EVALUATION KIT AVAILABLE
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
General Description
Benefits and Features
The MAX11321–MAX11328 are 12-/10-bit with external
reference and 500kHz, full-linear-bandwidth, high-speed,
low-power, serial-output successive approximation register (SAR) analog-to-digital converters (ADCs). The
MAX11321–MAX11328 provide external access to the
output of the integrated mux and ADC input, to simplify
conditioning. The MAX11321–MAX11328 include both
internal and external clock modes. These devices feature
scan mode in both internal and external clock modes. The
internal clock mode features internal averaging to increase
SNR. The external clock mode features the SampleSetK
technology, a user-programmable analog input channel
sequencer. The SampleSet approach provides greater
sequencing flexibility for multichannel applications while
alleviating significant microcontroller or DSP (controlling
unit) communication overhead.
S Scan Modes, Internal Averaging, and Internal Clock
S 16-Entry First-In/First-Out (FIFO)
S SampleSet: User-Defined Channel Sequence with
Maximum Length of 256
S Input Pins
Any Combination of Single-Ended, Differential
and Pseudo-Differential Pairs Allowed
S Analog Multiplexer with True Differential
Track/Hold
16-/8-/4-Channel Single-Ended
12-/8-/4-Channel Fully-Differential Pairs
15-/8-/4-Channel Pseudo-Differential Relative to
a Common Input
S Externally Accessible Multiplex Output and
ADC Input
S Two Software-Selectable Bipolar Input Ranges
QVREF+/2, QVREF+
S Flexible Input Configuration Across All Channels
S High Accuracy
Q1 LSB INL, Q1 LSB DNL, No Missing Codes
S 70dB SINAD Guaranteed at 100kHz Input
Frequency
S 1.5V to 3.6V Digital I/O Supply Voltage
S 2.35V to 3.6V Supply Voltage
S Extended Battery Life for Portable Applications
5.4mW at 1Msps with 3V Supplies
2µA Full-Shutdown Current
S External Differential Reference (1V to VDD)
S 16MHz, 3-Wire SPI-/QSPI-/MICROWIRE-/DSPCompatible Serial Interface
S Wide -40NC to +125NC Operation
S Space-Saving, 32-Pin, 5mm x 5mm TQFN Packages
S 1Msps Conversion Rate, No Pipeline Delay
External pins provide access to the output of the
multiplexer and ADC inputs to simplify multichannel signal conditioning. The internal clock mode features an integrated FIFO allowing data to be sampled at high speeds
and then held for readout at any time or at a lower clock
rate. Internal averaging is also supported in internal clock
mode improving SNR for noisy input signals. The devices
feature analog input channels that can be configured to
be single-ended inputs, fully differential pairs, or pseudodifferential inputs with respect to one common input. The
MAX11321–MAX11328 operate from a 2.35V to 3.6V supply and consume only 5.4mW at 1Msps.
The MAX11321–MAX11328 include AutoShutdownK,
fast wake-up, and a high-speed 3-wire serial interface.
The devices feature full power-down mode for optimal
power management. The 48MHz, 3-wire serial interface
directly connects to SPI, QSPIK, and MICROWIREM
devices without external logic.
Excellent dynamic performance, low voltage, low power,
ease of use, and small package size make these converters ideal for portable battery-powered data-acquisition
applications, and for other applications that demand low
power consumption and small space.
Applications
High-Speed Data Acquisition Systems
The MAX11321–MAX11328 are available in 32-pin, 5mm
x 5mm, TQFN packages and operate over the -40NC to
+125NC temperature range.
High-Speed Closed-Loop Systems
SampleSet and AutoShutdown are trademarks of Maxim
Battery-Powered Instruments
Integrated Products, Inc.
QSPI is a trademark of Motorola, Inc.
MICROWIRE is a registered trademark of National Semiconductor
Corp.
Ordering Information appears at end of data sheet.
Industrial Control Systems
Medical Instrumentation
Portable Systems
For related parts and recommended products to use with this part,
refer to www.maximintegrated.com/MAX11321-MAX11328.related.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-6467; Rev 0; 9/12
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
ABSOLUTE MAXIMUM RATINGS
VDD to GND..............................................................-0.3V to +4V
AOP, AON, AIP, AIN, OVDD, AIN0–AIN13, CNVST/AIN14, REF+,
REF-/AIN15 to GND........................................ -0.3V to the lower of
(VDD + 0.3V) and +4V
CS, SCLK, DIN, DOUT, EOC TO GND........-0.3V to the lower of
(VOVDD + 0.3V) and +4V
DGND to GND.......................................................-0.3V to +0.3V
Input/Output Current (all pins)............................................50mA
Continuous Power Dissipation (TA = +70NC)
TQFN (derate 34.4mW/NC above +70NC)..................2758mW
Operating Temperature Range......................... -40NC to +125NC
Junction Temperature......................................................+150NC
Storage Temperature Range............................. -65NC to +150NC
Lead Temperature (soldering, 10s).................................+300NC
Soldering Temperature (reflow).......................................+260NC
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
TQFN
Junction-to-Ambient Thermal Resistance (BJA)............29NC/W
Junction-to-Case Thermal Resistance (BJC)................1.7NC/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS (MAX11322/MAX11325/MAX11328)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Q1.0
LSB
DC ACCURACY (Notes 3 and 4)
Resolution
RES
Integral Nonlinearity
INL
Differential Nonlinearity
DNL
12 bit
12
No missing codes
Offset Error
Gain Error
Bits
(Note 5)
Q1.0
LSB
1.2
Q3.0
LSB
0.02
Q5.5
LSB
Offset Error Temperature Coefficient
OETC
Q2
ppm/NC
Gain Temperature Coefficient
GETC
Q0.8
ppm/NC
Channel-to-Channel Offset Matching
Line Rejection
LSB
Q0.5
PSR
(Note 6)
0.3
Q2
LSB/V
DYNAMIC PERFORMANCE (100kHz, Input Sine Wave) (Notes 3 and 7)
Signal-to-Noise Plus Distortion
SINAD
70
71.9
dB
Signal-to-Noise Ratio
SNR
70
72.3
dB
Total Harmonic Distortion
(Up to the 5th Harmonic)
THD
Spurious-Free Dynamic Range
SFDR
Intermodulation Distortion
Full-Power Bandwidth
Full-Linear Bandwidth
Maxim Integrated
IMD
-83
77
-76
dB
84
dB
f1 = 99.2432kHz, f2 = 69.2139kHz
-85
dB
-3dB
30
-0.1dB
5
SINAD ≥ 70dB
0.5
MHz
MHz
2
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
ELECTRICAL CHARACTERISTICS (MAX11322/MAX11325/MAX11328) (continued)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
-0.5dB below full-scale of 99.2432kHz
sine wave input to the channel being
sampled, apply full-scale 69.2139kHz
sine wave signal to all 15 nonselected
input channels.
