Op-amp rejects noise for car use, claims Rohm

Rohm low-noise automotive op-amp

“Greater digitalisation and application density in automotive systems exacerbate the problem of EMC, since each additional component constitutes a potential source of interference. This presents significant problems for sensors and other small-signal devices,” it said. “Since 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 may be required if the application fails testing.” – adding the claim that in these op-amps output voltage fluctuations are suppressed in all frequency bands to less than ±1%, compared to ±3.5% to ±10% with conventional products.

Rohm low-noise op-amp restThe test set-up

Specified power supply rejection ratio is 100dB typ (70dB min).

In the BA8290xYxx-C series, there are some duals

  • BA82904YF-C SOP8 package
  • BA82904YFV-C SSOP
  • B8BA82904YFVM-C MSOP8

and some quads

  • BA82902YF-C SOP14
  • BA82902YFV-C SSOP-B14

– odd that the duals are numbered ’04’ and the quads ’02’.

Rohm low noise op amp appTypical application – blue arrow is noise, said Rohm

They are made on a bipolar process, qualified to AEC-Q100, and operate from 3 to 36V across -40 to +125°C. Specifications are largely with a 5V single rail supply. Consumption is 0.5mA for the duals or 0.7mA in the quads.

Input offset voltage is ±2mV typ (±6mV max) and inputs can range between Vee and Vcc-1.5V. Unusually, the data sheet has a good section on how not to annoy the parasitic transistors on the inputs.

Outputs can source 30mA and sink 20mA.

The parts are sampling now, with OEM quantities expected in June 2018.

Potential applications:

  • EV/HEV inverters
  • ECUs
  • Automatic gearboxes
  • Electric power steering
  • Automotive lamps
  • Car A/C
  • EV chargers
  • Car navigation
  • Combination switches

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