LTC2752 Linear Technology, LTC2752 Datasheet - Page 22

• Manufacturer Part Number: LTC2752
• Description: Dual16-Bit SoftSpan IOUT DACs
• Manufacturer: Linear Technology

LTC2752
applicaTions inForMaTion
in 5V or 10V full-scale systems. However, as the circuit
bandwidths increase, filtering the output of the reference
may be required to minimize output noise.
Grounding
As with any high resolution converter, clean grounding
is important. A low impedance analog ground plane is
necessary, as are star grounding techniques. Keep the
board layer used for star ground continuous to minimize
ground resistances; that is, use the star-ground concept
without using separate star traces. The I
of particular concern; INL will be degraded by the code
dependent currents carried by the I
pins if voltage drops to ground are allowed to develop.

V
5V
REF
1
1/2 LT1469
ALTERNATE AMPLIFIER FOR OPTIMUM SETTLING TIME PERFORMANCE
+
–
Figure 5. Optional Circuits for Driving I
3
2
I
I
OUT2AS
BAT54S
OUT2AF
ZETEX
150pF
47, 48
9
8
5, 6
1, 2
4
3
1
2 3
R
R
GE
R
REFA
OUT2XF
OFSA
INA
COMA
6
ADJA
OUT2
LT1468
and I
+
–
pins are
OUT2XS
2
3
200Ω
DAC A
200Ω
OUT2
DAC B
The best strategy here is to tie the pins to the star ground
plane by multiple vias located directly underneath the part.
Alternatively, the pins may be routed to the star ground
point if necessary; join the force and sense pins together
at the part and route one trace for each channel of no more
than 120 squares of 1oz. copper.
In the rare case in which neither of these alternatives is
practicable, a force/sense amplifier should be used as a
ground buffer (see Typical Applications). Note, however,
that the voltage offset of the ground buffer amp directly
contributes to the effects on accuracy specified in Table
5 under V
calculated by substituting the total offset from I
I
from GND with a Force/Sense Amplifier
1000pF
OUT2XS
V
LTC2752
OSADJA
I
I
OUT1A
OUT2A
R
2752 F05
FBA
for V
*SCHOTTKY BARRIER DIODE
OS1
I
I
OUT2AS
OUT2AF
45, 46
44
8, 9
43
. The combined effects of the offsets can be
OS1
8
9
in the equations.
1
2
–
+
6
3
ZETEX*
BAT54S
LT1012
15pF
2
3
–
+
–
+
1/2 LT1469
2
3
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1
V
OUTA
OUT1X
2752f
to