Crosstalk
TYP
MAX
-88
UNITS
dB
CONVERSION RATE
Power-Up Time
tPU
Acquisition Time
tACQ
Conversion Time
tCONV
External Clock Frequency
fSCLK
Conversion cycle, external clock
2
Internally clocked (Note 8)
Externally clocked, fSCLK = 16MHz,
16 cycles (Note 8)
Aperture Jitter
ns
5.9
µs
1000
ns
0.16
Aperture Delay
RMS
Cycles
156
16
MHz
8
ns
30
ps
ANALOG INPUT
Input Voltage Range
VINA
Absolute Input Voltage Range
Static Input Leakage Current
Input Capacitance
Unipolar, (single ended and pseudodifferential)
Bipolar
(Note 9)
Range bit set to 0
-VREF+/2
Range bit set to 1
-VREF+
AIN+, AIN- relative to GND
IILA
CAIN
0
-0.1
VREF+
VREF+/2
VREF+
VREF+ + 0.1
-0.1
VAIN = VDD, GND
V
During acquisition time;
RANGE bit = 0 (Note 10)
15
During acquisition time;
RANGE bit = 1 (Note 10)
7.5
Q1.5
V
FA
pF
EXTERNAL REFERENCE INPUT
REF- Input Voltage Range
VREF-
-0.3
REF+ Input Voltage Range
VREF+
1
REF+ Input Current
IREF+
+1
VDD + 50mV
VREF+ = 2.5V, fSAMPLE = 1Msps
36.7
VREF+ = 2.5V, fSAMPLE = 0Msps
0.1
V
V
FA
DIGITAL INPUTS (SCLK, DIN, CS, CNVST)
Input Voltage Low
VIL
Input Voltage High
VIH
Input Hysteresis
Maxim Integrated
VHYST
VOVDD
O 0.25
VOVDD
O 0.75
V
V
VOVDD
O 0.15
mV
3
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
ELECTRICAL CHARACTERISTICS (MAX11322/MAX11325/MAX11328) (continued)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
Input Leakage Current
IIN
Input Capacitance
CIN
CONDITIONS
MIN
VAIN = 0V or VDD
TYP
MAX
UNITS
Q0.09
Q1.0
FA
3
pF
DIGITAL OUTPUTS (DOUT, EOC)
Output Voltage Low
VOL
ISINK = 200FA
Output Voltage High
VOH
ISOURCE = 200FA
Three-State Leakage Current
Three-State Output Capacitance
VOVDD
O 0.15
VOVDD
O 0.85
V
V
IL
CS = VDD
-0.3
COUT
CS = VDD
4
Q1.5
FA
pF
POWER REQUIREMENTS
Positive Supply Voltage
Digital I/O Supply Voltage
VDD
VOVDD
2.35
3.0
3.6
V
1.5
3.0
3.6
V
1.8
2.5
fSAMPLE = 1Msps
Positive Supply Current
IDD
fSAMPLE = 0Msps (1Msps devices)
1
Full shutdown
Normal mode
(External
Reference)
Power Dissipation
AutoStandby
Full/
AutoShutdown
0.0015
VDD = 3V,
fSAMPLE = 1Msps
5.4
VDD = 2.35V,
fSAMPLE = 1Msps
3.8
VDD = 3V,
fSAMPLE = 1Msps
2.6
VDD = 2.35V,
fSAMPLE = 1Msps
1.6
VDD = 3V
4.5
VDD = 2.35V
2.1
mA
0.006
mW
FW
TIMING CHARACTERISTICS (Figure 1) (Note 11)
SCLK Clock Period
tCP
SCLK Duty Cycle
tCH
SCLK Fall to DOUT Transition
tDOT
CLOAD =
10pF
16th SCLK Fall to DOUT Disable
tDOD
CLOAD = 10pF, channel ID on
15
ns
CLOAD = 10pF, channel ID off
16
ns
CLOAD = 10pF
14
ns
14th SCLK Fall to DOUT Disable
SCLK Fall to DOUT Enable
tDOE
Externally clocked conversion
62.4
ns
40
60
VOVDD = 1.5V to 2.35V
4
16.5
VOVDD = 2.35V to 3.6V
4
15
%
ns
DIN to SCLK Rise Setup
tDS
4
ns
SCLK Rise to DIN Hold
tDH
1
ns
Maxim Integrated
4
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
ELECTRICAL CHARACTERISTICS (MAX11322/MAX11325/MAX11328) (continued)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CS Fall to SCLK Fall Setup
tCSS
4
ns
SCLK Fall to CS Fall Hold
tCSH
1
ns
CNVST Pulse Width
tCSW
5
ns
CS or CNVST Rise to EOC Low
(Note 6)
CS Pulse Width
See Figure 6
tCNV_INT
See Figure 7, fSAMPLE = 1Msps
tCSBW
5.3
6.2
5
Fs
ns
ELECTRICAL CHARACTERISTICS (MAX11321/MAX11324/MAX11327)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DC ACCURACY (Notes 3 and 4)
Resolution
RES
Integral Nonlinearity
INL
Differential Nonlinearity
DNL
10 bit
10
±0.4
LSB
±0.4
LSB
0.7
±1.2
LSB
0
±1.5
LSB
No missing codes
Offset Error
Gain Error
Bits
(Note 5)
Offset Error Temperature
Coefficient
OETC
±2
ppm/NC
Gain Temperature Coefficient
GETC
±0.8
ppm/NC
±0.5
LSB
Channel-to-Channel Offset
Matching
Line Rejection
PSR
(Note 6)
0.2
±1.0
LSB/V
DYNAMIC PERFORMANCE (100kHz, Input Sine Wave) (Notes 3 and 7)
Signal-to-Noise Plus Distortion
SINAD
61
61.5
dB
Signal-to-Noise Ratio
SNR
61
61.5
dB
Total Harmonic Distortion
(Up to the 5th Harmonic)
THD
Spurious-Free Dynamic Range
SFDR
Intermodulation Distortion
Full-Power Bandwidth
Full-Linear Bandwidth
Maxim Integrated
IMD
-82.5
76
83.4
-75
dB
dB
f1 = 99.2432kHz, f2 = 69.2139kHz
-83
dB
-3dB
30
MHz
-0.1dB
5
MHz
0.5
MHz
SINAD ≥ 61dB
5
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
ELECTRICAL CHARACTERISTICS (MAX11321/MAX11324/MAX11327) (continued)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
-0.5dB below full-scale of 99.2432kHz
sine-wave input to the channel being
sampled; apply full-scale 69.2139kHz sine
wave signal to all 15 nonselected
input channels
Crosstalk
TYP
MAX
-88
UNITS
dB
CONVERSION RATE
Power-Up Time
tPU
Acquisition Time
tACQ
Conversion Time
External Clock Frequency
tCONV
Conversion cycle, external clock
2
Internally clocked, fSAMPLE = 1Msps,
(Note 8)
Externally clocked, fSCLK = 16MHz,
16 cycles (Note 8)
fSCLK
Aperture Jitter
156
ns
5.9
µs
1000
ns
0.16
Aperture Delay
RMS
Cycles
16
MHz
8
ns
30
ps
ANALOG INPUT
Unipolar (single-ended and pseudo
differential)
Input Voltage Range
VINA
Bipolar (Note 9)
Absolute Input Voltage Range
Static Input Leakage Current
Input Capacitance
0
VREF+
RANGE bit set to 0
-VREF+
/2
+VREF+
/2
RANGE bit set to 1
-VREF+
+VREF+
-0.1
VREF+
+ 0.1
V
±1.5
FA
AIN+, AIN- relative to GND
IILA
CAIN
-0.1
VAIN_ = VDD, GND
During acquisition time,
RANGE bit = 0 (Note 10)
15
During acquisition time,
RANGE bit = 1 (Note 10)
7.5
V
pF
EXTERNAL REFERENCE INPUT
REF- Input Voltage Range
VREF-
REF+ Input Voltage Range
VREF+
REF+ Input Current
IREF+
-0.3
+1
V
1
VDD
+50mV
V
VREF+ = 2.5V, fSAMPLE = 1Msps
36.7
FA
VREF+ = 2.5V, fSAMPLE = 0Msps
0.1
FA
DIGITAL INPUTS (SCLK, DIN, CS, CNVST)
Input Voltage Low
Maxim Integrated
VIL
VOVDD
O 0.25
V
6
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
ELECTRICAL CHARACTERISTICS (MAX11321/MAX11324/MAX11327) (continued)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
Input Voltage High
Input Hysteresis
SYMBOL
CONDITIONS
MIN
VIH
IIN
Input Capacitance
CIN
MAX
VAIN_ = 0V or VDD
UNITS
V
VOVDD
O 0.15
VHYST
Input Leakage Current
TYP
VOVDD
O 0.75
±0.09
mV
±1.0
3
FA
pF
DIGITAL OUTPUTS (DOUT, EOC)
Output Voltage Low
VOL
ISINK = 200FA
Output Voltage High
VOH
ISOURCE = 200FA
Three-State Leakage Current
Three-State Output Capacitance
VOVDD
O 0.15
VOVDD
O 0.85
V
V
IL
CS = VDD
-0.3
COUT
CS = VDD
4
±1.5
FA
pF
POWER REQUIREMENTS
Positive Supply Voltage
Digital I/O Supply Voltage
VDD
VOVDD
2.35
3.0
3.6
V
1.5
3.0
3.6
V
1.8
2.5
fSAMPLE = 1Msps
Positive Supply Current
IDD
fSAMPLE = 0Msps (1Msps devices)
1
Full shutdown
Normal mode
(external
reference)
Power Dissipation
AutoStandby
Full/
AutoShutdown
0.0015
VDD = 3V,
fSAMPLE = 1Msps
5.4
VDD = 2.35V,
fSAMPLE = 1Msps
3.8
VDD = 3V,
fSAMPLE = 1Msps
2.6
VDD = 2.35V,
fSAMPLE = 1Msps
1.6
VDD = 3V
4.5
VDD = 2.35V
2.1
mA
0.006
mW
FW
TIMING CHARACTERISTICS (Figure 1) (Note 11)
SCLK Clock Period
tCP
SCLK Duty Cycle
tCH
SCLK Fall to DOUT Transition
tDOT
CLOAD =
10pF
16th SCLK Fall to DOUT Disable
tDOD
CLOAD = 10pF, channel ID on
15
ns
CLOAD = 10pF, channel ID off
16
ns
CLOAD = 10pF
14
ns
14th SCLK Fall to DOUT Disable
SCLK Fall to DOUT Enable
Maxim Integrated
tDOE
Externally clocked conversion
62.4
ns
40
60
VOVDD = 1.5V to 2.35V
4
16.5
VOVDD = 2.35V to 3.6V
4
15
%
ns
7
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
ELECTRICAL CHARACTERISTICS (MAX11321/MAX11324/MAX11327) (continued)
(VDD = 2.35V to 3.6V, VOVDD = 1.5V to 3.6V, fSAMPLE = 1Msps, fSCLK = 16MHz, 50% duty cycle, VREF+ = VDD, TA = -40NC to +125NC,
unless otherwise noted. Typical values are at TA = +25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DIN to SCLK Rise Setup
tDS
4
ns
SCLK Rise to DIN Hold
tDH
1
ns
CS Fall to SCLK Fall Setup
tCSS
4
ns
SCLK Fall to CS Fall Hold
tCSH
1
ns
CNVST Pulse Width
tCSW
5
ns
CS or CNVST Rise to EOC Low
(Note 7)
tCNV_INT
See Figure 6
See Figure 7, fSAMPLE = 1Msps
5.3
tCSBW
CS Pulse Width
5
6.2
Fs
ns
Note 2: Limits are 100% production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by design.
