DEMO MANUAL DC2395A
LTC2325/LTC2324/LTC2320
Quad/Octal 16-Bit/14-Bit/12-Bit,
5Msps/2Msps/1.5Msps, Serial,
High Speed SAR ADCs
Description
Demonstration circuit 2395A features the
LTC
®
2325/
LTC2324/LTC2320
family. With up to 5Msps, these differ-
ential, multiple channel, 16-bit, serial, high speed succes-
sive approximation register (SAR) ADCs are available in a
52-lead QFN package. Each ADC has an internal 20ppm/°C
maximum drift reference and an SPI-compatible serial
interface that supports CMOS and LVDS logic. Note the
demo board is configured for CMOS operation by default;
see the note under JP8 for LVDS operation. The following
text refers to the LTC2325, but applies to all members of the
family, the only difference being the number of channels,
the sample rate and/or the number of bits. The DC2395A
demonstrates the DC and AC performance of the LTC2325
in conjunction with the DC890 PScope™ data collection
board. Alternatively, by connecting the DC2395A into a
customer application, the performance of the LTC2325
can be evaluated directly in that circuit.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2395A
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and PScope
is a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
Assembly options
Table 1. DC2395A Assembly Options
VERSION
DC2395A-A
DC2395A-B
DC2395A-C
DC2395A-D
DC2395A-E
DC2395A-F
DC2395A-G
DC2395A-H
DC2395A-I
U1 PART NUMBER
LTC2320CUKG-16#PBF
LTC2324CUKG-16#PBF
LTC2325CUKG-16#PBF
LTC2320CUKG-14#PBF
LTC2324CUKG-14#PBF
LTC2325CUKG-14#PBF
LTC2320CUKG-12#PBF
LTC2324CUKG-12#PBF
LTC2325CUKG-12#PBF
MAX CONVERSION RATE
1.5Msps
2Msps
5Msps
1.5Msps
2Msps
5Msps
1.5Msps
2Msps
5Msps
# OF BITS
16
16
16
14
14
14
12
12
12
MAX CLOCK FREQUENCY
52.5MHz
110MHz
110MHz
52.5MHz
110MHz
110MHz
52.5MHz
110MHz
110MHz
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DEMO MANUAL DC2395A
boArD photo
7V DC POWER SUPPLY
–7V DC POWER SUPPLY
SIGNAL
GENERATOR
TO DC890B
CLOCK SIGNAL
FROM GENERATOR
Figure 1. DC2395A Connection Diagram
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DEMO MANUAL DC2395A
Quick stArt proceDure
Demonstration circuit 2395A is easy to set up and evaluate
for performance. Refer to Figure 1 and follow the proce-
dure below.
n
Connect the DC2395A to a DC890 USB high speed data
collection board using edge connector P1.
Connect the DC890 to a host PC with a standard USB
A/B cable.
Apply a low jitter signal source to J11 to test channel 1.
Note that the DC2395A is capable of accepting a
differential input signal as well as a single-ended signal.
See the Hardware Setup section for the jumper positions
that correspond to these configurations.
As a clock source, apply a low jitter 10dBm sine wave or
square wave to connector J9. See Table 1 for maximum
clock frequencies. Note that J9 has a 50Ω termination
resistor to ground.
Run the PScope software (Pscope.exe version K73,
or later) supplied with the DC890 or download it from
n
www.linear.com/software.
Complete software doc-
umentation is available from the Help menu. Updates
can be downloaded from the Tools menu. Check for
updates periodically, as new features may be added.
The PScope software should recognize the DC2395A
and configure itself automatically.
Click the Collect button (Figure 2) to begin acquiring
data. The Collect button then changes to Pause, which
can be used to stop data acquisition.
n
n
DRIVE OPTIONS
There are several ways to drive the LTC2325 on the
DC2395A. It can be driven with a true differential source,
or a single-ended source in either pseudo-differential
bipolar or unipolar mode. For details on how to configure
the DC2395A for any of these see Table 2.
An example input circuit for channel 1 is shown in Figure 3.
n
n
Table 2. Resistor Values for Different Input Configurations
INPUT CONFIGURATION
Differential
Single-Ended Differential ADC Drive
Single-Ended Bipolar ADC Drive
Unipolar ADC Drive
*DNI = Do not install
R32, 52, 72, 104,
146, 179, 202, 222
0Ω
0Ω
0Ω
DNI
R17, 37, 57, 88,
125, 163, 187, 207
DNI
DNI
DNI
0Ω
R15, 35, 55, 75,
122, 159, 185, 205
DNI
301Ω
DNI
301Ω
R16, 36, 56, 76,
R24, 44, 64, 100,
123, 160, 186, 206 143, 173, 194, 214
0Ω
301Ω
0Ω
301Ω
DNI
DNI
0Ω
0Ω
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DEMO MANUAL DC2395A
Quick stArt proceDure
Figure 2. DC2395A PScope Screenshot
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+6V
C2080.1uF
R217
0
C129
10uF
8
5
+
7
C204 0.1uF
-
4
C127
DNI
6
LT1819CMS8
U21B
BNC
Quick stArt proceDure
R216
DNI
R213
49.9
C128
DNI
-6V
R221
R220 1K
R207 DNI
DNI
0
R215
R222 0
R218
DNI
2
R219
0
5
6
J11B
VCM_BIAS1
AIN1+
C126
220pF
R205
301
R206
301
AIN1-
REF_OUT1
C207
10uF
R212 DNI
R214
1K
R210
150
C123
10uF
R211
0
C203
DNI
8
BNC
R203
0
1
J11A
C124
DNI
3
4
Figure 3. Example Input Circuit, Single-Ended Differential ADC Drive
R204
DNI
C125
DNI
+
3
-
1
U21A
LT1819CMS8
C206
10uF
2
4
R208
49.9
R209
DNI
DEMO MANUAL DC2395A
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