MAX11321 Datasheet, PDF (19/37 Pages) Maxim Integrated Products – 1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with Post-Mux External Signal Conditioning Access

MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Alternatively, set SWCNV to 1 in the ADC Mode Control
register (Figure 4) to initiate conversions with CS rising
edge instead of cycling CNVST (Table 2). For proper
operation, CS must be held low for 17 clock cycles to
guarantee that the device interprets the SWCNV setting.
Wait until EOC goes low before pulling CS low to com-
municate with the serial interface. Upon completing the
conversion, SWCNV is reset to 0 (Figure 7).
Analog Input
The MAX11321–MAX11328 produce a digital output that
corresponds to the analog input voltage as long as the
analog inputs are within the specified operating range.
Internal protection diodes confine the analog input volt-
age within the region of the analog power input rails
(V_DD, GND) and allow the analog input voltage to swing
from GND - 0.3V to V_DD + 0.3V without damaging the
device. Input voltages beyond GND - 0.3V and V_DD +
0.3V forward bias the internal protection diodes. Limit the
forward diode current to less than 50mA to avoid dam-
age to the MAX11321–MAX11328.
ECHO
When writing to the ADC Configuration register, set
ECHO to 1 in ADC Configuration register to echo back
the configuration data onto DOUT at time n+1 (Figure 8,
Table 6).
Scan Modes
The MAX11321–MAX11328 feature nine scan modes
(Table 3).
Manual Mode
The next channel to be selected is identified in each SPI
frame. The conversion results are sent out in the next
frame. The manual mode works with the external clock
only. The FIFO is unused.
Repeat Mode
Repeat scanning channel N for number of times and
store all the conversion results in the FIFO. The number of
scans is programmed in the ADC Configuration register.
The repeat mode works with the internal clock only.
Custom_Int and Custom_Ext
In Custom_Int and Custom_Ext modes, the device scans
preprogrammed channels in ascending order. The chan-
nels to be scanned in sequence are programmed in the
Custom Scan0 or Custom Scan1 registers (see Table 12
and Table 13). A new I/P MUX is selected every frame
on the thirteenth falling edge of SCLK. Custom_Int works
with the internal clock. Custom_Ext works with the exter-
nal clock.
Standard_Int and Standard_Ext
In Standard_Int and Standard_Ext modes, the device
scans channels 0 through N in ascending order where
N is the last channel specified in the ADC Mode Control
register. A new I/P MUX is selected every frame on the
thirteenth falling edge of SCLK. Standard_Int works with
the internal clock. Standard_Ext works with the external
clock.
Upper_Int and Upper_Ext
In Upper_Int and Upper_Ext modes, the device scans
channels N through 15/11/7/3 in ascending order where
N is the first channel specified in the ADC Mode Control
register. A new I/P MUX is selected every frame on the
thirteenth falling edge of SCLK. Upper_Int works with the
internal clock. Upper_Ext works with the external clock.
SampleSet
The SampleSet mode of operation allows the definition
of a unique channel sequence combination with maxi-
mum length of 256. SampleSet is supported only in the
external clock mode. SampleSet is ideally suited for mul-
tichannel measurement applications where some analog
inputs must be converted more often than others.
CS
DIN
DOUT
t = n-1
t=n
t = n+1
t = n+2
TURN ON ECHO
CONFIGURATION
DATA
CONFIGURATION
DATA
CONFIGURATION
DATA
CONFIGURATION
DATA
CONFIGURATION
DATA
Figure 8. Echo Back the Configuration Data
Maxim Integrated
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