Datasheet

MAX1302
8-Channel, ±V
REF
Multirange Inputs,
Serial 16-Bit ADC
______________________________________________________________________________________ 13
Detailed Description
The MAX1302 multirange, low-power, 16-bit successive-
approximation ADC operates from a single +5V supply
and has a separate digital supply allowing digital inter-
face with 2.7V to 5.25V systems. This 16-bit ADC has
internal track-and-hold (T/H) circuitry that supports single-
ended and fully differential inputs. For single-ended con-
versions, the valid analog input voltage range spans from
-V
REF
below ground to +V
REF
above ground. The maxi-
mum allowable differential input voltage spans from -2 x
V
REF
to +2 x V
REF
. Data can be converted in a variety of
software-programmable channel and data-acquisition
configurations. Microprocessor (µP) control is made easy
through an SPI-/QSPI-/MICROWIRE-compatible serial
interface.
The MAX1302 has eight single-ended analog input
channels or four differential channels (see the Block
Diagram ). Each analog input channel is independently
software programmable for seven single-ended input
ranges (0V to +V
REF
/2, -V
REF
/2 to 0V, 0V to +V
REF
, -V
REF
to 0V, ±V
REF
/4, ±V
REF
/2, and ±V
REF
) and three differential
input ranges (±V
REF
/2, ±V
REF
, and ±2 x V
REF
).
Additionally, all analog input channels are fault tolerant to
±6V. A fault condition on an idle channel does not affect
the conversion result of other channels.
Pin Description (continued)
PIN NAME FUNCTION
21 AGND3
Analog Signal Ground 3. AGND3 is the ADC negative reference potential. Connect AGND3 to AGND1.
DGND, DGNDO, AGND3, AGND2, and AGND1 must be connected together.
22 AVDD2
Analog Supply Voltage 2. Connect AVDD2 to a +4.75V to +5.25V power-supply voltage. Bypass AVDD2
to AGND2 with a 0.1µF capacitor.
23 AGND2
Analog Ground 2. This ground carries approximately five times more current than AGND1. DGND,
DGNDO, AGND3, AGND2, and AGND1 must be connected together.
24 AGND1 Analog Ground 1. DGND, DGNDO, AGND3, AGND2, and AGND1 must be connected together.
4–20mA
PLC
ACCELERATION
PRESSURE
TEMPERATURE
WHEATESTONE
WHEATESTONE
1µF
0.1µF
AGND2
DGNDOAGND3 DGND
AVDD2
DVDD
AVDD1
0.1µF 0.1µF 0.1µF
5.0V 5.0V 5.0V
MAX1302
CHO
CH1
CH2
CH3
CH4
CH5
CH6
CH7
REF
AGND1
REFCAP
0.1µF
3.3V
MC68HCXX
µC
DVDD0
SCLK
CS
DIN
SSTRB
DOUT
V
DD
SCK
I/O
MOSI
I/O
MISO
V
SS
Figure 1. Typical Application Circuit