2
dc1925af
DEMO MANUAL DC1925A
ASSEMBLY OPTIONS
DC890 QUICK START PROCEDURE
DC890 QUICK START PROCEDURE
DC590 SETUP
Table 1. DC1925A Assembly Options
ASSEMBLY VERSION
U1 PART NUMBER
MAX CONVERSION RATE
NUMBER OF BITS
MAX CLK IN FREQUENCY
DC1925A-A
LTC2378CMS-20
1Msps
20
80MHz
DC1925A-B
LTC2377CMS-20
500ksps
20
40MHz
DC1925A-C
LTC2376CMS-20
250ksps
20
20MHz
Check to make sure that all switches and jumpers are
set as shown in the connection diagram of Figure 1.
In particular make sure that VCCIO (JP3) is set to the
2.5V position. Operating the DC1925A with the DC890
while JP3 is in the 3.3V position will cause noticeable
performance degradation in SNR and THD. The default
connections configure the ADC to use the onboard refer-
ence and regulators to generate the required common
mode voltages. The analog input is DC coupled. Connect
the DC1925A to a DC890 USB high speed data collection
board using connector P1. Then, connect the DC890 to a
host PC with a standard USB A/B cable. Apply ±9V to the
indicated terminals. Then apply a low jitter differential sine
source to J2 and J4. Connect a low jitter 80MHz 2.5V
P-P
sine wave or square wave to connector J1. Note that J1
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 www.
linear.com/software.
Complete software documentation 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 DC1925A and
configure itself automatically.
Click the Collect button (See Figure 5) to begin acquiring
data. The Collect button then changes to Pause, which
can be clicked to stop data acquisition.
IMPORTANT! To avoid damage to the DC1925A, make
sure that VCCIO (JP6) of the DC590 is set to 3.3V before
connecting the DC590 to the DC1925A.
VCCIO (JP3) of the DC1925A should be in the 3.3V position
for DC590 operation. To use the DC590 with the DC1925A,
it is necessary to apply –9V and ground to the –9V and
GND terminals. Connect the DC590 to a host PC with a
standard USB A/B cable. Connect the DC1925A to a DC590
USB serial controller using the supplied 14-conductor
ribbon cable. Apply a signal source to J4 and J2 or J4
depending on how the DC1925A is configured.
Run the QuikEval software (version K92-01 or later) sup-
plied with the DC590 or download it from www.linear.
com/software. The correct control panel will be loaded
automatically. Click the Collect button (See Figure 6) to
begin reading the ADC.
