF - 50uF | Good | Poor | Good | 0.3% to 0.5% |
聚苯乙烯 | Polystyrene | 10 pF - 1 uF | Very good | Good | Very good | 0.001% to 0.02% |
聚碳酸酯 | Polycarbonate | 100pF - 20 uF | Very good | Very good | Good | |
聚丙烯 | Polypropylene | 100pF - 50 uF | Very good | Good | Very good | 0.001% to 0.02% |
聚四氟乙烯 特氟龙 |
Teflon | 100 pF - 1 uF | Very good | Very good | Very good | 0.003% to 0.02% |
玻璃 | Glass | 10 pF - 1000 pF | Good | Good | Very good | |
陶瓷 | Porcelain | 100 pF - 0.1 uF | Good | Good | Good |