Datasheet

LM2588
www.ti.com SNVS117D –APRIL 1998–REVISED APRIL 2013
Figure 43. T1 - Top View Figure 44. T2 - Top View
Schott 67141450 Schott 67140860
Figure 45. T3 - Top View Figure 46. T4 - Top View
Schott 67140920 Schott 67140930
Step-Up (Boost) Regulator Operation
Figure 47 shows the LM2588 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 LM2588 Boost Regulator works is as follows (refer to Figure 47). 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 the Flyback Regulator section.
Figure 47. 12V Boost Regulator
By adding a small number of external components (as shown in Figure 47), the LM2588 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 48. Typical performance of this regulator is shown in
Figure 49.
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