Datasheet

USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.1 (04-26-10) 68 SMSC USB251x
DATASHEET
9.2.1 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.
Table 9.12 Package Thermal Resistance Parameters
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
Table 9.13 Legend
SYMBOL
USB2512/12i
USB2513/13i
USB2514/14i
(°C/W)
USB2512A/12Ai
(°C/W)
USB2512B/12Bi
USB2513B/13Bi
USB2514B/14Bi
(°C/W)
USB2513/13i
USB2514/14i
(°C/W)
VELOCITY
(meters/sec)
PACKAGE
36-PIN QFN 48-PIN QFN -
Θ
JA
34.2 36.2 40.1 31.6 0
29.9 33.4 35.0 27.6 1
Ψ
JT
0.3 0.4 0.5 0.3 0
0.5 0.7 0.7 0.4 1
Θ
JC
3.0 5.1 6.3 3.0 0
3.0 5.1 6.3 3.0 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