THS6012 Datasheet, PDF (26/35 Pages) Texas Instruments – 500-mA DUAL DIFFERENTIAL LINE DRIVER

THS6012
500-mA DUAL DIFFERENTIAL LINE DRIVER
SLOS226C– SEPTEMBER 1998 – REVISED FEBRUARY 2000
APPLICATION INFORMATION
PCB design considerations (continued)
NORMALIZED FREQUENCY RESPONSE
vs
FREQUENCY
3
VCC = ±15 V
2 ^{VI = 200 mV}
RL = 25 Ω
1 ^{RF = 1 kΩ}
Gain = 1
0
–1
CI = 0 pF
(Stray C Only)
–2
CI = 1.8 pF
–3
1 kΩ
–4
Cin
Vin
–
Vout
–5
+
RL =
50 Ω 25 Ω
–6
–7
100
1M
10M
f – Frequency – Hz
100M
500M
Figure 44. Driver Normalized Frequency Response vs Frequency
D 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.
26
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265