TLC082-Q1_16 Datasheet, PDF (25/38 Pages) Texas Instruments – Wide-Bandwidth High-Output-Drive Single-Supply Operational Amplifiers

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TLC082-Q1, TLC084-Q1
SLOS510D – SEPTEMBER 2006 – REVISED AUGUST 2016
Layout Guidelines (continued)
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-Q1 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-Q1 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 R_θJA, use Equation 1 to calculate the maximum power dissipation.
P_D
=
æ
ç
è
T_MAX - T_A
R_qJA
ö
÷
ø
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)
R_qJA = R _qJC + R _qCA
R_qJC = Thermal coefficient from junction to case
R_qCA = Thermal coefficient from case to ambient air (°C/W)
(1)
The next consideration is the package constraints. The two sources of heat within an amplifier are quiescent
power and output power. The designer should never forget about the quiescent heat generated within the device,
especially multi-amplifier devices. Because these devices have linear output stages (class A-B), most of the heat
dissipation is at low-output voltages with high-output currents.
The other key factor when dealing with power dissipation is how the devices are mounted on the PCB. The
PowerPAD devices are extremely useful for heat dissipation. But, the device should always be soldered to a
copper plane to fully use the heat dissipation properties of the thermal pad. The SOIC package, on the other
hand, is highly dependent on how it is mounted on the PCB. As more trace and copper area is placed around the
device, R_θJA decreases and the heat dissipation capability increases. The currents and voltages shown in Typical
Characteristics are for the total package. For the dual or quad amplifier packages, the sum of the RMS output
currents and voltages should be used to choose the proper package.
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