LM2587T-3.3 National Semiconductor, LM2587T-3.3 Datasheet - Page 18

• Manufacturer Part Number: LM2587T-3.3
• Description: IC, FLYBACK REGULATOR, TO-220-5
• Manufacturer: National Semiconductor

Specifications of LM2587T-3.3

• Input Voltage: 40V
• Output Current: 5A
• Output Voltage: 3.3V
• No. Of Outputs: 1
• Supply Voltage Range: 4V To 40V
• No. Of Pins: 5
• Operating Temperature Range: -40°C To +125°C
• Termination Type: Through Hole
• Filter Terminals: Through Hole
• Rohs Compliant: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

www.national.com
Step-Up (Boost) Regulator
Operation
Figure 33
ulator. This is a switching regulator that produces an output
voltage greater than the input supply voltage.
A brief explanation of how the LM2587 Boost Regulator works
is as follows (refer to
By adding a small number of external components (as shown in
the applied input voltage. The switching waveforms observed during the operation of this circuit are shown in
shown in
Figure
shows the LM2587 used as a step-up (boost) reg-
35.
Figure
33). When the NPN switch turns
FIGURE 33. 12V Boost Regulator
FIGURE 32. Schott 67140930
Figure
33), the LM2587 can be used to produce a regulated output voltage that is greater than
Top View
T4
18
on, the inductor current ramps up at the rate of V
energy in the inductor. When the switch turns off, the lower
end of the inductor flies above V
through diode (D) into the output capacitor (C
(V
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.
OUT
− V
IN
)/L. Thus, energy stored in the inductor during the
1231647
Figure
34. Typical performance of this regulator is
IN
, discharging its current
1231619
OUT
) at a rate of
IN
/L, storing