Parts are tested with MUX externally connected to the ADC input.
Note 3: Channel ID disabled.
Note 4: Tested in single-ended mode.
Note 5: Offset nulled.
Note 6: Line rejection D(DOUT) with VDD = 2.35V to 3.6V and VREF+ = 2.35V.
Note 7: Tested and guaranteed with fully differential input.
Note 8: Conversion time is defined as the number of clock cycles multiplied by the clock period with a 50% duty cycle.
Maximum conversion time: 4.73Fs + N x 16 x tOSC_MAX
tOSC_MAX = 88.2ns, tOSC_TYP = 75ns.
Note 9: The operational input voltage range for each individual input of a differentially configured pair is from VDD to GND. The
operational input voltage difference is from -VREF+/2 to +VREF+/2 or -VREF+ to +VREF+.
Note 10: See Figure 3 (Equivalent Input Circuit).
Note 11: Guaranteed by characterization.
tCSBW
CS
tCSS
SCLK
tCH
1ST
CLOCK
tCP
tCSH
16TH
CLOCK
tDH
tDS
tDOT
DIN
tDOD
tDOE
DOUT
Figure 1. Detailed Serial-Interface Timing Diagram
Maxim Integrated
8
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Typical Operating Characteristics
(MAX11322ATJ+/MAX11325ATJ+/MAX11328ATJ+, TA = +25°C, unless otherwise noted.)
DIFFERENTIAL NONLINEARITY
vs. OUTPUT CODE
0.5
DNL (LSB)
INL (LSB)
0.4
0.2
0
-0.2
fSAMPLE = 1Msps
-0.4
3
0
MAX11321 toc03
0.6
1.0
2
OFFSET ERROR (LSB)
fSAMPLE = 1Msps
0.8
MAX11321 toc01
1.0
OFFSET ERROR
vs. TEMPERATURE
MAX11321 toc02
INTEGRAL NONLINEARITY
vs. DIGITAL OUTPUT CODE
1
0
-1
-0.5
-0.6
-2
-0.8
-1.0
1024
0
2048
3072
1024
2048
3072
4096
-40 -25 -10 5 20 35 50 65 80 95 110 125
DIGITAL OUTPUT CODE (DECIMAL)
DIGITAL OUTPUT CODE (DECIMAL)
TEMPERATURE (°C)
GAIN ERROR
vs. TEMPERATURE
HISTOGRAM FOR 30,000
CONVERSIONS
SNR AND SINAD
vs. ANALOG INPUT FREQUENCY
-1
-2
30,000 CODE HITS
25,000
20,000
15,000
10,000
73.5
73.0
SNR
72.5
72.0
SINAD
71.5
5,000
0
-3
fSAMPLE = 1Msps
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
2046
2047
2048
2049
71.0
2050
20
0
40
OUTPUT CODE (DECIMAL)
TEMPERATURE (°C)
THD vs. ANALOG INPUT FREQUENCY
fSAMPLE = 1Msps
80
100
SFDR vs. ANALOG INPUT FREQUENCY
96
MAX11321 toc07
-80
60
fIN (kHz)
92
SFDR (dB)
-85
THD (dB)
fSAMPLE = 1Msps
94
MAX11321 toc08
0
30,000
74.0
SNR AND SINAD (dB)
1
fSAMPLE = 1Msps
MAX11321 toc05
2
35,000
NUMBER OF OCCURENCES
MAX11321 toc04
3
GAIN ERROR (LSB)
-3
0
4096
MAX11321 toc06
-1.0
90
88
86
-90
84
82
-95
80
0
20
40
60
fIN (kHz)
Maxim Integrated
80
100
0
20
40
60
80
100
fIN (kHz)
9
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Typical Operating Characteristics (continued)
(MAX11322ATJ+/MAX11325ATJ+/MAX11328ATJ+, TA = +25°C, unless otherwise noted.)
SINAD vs. INPUT RESISTANCE
72.5
-70
MAX11321 toc10
MAX11321 toc09
BUFFER BETWEEN AOP AND AIP
BUFFER BETWEEN AON AND AIN
THD vs. INPUT RESISTANCE
73
BUFFER BETWEEN AOP AND AIP
BUFFER BETWEEN AON AND AIN
fSAMPLE = 1Msps
fIN = 100kHz
AOP SHORTED TO AIP
AON SHORTED TO AIN
-75
AOP SHORTED TO AIP
AON SHORTED TO AIN
THD (dB)
72.0
SINAD (dB)
-80
AOP SHORTED TO AIP
AON SHORTED TO AIN
71
71.5
BUFFER BETWEEN AOP AND AIP
BUFFER BETWEEN AON AND AIN
-85
fSAMPLE = 1Msps
fIN = 100kHz
fSAMPLE = 1Msps
fIN = 100kHz
70
71.0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
500
1000
1500
2000
2500
3000
3500
4000
4500
0
5000
500
1000
1500
2000
2500
3000
3500
4000
RIN (I)
RIN (I)
RIN (I)
SFDR vs. INPUT RESISTANCE
100kHz SINE-WAVE INPUT
(8192 POINT FFT PLOT)
REFERENCE CURRENT
vs. SAMPLING RATE
AOP SHORTED TO AIP
AON SHORTED TO AIN
80
75
500
1500
2000
2500
3000
3500
4000
4500
40
-40
AHD3 = -86.69dB
f = 300kHz
-60
AHD2 = -102.99dB
f = 200kHz
-80
5000
30
20
0
500
0
50 100 150 200 250 300 350 400 450 500
1000
fSAMPLE (ksps)
FREQUENCY (kHz)
SUPPLY CURRENT vs. TEMPERATURE
SNR vs. REFERENCE VOLTAGE
MAX11321 toc16
74
MAX11321 toc15
2.5
5000
0
-120
fSAMPLE = 1Msps
VDD = 3.0V
4500
10
RIN (I)
3.0
50
-100
fSAMPLE = 1Msps
fIN = 100kHz
1000
-20
AMPLITUDE (dB)
SFDR (dB)
85
fSAMPLE = 1Msps
fIN = 100kHz
IREF (µA)
BUFFER BETWEEN AOP AND AIP
BUFFER BETWEEN AON AND AIN
0
MAX11321 toc13
90
0
-90
0
MAX11321 toc12
0
MAX11321 toc14
SNR (dB)
72
MAX11321 toc11
SNR vs. INPUT RESISTANCE
73.0
73
SNR (dB)
IVDD (mA)
72
2.0
71
70
1.5
69
1.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
Maxim Integrated
fSAMPLE = 1Msps
fIN = 100kHz
68
1.0
1.4
1.8
2.2
2.6
3.0
3.4
VREFP (V)
10
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
VDD
GND
REF+
GND
DIN
CS
SCLK
VDD
VDD
GND
REF+
GND
23
SCLK
24
VDD
CS
TOP VIEW
DIN
Pin Configurations
22
21
20
19
18
17
24
23
22
21
20
19
18
17
DGND 25
16
REF-
DGND 25
16
REF-
OVDD 26
15
CNVST
OVDD 26
15
CNVST
DOUT 27
14
AIN
DOUT 27
14
AIN
13
AIP
EOC 28
13
AIP
12
AON
AIN0 29
12
AON
11
AOP
AIN1 30
11
AOP
10
GND
AIN2 31
10
GND
9
GND
AIN3 32
9
GND
EOC 28
MAX11321
MAX11322
AIN0 29
AIN1 30
AIN2 31
+
1
2
3
4
5
6
7
8
1
2
3
4
5
6
7
8
GND
GND
GND
GND
GND
GND
GND
AIN4
AIN5
AIN6
AIN7
GND
GND
GND
GND
+
GND
AIN3 32
MAX11324
MAX11325
SCLK
VDD
VDD
GND
REF+
GND
TOP VIEW
DIN
TQFN
8 CHANNEL
CS
TQFN
4 CHANNEL
24
23
22
21
20
19
18
17
DGND 25
16
REF-/AIN15
OVDD 26
15
CNVST/AIN14
DOUT 27
14
AIN
13
AIP
12
AON
11
AOP
10
AIN13
9
AIN12
EOC 28
MAX11327
MAX11328
AIN0 29
AIN1 30
AIN2 31
+
4
5
6
7
8
AIN8
AIN9
AIN10
AIN11
AIN5
3
AIN7
2
AIN6
1
AIN4
AIN3 32
TQFN
16 CHANNEL
Maxim Integrated
11
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Pin Description
MAX11321
MAX11322
(4 CHANNEL)
MAX11324
MAX11325
(8 CHANNEL)
MAX11327
MAX11328
(16 CHANNEL)
NAME
1–10, 17, 19
5–10, 17, 19
17, 19
GND
Ground
11
11
11
AOP
Positive Output from the Multiplexer
12
12
12
AON
Negative Output from the Multiplexer
13
13
13
AIP
Positive Input to the ADC
14
14
14
AIN
Negative Input to the ADC
15
15
—
CNVST
16
16
—
REF-
External Differential Reference Negative Input
18
18
18
REF+
External Positive Reference Input. Apply a reference voltage at
REF+. Bypass to GND with a 0.47FF capacitor.
