ZHCSCX2E January 2014 – October 2017 LM15851
PRODUCTION DATA.
The LM15851device is capable of impressive speeds and performance at low power levels for speed. However, the power consumption is still high enough to require attention to thermal management. The VQFN package has a primary-heat transfer path through the center pad on the bottom of the package. The thermal resistance of this path is provided as RθJCbot.
For reliability reasons, the die temperature must be kept to a maximum of 135°C which is the ambient temperature (TA) plus the ADC power consumption multiplied by the net junction-to-ambient thermal resistance (RθJA). Maintaining this temperature is not a problem if the ambient temperature is kept to a maximum of 85°C as specified in the Recommended Operating Conditions table and the center ground pad on the bottom of the package is thermally connected to a large-enough copper area of the PC board.
The package of the LM15851device has a center pad that provides the primary heat-removal path as well as excellent electrical grounding to the PCB. Recommended land pattern and solder paste examples are provided in the 机械、封装和可订购信息 section. The center-pad vias shown must be connected to internal ground planes to remove the maximum amount of heat from the package, as well as to ensure best product parametric performance.
If needed to further reduce junction temperature, TI recommends to build a simple heat sink into the PCB which occurs by including a copper area of about 1 to 2 cm2 on the opposite side of the PCB. This copper area can be plated or solder-coated to prevent corrosion, but should not have a conformal coating which would provide thermal insulation. Thermal vias will be used to connect these top and bottom copper areas and internal ground planes. These thermal vias act as heat pipes to carry the thermal energy from the device side of the board to the opposite side of the board where the heat can be more effectively dissipated.