Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 2.3 (06-11-13) 52 SMSC USB251xB/xBi
DATASHEET
6.2.1 Package Thermal Specifications
Thermal parameters are measured or estimated for devices with the exposed pad soldered to thermal
vias in a multilayer 2S2P PCB per JESD51. Thermal resistance is measured from the die to the
ambient air. The values provided are based on the package body, die size, maximum power
consumption, 85°C ambient temperature, and 125°C junction temperature of the die.
Use the following formulas to calculate the junction temperature:
T
J
= P x Θ
JA
+ T
A
T
J
= P x Ψ
JT
+ T
T
T
J
= P x Θ
JC
+ T
C
Max Power Supported = (T
J Max. Spec.
x T
Amb.
)/ Θ
JA
Table 6.9 Legend
SYMBOL
USB2512B/12Bi
USB2513B/13Bi
USB2514B/14Bi
(°C/W)
VELOCITY
(meters/s)
Θ
JA
40.1 0
35.0 1
Ψ
JT
0.5 0
0.7 1
Θ
JC
6.3 0
6.3 1
SYMBOL DESCRIPTION
T
J
Junction temperature
P Power dissipated
Θ
JA
Junction-to-ambient-temperature
Θ
JC
Junction-to-top-of-package
Ψ
JT
Junction-to-bottom-of-case
T
A
Ambient temperature
T
C
Temperature of the bottom of the case
T
T
Temperature of the top of the case