20, 21
20, 21
20, 21
VDD
Power-Supply Input. Bypass to GND with a 10FF in parallel with
a 0.1FF capacitors.
22
22
22
SCLK
Serial Clock Input. Clocks data in and out of the serial interface.
23
23
23
CS
Active-Low Chip Select Input. When CS is low, the serial
interface is enabled. When CS is high, DOUT is high impedance
or three-state.
24
24
24
DIN
Serial Data Input. DIN data is latched into the serial interface on
the rising edge of SCLK.
25
25
25
DGND
Digital I/O Ground
26
26
26
OVDD
Digital Power-Supply Input. Bypass to GND with a 10FF in
parallel with a 0.1FF capacitors.
27
27
27
DOUT
Serial Data Output. Data is clocked out on the falling edge of
SCLK. When CS is high, DOUT is high impedance or threestate.
28
28
28
EOC
29–32
—
—
AIN0–AIN3
—
—
29–32 , 1–10
—
29–32, 1–4
—
AIN0–AIN7
CNVST/
AIN14
—
—
15
—
—
16
—
—
—
Maxim Integrated
FUNCTION
Active-Low Conversion Start Input
End of Conversion Output. Data is valid after EOC is driven low
(internal clock mode only).
Analog Inputs
AIN0–AIN13 Analog Inputs
Analog Inputs
Active-Low Conversion Start Input/Analog Input 14
REF-/AIN15 External Differential Reference Negative Input /Analog Input 15
EP
Exposed Pad. Connect EP directly to GND plane for guaranteed
performance.
12
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Functional Diagrams
HIGH-INPUT IMPEDANCE
PGA/FILTER/BUFFER
AOP
AON
AIN
AIP
REF+
REF-
AIN0
REF+
REF-
AIN1
ADC
AIN2
AIN3
I/P
MUX
SINGLEENDED/
DIFFERENTIAL
BUS
CS
SCLK
OSCILLATOR
CS
SCLK
AIN(N-1)
CONTROL LOGIC
AND
SEQUENCER
AIN(N)
DIN
DOUT
CNVST
EOC
MAX11321–MAX11328
Maxim Integrated
13
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Functional Diagrams (continued)
AOP
AON
AIN
AIP
REF+
REF-
AIN0
REF+
REF-
AIN1
ADC
AIN2
CS
AIN3
I/P
MUX
SINGLEENDED/
DIFFERENTIAL
BUS
SCLK
OSCILLATOR
CS
SCLK
AIN(N-1)
CONTROL LOGIC
AND
SEQUENCER
AIN(N)
DIN
DOUT
CNVST
EOC
MAX11321–MAX11328
Detailed Description
The MAX11321–MAX11328 are 12-/10-bit with external
reference and industry-leading 500kHz, full linear bandwidth, high-speed, low-power, serial output successive
approximation register (SAR) analog-to-digital converters
(ADC). These devices feature scan mode, internal averaging to increase SNR, and AutoShutdown.
The external clock mode features the SampleSet technology, a user-programmable analog input channel sequencer. The user may define and load a unique sequencing
pattern into the ADC allowing both high- and low-frequency inputs to be converted without interface activity. This
feature frees the controlling unit for other tasks while lowering overall system noise and power consumption.
The MAX11321–MAX11328 include internal clock. The
internal clock mode features an integrated FIFO, allowing
data to be sampled at high speed and then held for readout at any time or at a lower clock rate. Internal averaging
Maxim Integrated
is also supported in this mode improving SNR for noisy
input signals. All input channels are configurable for single-ended, fully differential or pseudo-differential inputs
in unipolar or bipolar mode. The MAX11321–MAX11328
operate from a 2.35V to 3.6V supply and consume only
5.4mW at 1Msps.
The MAX11321–MAX11328 include AutoShutdown, fast
wake-up, and a high-speed 3-wire serial interface. The
devices feature full power-down mode for optimal power
management.
Data is converted from analog voltage sources in a
variety of channel and data-acquisition configurations.
Microprocessor (FP) control is made easy through a 3-wire
SPI-/QSPI-/MICROWIRE-compatible serial interface.
AOP and AON are the output pins of the internal multiplexer while AIP and AIN are the ADC inputs which are all
accessible externally through pins. This allows flexibility
to the system designer to process all signals through one
PGA (programmable gain amplifier), filter or gain stage
14
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
in single-ended or differential configuration. The external
buffering stage should be designed to properly drive the
input sampling network of the ADC.
The external buffer should also have very high input
impedance (low-leakage current) to ensure best linearity.
If additional signal processing is not required, connect
AOP to AIP and AON to AIN. It is recommended to limit
the source impedance to not affect the sampling accuracy of the ADC causing degradation in linearity and total
harmonic distortion. See the SINAD vs. Input Resistance
graph in the Typical Operating Characteristics.
Input Bandwidth
The ADC’s input-tracking circuitry features a 500MHz
small-signal full-linear bandwidth to digitize high-speed
transient events and measure periodic signals with
bandwidths exceeding the ADC’s sampling rate by using
undersampling techniques. Anti-alias filtering of the input
signals is necessary to avoid high-frequency signals
aliasing into the frequency band of interest.
3-Wire Serial Interface
The MAX11321–MAX11328 feature a serial interface
compatible with SPI/QSPI and MICROWIRE devices. For
SPI/QSPI, ensure the CPU serial interface runs in master
mode to generate the serial clock signal. Select the SCLK
frequency of 48MHz or less, and set clock polarity (CPOL)
and phase (CPHA) in the control registers to the same
value. The MAX11321–MAX11328 operate with SCLK
idling high, and thus operate with CPOL = CPHA = 1.
Set CS low to latch input data at DIN on the rising edge
of SCLK. Output data at DOUT is updated on the falling
edge of SCLK. A high-to-low transition on CS samples
the analog inputs and initiates a new frame. A frame is
defined as the time between two falling edges of CS.
There is a minimum of 16 bits per frame. The serial data
input, DIN, carries data into the control registers clocked
in by the rising edge of SCLK. The serial data output,
DOUT, delivers the conversion results and is clocked out
by the falling edge of SCLK. DOUT is a 16-bit data word
containing a 4-bit channel address, followed by a 12-bit
conversion result led by the MSB when CHAN_ID is set
to 1 in the ADC Mode Control register (Figure 2a). When
CHAN_ID is set to 1 keep the SCLK high for at least 25ns
before the CS falling edge (Figure 2b). When CHAN_ID is
set to 0 (external clock mode only), the 16-bit data word
includes a leading zero and the 12-bit conversion result
is followed by 3 trailing zeros (Figure 2c). In the 10-bit
conversion result is followed by 5 trailing zeros.
CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
DI[15] DI[14]
DIN
DOUT
Ch[3]
Ch[2]
15
16
DI[0]
DI[1]
Ch[1]
Ch[0]
MSB MSB-1
LSB+1
LSB
Figure 2a. External Clock Mode Timing Diagram with CHAN_ID=1
CS
SCLK
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
tQUIET > tSCLK
DIN
DOUT
DI[15]
Ch[3]
DI[1]
Ch[2]
Ch[1] Ch[0]
MSB MSB-1
LSB+1
DI[0]
LSB
Figure 2b. External Clock Mode Timing Diagram with CHAN_ID=1 for Best Performance
Maxim Integrated
15
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
CS
SCLK
DIN
DOUT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
DI[15] DI[14]
0
16
DI[1]
MSB] MSB-1 MSB-2
LSB
DI[0]
0
Figure 2c. External Clock Mode Timing Diagram with CHAN_ID=0
Single-Ended, Differential,
and Pseudo-Differential Input
The MAX11321–MAX11328 include up to 16 analog input
channels that can be configured on a pin-by-pin basis
to 16 single-ended inputs, 8 fully differential pairs, or 15
pseudo-differential inputs with respect to one common
input (REF-/AIN15 is the common input).
The analog input range is 0V to VREF+ in single-ended
and pseudo-differential mode (unipolar) and QVREF+/2 or
QVREF+ in fully differential mode (bipolar) depending on
the RANGE register settings. See Table 7 for the RANGE
register settings.
Unipolar mode sets the differential input range from 0
to VREF+. If the positive analog input swings below the
negative analog input in unipolar mode, the digital output
code is zero. Selecting bipolar mode sets the differential
input range to QVREF+/2 or QVREF+ depending on the
RANGE register settings (Table 7).
In single-ended mode, the ADC always operates in unipolar mode. The analog inputs are internally referenced
to GND with a full-scale input range from 0V to VREF+.
Single-ended conversions are internally referenced to
GND (Figure 3).
The MAX11321–MAX11328 feature up to 15 pseudo
differential inputs by setting the PDIFF_COM bits in the
Unipolar register to 1 (Table 10). The 15 analog input signals inputs are referenced to a DC signal applied to the
REF-/AIN15.
Fully Differential Reference (REF+, REF-)
When the reference is used in fully differential mode
(REFSEL = 1), the full-scale range is set by the difference
between REF+ and REF-. The output code reaches its
Maxim Integrated
DAC
COMPARATOR
AIP
HOLD
AIN
(GND)
DAC
Figure 3. Equivalent Input Circuit
maximum value if the input signal exceeds this reference
range.
ADC Transfer Function
The output format of the MAX11321–MAX11328 is straight
binary in unipolar mode and two’s complement in bipolar
mode. The code transitions midway between successive
integer LSB values, such as 0.5 LSB, 1.5 LSB. Figure
4 and Figure 5 show the unipolar and bipolar transfer
function, respectively. Output coding is binary, with for
example, 1 LSB = VREF+/4096 in the 12-bit devices such
as the MAX11322/MAX11325/MAX11328.
Internal FIFO
The MAX11321–MAX11328 contain a FIFO buffer that can
hold up to 16 ADC results. This allows the ADC to handle
multiple internally clocked conversions without tying up
the serial bus. If the FIFO is filled and further conversions
are requested without reading from the FIFO, the oldest
ADC results are overwritten by the new ADC results. Each
16
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
OUTPUT CODE (hex)
OUTPUT CODE (hex)
FFF
FS = VREF+
7FF
FFE
ZS = 0
7FE
FFD
1 LSB =
VREF+
4096
FFC
001
FFB
VREF+
2
ZS = 0
-VREF+
-FS =
2
VREF+
1 LSB =
4096
+FS =
000
FFF
004
FFE
003
002
801
001
800
000
0
1
2
3
4
FS -1.5 LSB
FS
INPUT VOLTAGE (LSB)
Figure 4. Unipolar Transfer Function for 12-Bit Resolution
result contains 2 bytes, with the MSB preceded by four
leading channel address bits. After each falling edge of
CS, the oldest available byte of data is available at DOUT.
When the FIFO is empty, DOUT is zero.
External Clock
Apply a soft reset when changing from internal to external
clock mode: RESET [1:0] = 10. The detailed operation
of external clock mode is dependent on the mode of
operation selected for the device using SCAN[3:0] bit
settings (see Table 3). In external clock mode the analog
inputs are sampled at the falling edge of CS. Serial clock
(SCLK) is used to perform the conversion.
Depending on the mode selected, the sequencer reads
in the channel to be converted from the serial data input
(DIN) at each frame (e.g. manual mode). The conversion
results are sent to the serial output (DOUT) at the next
frame.
In other external clocked modes the sequence of channel
to be converted is determined by the mode (SCAN[3:0])
selected in Table 3. See the Applications Information for
more detail on programming modes.
Maxim Integrated
-FS
0
-FS +0.5 LSB
+FS -1.5 LSB
INPUT VOLTAGE (LSB)
+FS
Figure 5. Bipolar Transfer Function for 12-Bit Resolution
Internal Clock
Apply a soft reset when changing from internal to external clock mode: RESET [1:0] = 10. The MAX11321–
MAX11328 operate from an internal oscillator, which is
accurate within Q15% of the 13.33MHz nominal clock
rate. Request internally timed conversions by writing the
appropriate sequence to the ADC Mode Control register
(Table 2).
The wake-up, acquisition, conversion, and shutdown
sequences are initiated through CNVST and are performed automatically using the internal oscillator. Results
are added to the internal FIFO.
With CS high, initiate a scan by setting CNVST low for
at least 5ns before pulling it high (Figure 6). Then, the
MAX11321–MAX11328 wake up, scan all requested
channels, store the results in the FIFO, and shut down.
After the scan is complete, EOC is pulled low and the
results are available in the FIFO. Wait until EOC goes
low before pulling CS low to communicate with the serial
interface. EOC stays low until CS or CNVST is pulled low
again. Do not initiate a second CNVST before EOC goes
low; otherwise, the FIFO may become corrupted.
17
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
UP TO N INTERNALLY
CLOCKED ACQUISITIONS
AND CONVERSIONS
CNVST
tCSW
CS
EOC
tCNV_INT
SCLK
1
16
1
16
SET MODE REG
SET MODE REG
READ DATA FROM FIFO
READ DATA FROM FIFO
DIN
DOUT
INTERNAL
OSCILLATOR ON
SCAN OPERATION AND
RESULTS STORED IN FIFO
Figure 6. Internal Conversions with CNVST
UP TO N INTERNALLY
CLOCKED ACQUISITIONS
AND CONVERSIONS
tCNV_INT
(N = 1)
CS
EOC
SCLK
1
17
SET MODE REG
1
16
SET MODE REG
SWCNV = 1
DIN
DOUT
MODE CONTROL
INTERNAL OSCILLATOR ON
READ DATA FROM FIFO
SCAN OPERATION AND
RESULTS STORED IN FIFO
Figure 7. Internal Conversions with SWCNV
Maxim Integrated
18
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 communicate 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 voltage within the region of the analog power input rails
(VDD, GND) and allow the analog input voltage to swing
from GND - 0.3V to VDD + 0.3V without damaging the
device. Input voltages beyond GND - 0.3V and VDD +
0.3V forward bias the internal protection diodes. Limit the
forward diode current to less than 50mA to avoid damage 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 channels 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 external 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 maximum length of 256. SampleSet is supported only in the
external clock mode. SampleSet is ideally suited for multichannel measurement applications where some analog
inputs must be converted more often than others.
t = n-1
t=n
t = n+1
t = n+2
TURN ON ECHO
CONFIGURATION
DATA
CONFIGURATION
DATA
CONFIGURATION
DATA
CONFIGURATION
DATA
CONFIGURATION
DATA
CS
DIN
DOUT
Figure 8. Echo Back the Configuration Data
Maxim Integrated
19
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
The SampleSet approach provides greater sequencing
flexibility for multichannel applications while alleviating significant microcontroller communication overhead.
SampleSet technology allows the user to exploit available
ADC input bandwidth without need for constant communication between the ADC and controlling unit. The user
may define and load a unique sequencing pattern into
the ADC allowing both high- and low-frequency inputs
to be converted appropriately without interface activity.
With the unique sequence loaded into ADC memory, the
pattern may be repeated indefinitely or changed at any
time.
