THS3202_16 Datasheet, PDF (22/37 Pages) Texas Instruments – 2-GHz, LOW DISTORTION, DUAL CURRENT-FEEDBACK AMPLIFIERS

THS3202
SLOS242F – SEPTEMBER 2002 – REVISED JANUARY 2010
www.ti.com
PowerPAD PCB LAYOUT CONSIDERATIONS
ÎÎÎ ÎÎÎ 1. Prepare the PCB with a top side etch pattern as shown in Figure 80. There should be etch for the leads as
well as etch for the thermal pad.
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎÎ_{68 Mils x 70 Mils}
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎ^{(Via diameter = 10 mils)}
Figure 80. DGN PowerPAD PCB Etch and Via Pattern
2. Place five holes in the area of the thermal pad. These holes should be 10 mils (0,254 mm) 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 THS320x family IC. These additional vias may be larger than the 10-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 ground plane.
5. When connecting these holes to the ground 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 THS320x family 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 exposed. The bottom-side solder mask should cover the five 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 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.
POWER DISSIPATION AND THERMAL CONSIDERATIONS
To maintain maximum output capabilities, the THS3202 does not incorporate automatic thermal shutoff
protection. The designer must take care to ensure that the design does not violate the absolute maximum
junction temperature of the device. Failure may result if the absolute maximum junction temperature of +150°C is
exceeded. For best performance, design for a maximum junction temperature of +125°C. Between +125°C and
+150°C, damage does not occur, but the performance of the amplifier begins to degrade.
The thermal characteristics of the device are dictated by the package and the PCB. Maximum power dissipation
for a given package can be calculated using the following formula.
P _Dmax
+
T_max *
q_JA
T_A
where:
P_Dmax is the maximum power dissipation in the amplifier (W).
T_max is the absolute maximum junction temperature (°C).
T_A is the ambient temperature (°C).
θ_JA = θ_JC + θ_CA
θ_JC is the thermal coefficient from the silicon junctions to the case (°C/W).
θ_CA is the thermal coefficient from the case to ambient air (°C/W).
22
Submit Documentation Feedback
Product Folder Link(s): THS3202
Copyright © 2002–2010, Texas Instruments Incorporated