THS6012_16 Datasheet, PDF (23/37 Pages) Texas Instruments – 500-mA DUAL DIFFERENTIAL LINE DRIVER

THS6012
www.ti.com
SLOS226F – SEPTEMBER 1998 – REVISED JUNE 2012
NORMALIZED FREQUENCY RESPONSE
vs
FREQUENCY
3
V_CC = ±15 V
2 ^VI ^{= 200 mV}
R_L = 25 Ω
1 ^RF ^{= 1 kΩ}
Gain = 1
0
–1
C_I = 0 pF
(Stray C Only)
–2
C_I = 1.8 pF
–3
1 kΩ
–4
C_in
V_in
–
V_out
–5
+
R_L =
50 Ω 25 Ω
–6
–7
100
1M
10M
f – Frequency – Hz
100M
500M
Figure 44. Driver Normalized Frequency Response vs Frequency
• Proper power supply decoupling - Use a minimum of a 6.8-μF tantalum capacitor in parallel with a 0.1-μF
ceramic capacitor on each supply terminal. It may be possible to share the tantalum among several amplifiers
depending on the application, but a 0.1-μF ceramic capacitor should always be used on the supply terminal of
every amplifier. In addition, the 0.1-μF capacitor should be placed as close as possible to the supply terminal.
As this distance increases, the inductance in the connecting etch makes the capacitor less effective. The
designer should strive for distances of less than 0.1 inches between the device power terminal and the
ceramic capacitors.
Because of its power dissipation, proper thermal management of the THS6012 is required. Although there are
many ways to properly heatsink this device, the following steps illustrate one recommended approach for a
multilayer PCB with an internal ground plane.
1. Prepare the PCB with a top side etch pattern as shown in Figure 45. There should be etch for the leads as
well as etch for the thermal pad.
2. Place 18 holes in the area of the thermal pad. These holes should be 13 mils in diameter. They are kept
small so that solder wicking through the holes is not a problem during reflow.
3. It is recommended, but not required, to place six more holes under the package, but outside the thermal pad
area. These holes are 25 mils in diameter. They may be larger because they are not in the area to be
soldered so that wicking is not a problem.
4. Connect all 24 holes, the 18 within the thermal pad area and the 6 outside the pad area, 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.
However, in this application, low thermal resistance is desired for the most efficient heat transfer. Therefore,
the holes under the THS6012 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 exposed the terminals of the package and the thermal pad area with
its five holes. The four larger holes outside the thermal pad area, but still under the package, should be
covered with solder mask.
7. Apply solder paste to the exposed thermal pad area and all of the operational amplifier terminals.
8. With these preparatory steps in place, the THS6012 is simply placed in position and run through the solder
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