Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF Download HTML

ADC12D040 Datasheet(PDF) 21 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor. Click here to check the latest version.
Part No. ADC12D040
Description  Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference and Sample-and-Hold
Download  22 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  NSC [National Semiconductor (TI)]
Direct Link  http://www.national.com
Logo NSC - National Semiconductor (TI)

ADC12D040 Datasheet(HTML) 21 Page - National Semiconductor (TI)

Back Button ADC12D040 Datasheet HTML 14Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 15Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 16Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 17Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 18Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 19Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 20Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 21Page - National Semiconductor (TI) ADC12D040 Datasheet HTML 22Page - National Semiconductor (TI)  
Zoom Inzoom in Zoom Outzoom out
 21 / 22 page
background image
Applications Information (Continued)
Be especially careful with the layout of inductors. Mutual
inductance can change the characteristics of the circuit in
which they are used. Inductors should not be placed side by
side, even with just a small part of their bodies beside each
other.
The analog input should be isolated from noisy signal traces
to avoid coupling of spurious signals into the input. Any
external component (e.g., a filter capacitor) connected be-
tween the converter’s input pins and ground or to the refer-
ence input pin and ground should be connected to a very
clean point in the analog ground plane.
Figure 6 gives an example of a suitable layout. All analog
circuitry (input amplifiers, filters, reference components, etc.)
should be placed in the analog area of the board. All digital
circuitry and I/O lines should be placed in the digital area of
the board. Furthermore, all components in the reference
circuitry and the input signal chain that are connected to
ground should be connected together with short traces and
enter the analog ground plane at a single point. All ground
connections should have a low inductance path to ground.
6.0 DYNAMIC PERFORMANCE
To achieve the best dynamic performance, the clock source
driving the CLK input must be free of jitter. Isolate the ADC
clock from any digital circuitry with buffers, as with the clock
tree shown in Figure 7.
As mentioned in Section 5.0, it is good practice to keep the
ADC clock line as short as possible and to keep it well away
from any other signals. Other signals can introduce jitter into
the clock signal, which can lead to reduced SNR perfor-
mance, and the clock can introduce noise into other lines.
Even lines with 90˚ crossings have capacitive coupling, so
try to avoid even these 90˚ crossings of the clock line.
7.0 COMMON APPLICATION PITFALLS
Driving the inputs (analog or digital) beyond the power
supply rails. For proper operation, all inputs should not go
more than 100 mV beyond the supply rails (more than
100 mV below the ground pins or 100 mV above the supply
pins). Exceeding these limits on even a transient basis may
cause faulty or erratic operation. It is not uncommon for high
speed digital components (e.g., 74F and 74AC devices) to
exhibit overshoot or undershoot that goes above the power
supply or below ground. A resistor of about 50
Ω to 100Ω in
series with any offending digital input, close to the signal
source, will eliminate the problem.
Do not allow input voltages to exceed the supply voltage,
even on a transient basis. Not even during power up or
power down.
Be careful not to overdrive the inputs of the ADC12D040 with
a device that is powered from supplies outside the range of
the ADC12D040 supply. Such practice may lead to conver-
sion inaccuracies and even to device damage.
Attempting to drive a high capacitance digital data bus.
The more capacitance the output drivers must charge for
each conversion, the more instantaneous digital current
flows through V
DR and DR GND. These large charging cur-
rent spikes can couple into the analog circuitry, degrading
dynamic performance. Adequate bypassing and maintaining
separate analog and digital areas on the pc board will reduce
this problem.
Additionally, bus capacitance beyond the specified 20 pF/pin
will cause t
OD to increase, making it difficult to properly latch
the ADC output data. The result could, again, be an apparent
reduction in dynamic performance.
The digital data outputs should be buffered (with 74ACQ541,
for example). Dynamic performance can also be improved
by adding series resistors at each digital output, close to the
ADC12D040, which reduces the energy coupled back into
the converter output pins by limiting the output current. A
reasonable value for these resistors is 47
Ω to 56Ω.
Using an inadequate amplifier to drive the analog input.
As explained in Section 1.3, the capacitance seen at the
input alternates between 8 pF and 7 pF, depending upon the
phase of the clock. This dynamic load is more difficult to
drive than is a fixed capacitance.
If the amplifier exhibits overshoot, ringing, or any evidence of
instability, even at a very low level, it will degrade perfor-
mance. A small series resistor at each amplifier output and a
capacitor across the analog inputs (as shown in Figure 5) will
improve performance. The LMH6702 and the LMH6628
have been successfully used to drive the analog inputs of the
ADC12D040.
Also, it is important that the signals at the two inputs have
exactly the same amplitude and be exactly 180o out of phase
with each other. Board layout, especially equality of the
length of the two traces to the input pins, will affect the
effective phase between these two signals. Remember that
an operational amplifier operated in the non-inverting con-
figuration will exhibit more time delay than will the same
device operating in the inverting configuration.
Operating with the reference pins outside of the speci-
fied range. As mentioned in Section 1.2, V
REF should be in
the range of
1.0V
≤ V
REF
≤ 2.2V
Operating outside of these limits could lead to performance
degradation.
Using a clock source with excessive jitter, using exces-
sively long clock signal trace, or having other signals
coupled to the clock signal trace. This will cause the
sampling interval to vary, causing excessive output noise
and a reduction in SNR and SINAD performance.
20046017
FIGURE 7. Isolating the ADC Clock from other Circuitry
with a Clock Tree
www.national.com
21


