Data Brief
For further information contact your local STMicroelectronics sales office
December 2007 Rev 2 1/4
4
STEVAL-ISA028V1
Single phase 20 A step-down converter evaluation board
based on the L6727
Features
■BOM optimized for 12 V input / 1.25 V output @
20 A
■High flexibility to host wide range designs
■Customizable output voltage
■L6726A / L6727 compatibility
■Controller input voltage (VCC) range from 5 V to
12 V
■Conversion input voltage (VIN) up to 13.2 V
■DPAK / SO-8 / PowerSO-8 / PowerFLAT
MOSFET compatibility
■Multi-footprint for input and output capacitors
■Through-hole / SMD inductor compatibility
■4-layer PCB
Description
This evaluation board demonstrates the key
features of STMicroelectronics’ L6727, a new
powerful new buck controller. The L6727 makes
the design of complete step-down voltage
regulators simple and cost effective. It provides a
full solution by integrating a 0.8 V reference,
control logic and protection, and NMOS drivers in
an 8-pin package. The L6727 evaluation board
implements a step-down DC/DC converter in a
four-layer PCB and demonstrates the operation of
the device in a general-purpose application. The
input voltage can range from 5 V to 12 V and the
output voltage is fixed at 1.25 V. The application
can deliver an output current up to 20 A. Airflow
must be applied with current higher than 18 A
(@VIN = 5 V). The switching frequency is 300 kHz.
STEVAL-ISA028V1
www.st.com
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Board schematic STEVAL-ISA028V1
2/4
1 Board schematic
Figure 1. Schematic
C14
1uF
0
C381uF
C15
NC
R16
0
C16
NC
C17
NC
C18
2200uF
COMP
0
FB
R7
33k
R9
2.2k
R13
3.9k
0
R6
12k
0 0
C24
10nF
C35
33pF
0
C36
NC
PHASE
R8
0
R14
NC
1
3 2
Q6
NC
R12
NC
1 2
L1
NC
PHASE
4
51
6
7
8
2
3
Q1
NC
HSG
OUT
PHASE
HSD
GND
4
51
6
7
8
2
3
Q2
NC
LSG1
LGATELGATE
PHASE
R11
0
HSG
R10
NC
0
R1
3.3
C37
NC
00
VCC
COMP
C19
NC
C20
NC
C21
NC
PHASE
VCC_PIN C22
NC
VCC_PIN
R15
NC
FB
R18
NC
000
LGATE
0
OUT
VCC 5
GND
3FB 6
UGATE
2
BOOT
1
COMP 7
PHASE 8
LGATE
4
L6726A/27
U1
COMP FB
GND
4
51
6
7
8
2
3
Q3
NC
1
3 2
Q4
STD55NH2LL
LSG2
1
3 2
Q5
STD90NH2LL
PHASE
0
C11
4.7uF
C12
4.7uF
C13
4.7uF
HSDHSD
VIN_POWER
000
C3
NC
C2
1800uF
0 0
VOUT
0
VIN1
VIN_POWER
GNDIN_POWER
C25
2200uF
C26
NC
0 0
C27
NC
C28
NC
C29
NC
C30
NC
00
GNDIN1
0 0
C31
NC
C32
NC
C33
NC
C34
NC
0000
OUT
R3
2.2
R5
0
LSG1
C5
NC
UGATE
C7
NC
UGATE
C9
NC
00 0
C4
NC
C6
NC
C8
NC
00 0
0
GNDOUT
C1
1800uF
0
D1
1N4148 R2
3.3
C10
100nF
BOOT
BOOT
12
L2
T60-18 6Ts
PHASE
UGATE
VOUT1
R17
2.2
GND
GNDOUT1
0
GNDCC
VCC
GND
VCC
LGATE R4
1.8
C23
6.8nF
0
VCC
GND
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STEVAL-ISA028V1 Revision history
3/4
2 Revision history
Table 1. Document revision history
Date Revision Changes
10-Jul-2007 1 Initial release
06-Dec-2007 2 Content reworked to improve readability. No content change.
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STEVAL-ISA028V1
4/4
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