a5975d STMicroelectronics, a5975d Datasheet - Page 31

• Manufacturer Part Number: a5975d
• Description: Up To 3 A Step-down Switching Regulator For Automotive Applications
• Manufacturer: STMicroelectronics

A5975D
In applications where the current to the output is pulsed, the thermal impedance should be
considered instead of the thermal resistance.
The thermal impedance of the system could be much lower than the thermal resistance,
which is a static parameter. And so the maximum power losses can be higher than 2.5 W if
a pulsed output power is requested from the load:
Therefore, depending on the pulse duration and its frequency, the maximum output current
can be delivered to the load.
The characterization of the thermal impedance is strictly dependent on the layout of the
board. In
of the A5975D is provided.
Figure 17. Measurement of the thermal impedance of the demonstration board
As can be seen, for example, for load pulses with a duration of 1 second, the actual thermal
impedance is lower than 20 °C/W. This means that, for short pulses, the device can deliver a
higher output current value.
Figure 17
the measurement of the thermal impedance of the demonstration board
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Doc ID 018760 Rev 1
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Application information
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