ADS-950MC ETC, ADS-950MC Datasheet - Page 3

• Manufacturer Part Number: ADS-950MC
• Description: 18-Bit/ 500kHz/ Low-Power Sampling A/D Converters
• Manufacturer: ETC

TECHNICAL NOTES
1. Obtaining fully specified performance from the ADS-950
2. The ADS-950 achieves its specified accuracies without the
ANALOG OUTPUT
Internal Reference
External Current
DIGITAL OUTPUTS
Logic Levels
Output Coding
POWER REQUIREMENTS
Power Supply Ranges
Power Supply Currents
Power Dissipation
Power Supply Rejection
Footnotes:
requires careful attention to pc-card layout and power
supply decoupling. The device's analog and digital ground
systems are not connected to each other internally. For
optimal performance, tie all ground pins (3, 12 and 13)
directly to a large analog ground plane beneath the
package.
Bypass all power supplies and the +5V REFERENCE
OUTPUT (pin 5) to ground with 10µF tantalum capacitors in
parallel with 0.1µF ceramic capacitors. Locate the bypass
capacitors as close to the unit as possible. Tie a 47µF
capacitor between COMPENSATION (pin 7) and ground.
need for external calibration. If required, the device's small
initial errors can be reduced to zero using the adjustment
circuitry shown in Figure 2. When using this circuitry, or any
similar offset and gain calibration hardware, make adjust-
ments following warmup. To avoid interaction, always adjust
offset before gain. Float pin 6 if not using gain adjust
circuits.
Voltage
Drift
Logic "1"
Logic "0"
Logic Loading "1"
Logic Loading "0"
+15V Supply
–15V Supply
+5V Supply
–5V Supply
+15V Supply
–15V Supply
+5V Supply
–5V Supply
®
All power supplies must be on before applying a start convert pulse. All
supplies and the clock (START CONVERT) must be present during warmup
periods. The device must be continuously converting during this time.
Contact DATEL for other input voltage ranges.
A 500kHz clock with a 1µsec positive pulse width (50% duty cycle) is
used for all production testing. Any duty cycle may be used as long as a
minimum positive pulse width of 20nsec is maintained. For applications
requiring lower sampling rates, clock frequencies lower than 1MHz
may be used.
®
+4.95
+14.5
–14.5
+4.75
–4.75
MIN.
+2.4
—
—
—
—
—
—
—
—
—
—
—
+25°C
+15.0
–15.0
TYP.
+104
+5.0
+5.0
–5.0
1.45
±30
+29
–15
–54
—
—
—
—
—
1
MAX.
+15.5
+5.25
±0.05
+5.05
–15.5
–5.25
+0.4
1.65
—
–4
+4
—
—
—
—
—
—
3
+14.5
–14.5
+4.75
–4.75
+4.95
MIN.
+2.4
—
—
—
—
—
—
—
—
—
—
—
3. Applying a start convert pulse while a conversion is in
THERMAL REQUIREMENTS
All DATEL sampling A/D converters are fully characterized and
specified over operating temperature (case) ranges of 0 to
+70°C and –55 to +125°C. All room-temperature (T
production testing is performed without the use of heat sinks or
forced-air cooling. Thermal impedance figures for each device
are listed in their respective specification tables.
These devices do not normally require heat sinks, however,
standard precautionary design and layout procedures should be
used to ensure devices do not overheat. The ground and power
planes beneath the package, as well as all pcb signal runs to
and from the device, should be as heavy as possible to help
conduct heat away from the package. Electrically-insulating,
thermally-conductive "pads" may be installed underneath the
package. Devices should be soldered to boards rather than
"socketed", and of course, minimal air flow over the surface can
greatly help reduce the package temperature.
Effective bits is equal to:
This is the time required before the A/D output data is valid once the analog input
is back within the specified range.
progress (EOC = logic "1") will initiate a new and probably
inaccurate conversion cycle. Data for the interrupted and
subsequent conversions will be invalid.
Complementary Offset Binary
0 to +70°C
+15.0
–15.0
TYP.
+104
+5.0
+5.0
–5.0
1.45
±30
+29
–15
–54
—
—
—
—
—
1
(SNR + Distortion) – 1.76 +
MAX.
+5.05
+15.5
–15.5
+5.25
–5.25
±0.05
+0.4
1.65
+4
—
—
—
–4
—
—
—
—
+14.5
+4.75
+4.95
–14.5
–4.75
+2.4
MIN.
—
—
—
—
—
—
—
—
—
—
—
–55 to +125°C
6.02
20 log
+15.0
–15.0
TYP.
+104
+5.0
+5.0
–5.0
1.45
±30
+29
–15
–54
—
—
—
—
—
1
Actual Input Amplitude
Full Scale Amplitude
ADS-950
MAX.
+5.05
+15.5
–15.5
+5.25
–5.25
±0.05
+0.4
1.65
+4
—
—
—
–4
—
—
—
—
A
= +25°C)
%FSR/%V
UNITS
ppm/°C
Watts
Volts
Volts
Volts
Volts
Volts
Volts
Volts
mA
mA
mA
mA
mA
mA
mA