MAX1165EVKIT Datasheet, PDF (2/5 Pages) Maxim Integrated Products – MAX1165 Evaluation Kit

MAX1165 Evaluation Kit
Detailed Description of
Hardware
The MAX1165 (U1) is a single-channel, 16-bit data-
acquisition system. Anti-alias filtering is performed by
R2 and C7. The input signal can be applied directly to
the AIN pad, or an optional MAX4430 precision buffer
(U3) can be used instead. Capacitors C4 and C6
bypass the reference. Schmitt trigger (U2) ensures
proper system timing by keeping the CS rising and
falling edges clean.
Analog Input Buffer
When powered from ±5V supplies, the analog input
buffer (U3) has an input common-mode range of -2.5V
to +4.1V.
1) With the power off, connect the +5VDC power sup-
ply between BUF+5 and AGND.
2) With the power off, connect the -5VDC power sup-
ply between BUF-5 and AGND.
3) With the power off, connect the DC power supply
ground return to AGND.
4) Install a shunt across jumper JU3.
5) Apply analog input signal to BUFIN pad.
If the full unipolar 0 to 5V range is needed, apply +7V to
BUF+5 and -3V to BUF-5. The input common-mode
range is -0.5V to +6.1V.
Generating a Crossplot
To see a visual indication of relative LSB size and DNL
performance, create a crossplot fixture using a function
generator, a latch, a resistor network, and an oscillo-
scope. Latch the data on the falling edge of EOC.
Connect the least significant bits together, using resis-
tors of varying weights (for example, D0 = 75.0kΩ ±1%,
D1 = 39.1kΩ ±1%, D2 = 20.0kΩ ±1%, D3 = 10.0kΩ
±1%, D4 = 4.99kΩ ±1%). Drive the analog inputs with a
linear ramping signal, such as a 100Hz triangle wave.
Connect an oscilloscope in X-Y mode with X = analog
input and Y = weighted sum of the latched digital out-
puts. The resulting staircase plot gives a visual indica-
tion of relative LSB sizes and DNL performance.
Evaluating the MAX1165/MAX1166 and
MAX1065/MAX1066
The MAX1166 has an 8-bit interface. Its high-byte
enable (HBEN) is on the pad labeled RESET. To evalu-
ate the MAX1166, request a free sample of the
MAX1166BEUP. Remove the MAX1165 and install the
MAX1166, leaving U1 pins 1–4 and 25–28 unconnected.
The MAX1065 is a 14-bit version of the MAX1165. To
evaluate the MAX1065, request a free sample of the
MAX1065AEUI. Remove the MAX1165 and install the
MAX1065.
The MAX1066 is a 14-bit version of the MAX1165, with
an 8-bit interface. Its high-byte enable (HBEN) is on the
pad labeled RESET. To evaluate the MAX1066, request
a free sample of the MAX1066AEUP. Remove the
MAX1165 and install the MAX1066, leaving U1 pins 1–4
and 25–28 unconnected.
See Table 2 for device comparison.
Troubleshooting
Problem: no output measurement. System seems to
report zero voltage, or fails to make a measurement.
Check AVDD and DVDD supply voltages. Check the
4.096V reference voltage using a digital voltmeter. Use
an oscilloscope to verify the R/C, CS, and EOC signals.
Ensure that a resistor is installed in socket R2; other-
wise, the analog input is unconnected.
If using the input buffer U3, ensure that the ±5V power
supply is connected and JU3 is closed.
Problem: measurements are erratic, unstable; poor
accuracy.
Check the reference voltage using a digital voltmeter.
Use an oscilloscope to check for noise. When probing
for noise, keep the oscilloscope ground return lead as
short as possible, preferably less than 1/2in (10mm).
Increase C6 and C7 capacitance. Short JU1 and apply
an external 4.096V reference at REF to improve accuracy.
Check for ground loops in your system.
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