ACS704 Allegro Micro Systems, Inc., ACS704 Datasheet - Page 18

• Manufacturer Part Number: ACS704
• Manufacturer: Allegro Micro Systems, Inc.

ACS704ELC005-DS, Rev. 7
The eight PC boards in the figure above do not represent an ideal PC board for use with the ACS704. The ACS704 evaluation
boards, for sale at the Allegro Web site On-Line Store, represent a more optimal PC board design (see photo below). On the
evaluation boards, the current to be sensed flows through very wide traces that were fabricated using 2 layers of 2 oz. copper.
Thermal management tests were conducted on the Allegro evaluation boards and all tests were performed using the same test
conditions described in the bulleted list above. The results for these thermal tests are shown in the table below. When using
the Allegro evaluation boards we see that even at an applied current of 20 A the junction temperature of the ACS704 is only
~30 degrees above ambient temperature.
The results of the testing are shown in the following table.
Effect of PCB Layout on ACS704 Thermal Performance
Tested at 15A, T
Sides with Traces
PC Boards
ACS704 Thermal Performance on the Allegro Eval PC Boards
1
2
A
= 20°C, still air, 2 oz. copper traces
Applied Current (A)
T
A
Trace Width (mm)
ACS704ELC-005
= 20°C, Still Air
15
20
1.5
1.5
1.5
1.5
4
4
4
4
Improved PC Board Designs
Temp Rise Above Ambient
Trace Length (mm)
50
50
10
10
50
50
10
10
(°C)
22
31
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
Above Ambient (°C)
Temperature Rise
Overheated
106
110
90
48
53
38
54
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