Sky Works


1 A step-down switching regulator demonstration board based on the L5981

Topologie: Buck
Eingangsspannung (min.): 3.30 V
Eingangsspannung (max.): 18.00 V
Schaltfrequenz (min.): 250.00 kHz
Schaltfrequenz (max.): 1000.00 kHz
Ausgang 1: 3.30 V / 1.000 A

Erstveröffentlichung am 20.10.2005, Version 1 vom


The EVAL5981 demonstration board provides the design engineer with a fully functional step-down switching regulator with an output current of up to 1 A. The L5981 integrates STMicroelectronics step-down switching regulator, together with all the external components required for a typicalapplication.The rated voltage of the input capacitor and the Schottky diode rectifier repetitive peak reverse voltage are both 25 V, making the board capableof covering the entire 2.9 V - 18 V input voltage range of the L5981 device.The board features an external resistor divider (R1 and R2) designed for an output voltage of 3.3 V.The output voltage can be set to a level from 0.6 V up to the rated voltage of the output capacitor (16 V). The compensation network on the demonstration board allows the use of MLCC as output filter to keep the loop stable. The inductor saturation current and forward current of the Schottky diode are within the current limit values.The switching frequency on the demonstration board is set to 500 kHz by means of the R5 resistor connected to pin Fsw.


  • 1 A DC output current2.9 V to 18 V input voltage Output voltage adjustable from 0.6 V250 kHz switching frequency, programmable
  • up to 1 MHzInternal soft-start and inhibitLow dropout operation: 100% duty cycle Voltage feedforward Zero load current operation Overcurrent and thermal protection VFQFPN8 3 mm x 3 mm package
  • refer
  • Table 7.Inductors
  • Page no 16


  Artikel Nr. SPEC Produktserie L
RDC typ.
RDC max.
Version Muster
7447779115 PDF WE-PD SMT-Speicherdrossel 15 1.6 2.2 70 81 19.5 Robust