MAX1322ECM Maxim Integrated, MAX1322ECM Datasheet - Page 19

• Manufacturer Part Number: MAX1322ECM
• Description: Analog to Digital Converters - ADC
• Manufacturer: Maxim Integrated

Specifications of MAX1322ECM

• Number Of Channels: 2
• Architecture: SAR
• Conversion Rate: 526 KSPs
• Resolution: 14 bit
• Input Type: Single-Ended
• Snr: 76 dB
• Interface Type: Parallel
• Operating Supply Voltage: 2.7 V to 5.25 V, 4.75 V to 5.25 V
• Maximum Operating Temperature: + 85 C
• Package / Case: LQFP-48
• Maximum Power Dissipation: 1818 mW
• Minimum Operating Temperature: - 40 C
• Number Of Converters: 1
• Voltage Reference: 2.5 V

Figure 7 shows the interface signals for a read operation
after a conversion with all eight channels enabled. At the
falling edge of EOLC, on the 38th clock pulse after the ini-
tiation of a conversion, driving CS and RD low places the
first conversion result onto the parallel bus, which can be
latched on the rising edge of RD. Successive low pulses
of RD place the successive conversion results onto the
bus. Pulse CONVST low to initiate a new conversion.
At power-up, all channels are selected for conversion
(see the Configuration Register section). After applying
power, allow a 1.0ms wake-up time to elapse before ini-
tiating the first conversion. Then, hold CONVST high for
at least 2.0µs after the wake-up time is complete. If
using an external clock, apply 20 clock pulses to CLK
with CONVST high before initiating the first conversion.
The internal-reference circuits provide for analog input
voltages of 0 to +5V unipolar (MAX1316/MAX1317/
MAX1318), ±5V bipolar (MAX1320/MAX1321/MAX1322),
or ±10V bipolar (MAX1324/MAX1325/MAX1326). Install
external capacitors for reference stability, as indicated in
Table 4, and as shown in the Typical Operating Circuits .
Connect a +2.0V to +3.0V external reference at REF
and/or REF. When connecting an external reference, the
input impedance is typically 5kΩ. The external reference
must be able to drive 200µA of current and have a low
output impedance. For more information about using
external references see the Transfer Functions section.
Table 4. Reference Bypass Capacitors
NA = Not applicable (connect MSV directly to AGND).
8-/4-/2-Channel, 14-Bit, Simultaneous-Sampling ADCs
MSV bypass capacitor to AGND
REF
REF bypass capacitor to AGND
REF+ bypass capacitor to AGND
REF+ to REF- capacitor
REF- bypass capacitor to AGND
COM bypass capacitor to AGND
MS
with ±10V, ±5V, and 0 to +5V Analog Input Ranges
bypass capacitor to AGND
LOCATION
______________________________________________________________________________________
Reading After Conversion
Power-Up Reset
External Reference
Internal Reference
Reference
UNIPOLAR (µF)
MS
2.2 || 0.1
2.2 || 0.1
2.2 || 0.1
0.01
0.01
0.1
0.1
For best performance use PC boards with ground
planes. Board layout should ensure that digital and
analog signal lines are separated from each other. Do
not run analog and digital lines parallel to one another
(especially clock lines), or do not run digital lines
underneath the ADC package. Figure 8 shows the rec-
ommended system ground connections when not using
a ground plane. A single-point analog ground (star
ground point) should be established at AGND, sepa-
rate from the logic ground. All other analog grounds
and DGND should be connected to this ground.
Figure 8. Power-Supply Grounding and Bypassing
AV
+5V
DD
INPUT VOLTAGE RANGE
OPTIONAL
FERRITE
BEAD
Layout, Grounding, and Bypassing
RETURN
MAX1316–MAX1318
MAX1320–MAX1322
MAX1324–MAX1326
AGND
DV
0.01 (connect REF
0.01 (connect REF
SUPPLIES
DD
BIPOLAR (µF)
DGND
2.2 || 0.1
2.2 || 0.1
NA
0.1
0.1
+3V TO +5V
MS
MS
V
DD
CIRCUITRY
to REF)
to REF)
DIGITAL
RETURN
GND
19