LM2585S-12 National Semiconductor, LM2585S-12 Datasheet - Page 18

• Manufacturer Part Number: LM2585S-12
• Description: DC/DC Converter IC
• Manufacturer: National Semiconductor

Specifications of LM2585S-12

• Input Voltage: 40V
• Output Voltage: 12V
• No. Of Pins: 5
• Peak Reflow Compatible (260 C): No
• Termination Type: SMD
• Supply Voltage Max: 40V
• Leaded Process Compatible: No
• Mounting Type: Through Hole
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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FIGURE 23. Pulse PE-68413
FIGURE 24. Renco RL-5751
FIGURE 25. Renco RL-5533
FIGURE 26. Renco RL-5532
(Surface Mount)
Top View
Top View
Top View
Top View
T5
T7
T6
T5
1251543
1251540
1251542
1251539
18
Step-Up (Boost) Regulator
Operation
Figure 30 shows the LM2585 used as a step-up (boost) reg-
ulator. This is a switching regulator that produces an output
voltage greater than the input supply voltage.
A brief explanation of how the LM2585 Boost Regulator works
is as follows (refer to Figure 30). When the NPN switch turns
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
FIGURE 28. Schott 67140900
FIGURE 29. Schott 67140890
FIGURE 27. Top View
Schott 26606
Top View
Top View
T7
T6
T5
IN
, discharging its current
OUT
1251546
) at a rate of
IN
1251547
/L, storing
1251544