MAX1303BEUP+ Maxim Integrated Products, MAX1303BEUP+ Datasheet - Page 25

• Manufacturer Part Number: MAX1303BEUP+
• Description: ADC Single SAR 115KSPS 16-Bit Serial 20-Pin TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX1303BEUP+

• Package: 20TSSOP
• Resolution: 16 Bit
• Sampling Rate: 115 KSPS
• Architecture: SAR
• Number Of Adcs: 1
• Number Of Analog Inputs: 4|2
• Digital Interface Type: Serial (SPI, QSPI, Microwire)
• Input Type: Voltage
• Signal To Noise Ratio: 90(Typ) dB
• Polarity Of Input Voltage: Unipolar|Bipolar

• External-acquisition-mode control byte
• Internal-clock-mode control byte
• Reset byte
• Partial power-down-mode control byte
This prevents the MAX1302/MAX1303 from inadvertent-
ly exiting full power-down mode because of a CS glitch
in a noisy digital environment.
The MAX1302/MAX1303 power up in normal operation
configured for external clock mode with all circuitry
active (Tables 7 and 8). Each analog input channel
(CH0–CH7) is set for single-ended conversions with a
±V
Allow the power supplies to stabilize after power-up. Do
not initiate any conversions until the power supplies
have stabilized. Additionally, allow 10ms for the internal
reference to stabilize when C
= 0.1µF. Larger reference capacitors require longer
stabilization times.
The MAX1302/MAX1303 operate with either an internal or
external reference. The reference voltage impacts the
ADC’s FSR (Figures 12, 13, and 14). An external refer-
ence is recommended if more accuracy is required than
the internal reference provides, and/or multiple converters
require the same reference voltage.
The MAX1302/MAX1303 contain an internal 4.096V
bandgap reference. This bandgap reference is connect-
ed to REFCAP through a nominal 5kΩ resistor (Figure 17).
The voltage at REFCAP is buffered creating 4.096V at
Figure 17. Internal Reference Operation
REF
MAX1302
MAX1303
bipolar input range (Table 6).
ADC REF
SAR
REFERENCE
BANDGAP
4.096V
Internal or External Reference
5kΩ
4.096V
______________________________________________________________________________________
1x
8-/4-Channel, ±V
REF
= 1.0µF and C
Power-On Reset
Internal Reference
V
REFCAP
RCTH
AGND1
REF
RECAP
1.0µF
0.1µF
REF. When using the internal reference, bypass
REFCAP with a 0.1µF or greater capacitor to AGND1 and
bypass REF with a 1.0µF or greater capacitor to AGND1.
For external reference operation, disable the internal
reference and reference buffer by connecting REFCAP
to AV
becomes a high-impedance input and accepts an
external reference voltage. The MAX1302/MAX1303
external reference current varies depending on the
applied reference voltage and the operating mode (see
the External Reference Input Current vs. External
Reference Input Voltage in the Typical Operating
Characteristics).
Additional samples can be taken and averaged (over-
sampling) to remove the effect of transition noise on
conversion results. The square root of the number of
samples determines the improvement in performance.
For example, with 2/3 LSB
noise, 16 (4
the noise to 1 LSB
Figure 19 illustrates a simple interface between the
MAX1302/MAX1303 and a 4–20mA signal. 4–20mA sig-
naling can be used as a binary switch (4mA represents
a logic-low signal, 20mA represents a logic-high sig-
nal), or for precision communication where currents
between 4mA and 20mA represent intermediate analog
data. For binary switch applications, connect the
4–20mA signal to the MAX1302/MAX1303 with a resis-
tor to ground. For example, a 200Ω resistor converts
the 4–20mA signal to a 0.8V to 4V signal. Adjust the
resistor value so the parallel combination of the resistor
and the MAX1302/MAX1303 source impedance is
200Ω. In this application, select the single-ended 0 to
V
that require precision measurements of continuous
analog currents between 4mA and 20mA, use a buffer
to prevent the MAX1302/MAX1303 input from diverting
current from the 4–20mA signal.
REF
REF
DD1
range (R[2:0] = 011, Table 6). For applications
. With AV
Serial 16-Bit ADCs
Multirange Inputs,
2
= 16) samples must be taken to reduce
Applications Information
Interface with 4–20mA Signals
P-P
DD1
.
connected to REFCAP, REF
RMS
(4 LSB
Noise Reduction
External Reference
P-P
) transition
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