USB251xB/xBi
6.2.1 PACKAGE THERMAL SPECIFICATIONS
Thermal parameters are measured or estimated for devices with the exposed pad soldered to thermal vias in a multi-
layer 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.
Symbol
JA
JT
JC
USB2512B/12Bi USB2513B/13Bi
USB2514B/14Bi
(°C/W)
40.1
35.0
0.5
0.7
6.3
6.3
Velocity (meters/s)
0
1
0
1
0
1
Use the following formulas to calculate the junction temperature:
TJ = P x JA + TA
TJ = P x JT + TT
TJ = P x JC + TC
Max Power Supported = (TJ Max. Spec. x TAmb.)/ JA
TABLE 6-9: LEGEND
Symbol
Description
TJ
Junction temperature
P
Power dissipated
JA
Junction-to-ambient-temperature
JC
Junction-to-top-of-package
JT
Junction-to-bottom-of-case
TA
Ambient temperature
TC
Temperature of the bottom of the case
TT
Temperature of the top of the case
2010 - 2015 Microchip Technology Inc.
DS00001692C-page 43