LT7184S datasheet(41/52 Pages) AD

41 / 52 page

Data Sheet

LT7184S

analog.com

Rev. 0

41 of 52

Thermal Considerations

Care should be taken in the layout of the PCB to ensure good heat dissipation from the LT7184S package. The ground

pins on the bottom of the package should be soldered to a ground plane. The ground pins should be connected to

the large copper ground plane below the LT7184S with thermal vias; the ground plane will spread the heat dissipated

by the LT7184S. Placing additional vias can reduce thermal resistance further. The maximum load current must be

derated as the ambient temperature rises such that the junction temperature approaches the maximum junction

temperature rating.

The temperature rise of the LT7184S is worst when operating at a very high load, high PVIN, and high switching

frequency. If the case temperature is too high for a given application, then either PVIN, switching frequency, or load

current can be decreased to reduce the temperature to an acceptable level.

The internal junction temperature of the LT7184S is reported via the READ_TEMPERATURE_1 command. When the

internal READ_TEMPERATURE value passes the programmable OT_WARN_LIMIT, the STATUS_TEMPERATURE_OT

Warning bit is set. When the internal READ_TEMPERATURE value passes the programmable OT_FAULT_LIMIT, then

the STATUS_TEMPERATURE_OT Fault flag is set. The LT7184S can be programmed to latch off or restart when the

overtemperature fault occurs. However, the STAUTS_TEMPERATURE_OT Warning and STATUS_TEMPERATURE_OT

Fault flags can only be reset by issuing a CLEAR_FAULTS command or by cycling the OPERATION commands, the RUN

pins, or the EXTVCC and PVIN0 power supplies.

Figure 42. Recommended PCB Layout

LT7184S Arkusz danych(PDF) 41 Page - Analog Devices