Similar Part No. - ADC12D040

ManufacturerPart No.DatasheetDescription
National Semiconductor (TI)
National Semiconductor ...
ADC12D040 NSC-ADC12D040 Datasheet
990Kb / 22P
   Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference
Texas Instruments
Texas Instruments
ADC12D040 TI1-ADC12D040 Datasheet
1Mb / 31P
[Old version datasheet]   Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference
National Semiconductor (TI)
National Semiconductor ...
ADC12D040CIVS NSC-ADC12D040CIVS Datasheet
990Kb / 22P
   Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference
Texas Instruments
Texas Instruments
ADC12D040CIVS/NOPB TI1-ADC12D040CIVS/NOPB Datasheet
1Mb / 31P
[Old version datasheet]   Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference
National Semiconductor (TI)
National Semiconductor ...
ADC12D040CIVSX NSC-ADC12D040CIVSX Datasheet
990Kb / 22P
   Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference
More results

Similar Description - ADC12D040

ManufacturerPart No.DatasheetDescription
Texas Instruments
Texas Instruments
ADC12D040 TI1-ADC12D040_14 Datasheet
1Mb / 31P
[Old version datasheet]   Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference
National Semiconductor (TI)
National Semiconductor ...
ADC12D040 NSC-ADC12D040_05 Datasheet
990Kb / 22P
   Dual 12-Bit, 40 MSPS, 600 mW A/D Converter with Internal/External Reference
ADC12040 NSC-ADC12040 Datasheet
519Kb / 20P
   12-Bit, 40 MSPS, 340 mW A/D Converter with Internal Sample-and-Hold
ADC12010 NSC-ADC12010 Datasheet
606Kb / 22P
   12-Bit, 10 MSPS, 160 mW A/D Converter with Internal Sample-and-Hold
Texas Instruments
Texas Instruments
ADC12020 TI1-ADC12020 Datasheet
1Mb / 29P
[Old version datasheet]   12-Bit, 20 MSPS, 185 mW A/D Converter with Internal Sample-and-Hold
ADC12040 TI1-ADC12040 Datasheet
1Mb / 29P
[Old version datasheet]   12-Bit, 40 MSPS, 340mW A/D Converter with Internal Sample-and-Hold
National Semiconductor (TI)
National Semiconductor ...
ADC12040 NSC-ADC12040_06 Datasheet
884Kb / 19P
   12-Bit, 40 MSPS, 340mW A/D Converter with Internal Sample-and-Hold
Texas Instruments
Texas Instruments
ADC12040 TI1-ADC12040_14 Datasheet
1Mb / 30P
[Old version datasheet]   12-Bit, 40 MSPS, 340mW A/D Converter with Internal Sample-and-Hold
National Semiconductor (TI)
National Semiconductor ...
ADC12L063 NSC-ADC12L063 Datasheet
581Kb / 22P
   12-Bit, 62 MSPS, 354 mW A/D Converter with Internal Sample-and-Hold
Texas Instruments
Texas Instruments
ADC12L063 TI1-ADC12L063_14 Datasheet
1Mb / 31P
[Old version datasheet]   12-Bit, 62 MSPS, 354 mW A/D Converter with Internal Sample-and-Hold
More results


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22 


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz