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11 - Rev 1.0 February 2018
P
OWER
C
ONSIDERATIONS
Maximum Current and Voltage
The PAC5532EVK1 evaluation module was designed to operate with voltages in the 80V to 120V range.
Transients can go to as high as 160V (Abs Max).
The recommended operating current is 10A RMS per phase. Higher currents could be achieved, albeit the
user is responsible for applying different techniques to handle the increased thermal dissipation needs.
Please see the “Increasing Output Power” section for more information on how to achieve higher current
loading.
SENSE Resistors
The SENSE resistors utilized to digitize motor winding current will determine how much current the three
phase inverter will be able to handle. The PAC5532EVK1 module ships with 0.01 Ohm 3W SENSE resistors.
For higher current handling, a smaller SENSE resistor could be employed.
The equation utilized to compute maximum tri phase inverter leg current is:
=
Users are encouraged to modify SENSE resistor value according to their application. The following table
showcases different resistance values, maximum currents and suggested part numbers.
NOTE
: For increased current handling, adding thermal heat sinking to the power FETs must be considered.
Power FETs
The PAC5532EVK1 ships with six IRFB4227PBF TO-220 Power FETs. These power switches are rated at
200V and 130A. RDSON is about 0.020 Ohms. In order to obtain the maximum performance out of these
components, some form of heat sinking is required. The evaluation module ships without a heat radiation
device. The appendix offers guidelines the measurements users can employ to fabricate their own version of
a simple metal heat plate.
Users are also encouraged to modify the evaluation module by exchanging power switches with other
components offering better thermal performance. Power FETs designed with a lower RDSON would tend to
require less heat sinking. Traditionally, such FETs would have a lower maximum voltage, but for applications
requiring smaller voltages, this may be an acceptable option.
Resistance (
Ω
)
Rated Power (W)
Maximum RMS Current (A)
Part Number
0.01
3
17.3
CRA2512-FZ-R010ELF
0.002
5
50
CSS2H-2512K-2L00F