ST ISA024V1 User Manual

STEVAL-ISA024V1

20 A step-down DC-DC converter demonstration board with

3.3 V

and 250 kHz switching frequency, based on the L6725

out

Features

■ Input voltage, V

■ Output voltage: 3.3 V

■ Selectable switching frequency: 250 kHz / 500

kHz

■ Over-voltage protection

■ Thermal shutdown

: from 4.5 V to 14 V

IN

Description

This 4-layer PCB demonstration board is
designed as a step-down DC-DC converter to
demonstrate the operation of the L6725 device in
a general-purpose application. The input voltage
can range from 4.5 V to 14 V with an output
voltage of 3.3 V. The module can deliver an output
current in excess of 20 A. The L6725 device can
manage minimum ON times (T
100 ns. This makes possible conversions with
very low duty cycles and very high switching
frequencies. The switching frequency is initially
set at 250 kHz (controller free-running FSW), but
a switching frequency of 500 kHz can also be
selected.

) shorter than

ON

Data Brief

STEVAL-ISA024V1

September 2008 Rev 1 1/4

For further information contact your local STMicroelectronics sales office.

www.st.com

4

Board schematic STEVAL-ISA024V1

J1

J2

1 Board schematic

Figure 1. Schematic

C11

C9

R9

D1

C12-C13

C10

OCH

BOOT

VCCD R

R11

HGATE

5

8

11

7

3

EAREF

L1

Q4-6

PHASE

VOUT

6

C5

GOUT

C16-C19

C15

R12

C1

D3

C4

Q1-3

R10

LGATE

PGND

9

10

SS

2

R3

R1

16

VFB

R4

C2

COMP

1

R2

C3

U1

OCL

4

R7

12

VCC

L6725

15

GND

C7

R8

R5

R6

C8

VIN

2/4

GIN

VCC

EXT REF