For example, the maximum throughput of MAX11321–
MAX11328 is 1Msps. Traditional ADC scan modes allow
SampleSet REPEATS: LENGTH = 256
SAMPLE SET
(DEPTH = 256)
1ST CYCLE
2ND CYCLE
3RD CYCLE
4TH CYCLE
5TH CYCLE
6TH CYCLE
7TH CYCLE
8TH CYCLE
9TH CYCLE
POTENTIAL SampleSet PATTERN
CHANNEL:
AIN2/
AIN3
AIN0
AIN1
AIN0
AIN1
AIN0
AIN1
AIN2/
AIN3
AIN4
AIN5
AIN6
AIN7
AIN8
AIN9
AIN10
AIN11
AIN12
AIN13
AIN14
AIN15
AIN2/
AIN3
AIN0
AIN1
AIN0
AIN1
AIN2/
AIN3
ENTRY NO.:
1
2
3
4
5
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
254
255
256
120 CONVERSIONS:
AIN0 AND AIN1
120 CONVERSIONS:
AIN0 AND AIN1
ANALOG
INPUTS
AIN0
100kHz
100 CYCLES
AIN1
135
10kHz
10 CYCLES
1
FULLY
DIFFERENTIAL
122
1kHz
1 CYCLES
256
AIN2
AIN3
123
AIN4
124
AIN5
125
AIN6
tS = 1/fS = 1/3Msps = 333.33ns
AIN7
CS
10
8
AIN0
AIN8
12
6
14
4
AIN9
16
2
32
18
TS
5µs
10µs
30
20
28
22
fin = 100kHz
AIN10
26
24
AIN11
AIN1
7
9
11
5
3
TS
AIN12
13
15
17
5µs
AIN13
31
19
29
21
23
25
10µs
27
Figure 9. SampleSet Use-Model Example
Maxim Integrated
20
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
up to 16-channel conversions in ascending order. In this
case, the effective throughput per channel is 1Msps/16
channel or 62.5ksps. The maximum input frequency that
the ADC can resolve (Nyquist Theorem) is 31.25kHz.
If all 16 channels must be measured, with some channels having greater than 31.25kHz input frequency, the
user must revert back to manual mode requiring constant communication on the serial interface. SampleSet
technology solves this problem. Figure 9 provides a
SampleSet use-model example.
Averaging Mode
In averaging mode, the device performs the specified
number of conversions and returns the average for each
requested result in the FIFO. The averaging mode works
with internal clock only.
Scan Modes and Unipolar/Bipolar Setting
When the Unipolar or Bipolar registers are configured
as pseudo-differential or fully differential, the analog
input pairs are repeated in this automated mode. For
example, if N is set to 15 to scan all 16 channels and
all analog input pairs are configured for fully-differential
conversion, the ADC converts the channels twice. In this
case, the user may avoid dual conversions on input pairs
by implementing Manual mode or using Custom_Int or
Custom_Ext scan modes and only scan even (or odd)
channels (e.g. 0, 2, 4).
Table 1. Register Access and Control
REGISTER IDENTIFICATION CODE
REGISTER NAME
DIN ≡ DATA INPUTS
BIT 15
BIT 14
BIT 13
BIT 12
BIT 11
ADC Mode Control
0
DIN
DIN
DIN
DIN
BIT [10:0]
DIN
ADC Configuration
1
0
0
0
0
DIN
Unipolar
1
0
0
0
1
DIN
Bipolar
1
0
0
1
0
DIN
RANGE
1
0
0
1
1
DIN
Custom Scan0
1
0
1
0
0
DIN
Custom Scan1
1
0
1
0
1
DIN
SampleSet
1
0
1
1
0
DIN
Reserved. Do not use.
1
1
1
1
1
DIN
Table 2. ADC Mode Control Register
BIT NAME
BIT
DEFAULT
STATE
FUNCTION
REG_CNTL
15
0
SCAN[3:0]
14:11
0001
ADC Scan Control register (Table 3)
CHSEL[3:0]
10:7
0000
Analog Input Channel Select register (Table 4).
See Table 3 to determine which modes use CHSEL[3:0] for the channel scan
instruction.
RESET[1:0]
Maxim Integrated
6:5
00
Set to 0 to select the ADC Mode Control register
RESET1
RESET0
FUNCTION
0
0
No reset
0
1
Reset the FIFO only (resets to zero)
1
0
Reset all registers to default settings (includes FIFO)
1
1
Unused
21
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 2. ADC Mode Control Register (continued)
BIT NAME
BIT
DEFAULT
STATE
PM[1:0]
4:3
00
Power Management Modes (Table 5). In external clock mode, PM[1:0] selects
between normal mode and various power-down modes of operation.
CHAN_ID
2
0
External Clock Mode. Channel address is always present in internal clock mode.
Set to 1, DOUT is a 16-bit data word containing a 4-bit channel address, followed by
a 12-bit conversion result led by the MSB.
FUNCTION
SWCNV
1
0
Set to 1 to initiate conversions with the rising edge of CS instead of cycling CNVST
(internal clock mode only).
This bit is used for the internal clock mode only and must be reasserted in the ADC
mode control, if another conversion is desired.
—
0
0
Unused
Table 3. ADC Scan Control
SCAN3
0
SCAN2
0
SCAN1
0
SCAN0
0
MODE NAME
Null
FUNCTION
Continue to operate in the previously selected mode. Ignore data
on bits [10:0]. This feature is provided so that DIN can be held low
when no changes are required in the ADC Mode Control register.
Bits [6:3, 1] can be still written without changing the scan mode
properties.
The next channel to be selected is identified in each SPI frame. The
conversion results are sent out in the next frame.
0
0
0
1
Manual
Clock mode: External clock only
Channel scan/sequence: Single channel per frame
Channel selection: See Table 4, CHSEL[3:0]
Averaging: No
Scans channel N repeatedly. The FIFO stores 4, 8, 12, or 16
conversion results for channel N.
0
0
1
0
Repeat
Clock mode: Internal clock only
Channel scan/sequence: Single channel per frame
Channel selection: See Table 4, CHSEL[3:0]
Averaging: Can be enabled
Scans channels 0 through N. The FIFO stores N conversion results.
Clock mode: Internal clock
0
0
1
1
Standard_Int
Channel scan/sequence: N channels in ascending order
Channel selection: See Table 4, CHSEL[3:0] determines channel N
Averaging: Can be enabled
Maxim Integrated
22
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 3. ADC Scan Control (continued)
SCAN3
SCAN2
SCAN1
SCAN0
MODE NAME
FUNCTION
Scans channels 0 through N
Clock mode: External clock only
0
1
0
0
Standard_Ext
Channel scan/sequence: N channels in ascending order
Channel selection: See Table 4, CHSEL[3:0] determines channel N
Averaging: No
Scans channel N through the highest numbered channel. The FIFO
stores X conversion results where:
0
1
0
1
Upper_Int
X = Channel 16–N
16-channel devices
X = Channel 8–N
8-channel devices
Clock mode: Internal clock only
Channel scan/sequence: Channel N through the highest numbered
channel in ascending order
Channel selection: See Table 4, CHSEL[3:0] determines channel N
Averaging: Can be enabled
Scans channel N through the highest numbered channel
Clock mode: External clock only
0
1
1
0
Upper_Ext
Channel scan/sequence: Channel N through the highest numbered
channel in ascending order
Channel selection: See Table 4, CHSEL[3:0] determines channel N
Averaging: No
Scans preprogrammed channels in ascending order. The FIFO
stores conversion results for this unique channel sequence.
Clock mode: Internal clock only
0
1
1
1
Custom_Int
Channel scan/sequence: Unique ascending channel sequence
Maximum depth: 16 conversions
Channel selection: See Table 12, Custom Scan0 register and Table
13, Custom Scan1 register
Averaging: Can be enabled
Scans preprogrammed channels in ascending order
Clock mode: External clock only
Channel scan/sequence: Unique ascending channel sequence
1
0
0
0
Custom_Ext
Maximum depth: 16 conversions
Channel selection: See Table 12, Custom Scan0 register and Table
13, Custom Scan1 register
Averaging: No
Maxim Integrated
23
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 3. ADC Scan Control (continued)
SCAN3
SCAN2
SCAN1
SCAN0
MODE NAME
FUNCTION
Scans preprogrammed channel sequence with maximum length of
256. There is no restriction on the channel pattern.
Clock mode: External clock only
1
0
0
1
SampleSet
Channel scan/sequence: Unique channel sequence
Maximum depth: 256 conversions
Channel Selection: See Table 4
Averaging: No
1
0
1
0
Null
Continue to operate in the previously selected mode. Ignore data on
bits [10:0].
1
0
1
1
Null
Continue to operate in the previously selected mode. Ignore data on
bits [10:0].
1
1
0
0
Null
Continue to operate in the previously selected mode. Ignore data on
bits [10:0].
1
1
0
1
Null
Continue to operate in the previously selected mode. Ignore data on
bits [10:0].
1
1
1
0
Null
Continue to operate in the previously selected mode. Ignore data on
bits [10:0].
1
1
1
1
Null
Continue to operate in the previously selected mode. Ignore data on
bits [10:0].
