TECHNICAL NOTES
+25°C 0 to +70°C –55 to +125°C
ANALOG OUTPUT MIN. TYP. MAX. MIN. TYP. MAX. MIN. TYP. MAX. UNITS
Internal Reference
Voltage 3.15 +3.2 — — +3.2 — — +3.2 — Volts
Drift — ±30 — — ±30 — — ±30 — ppm/°C
External Current — 5 — — 5 — — 5 — mA
DIGITAL OUTPUTS
Logic Levels
Logic "1" +2.4 — — +2.4 — — +2.4 — — Volts
Logic "0" — — +0.4 — — +0.4 — — +0.4 Volts
Logic Loading "1" — — –4 — — –4 — — –4 mA
Logic Loading "0" — — +4 — — +4 — — +4 mA
Output Coding Offset Binary / Complementary Offset Binary / Two's Complement / Complementary Two's Complement
POWER REQUIREMENTS
Power Supply Ranges ➅
+5V Supply +4.75 +5.0 +5.25 +4.75 +5.0 +5.25 +4.9 +5.0 +5.25 Volts
–5V Supply –4.75 –5.0 –5.25 –4.75 –5.0 –5.25 –4.9 –5.0 –5.25 Volts
Power Supply Currents
+5V Supply — +220 260 — +220 260 — +220 260 mA
–5V Supply –150 –170 — –150 –170 — –150 –170 — mA
Power Dissipation — 1.85 2.15 — 1.85 2.15 — 1.85 2.15 Watts
Power Supply Rejection — — ±0.07 — — ±0.07 — — ±0.07 %FSR/%V
Footnotes:
➀ 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. There is a slight degradation in
performance when operating the device in the unipolar mode.
➁ When COMP. BITS (pin 35) is low, logic loading "0" will be –350μA.
➂ A 3MHz clock with a positive pulse width is used for all production testing. See
Timing Diagram for more details.
(SNR + Distortion) – 1.76 + 20 log Full Scale Amplitude
Actual Input Amplitude
6.02
➃ Effective bits is equal to:
➄ This is the time required before the A/D output data is valid once the analog input is
back within the specifi ed range.
➅ The minimum supply voltages of +4.9V and –4.9V for ±VDD are required for –55°C
operation only. The minimum limits are +4.75V and –4.75V when operating at
+125°C.
1. Obtaining fully specifi ed performance from the ADS-933 requires care-
ful attention to pc-card layout and power supply decoupling. The device's
analog and digital ground systems are connected to each other internally.
For optimal performance, tie all ground pins (2, 4, 7, 30 and 36) directly to a
large analog ground plane beneath the package.
Bypass all power supplies and the +3.2V reference output to ground with
4.7F tantalum capacitors in parallel with 0.1F ceramic capacitors. Locate
the bypass capacitors as close to the unit as possible.
2. The ADS-933 achieves its specifi ed accuracies without the need for exter-
nal calibration. If required, the device's small initial offset and gain 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 hard-
ware, make adjustments following warmup. To avoid interaction, always
adjust offset before gain. Tie pins 5 and 6 to ANALOG GROUND (pin 4) if not
using offset and gain adjust circuits.
3. Pin 35 (COMP. BITS) is used to select the digital output coding format of the
ADS-933 (see Tables 2a and 2b). When this pin has a TTL logic "0" applied,
it complements all of the ADS-933's B1-B16 & B1outputs.
When pin 35 has a logic "1" applied, the output coding is complementary
offset binary. Applying a logic "0" to pin 35 changes the coding to offset
binary. Using the MSB output (pin 29) instead of the MSB output (pin 28)
changes the respective output codings to complementary two's comple-
ment and two's complement.
Pin 35 is TTL compatible and can be directly driven with digital logic in
applications requiring dynamic control over its function. There is an internal
pull-up resistor on pin 35 allowing it to be either connected to +5V or left
open when a logic "1" is required.
4. To enable the three-state outputs, connect OUTPUT ENABLE (pin 34) to a
logic "0" (low). To disable, connect pin 34 to a logic "1" (high).
5. Applying a start convert pulse while a conversion is in progress (EOC =
logic "1") will initiate a new and probably inaccurate conversion cycle. Data
from both the interrupted and subsequent conversions will be invalid.
6. Do not enable/disable or complement the output bits or read from the FIFO
during the conversion process (from the rising edge of EOC to the falling
edge of EOC).
7. The OVERFLOW bit (pin 33) switches from 0 to 1 when the input voltage
exceeds that which produces an output of all 1’s or when the input equals
or exceeds the voltage that produces all 0’s. When COMP BITS is activated,
the above conditions are reversed.
ADS-933
16-Bit, 3 MHz Sampling A/D Converters
®®
DATEL • 11 Cabot Boulevard, Mansfi eld, MA 02048-1151 USA • Tel: (508) 339-3000 • www.datel.com • e-mail: help@datel.com
01 Apr 2011 MDA_ADS-933.B02 Page 3 of 8