LED发光二极管限流电阻计算
LED（发光二极管）必须串联限流电阻以防止过流烧毁。正确计算限流电阻值是LED电路设计的第一步。
一、限流电阻计算公式
$R = \dfrac{U_s - U_f}{I_f}$文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html
其中：$U_s$ 为电源电压（V），$U_f$ 为LED正向压降（V），$I_f$ 为LED工作电流（A）。文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html
二、常见LED参数参考
| LED颜色 | 正向压降 $U_f$ | 典型电流 $I_f$ |
|---|---|---|
| 红色 | 1.8-2.2V | 20mA |
| 绿色 | 2.0-2.4V | 20mA |
| 蓝色/白色 | 3.0-3.4V | 20mA |
| 黄色 | 2.0-2.2V | 20mA |
三、计算示例
红色LED（$U_f=2V$，$I_f=20mA$）接5V电源：文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html
$R = \dfrac{5V - 2V}{0.02A} = \dfrac{3}{0.02} = 150\Omega$，选用150Ω电阻。文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html
四、电阻功率选择
$P_R = I_f^2 \times R = (0.02)^2 \times 150 = 0.06\text{W}$，选用1/4W（0.25W）电阻即可。文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html
五、多个LED接法
串联：$R = \dfrac{U_s - n \times U_f}{I_f}$（$n$ 个LED串联，电压累加）文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html
并联：每个LED单独串联限流电阻，不建议多LED共用一个电阻。文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html 文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html文章源自公式库网-https://www.gongshiku.com/html/201910/ledfaguangerjiguanxianliudianzuzhizaixianjisuanqi_ledxianliujisuan_lederjiguanzuzhi.html
