STEVAL-ISA028V1
Single phase 20 A step-down converter evaluation board based on the L6727
Data Brief
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 STEVAL-ISA028V1
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.
December 2007
Rev 2
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www.st.com 4
For further information contact your local STMicroelectronics sales office
1
5 6 7 8
5 6 7 8
0
C4 H SG 4
1 2 3 1 2 3
R 16 0
C1 1800uF C5 LSG1 4 LSG2 4
1 2 3
C2 1800uF C6 C7 C8 C9
5 6 7 8
H SD SD H
U GATE 4. 7uF Q4 STD 55N H 2LL C 11 C 12 C 13 4. 7uF 4. 7uF U GATE R3
3
H SG 1 2. 2
U1
PH ASE
2
2
LGATE VC C LGATLGATE R 5 E 1
3 3
4 LGATE LSG1 0 C 23 6. 8nF Q5 STD 90N H 2LL 1 Q6 NC NC R4 1. 8
LGATE
5
2
VC C _PI N
PH ASE
C OM P
R6 12k R8 0 R 14 R 13 3. 9k NC NC C 36 C 37 NC 2. 2k R9 0
R7
C 24
FB
2/4
L1 PH ASE 1 2 NC NC
H SD PH ASE PH ASE
Figure 1.
Board schematic
VI N 1
VI N _POW ER OU T
GN D I N 1 NC Q1 NC Q2 NC Q3 NC NC NC NC NC
Schematic
GN D I N _POW ER C3 NC
VC C D1 1N 4148 R2
GN D
0
0
0
0
0
0
0
0
0
VC C
PH ASE
VC C 3. 3 1uF VI N _POW ER C 38 BOOT 100nF C 10
GN D
GN D
GN D C C
Board schematic
GN D
0
0
0
PH ASE
0
0
BOOT 8 7 2. 2 1 C 15 C 16 NC 6 VC C _PI N VC C 3. 3 1uF R1 C14 FB L2 2 T60-18 6Ts C OMP C OMP FB
1
L6726A/27
R 17 VOU T1 VOU T OU T
BOOT
PH ASE
U GATE
2
U GATE
GN D
3
GN D
C 17 NC
C 18
C 19 2200uF N C
C 20 NC
C 21 NC
C 22 NC GN D OU T1 GN D OU T
R 18 NC R 15 NC
0
0 0
0
0
0
0
0
0
0
0
0
0
C OMP
FB
OU T
C 25 R 10 NC R 11
C 26 2200uF N C
C 27 NC
C 28 NC
C 29 NC
C 30 NC
C 31 NC
C 32 NC
C 33 NC
C 34 NC
33k
10nF
C 35
0
0
0
0
0
0
0
0
0
0
33pF
R 12 NC
STEVAL-ISA028V1
0
0
STEVAL-ISA028V1
Revision history
2
Revision history
Table 1.
Date 10-Jul-2007 06-Dec-2007
Document revision history
Revision 1 2 Initial release Content reworked to improve readability. No content change. Changes
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STEVAL-ISA028V1
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