低功耗运算放大器降低电缆成本的pH探头

摘要：该电路显示了如何使用一个MAX406 CMOS运算放大器非常高的输入阻抗非常高的输出阻抗缓冲pH值探头。所具备的优势，是一个标准的低成本电缆代替高成本的聚四氟乙烯介质同轴电缆的使用。该电路可连续数千小时的单节锂电池供电，电池的消耗是如此之低。驾驶一台液晶显示器显示的MAX130A集成ADC的使用。
Maxim > App Notes > Amplifier and Comparator Circuits Sensors
Keywords: op-amp, low power, buffer, pH probe, integrating ADC, analog to digital converter, op amps, opamp Nov 21, 2000

APPLICATION NOTE 34
Low-Power Op-Amp Reduces Cable Costs for pH Probe


Abstract: The circuit shows how to use the very high-input impedance of a MAX406 CMOS op amp to buffer the extremely high-
output impedance of a pH probe. The advantage gained is the use of a standard low-cost cable instead of a high-cost Teflon
dielectric coax cable. Battery drain is so low that the circuit can be continuously powered for thousands of hours on a single
lithium cell. Use of a MAX130A integrating ADC is shown for driving a LCD display.


The extremely high source impedance of a pH probe (1012 Ω) often mandates t