Datasheet

T
A
MAX
D
JA
T -
P =
θ
æ ö
ç ÷
è ø
TLC080 , TLC081, TLC082
TLC083, TLC084, TLC085, TLC08xA
www.ti.com SLOS254F –JUNE 1999– REVISED DECEMBER 2011
The PowerPAD must be connected to the most negative supply voltage (GND pin potential) of the device.
1. Prepare the PCB with a top side etch pattern (see the landing patterns at the end of this data sheet). There
should be etch for the leads as well as etch for the thermal pad.
2. Place five holes (dual) or nine holes (quad) in the area of the thermal pad. These holes should be 13 mils in
diameter. Keep them small so that solder wicking through the holes is not a problem during reflow.
3. Additional vias may be placed anywhere along the thermal plane outside of the thermal pad area. This helps
dissipate the heat generated by the TLC08x IC. These additional vias may be larger than the 13-mil diameter
vias directly under the thermal pad. They can be larger because they are not in the thermal pad area to be
soldered so that wicking is not a problem.
4. Connect all holes to the internal plane that is at the same potential as the ground pin of the device.
5. When connecting these holes to this internal plane, do not use the typical web or spoke via connection
methodology. Web connections have a high thermal resistance connection that is useful for slowing the heat
transfer during soldering operations. This makes the soldering of vias that have plane connections easier. In
this application, however, low thermal resistance is desired for the most efficient heat transfer. Therefore, the
holes under the TLC08x PowerPAD package should make their connection to the internal ground plane with
a complete connection around the entire circumference of the plated-through hole.
6. The top-side solder mask should leave the terminals of the package and the thermal pad area with its five
holes (dual) or nine holes (quad) exposed. The bottom-side solder mask should cover the five or nine holes
of the thermal pad area. This prevents solder from being pulled away from the thermal pad area during the
reflow process.
7. Apply solder paste to the exposed thermal pad area and all of the IC terminals.
8. With these preparatory steps in place, the TLC08x IC is simply placed in position and run through the solder
reflow operation as any standard surface-mount component. This results in a part that is properly installed.
For a given θ
JA
, the maximum power dissipation is shown in Figure 53 and is calculated by the following formula:
(1)
Where:
P
D
= Maximum power dissipation of TLC08x IC (watts)
T
MAX
= Absolute maximum junction temperature (150°C)
T
A
= Free-ambient air temperature (°C)
θ
JA
= θ
JC
+ θ
CA
θ
JC
= Thermal coefficient from junction to case
θ
CA
= Thermal coefficient from case to ambient air (°C/W)
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