STMicroelectronics — L6981/L6982 Synchronous Step-Down Regulator IC

STMicroelectronics L6981/L6982 Synchronous Step-Down Regulator IC

Synchronous step-down converters save power with low quiescent current

The L6981 and L6982 from STMicroelectronics are easy-to-use, synchronous step-down regulator ICs which feature a wide input-voltage range of 3.5 V to 38 V, making them ideal for use in 24 V industrial power buses. The L6981 can supply up to 1.5 A dc to the load, and the L6982 can supply 2 A.


The L6981 and L6982 are based on a peak current-mode architecture. Housed in an SO8 package with internal compensation, these devices minimize the complexity and size of power-system designs.


The regulators are available in versions operating in a low-consumption mode (LCM) or a low-noise mode (LNM). The LCM maximizes efficiency at light loads with controlled output-voltage ripple: this variant is suitable for battery-powered applications.


LNM keeps the switching frequency constant and minimizes output-voltage ripple in light-load operations. This is ideal for noise-sensitive applications.


Typical shut-down current is 2 µA when the device is disabled. As soon as the Enable pin is pulled up, the device is enabled and the internal 1.3 ms soft-start begins. Pulse-by-pulse current sensing on both power elements provides effective constant current protection. Thermal shut-down protection prevents thermal run-away.


The L6981 and L6982 are included in the ST 10-year longevity program which ensures long-term component supply.


  • Adjustable output-voltage range:
    • From 0.85 V to input-voltage value
  • Internal soft-start
  • Output-voltage sequencing
  • Synchronization to external clock in LNM devices


  • 24 V industrial power buses
  • 12 V and 24 V battery-powered equipment
  • Decentralized intelligent nodes
  • Sensors
  • Always-on applications

Evaluation Boards

Board Part Numbers: STEVAL-L6982CDR and STEVAL-L6982NDR

The STEVAL-L6982CDR is a 38 V, 2 A synchronous step-down switching regulator evaluation board based on the L6982CDR. The STEVAL-L6982NDR is a 38 V, 2 A synchronous step-down switching regulator evaluation board based on the L6982NDR.

Board Part Numbers: STEVAL-L6981CDR and STEVAL-L6981NDR

The STEVAL-L6981CDR evaluation board for the low-current converter is based on the L6981CDR step-down regulator, and the STEVAL-L6981NDR evaluation board for the low-noise version is based on the L6981NDR step-down regulator.

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