STMicroelectronics – Robust 2A switching regulator accepts input voltages up to 38V


The A6986 from STMicroelectronics is a step-down monolithic switching regulator for battery-powered automotive systems which has a maximum output of 2A.

Two features of the A6986 are particularly useful to designers of systems which run on the power supplied by an automotive battery:
• Its 100% duty-cycle capability helps it to withstand cold-crank events
• It has a wide input-voltage range of 4V to 38V. The output voltage is adjustable in a range from 0.85V up to the input-voltage value.

The device has two operating modes in which regulation is optimised either for high power efficiency or for noise reduction. In Low Consumption Mode (LCM), it maximises light-load efficiency while limiting the output-voltage ripple. This is suitable for applications which are active when the vehicle is stationary.

In Low Noise Mode (LNM), the A6986 operates at a constant switching frequency, and minimises output-voltage ripple over the entire load-current range. This is helpful for noise-sensitive applications such as car audio systems. The regulator implements synchronous rectification to achieve high efficiency when controlling medium or heavy loads. An adjustable switching frequency up to a maximum of 2MHz allows for the use of small supporting components, helping the designer to reduce the size of the power system.

Pulse-by-pulse current sensing on both power elements enables effective constant-current protection.


  • AEC-Q100 qualified
  • 30μA quiescent current
  • 8μA shut-down current
  • Embedded output-voltage supervisor
  • Adjustable soft-start time
  • Internal current limiting
  • Over-voltage protection
  • Output-voltage sequencing


  • Battery-powered automotive applications
  • Car body applications in LCM
  • Car audio and low-noise applications in LNM

The STEVAL-ISA158V1, an evaluation board for the A6986, demonstrates the device’s performance over its input-voltage range of 4V to 38V.

Orderable Part Number: STEVAL-ISA158V1