90 kHz CMOS op-amp for low-frequency sensor conditioning
The ROHM BU7421SG-TR is a single-channel CMOS operational amplifier designed for applications where power consumption and signal fidelity at low frequencies matter more than raw speed. Its 90 kHz gain-bandwidth product and 0.05 V/µs slew rate make it a natural fit for conditioning slow-moving signals from thermocouples, RTDs, strain gauges, or photodiodes — any sensor output that changes in the tens-of-hertz to single-kilohertz range. The 8.5 µA supply current per channel keeps the power budget tight, and the rail-to-rail output swing lets you drive an ADC input directly without an extra gain stage.
Input bias and offset — DC accuracy for precision loops
With a 1 pA typical input bias current and 1 mV input offset voltage, the BU7421SG-TR handles high-impedance sources like pH probes or piezoelectric sensors without loading the signal. The 8 mA output drive per channel is enough to swing a small relay or drive a 2 kΩ load to the rails, but not intended for heavy capacitive loads — keep the load capacitance under a few hundred picofarads unless you add a series resistor.
Package and footprint — SOT-753 / SC-74A
The small footprint suits dense PCB layouts, but the fine pitch means a stencil with good aperture ratio is needed for consistent solder paste deposition in reflow assembly.