欢迎访问ic37.com |
会员登录 免费注册
发布采购

5962-89805012A 参数 Datasheet PDF下载

5962-89805012A图片预览
型号: 5962-89805012A
PDF下载: 下载PDF文件 查看货源
内容描述: 集成电路真RMS至DC转换器 [Integrated Circuit True RMS-to-DC Converter]
分类和应用: 转换器模拟特殊功能转换器
文件页数/大小: 8 页 / 152 K
品牌: ADI [ ADI ]
 浏览型号5962-89805012A的Datasheet PDF文件第1页浏览型号5962-89805012A的Datasheet PDF文件第2页浏览型号5962-89805012A的Datasheet PDF文件第3页浏览型号5962-89805012A的Datasheet PDF文件第4页浏览型号5962-89805012A的Datasheet PDF文件第5页浏览型号5962-89805012A的Datasheet PDF文件第7页浏览型号5962-89805012A的Datasheet PDF文件第8页  
AD536A  
Figure 9 is a simplified schematic of the AD536A; it is subdi-  
vided into four major sections: absolute value circuit (active  
rectifier), squarer/divider, current mirror, and buffer amplifier.  
The input voltage, VIN, which can be ac or dc, is converted to a  
unipolar current I1, by the active rectifier A1, A2. I1 drives one  
input of the squarer/divider, which has the transfer function:  
The current mirror also produces the output current, IOUT,  
which equals 2I4. IOUT can be used directly or converted to a  
voltage with R2 and buffered by A4 to provide a low impedance  
voltage output. The transfer function of the AD536A thus  
results:  
VOUT = 2R2 I rms = VIN rms  
I4 = I12/I3  
The dB output is derived from the emitter of Q3, since the  
voltage at this point is proportional to log VIN. Emitter fol-  
lower, Q5, buffers and level shifts this voltage, so that the dB  
output voltage is zero when the externally supplied emitter  
current (IREF) to Q5 approximates I3.  
The output current, I4, of the squarer/divider drives the current  
mirror through a low-pass filter formed by R1 and the externally  
connected capacitor, CAV. If the R1, CAV time constant is much  
greater than the longest period of the input signal, then I4 is  
effectively averaged. The current mirror returns a current I3,  
which equals Avg. [I4], back to the squarer/divider to complete  
the implicit rms computation. Thus:  
CONNECTIONS FOR dB OPERATION  
A powerful feature added to the AD536A is the logarithmic or  
decibel output. The internal circuit computing dB works accu-  
rately over a 60 dB range. The connections for dB measure-  
ments are shown in Figure 10. The user selects the 0 dB level by  
adjusting R1, for the proper 0 dB reference current (which is set  
to exactly cancel the log output current from the squarer-divider  
at the desired 0 dB point). The external op amp is used to pro-  
vide a more convenient scale and to allow compensation of the  
+0.33%/°C scale factor drift of the dB output pin. The special  
T.C. resistor, R2, is available from Tel Labs in Londonderry,  
N.H. (model Q-81) or from Precision Resistor Inc., Hillside,  
N.J. (model PT146). The averaged temperature coefficients of  
resistors R2 and R3 develop the +3300 ppm needed to reverse  
compensate the dB output. The linear rms output is available at  
Pin 8 on DIP or Pin 10 on header device with an output imped-  
ance of 25 k; thus some applications may require an additional  
buffer amplifier if this output is desired.  
2
I4 = Avg. I1 /I4 = I1 rms  
[
]
dB Calibration:  
1. Set VIN = 1.00 V dc or 1.00 V rms  
2. Adjust R1 for dB out = 0.00 V  
3. Set VIN = +0.1 V dc or 0.10 V rms  
4. Adjust R5 for dB out = 2.00 V  
Any other desired 0 dB reference level can be used by setting  
Figure 9. Simplified Schematic  
VIN and adjusting R1, accordingly. Note that adjusting R5 for  
the proper gain automatically gives the correct temperature  
compensation.  
Figure 10. dB Connection  
6–  
REV. B