THS1060_05 Datasheet, PDF (18/22 Pages) Texas Instruments – 10-BIT 60 MSPS IF SAMPLING COMMUNICATIONS

THS1060
10-BIT 60 MSPS IF SAMPLING COMMUNICATIONS
ANALOG-TO-DIGITAL CONVERTER
SLAS212A – MARCH 2000 – REVISED MARCH 2001
APPLICATION INFORMATION
digital outputs
The digital outputs can drive either TTL or 5-V CMOS inputs when DRV_DD = 5 V. To reduce capacitive loading,
each digital output of the THS1060 should drive only one digital input. The CMOS output drivers are capable
of handling up to a 15-pF load. For better SNR performance, use 3.3 V for DRV_DD. Resistors of 200 Ω in series
with the digital output can be used for optimizing SNR performance.
power supplies
Best performance is obtained when AV_DD is kept separate from DV_DD. Regulated or linear supplies, as opposed
to switched power supplies, must be used to minimize supply noise. It is also recommended to partition the
analog and digital components on the board in such a way that the analog supply plane does not overlap with
the digital supply plane in order to limit dielectric coupling between the different supplies.
using the TI PowerPAD
While it is not necessary to use the Texas Instruments PowerPAD to meet the minimum and maximum specs
indicated in this spec sheet, proper use of the PowerPAD improves the performance of the THS1060 especially
at T_A = 85°C.
For high-speed sampling applications (around 60 MSPS), significant performance enhancement above the
specified values can be achieved by properly applying the PowerPAD. This maintains the junction temperature
of the device at significantly lower levels and render the device even more insensitive to duty cycle variations
on the clock, as shown in Figure 18.
The THS1060 package makes use of the Texas Instruments PowerPAD which, when soldered to a thermal land,
creates a highly efficient path for heat energy and ground noise currents from the circuit die to the PCB ground
plane. The silicon die in a PowerPAD package is bonded to a copper alloy plate with a thin layer of thermally
and electrically conductive epoxy. The copper alloy plate or PowerPAD is exposed on the bottom of the device
package for a direct solder attachment to a PCB land or conductive pad. The land dimensions should have
minimum dimensions equal to the package dimensions minus 2 mm, see Figure 25.
For a multilayer circuit board, a second land having dimensions equal to or greater than the land to which the
device is soldered should be placed on the back of the circuit board (see Figure 26). A total of 9 thermal vias
or plated through-holes should be used to connect the two lands to a ground plane (buried or otherwise) having
a minimum total area of 3 inches square in 1 oz. copper. For the THS1060 package, the thermal via centers
should be spaced at a minimum of 1 mm. The ground plane need not be directly under or centered around the
device footprint if a wide ground plane thermal run having a width on the order of the device is used to channel
the heat from the vias to the larger portion of the ground plane. The THS1060 package has a standoff of 0.19
mm or 7.5 mils. In order to apply the proper amount of solder paste to the land. a solder paste stencil with a 6
mils thickness is recommended for this device. Too thin a stencil may lead to an inadequate connection to the
land. Too thick a stencil may lead to beading of solder in the vicinity of the pins which may lead to shorts. For
more information, refer to Texas Instruments literature number SLMA002 PowerPAD Thermally Enhanced
Package.
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