Table 4. Analog Input Channel Select
CHSEL3
CHSEL2
CHSEL1
CHSEL0
SELECTED CHANNEL (N)
0
0
0
0
AIN0
0
0
0
1
AIN1
0
0
1
0
AIN2
0
0
1
1
AIN3
0
1
0
0
AIN4
0
1
0
1
AIN5
0
1
1
0
AIN6
0
1
1
1
AIN7
1
0
0
0
AIN8
1
0
0
1
AIN9
1
0
1
0
AIN10
1
0
1
1
AIN11
1
1
0
0
AIN12
1
1
0
1
AIN13
1
1
1
0
AIN14
1
1
1
1
AIN15
Maxim Integrated
24
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Register Descriptions
The MAX11321–MAX11328 communicate between the
internal registers and the external circuitry through the
SPI-/QSPI-compatible serial interface. Table 1 details the
register access and control. Table 2 through Table 14
detail the various functions and configurations.
For ADC mode control, set bit 15 of the register code
identification to zero. The ADC Mode Control register
determines when and under what scan condition the
ADC operates.
U Full shutdown where all circuitry is shutdown.
U Partial shutdown where all circuitry is powered down
except for the internal bias generator.
AutoShutdown with External Clock Mode
When the PM_ bits in the ADC Mode Control register are
asserted (Table 5), the device shuts down at the rising
edge of CS in the next frame. The device powers up
again at the following falling edge of CS. There are two
available options:
U AutoShutdown where all circuitry is shutdown.
To set the ADC data configuration, set the bit 15 of the
register code identification to one.
U AutoStandby where all circuitry are powered down
except for the internal bias generator.
Power-Down Mode
AutoShutdown with Internal Clock Mode
The device shuts down after all conversions are completed. The device powers up again at the next falling edge
of CNVST or at the rising edge of CS after the SWCNV
bit is asserted.
The MAX11321–MAX11328 feature three power-down
modes.
Static Shutdown
The devices shut down when the SPM bits in the ADC
Configuration register are asserted (Table 6). There are
two shutdown options:
Table 5. Power Management Modes
PM1
PM0
MODE
0
0
Normal
FUNCTION
0
1
AutoShutdown
1
0
AutoStandby
1
1
—
All circuitry is fully powered up at all times.
The device enters full shutdown mode at the end of each conversion. All circuitry
is powered down. The device powers up following the falling edge of CS. It takes 2
cycles before valid conversions take place. The information in the registers is retained.
The device powers down all circuitry except for the internal bias generator. The part
powers up following the falling edge of CS. It takes 2 cycles before valid conversions
take place. The information in the registers is retained.
Unused.
Table 6. ADC Configuration Register
BIT NAME
BIT
DEFAULT
STATE
CONFIG_SETUP
15:11
N/A
REFSEL
AVGON
Maxim Integrated
10
9
0
0
FUNCTION
Set to 10000 to select the ADC Configuration register.
REFSEL
VOLTAGE REFERENCE
REF- CONFIGURATION
0
External single-ended
AIN15 (for the 16-channel devices)
1
External differential
REF-
Set to 1 to turn averaging on. Valid for internal clock mode only.
Set to 0 to turn averaging off.
25
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 6. ADC Configuration Register (continued)
BIT NAME
BIT
DEFAULT
STATE
FUNCTION
Valid for internal clock mode only.
AVGON
NAVG[1:0]
8:7
NAVG1
NAVG0
FUNCTION
0
X
X
Performs 1 conversion for each requested
result.
1
0
0
Performs 4 conversions and returns the
average for each requested result.
1
0
1
Performs 8 conversions and returns the
average for each requested result.
1
1
0
Performs 16 conversions and returns the
average for each requested result.
1
1
1
Performs 32 conversions and returns the
average for each requested result.
00
Scans channel N and returns 4, 8, 12, or 16 results. Valid for repeat mode only.
NSCAN[1:0]
6:5
NSCAN1
NSCAN0
0
0
Scans channel N and returns 4 results.
0
1
Scans channel N and returns 8 results.
1
0
Scans channel N and returns 12 results.
1
1
Scans channel N and returns 16 results.
00
FUNCTION
Static power-down modes
SPM[1:0]
4:3
00
SPM1
SPM0
MODE
0
0
Normal
FUNCTION
0
1
Full
Shutdown
All circuitry is powered down. The information
in the registers is retained.
1
0
Partial
Shutdown
All circuitry is powered down except for
the reference and reference buffer. The
information in the registers is retained.
1
1
—
All circuitry is fully powered up at all times.
Reserved
ECHO
2
0
Set to 0 to disable the instruction echo on DOUT.
Set to 1 to echo back the DIN instruction given at time = n onto the DOUT line at
time = n + 1. It takes 1 full cycle for the echoing to begin (Figure 8).
—
1:0
0
Unused
Maxim Integrated
26
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 7. RANGE Register (RANGE Settings Only Applies to Bipolar Fully Differential
Analog Input Configurations)
BIT NAME
BIT
DEFAULT
STATE
RANGE_SETUP
15:11
N/A
RANGE0/1
10
0
Set to 0 for AIN0/1: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN0/1: +VREF+, fS = 2(VREF+ - VREF-)
RANGE2/3
9
0
Set to 0 for AIN2/3: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN2/3: +VREF+, fS = 2(VREF+ - VREF-)
RANGE4/5
8
0
Set to 0 for AIN4/5: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN4/5: +VREF+, fS = 2(VREF+ - VREF-)
RANGE6/7
7
0
Set to 0 for AIN6/7: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN6/7: +VREF+, fS = 2(VREF+ - VREF-)
RANGE8/9
6
0
Set to 0 for AIN8/9: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN8/9: +VREF+, fS = 2(VREF+ - VREF-)
RANGE10/11
5
0
Set to 0 for AIN10/11: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN10/11: +VREF+, fS = 2(VREF+ - VREF-)
RANGE12/13
4
0
Set to 0 for AIN12/13: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN12/13: +VREF+, fS = 2(VREF+ - VREF-)
RANGE14/15
3
0
Set to 0 for AIN14/15: +VREF+/2, fS = VREF+ - VREFSet to 1 for AIN14/15: +VREF+, fS = 2(VREF+ - VREF-)
—
2:0
000
FUNCTION
Set to 10011 to select the RANGE register
Unused
ADC Output as a Function
of Unipolar and Bipolar Modes
The ADC Scan Control register (Table 3) determines the
ADC mode of operation. The Unipolar and Bipolar registers in Table 10 and Table 11 determine output coding
and whether input configuration is single-ended or fully
differential.
Table 9 details the conversion output for analog inputs,
AIN0 and AIN1. The truth table is consistent for any other
valid input pairs (AINn/AINn+1). Table 8 shows the applicable input signal format with respect to analog input
configurations.
CHSEL[3:0] is used for MANUAL, REPEAT,
STANDARD_EXT, STANDARD_INT, UPPER_EXT,
UPPER_INT modes of operation. CHSCAN[15:0] is used
for CUSTOM_EXT and CUSTOM_INT modes of operation.
SampleSet Mode of Operation
The SampleSet register stores the unique channel
sequence length. The sequence pattern is comprised of
up to 256 unique single-ended and/or differential conversions with any order or pattern.
Maxim Integrated
Patterns are assembled in 4-bit channel identifier nibbles as described in Table 4. Figure 10 presents the
SampleSet timing diagram. Note that two CS frames are
required to configure the SampleSet functionality. The
first frame indicates the sequence length. The second
frame is used to encode the channel sequence pattern.
After the SampleSet register has been coded (Table 14),
by the next falling edge of CS, the new SampleSet pattern
is activated (Figure 10). If the pattern length is less than
SEQ_LENGTH, the remaining channels default to AIN0. If
the select pattern length is greater than SEQ_LENGTH,
the additional data is ignored as the ADC waits for the rising edge of CS. If CS is asserted in the middle of a nibble,
the full nibble defaults to AIN0.
Upon receiving the SampleSet pattern, the user can
set the ADC Mode Control register to begin the conversion process where data readout begins with the first
SampleSet entry. While the last conversion result is read,
the ADC can be instructed to enter AutoShutdown, if
desired. If the user wishes to change the SampleSet
length, a new pattern must be loaded into the ADC as
described in Figure 10.
