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The TSU111, 112 and 114 from STMicroelectronics are operational amplifiers which may be used in circuits supplied by a lithium-ion coin cell battery, or by a regulated voltage in low-power applications.

The op amps draw just 900nA when operating from a supply voltage of 3.3V at 25°C while offering 11.5kHz of gain bandwidth product. They work with any supply voltage in the range 1.5V-5.5V, fitting the output-voltage profile of standard lithium coin cells.

Thanks to their zero-drift technology the TSU11x op amps provide accurate amplification of low-voltage sensor signals: the input-offset voltage is a maximum 150μV at an ambient temperature of 25°C.

The performance of two TSU111 op amps is demonstrated in ST’s P-NUCLEO-IKA02A1, a gas-sensing expansion board for STM32 Nucleo microcontroller development boards.

The TSU111 op amps perform signal conditioning for a choice of electrochemical gas sensors that may be mounted in standard sockets on the expansion board. The expansion board includes a low-current precision analogue temperature sensor, the STLM20, for compensation of gas readings.

  • 3.6μVp-p noise over 0.1Hz to 10Hz bandwidth
  • Rail-to-rail input and output
  • 10pA input bias current at 25°C
  • 4kV ESD rating on the human body model
  • Sensor signal conditioning
  • Battery-powered and portable devices


A gas-sensing expansion board for STM32 Nucleo microcontroller development boards.


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