B1077AS-4R7N AD [Analog Devices], B1077AS-4R7N Datasheet - Page 20

• Manufacturer Part Number: B1077AS-4R7N
• Description: 1.2 A, 20 V, 700 kHz/1.4 MHz, Nonsynchronous Step-Down Regulator
• Manufacturer: AD [Analog Devices]

ADP2300/ADP2301
THERMAL CONSIDERATIONS
The ADP2300/ADP2301 store the value of the inductor current
only during the on time of the internal MOSFET. Therefore, a small
amount of power is dissipated inside the ADP2300/ADP2301
package, which reduces thermal constraints.
However, when the application is operating under maximum
load with high ambient temperature and high duty cycle, the
heat dissipated within the package may cause the junction
temperature of the die to exceed the maximum junction
temperature of 125°C. If the junction temperature exceeds
140°C, the regulator goes into thermal shutdown and recovers
when the junction temperature drops below 125°C.
The junction temperature of the die is the sum of the ambient
temperature of the environment and the temperature rise of the
package due to power dissipation, as indicated in the following
equation:
where:
T
T
T
dissipation.
J
A
R
is the junction temperature.
is the rise in temperature of the package due to power
is the ambient temperature.
T
J
= T
A
+ T
R
Rev. 0 | Page 20 of 28
The rise in temperature of the package is directly proportional
to the power dissipation in the package. The proportionality
constant for this relationship is the thermal resistance from the
junction of the die to the ambient temperature, as shown in the
following equation:
where:
T
θ
ambient temperature of the package.
P
JA
D
R
is the rise in temperature of the package.
is the power dissipation in the package.
is the thermal resistance from the junction of the die to the
T
R
= θ
JA
× P
D