Data Sheet

LT8641A

analog.com

Rev 0

29 of 35

Temperature rise of the LT8641A is worst when operating at high load, high VIN, and high switching frequency. If the

case temperature is too high for a given application, then either VIN, switching frequency, or load current can be

decreased to reduce the temperature to an acceptable level. Figure 50 shows examples of how case temperature rise

can be managed by reducing VIN, switching frequency, or load.

The LT8641A’s internal power switches are capable of safely delivering up to 5A of peak output current. However,

due to thermal limits, the package can only handle 5A loads for short periods of time. This time is determined by how

quickly the case temperature approaches the maximum junction rating. Figure 51 shows an example of how case

temperature rise changes with the duty cycle of a 1kHz pulsed 5A load.

The LT8641A’s top switch current limit decreases with higher duty cycle operation for slope compensation. This also

limits the peak output current the LT8641A can deliver for a given application. See the curve in Typical Performance

Characteristics.

Figure 51. Case Temperature Rise vs 5A Pulsed Load

VIN = 12V

VOUT = 5V

fSW = 2MHz

STANDBY LOAD = 0.5A

1kHz PULSE LOAD = 5A

DUTY CYCLE OF 5A LOAD

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