Linear Technology LTC2351-14 Guide

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1278
6-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADC
1
LTC2351-14
DESCRIPTION
Demonstration circuit 1278 features the LTC2351-14
6-channel, 14-Bit, simultaneous sampling ADC. Total
throughput is 1.5MSPS; 250KSPS per channel, with a
typical channel-to-channel aperture skew of 200ps.
The board is designed to be used with the DC890B
Fast DAACS data collection board to show the AC
performance of the LTC2351-14. Alternatively, the
board can be directly connected to an application to
evaluate the ADC’s performance.
Design files for this circuit board are available. Call
the LTC factory.
LTC is a trademark of Linear Technology Corporation
QUICK START PROCEDURE
BASIC CONNECTIONS
Connect DC1278 to a DC890B USB High Speed Data
Collection Board using connector J2. Connect
DC890B to a host PC with a standard USB A/B cable.
Apply 5-7V DC to the VIN and GND terminals. Apply a
25MHz 3.3Vp-p sine wave or square wave to connec-
tor J3. Note that J3 has a 50 ohm termination resistor
to ground. CH0-CH5 are provided through connector
J1 (See schematic for details.). Run the QuickEval II
(Pscope.exe) evaluation software supplied with
DC890 or download it from www.linear.com/software.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1278
6-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADC
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Figure 1. CONNECTION DIAGRAM
40 pin Analog
Signal Connector
(Refer to Schematic)
To DC890
B
Controller
Master clock at
98
x co
n
vers
ion rate,
3.3Vpp
Sine or Square wave (See
Hardware Setup Section)
5
-
7VDC Supply

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1278
6-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADC
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Figure 2. SOFTWARE SCREENSHOT
Figure 3. CONFIGURE MENUS

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1278
6-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADC
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SOFTWARE CONFIGURATION
CONFIGURE DEVICE
The Pscope software should automatically config-
ure itself after detecting the demo board. To change
from Bipolar to Unipolar mode it will be necessary
to manually configure the software. In the
CONFIGURE menu (See Figure 3) select Device,
which will bring up another window. In this window,
select User Configure and adjust the other settings
as follows:
Bits: 14
Alignment: 14
Bipolar: Checked if BIP jumper is set high, Un-
Checked if BIP jumper is set to low. (Default is
checked)
Channels: 6
Positive Edge Clk: UN-Checked
FPGA: Serial 1408 Class.
CONFIGURE SOFTWARE SCREEN
The software interface is highly configurable and
displays any combination of time domain data, fre-
quency domain data, primitive wave and perform-
ance parameters (SNR, THD, SINAD, etc.). The
screen can be broken into multiple panes as shown
in Figure 2. Complete documentation on configur-
ing PSCOPE can be found in the help file.
Click the COLLECT button to begin acquiring data.
Complete software documentation is available from
the Help menu item, as features may be added peri-
odically.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1278
6-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADC
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HARDWARE SET-UP
JUMPERS
JP1, JP2 - Select number of channels to convert
and Unipolar / Bipolar selection. NCH2, NCH1,
NCH0 are set to 111 which selects all six channels.
These switches should be left in this position when
running Pscope software. UNI/BIP selection applies
to all channels. Refer to Figure 4.
JP3 – Enable Oscillator and Oscillator Division.
Presently not used. This may be used in the future
as serial clock, to allow a convert signal at 1X the
conversion rate.
JP4 – Digital Interface Header. Provides direct con-
nection to the LTC2351-14 CONV, SDO, and SCK
pins. This can be used to either monitor signals
with a logic analyzer or to drive the LTC2351-14
directly from the customer’s test equipment or pro-
totype circuitry. DC890B should be disconnected
before driving the LTC2351-14 externally with JP4.
Note that R34 should be removed if the CONV sig-
nal is being driven externally.
JP5 – Currently not used
SIGNAL CONNECTIONS
J1 – 40 pin connector with CH0-CH5 differential
inputs, multiple grounds, a mid-supply bias voltage
and Vref. Refer to schematic for pin out. The mid-
supply bias voltage can be used to bias the minus
ADC inputs for bipolar conversions.
J2 – Data connections to DC890B collection board.
J3 – Conversion Clock Input. This input has a 50
ohm termination resistor, and is intended to be
driven by a 3.3Vpp sine or square wave. This clock
is divided by 98 in the DC890B collection board to
control the serial interface and convert pulse. To run
the LTC2351-14 at maximum conversion rate, apply
a 25MHz signal to this input.
GROUNDING AND POWER CONNECTION
Connect a 5V to 7V power supply to the Vin and
GND turret posts. For optimum performance, this
supply should be floating with respect to any signal
generators connected to the analog inputs.
Figure 4 – JP1, JP2 CONFIGURATION

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1278
6-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADC
6

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 1278
6-CHANNEL, 14-BIT, 1.5MSPS SIMULTANEOUS SAMPLING ADC
7