January 2010

Doc ID 16021 Rev 2

1/14

AN3008

Application note

STOD2540, single inductor DC-DC converter

generates multiple supply voltages for E-paper display

Introduction

This application note describes how to use the STOD2540 DC-DC converter to generate

two output voltages using a single inductor and an external charge pump. The circuit shown

in Figure 1 generates a 70 V output from a 3.7 V input voltage.

The STOD2540 is a highly integrated boost converter that can provide an adjustable output

up to 35 V from a 3.0 to 5.5 V input voltage.

The STOD2540 operates in PFM (pulsed frequency modulation) mode. PFM control simply

means that the part only switches when the charge needs to be delivered to the output in

order to keep the output voltage regulated.

The converter is ideal for generating the necessary voltages to supply thin-film transistor

(TFT) LCDs, OLEDs and E-paper shelf labels. The low operating supply current makes the

device ideal for small, portable, battery supplied applications. In shutdown mode the load is

disconnected from the input and the quiescent current is less than 3 µA.

Figure 1.

High voltage power supply based on STOD2540

CIN: 4.7

μF

COUT: 2 x 1

μF 100 V

C1: 100 nF 50 V

C2: 4.7

μF 50 V

L1: 4.7

μH

D1, D2, D3: STPS2L40AF

R3

550k

COUT

CIN

C1

C2

D3

D2

R4

10k

L1

D1

U1

STOD2540

VIN

1

RSET

2

AGND

3

FB

4

Vo

5

Vcap

6

ENABLE

7

SW

8

PGND

9

CIN: 4.7

μF

COUT: 2 x 1

μF 100 V

C1: 100 nF 50 V

C2: 4.7

μF 50 V

L1: 4.7

μH

D1, D2, D3: STPS2L40AF

R3

550k

COUT

CIN

C1

C2

D3

D2

R4

10k

L1

D1

U1

STOD2540

VIN

1

RSET

2

AGND

3

FB

4

Vo

5

Vcap

6

ENABLE

7

SW

8

PGND

9

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