ST ISA039V1 User Manual
Single phase 5A step-down converter evaluation board
Features
■ Input voltage: from 5V to 12V
■ Output voltage: fixed @ 1.25V but
customizable by changing resistor
■ Output current:up to 5A
■ Swicthing frequency: 300KHz
Description
The purpose of this design is to demonstrate the
key features of STMicroelectronics L6727 a new
powerful buck controller. The L6727 allow simple,
cost effective design of complete step-down
voltage regulators. Indeed it provides a full
solution by integrating a 0.8V reference, control
logic and protection, and NMOS drivers in an 8pin package. L6727 demo board realizes in a twolayer PCB a step-down DC/DC converter and
shows the operation of the device in a generalpurpose low-current application. The input voltage
can range from 5V to 12V buses and the output
voltage is fixed at 1.25V. The application can
deliver an output current in excess of 5A. The
switching frequency is 300 kHz.
STEVAL-ISA039V1
based on L6727
Data Brief
STEVAL-ISA039V1
July 2007 Rev 1 1/4
For further information contact your local STMicroelectronics sales office
www.st.com
4
Board schematic STEVAL-ISA039V1
1 Board schematic
Figure 1. Schematic
R6
12k
VCC_PIN
COMP FB
COMP
C35
33k
R7
10nF
33pF
NC
00
3.9k
NC
NC
NC
C24
R12
R8
0
R13
C37
FB
R9
2.2k
R14
C36
PHASE
R10
NC
R11
0
0
R15
NC
0
0
R18
NC
C14
R1
LGATELGATE
R5
0
LSG1
1
3 2
STD90NH2LL
1
3 2
NC
LGATE
UGATE
BOOT
GND
3
1
4
GND
LGATE
UGATE2BOOT
U1
L6726A/27
PHASE
COMP
VCC
FB
6
8
7
5
VCC_PI N
1uF
COMP
FB
3.3
VCC
LGATE R4
Q5
Q6
PHASE
R17
2.2
UGATE
PHASE
R3
2.2
HSG
1
3 2
STD55NH2LL
0 0 0
C11
GNDCC
VCC
0
GND
VCC
GND
0
C381uF
UGATE
3.3
100nF
BOOT
C10
HSDHSD
Q4
VIN_POWER
4.7uF
0
VCC
R16
0
0
C1
1800uF
D1
1N4148
0 0
C2
1800uF
R2
C3
NC
C4
C5
C6
00 0
C7
00 0
C8
C9
VIN_POWER
GNDIN_POWER
VIN1
GNDIN1
NC
NC
NC
NC
NC
NC
0
1.8
C23
6.8nF
2200uF
0 0
00
0 0
0 0 0 0
C25
NC
C26
NC
C27
NC
C28
NC
C29
NC
C30
NC
C31
NC
C32
NC
C33
NC
C34
0
0 0
0
OUT
0 0 0
0
0
T60-18 6Ts
NC
C15
NC
C16
NC
C17
2200uF
C18
NC
C19
NC
C20
NC
C21
NC
C22
GNDOU T1
GNDOUT
2/4
4.7uF
L2
12
OUT
VOUT
C12
4.7uF
C13
VOUT1
HSG
Q1
NC
4
51
6
2
7
3
PHASE
GND
GND
8
HSD
LSG1
Q2
NC
4
51
PHASE
6
2
7
3
8
PHASE
1 2
L1
LSG2
4
2
3
NC
Q3
NC
OUT
51
6
7
8
PHASE
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