LM2621

SNVS033D – MAY 2004 – REVISED NOVEMBER 2015

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8.2.4 3.3-V / 0.5-A SEPIC Regulator

Figure 18. 3.3-V/0.5-A SEPIC Regulator

8.2.4.1 Design Requirements

Design requirement for the SEPIC is similar to that of a boost but the current flowing through the switch is the

addition of the current flowing through L1 and L2. As a result, the peak current through the main switch is

IIN+IOUT+0.5xDeltaIL1+0.5xDeltaIL2. See SLYT309 for detail on the specific design requirement of a SEPIC

converter.

8.2.4.2 Detailed Design Procedure

Follow the detailed design procedure in Detailed Design Procedure.

Table 3. Bill of Materials

Manufacturer

Part Number

Description

U1

TI

LM2621MM

Low Input Voltage Regulator

C1

Sanyo

10CV220AX, SMT AL-Electrolytic

220 µF

C2

TDK

C2012X7R1C225M, MLCC

2.2 µF

C3

Vishay

VJ0603A331KXXAT

33 pF

C4

TDK

C3225X7R0J107MT

100 µF

C5, C6

Vishay

VJ0603Y104KXXAT

0.1 µF

D1

Philips

BAT54C

VR = 1V

D2

Vishay

MBRS120

1A / VR = 20V

L1, L2

Coilcraft

DO1813P-682HC

6.8 µH

R1

Vishay

CRCW08054990FRT6

499

Ω

R2

Vishay

CRCW08051503FRT6

150 k

Ω

R3

Vishay

CRCW08053923FRT6

392 k

Ω

R4

Vishay

CRCW08059092FRT6

90.9 k

Ω

14

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