Noise-tolerant op-amps from Rohm

November 20, 2017 // By Graham Prophet
With its BA8290xYxx-C series, Rohm Semiconductor is offering automotive-grade op-amps with “unprecedented” noise immunity, that contributes to improved reliability and simpler designs in automotive sensor applications and allows the designer to reduce the amount of additional filtering required.

Output voltage fluctuations are suppressed in all frequency bands to less than ±1%, compared to ±3.5% to ±10% with conventional amplifiers. This allows, for example, sensor signals to be amplified without the need for noise countermeasures, which significantly reduces design load and contributes to greater reliability. The new series is suited for automotive applications, where sensors are used along with the core systems for electric vehicles (EV) and hybrid electric vehicles (HEV).


As it is extremely difficult to evaluate individual sources of noise during automotive development, noise evaluation has to be performed after installation. Unless careful attention is paid to the design of the noise suppression, major modifications (entailing increased costs and development time) may be required if the application fails testing. With this problem in mind, Rohm developed these, the first op-amps that eliminate the effects of noise in automotive sensor applications by utilising a vertically integrated production with analogue design technologies and bipolar processes.


TheBA8290xYxx-C series combines circuit design expertise (new noise countermeasures circuit), layout (based on market-proven analogue expertise) and use of bipolar processes. This approach reduces the number of components required for noise suppression (three RC filters for input, output and power supply), and also meets noise-related challenges in the development of automotive electrical systems, whilst contributing to lighter design load and higher reliability. Rohm is also developing high noise immunity op-amps for the industrial market.


The BA8290xYxx-C series is AEC-Q100 qualified for automotive applications. It is characterised by a low current consumption of 0.5 mA (BA82904YF-C/BA82904YFVM-C) and/or 0.7 mA (BA82902YF-C/BA82902YFVM-C). The ICs are available in four versions with two or four op-amps and a supply voltage range from 3.0V to 36V. Their input offset voltage is typically around ±2 mV and/or a maximum of ±6 mV, the input voltage range between VEE and VCC-1.5V. The operating temperature range is –40°C to +125°C. Package versions, SOP8 (BA82904YF), MSOP8 (BA82904YFVM-C), SOP14 (BA82902YF-C) and SSOP-B14