MAX1332 Datasheet, PDF (22/25 Pages) Maxim Integrated Products – 3Msps/2Msps, 5V/3V, 2-Channel, True-Differential 12-Bit ADCs

3Msps/2Msps, 5V/3V, 2-Channel, True-
Differential 12-Bit ADCs
DV_DD
SCLK
MAX1332
MAX1333 CNVST
DOUT
VDDINT
TCLK
RCLK ^{ADSP21_ _ _}
TFS
RFS
DR
ANALOG SUPPLY DIGITAL
GROUND
AV_DD
RETURN ^POINT
10Ω*
ANALOG
GROUND
POINT
DIGITAL SUPPLY
RETURN
DV_DD
AV_DD
AGND
DGND
DV_DD
DGND
DV_DD
MAX1332
MAX1333
DATA
DIGITAL
CIRCUITRY
Figure 19. Interfacing to the ADSP21_ _ _
Connect all digital grounds to the digital ground point.
For lowest noise operation, make the power supply
returns as low impedance and as short as possible.
Connect the analog ground point to the digital ground
point together at the IC.
High-frequency noise in the power supplies degrades
the ADC’s performance. Bypass AV_DD to AGND with
0.1µF and 1µF bypass capacitors. Likewise, bypass
DV_DD to DGND with 0.1µF and 1µF bypass capacitors.
Minimize capacitor lead lengths for best supply noise
rejection. To reduce the effects of supply noise, a 10Ω
resistor can be connected as a lowpass filter to attenu-
ate supply noise (see Figure 20).
Exposed Paddle
The MAX1332/MAX1333 TQFN package has an exposed
paddle on the bottom of the package, providing a very
low thermal resistance path for heat removal from the IC,
as well as a low-inductance path to ground. The pad is
electrically connected to AGND on the MAX1332/
MAX1333 and must be soldered to the circuit board ana-
log ground plane for proper thermal and electrical perfor-
mance. Refer to the Maxim Application Note HFAN-08.1:
Thermal Considerations for QFN and Other Exposed Pad
Packages, for additional information.
Definitions
Integral Nonlinearity (INL)
INL is the deviation of the values on an actual transfer
function from a straight line. For the MAX1332/
MAX1333, this straight line is between the end points of
*OPTIONAL
Figure 20. Power-Supply Grounding Condition
the transfer function once offset and gain errors have
been nullified. INL deviations are measured at every
step and the worst-case deviation is reported in the
electrical characteristics table.
Differential Nonlinearity (DNL)
DNL is the difference between an actual step width and
the ideal value of 1 LSB. A DNL error specification of
less than 1 LSB guarantees no missing codes and a
monotonic transfer function. For the MAX1332/
MAX1333, DNL deviations are measured at every step
and the worst-case deviation is reported in the electri-
cal characteristics table.
Offset Error
Offset error is a figure of merit that indicates how well
the actual transfer function matches the ideal transfer
function at a single point. Typically, the point at which
the offset error is specified is at or near the zero-scale
of the transfer function or at or near the midscale of the
transfer function.
For the MAX1332/MAX1333, operating with a unipolar
transfer function, the ideal zero-scale digital output
transition from 0x000 to 0x001 occurs at 0.5 LSB above
AGND. Unipolar offset error is the amount of deviation
between the measured zero-scale transition point and
the ideal zero-scale transition point.
For the MAX1332/MAX1333, operating with a bipolar
transfer function, the ideal midscale digital output tran-
sition from 0xFFF to 0x000 occurs at 0.5 LSB below
AGND. Bipolar offset error is the amount of deviation
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