MAX1276EVKIT Maxim Integrated, MAX1276EVKIT Datasheet - Page 15

• Manufacturer Part Number: MAX1276EVKIT
• Description: Data Conversion IC Development Tools Evaluation Kit/Evaluation System for the MAX1070/71/72/75#79/MAX1224/25/MAX1274#79
• Manufacturer: Maxim Integrated
• Series: MAX1276, MAX1278r

Specifications of MAX1276EVKIT

• Interface Type: QSPI, Serial (SPI, Microwire)

• Verify DOUT loading is within specification. Applying
Problem: Measurements are erratic, unstable;
poor accuracy.
• Check the reference voltage using a digital volt-
• If using direct-drive inputs, verify the sources have
• Use an oscilloscope to check for noise on the refer-
• If using an internal reference part, verify the JU3
• If using an external source for VREF, verify the JU3
• Verify instrument connections. Ensure that grounds
• Verify DOUT loading is within spec. Applying exces-
excessive loads to DOUT directly (pin 5 in header P1)
can cause timing/level errors and can engage the part’s
protection circuitry. In most cases, the buffered DOUT
pad should be used for observation and sampling (this
output is also available on pin 7 in header P1).
meter across the VREF and RGND SENSE pads.
Check the differential input voltage using a digital
voltmeter across the AIN+ and AIN- SENSE pads.
These pads have a resistor in series to prevent volt-
meters from injecting noise into sensitive nodes.
Note: The isolation resistors limit the bandwidth for
AC measurements.
adequate drive capability. Consider using the on-
board buffers if in doubt.
ence and supply voltages. When probing for noise,
keep the oscilloscope ground return lead as short as
possible, preferably less than 0.5in (10mm).
jumper is configured properly (see
that any added circuitry also using the internal refer-
ence level is not causing interference (pulling the J3
shunt provides a quick disconnect of the VREF I/O
pin to identify off-board loading effects).
jumper is connected and set properly (see
Verify that the external reference used has adequate
drive capability. Check that any added circuitry also
using the external reference is not causing interfer-
ence.
for the digital (SPI) signals are connected to DGND.
Connect grounds for the power supplies, external
reference supply (if used), and the input supplies (or
signal generator) to AGND.
sive loads to DOUT directly (pin 5 in header P1) can
cause timing/level errors and can engage the part’s
protection circuitry. In most cases, the buffered
DOUT pad should be used for observation and sam-
pling (this output is also available on pin 7 in header
P1). When using a logic analyzer, be sure to use the
buffered DOUT pin. Additional cable loading can be
a source of noise.
MAX1276 Evaluation Kit/Evaluation System
______________________________________________________________________________________
Table
6). Check
Table
6).
• Verify the SPI timing and levels. If using the Maxim
Problem: Measurements show high noise floor.
After confirming DC operation of the part and proper
connection of all devices and jumpers, inspect the
setup for any of the following possible causes of noise.
• Eliminate ground loops, for best performance multi-
• Experiment with earth ground connections. Only one
• Some oscilloscopes also provide earth connections
• If using direct-drive inputs, verify the sources have
• Use a spectrum analyzer to verify signal integrity
• Verify SPI inputs are correct and meet all timing and
• Look for sources of environmental noise. Check your
software, set the SPI conversion to run continuously
and use an oscilloscope to verify that the conver-
sion-start signal, serial clock, and the data output
signals (CONVST, SCLK, and DOUT) have the prop-
er timing. Marked pads are available for the oscillo-
scope probes.
ple ground return paths should be avoided. All sup-
ply grounds should be referenced to the AGND
pad(s), preferably the lower pad location (the upper
pad location is intended for convenience when
applying the +7V, -3V supplies). All DC sources
(CMP, CMM, external VREF) should also follow this
convention.
earth ground connection to the board is recom-
mended. In some setups, improved results can be
obtained if this earth is through a power supply con-
nected to the DGND pad. This depends on the digi-
tal generator used to supply the SPI inputs. Many of
these units supply an earth connection through their
dual-pin interfaces.
through their ground connections. In most cases,
oscilloscopes should be removed from the board
when making noise measurements to avoid multiple
earth connections and ground loops.
adequate drive capability. Consider using the on-
board buffers if in doubt. If using multiple boards,
verify that there are no ground loops between
the boards.
both at the source and at the inputs of the test ADC.
level requirements. Verify periodic sampling is as
expected when performing dynamic measurements.
lab and bench for possible sources of noise from
neighboring equipment or from AC mains.
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