Datasheet

LM2586
SNVS121D –MAY 1996–REVISED APRIL 2013 www.ti.com
Step-Up (Boost) Regulator Operation
Figure 46 shows the LM2586 used as a step-up (boost) regulator. This is a switching regulator that produces an
output voltage greater than the input supply voltage.
A brief explanation of how the LM2586 Boost Regulator works is as follows (refer to Figure 46). When the NPN
switch turns on, the inductor current ramps up at the rate of V
IN
/L, storing energy in the inductor. When the
switch turns off, the lower end of the inductor flies above V
IN
, discharging its current through diode (D) into the
output capacitor (C
OUT
) at a rate of (V
OUT
− V
IN
)/L. Thus, energy stored in the inductor during the switch on time
is transferred to the output during the switch off time. The output voltage is controlled by adjusting the peak
switch current, as described in Flyback Regulator.
Figure 46. 12V Boost Regulator
By adding a small number of external components (as shown in Figure 46), the LM2586 can be used to produce
a regulated output voltage that is greater than the applied input voltage. The switching waveforms observed
during the operation of this circuit are shown in Figure 47. Typical performance of this regulator is shown in
Figure 48.
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