测试 MC14468的基本功能MC14468 Datasheet01【测量MC14468输入电流】一、MC14468输入电流mc14468这个芯片是。 一颗古老的芯片原来用于离子型烟雾检测器 它内部有一个非常高阻抗的输入端口 根据他的数据手册可以看到。 它的输入电流大概在1P安左右 下面我们利用电容充电方法 来测量它的输入偏置电流。 这种方法之前也用于测量过其他高阻抗输入运放 也就是在他的在它的输入端口连接一个0.1微法的电容 它的偏置电流会在电容上逐步积累电压 这个电压将会使得它两边的同步隔离管脚电压同时上升 通过测量电压的上升速率 我们可以估计出它的输入偏电流的大小。 铺设单面PCB使用一分钟制板方法制作测试电路板一分钟之后得到测试电路板。 下面我们对芯片进行焊接 并使用高温水蒸气进行清理 然后再使用热风枪对电路板进行烘干 下面我们测量它的输入电压的上升速率。二、测量结果记录120个数据大约每隔一秒钟记录一个数据 可以看到电容上的电压在开始时上升比较快。 我们比对前10秒钟它的电压的变化。 在9.91秒钟它的电压从555.6毫伏上升到863.9毫伏。 根据0.1微法上电容的变化 我们可以计算出充电电流大概是83.75P安。 这个电流远远大于他手册中给定的几个PM的大小 在后期电压处于稳态。也许此时对应了它的偏置电压 已经使得它无法再继续往外输出电流了根据这个测量数据 我们还无法确定究竟它对应的输入电流大小是多少。接下来我们也使用镊子将电容进行短路 重新测量一下它的电压变化 可以看到他前面有一段很类似RC充电的过程 如果我们将这个过程看成内部电压源V0 通过内阻往0.1微法电容上充电。 可以根据测量的数据拟合这个充电电路中的参数 我们截取从第5秒到第35秒之间的测量数据 根据测量数据我们可以拟合出充电过程。 充电的时间常数参数大约是4.142秒 根据这个参数可以计算出充电内阻大约是41.4兆欧姆 内部电源大概是0.858伏 这个电压应该是内部的偏置电压。※总结 ※本文测试了MC14468芯片的输入阻抗 利用电容充电方法进行测量 但是所得的结果和数据手册中并不匹配。 通过对充电电压变化曲线来看 它内部应该是一个偏执 电压大约为0.585伏 内阻为41.4兆欧姆的输入特性。tdim[0.1214,1.3584,2.5666,4.2204,5.4281,6.6782,7.8864,9.0929,10.2801,11.5079,12.7154,13.9226,15.1316,16.3089,17.5453,18.7529,19.9404,21.1682,22.3755,23.5826,24.7913,25.9731,27.2050,28.4126,29.6202,30.8289,32.0355,33.2431,34.4506,35.6379,36.8672,38.0729,39.2804,40.4881,41.6680,42.9038,44.1106,45.2904,46.5254,47.7318,48.9402,50.1489,51.3293,52.5621,53.7704,54.9781,56.1856,57.3656,58.6008,59.8099,60.9884,62.2231,63.4300,64.6401,65.8447,67.0260,68.2605,69.4691,70.6757,71.8831,73.0907,74.2991,75.5066,76.6892,77.9216,79.1291,80.3349,81.5431,82.7255,83.9581,85.1666,86.3504,87.5834,88.7874,89.9966,91.2026,92.3864,93.6183,94.8267,96.0332,97.2405,98.4481,99.6566,100.8631,102.0433,103.2817,104.4857,105.6942,106.9008,108.0818,109.3167,110.5246,111.7066,112.9385,114.1467,115.3554,116.5607,117.7464,118.9759,120.1820,121.3907,122.6017,123.7807,125.0156,126.2208,127.4043,128.6357,129.8455,131.0501,132.2585,133.4396,134.6754,135.8801,137.0884,138.2947,139.5044,140.7111,141.9185,143.0992,144.3337]vdim[0.8450,0.8490,0.8522,0.0133,0.0701,0.3114,0.4560,0.5544,0.6252,0.6778,0.7177,0.7485,0.7721,0.7909,0.8059,0.8176,0.8271,0.8346,0.8406,0.8455,0.8494,0.8525,0.8550,0.8570,0.8586,0.8600,0.8610,0.8618,0.8626,0.8631,0.8636,0.8639,0.8643,0.8644,0.8648,0.8648,0.8650,0.8651,0.8653,0.8653,0.8653,0.8654,0.8655,0.8656,0.8656,0.8657,0.8657,0.8657,0.8657,0.8658,0.8657,0.8657,0.8657,0.8656,0.8658,0.8658,0.8658,0.8658,0.8658,0.8658,0.8658,0.8659,0.8659,0.8658,0.8659,0.8659,0.8659,0.8659,0.8660,0.8659,0.8659,0.8659,0.8659,0.8659,0.8660,0.8659,0.8659,0.8659,0.8660,0.8660,0.8660,0.8660,0.8660,0.8659,0.8660,0.8659,0.8659,0.8659,0.8660,0.8660,0.8659,0.8660,0.8659,0.8660,0.8659,0.8660,0.8660,0.8660,0.8660,0.8660,0.8661,0.8661,0.8661,0.8660,0.8661,0.8661,0.8661,0.8661,0.8661,0.8661,0.8661,0.8661,0.8661,0.8661,0.8661,0.8661,0.8660,0.8661,0.8660,0.8660]fromheadmimport*fromtsmodule.tsvisaimport*dm3068open()tdim[]vdim[]tstarttime.time()foriinrange(120):vdm3068vdc()ttime.time()-tstart tdim.append(t)vdim.append(v)tspsave(TD1,tdimtdim,vdimvdim)printff(i,v,t)time.sleep(1.0)plt.plot(tdim,vdim,lw3)plt.xlabel(Time(s),colorsteelblue,fontsize24)plt.ylabel(Out(V),colorsteelblue,fontsize24)plt.grid(True,whichboth,linestyle--,alpha0.7)plt.tight_layout()plt.show()fromheadmimport*fromscipy.optimizeimportcurve_fit tdim,vdimtspload(TD1,tdim,vdim)startid4endid35deflinefun(x,v0,v00,tao,t0):returnv00-(v00-v0)*exp(-(x-t0)/tao)xtdim[startid:endid]yvdim[startid:endid]param(0.1,0.85,5,5)param,convcurve_fit(linefun,x,y,p0param)printf(param)yfitlinefun(x,*param)plt.plot(tdim[startid:endid],vdim[startid:endid],lw3,labelDATA)plt.plot(x,yfit,lw3,labelFIT)plt.xlabel(Time(s),colorsteelblue,fontsize24)plt.ylabel(Vout(V),colorsteelblue,fontsize24)plt.grid(True,whichboth,linestyle--,alpha0.7)plt.legend(locupper left)plt.tight_layout()plt.show()■ 相关文献链接:测试 MC14468的基本功能-CSDN博客MC14468 Datasheet