THS6012_16 Datasheet, PDF (18/37 Pages) Texas Instruments – 500-mA DUAL DIFFERENTIAL LINE DRIVER

THS6012
SLOS226F – SEPTEMBER 1998 – REVISED JUNE 2012
www.ti.com
DEVICE PROTECTION FEATURES
The THS6012 has two built-in protection features that protect the device against improper operation. The first
protection mechanism is output current limiting. Should the output become shorted to ground the output current
is automatically limited to the value given in the data sheet. While this protects the output against excessive
current, the device internal power dissipation increases due to the high current and large voltage drop across the
output transistors. Continuous output shorts are not recommended and could damage the device. Additionally,
connection of the amplifier output to one of the supply rails (±V_CC) can cause failure of the device and is not
recommended.
The second built-in protection feature is thermal shutdown. Should the internal junction temperature rise above
approximately 180°C, the device automatically shuts down. Such a condition could exist with improper heat
sinking or if the output is shorted to ground. When the abnormal condition is fixed, the internal thermal shutdown
circuit automatically turns the device back on.
THERMAL INFORMATION
The THS6012 is packaged in a thermally-enhanced DWP package, which is a member of the PowerPAD family
of packages. This package is constructed using a downset leadframe upon which the die is mounted [see Figure
39(a) and Figure 39(b)]. This arrangement results in the lead frame being exposed as a thermal pad on the
underside of the package [see Figure 39(c)]. Because this thermal pad has direct thermal contact with the die,
excellent thermal performance can be achieved by providing a good thermal path away from the thermal pad.
The PowerPAD package allows for both assembly and thermal management in one manufacturing operation.
During the surface-mount solder operation (when the leads are being soldered), the thermal pad can also be
soldered to a copper area underneath the package. Through the use of thermal paths within this copper area,
heat can be conducted away from the package into either a ground plane or other heat dissipating device. This is
discussed in more detail in the PCB design considerations section of this document.
The PowerPAD package represents a breakthrough in combining the small area and ease of assembly of
surface mount with the, heretofore, awkward mechanical methods of heatsinking.
DIE
Side View (a)
Thermal
Pad
DIE
End View (b)
Bottom View (c)
A. The thermal pad is electrically isolated from all terminals in the package.
Figure 39. Views of Thermally Enhanced DWP Package
RECOMMENDED FEEDBACK AND GAIN RESISTOR VALUES
As with all current feedback amplifiers, the bandwidth of the THS6012 is an inversely proportional function of the
value of the feedback resistor. This can be seen from Figure 17 through Figure 20. The recommended resistors
with a ±15 V power supply for the optimum frequency response with a 25-Ω load system are 680-Ω for a gain = 1
and 620-Ω for a gain = 2 or -1. Additionally, using a ±5 V power supply, it is recommended that a 1-kΩ feedback
resistor be used for a gain of 1 and a 820-Ω feedback resistor be used for a gain of 2 or -1. These should be
used as a starting point and once optimum values are found, 1% tolerance resistors should be used to maintain
frequency response characteristics. Because there is a finite amount of output resistance of the operational
amplifier, load resistance can play a major part in frequency response. This is especially true with these drivers,
which tend to drive low-impedance loads. This can be seen in Figure 11, Figure 23, and Figure 24. As the load
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