27
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 8. Analog Input Configuration and Unipolar/Bipolar Waveforms
SUPPORTED WAVEFORMS
ANALOG INPUT
CONFIGURATION
REFSEL = 0
VIN+
Unipolar
(Binary
Coding)
REF+
RANGE: 1V TO VDD
REF+
VIN+
REF+
1V
GND, AIN15
PDIFF_COM = 1
0V
-0.3V
REF+
RANGE: 1V TO VDD
REF+
RANGE: 1V TO VDD
VIN(DC OFFSET
OR
SINUSOID)
VIN-
REF+
2
VIN-
VFS = 2REF+
RANGE = 1
REF+
VFS = REF+
RANGE = 0
Bipolar
(2’s
Complement)
VIN(DC OFFSET
OR
SINUSOID)
REF+
RANGE: 1V TO VDD
VIN+
Table 10. Unipolar Register:
Set desired channel(s) to 0
or PDIFF_COM to 1.
Counterpart Register
Table 11. Bipolar Register:
Set desired channel(s) to 0.
Table 10. Unipolar Register:
Set desired channel(s) to 1.
REF+
VIN+
REF+
VIN-
1V
0V
-0.3V
REF-
REF+
RANGE: 1V TO VDD
VFS = 2REF+
RANGE = 1
REF+
GND
Fully
Differential
VIN+
REF-
VIN+
Unipolar
(Binary
Coding)
Fully
Differential
REF+
RANGE: 1V TO VDD
VFS = REF+
RANGE = 0
SingleEnded
UNIPOLAR/BIPOLAR
REGISTER SETTING
REFSEL = 1
1V
GND
0V
-0.3V
REF-
Counterpart Register
Table 11. Bipolar Register:
Set desired channel(s) to 0.
Table 11. Bipolar Register:
Set desired channel(s) to 1.
Counterpart Register
Table 10. Unipolar Register:
Set desired channel(s) to 0.
Table 9. ADC Output as a Function of Unipolar/Bipolar Register Settings
CHANNEL SELECTION
BIT NAME
AIN0 Selection:
CHSEL[3:0] = 0000
CHSCAN0 = 1
AIN1 Selection:
CHSEL[3:0] = 0001
CHSCAN1 = 1
Maxim Integrated
UNIPOLAR REGISTER
BIPOLAR REGISTER
FUNCTION
UCH0/1
PDIFF_COM
BCH0/1
0
0
0
AIN0 (binary, unipolar)
0
0
1
AIN0/1 pair (two’s complement, bipolar)
1
0
0
AIN0/1 pair (binary, unipolar)
1
0
1
AIN0/1 pair (binary, unipolar); Unipolar register
takes precedence
X
1
X
AIN0 referred to REF-/AIN15 (binary, unipolar)
0
0
0
AIN1 (binary, unipolar)
0
0
1
AIN0/1 pair (two’s complement, bipolar)
1
0
0
AIN0/1 pair (binary, unipolar)
1
0
1
AIN0/1 pair (binary, unipolar), Unipolar register
takes precedence
X
1
X
AIN1 referred to REF-/AIN15 (binary, unipolar)
28
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 10. Unipolar Register
BIT NAME
BIT
DEFAULT
STATE
UNI_SETUP
15:11
—
UCH0/1
10
0
UCH2/3
9
0
UCH4/5
8
0
UCH6/7
7
0
UCH8/9
6
0
UCH10/11
5
0
UCH12/13
4
0
UCH14/15
3
0
PDIFF_COM
2
0
—
1:0
000
FUNCTION
Set to 10001 to select the Unipolar register.
Set to 1 to configure AIN0 and AIN1 for pseudo-differential conversion.
Set to 0 to configure AIN0 and AIN1 for single-ended conversion.
Set to 1 to configure AIN2 and AIN3 for pseudo-differential conversion.
Set to 0 to configure AIN2 and AIN3 for single-ended conversion.
Set to 1 to configure AIN4 and AIN5 for pseudo-differential conversion.
Set to 0 to configure AIN4 and AIN5 for single-ended conversion.
Set to 1 to configure AIN6 and AIN7 for pseudo-differential conversion.
Set to 0 to configure AIN6 and AIN7 for single-ended conversion.
Set to 1 to configure AIN8 and AIN9 for pseudo-differential conversion.
Set to 0 to configure AIN8 and AIN9 for single-ended conversion.
Set to 1 to configure AIN10 and AIN11 for pseudo-differential conversion.
Set to 0 to configure AIN10 and AIN11 for single-ended conversion.
Set to 1 to configure AIN12 and AIN13 for pseudo-differential conversion.
Set to 0 to configure AIN12 and AIN13 for single-ended conversion.
Set to 1 to configure AIN14 and AIN15 for pseudo-differential conversion.
Set to 0 to configure AIN14 and AIN15 for single-ended conversion.
Set to 1 to configure AIN0–AIN14 to be referenced to one common DC voltage on
the REF-/AIN15. Set to 0 to disable the 15:1 pseudo differential mode.
Unused.
Table 11. Bipolar Register
BIT NAME
BIT
DEFAULT
STATE
BIP_SETUP
15:11
—
Set to 10010 to select the Bipolar register.
BCH0/1
10
0
Set to 1 to configure AIN0 and AIN1 for bipolar fully differential conversion.
Set to 0 to configure AIN0 and AIN1 for unipolar conversion mode.
BCH2/3
9
0
Set to 1 to configure AIN2 and AIN3 for bipolar fully differential conversion.
Set to 0 to configure AIN2 and AIN3 for unipolar conversion mode.
BCH4/5
8
0
Set to 1 to configure AIN4 and AIN5 for bipolar fully differential conversion.
Set to 0 to configure AIN4 and AIN5 for unipolar conversion mode.
BCH6/7
7
0
Set to 1 to configure AIN6 and AIN7 for bipolar fully differential conversion.
Set to 0 to configure AIN6 and AIN7 for unipolar conversion mode.
BCH8/9
6
0
Set to 1 to configure AIN8 and AIN9 for bipolar fully differential conversion.
Set to 0 to configure AIN8 and AIN9 for unipolar conversion mode.
BCH10/11
5
0
Set to 1 to configure AIN10 and AIN11 for bipolar fully differential conversion.
Set to 0 to configure AIN10 and AIN11 for unipolar conversion mode.
BCH12/13
4
0
Set to 1 to configure AIN12 and AIN13 for bipolar fully differential conversion.
Set to 0 to configure AIN12 and AIN13 for unipolar conversion mode.
BCH14/15
3
0
Set to 1 to configure AIN14 and AIN15 for bipolar fully differential conversion.
Set to 0 to configure AIN14 and AIN15 for unipolar conversion mode.
—
2:0
000
Maxim Integrated
FUNCTION
Unused.
29
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Table 12. Custom Scan0 Register
BIT NAME
BIT
DEFAULT
STATE
CUST_SCAN0
15:11
—
Set to 10100 to select the Custom Scan0 register.
CHSCAN15
10
0
Set to 1 to scan AIN15. Set to 0 to omit AIN15.
CHSCAN14
9
0
Set to 1 to scan AIN14. Set to 0 to omit AIN14.
CHSCAN13
8
0
Set to 1 to scan AIN13. Set to 0 to omit AIN13.
CHSCAN12
7
0
Set to 1 to scan AIN12. Set to 0 to omit AIN12.
CHSCAN11
6
0
Set to 1 to scan AIN11. Set to 0 to omit AIN11.
CHSCAN10
5
0
Set to 1 to scan AIN10. Set to 0 to omit AIN10.
CHSCAN9
4
0
Set to 1 to scan AIN9. Set to 0 to omit AIN9.
CHSCAN8
3
0
Set to 1 to scan AIN8. Set to 0 to omit AIN8.
—
2:0
000
FUNCTION
Unused.
Table 13. Custom Scan1 Register
BIT NAME
BIT
DEFAULT
STATE
CUST_SCAN1
15:11
—
Set to 10101 to select the Custom Scan1 register.
CHSCAN7
10
0
Set to 1 to scan AIN7. Set to 0 to omit AIN7.
CHSCAN6
9
0
Set to 1 to scan AIN6. Set to 0 to omit AIN6.
CHSCAN5
8
0
Set to 1 to scan AIN5. Set to 0 to omit AIN5.
CHSCAN4
7
0
Set to 1 to scan AIN4. Set to 0 to omit AIN4.
CHSCAN3
6
0
Set to 1 to scan AIN3. Set to 0 to omit AIN3.
CHSCAN2
5
0
Set to 1 to scan AIN2. Set to 0 to omit AIN2.
CHSCAN1
4
0
Set to 1 to scan AIN1. Set to 0 to omit AIN1.
Set to 1 to scan AIN0. Set to 0 to omit AIN0.
CHSCAN0
3
0
—
2:0
000
FUNCTION
Unused.
Table 14. SampleSet Register
BIT NAME
BIT
DEFAULT STATE
SMPL_SET
15:11
—
SEQ_LENGTH
10:3
00000000
—
2:0
—
Maxim Integrated
FUNCTION
Set to 10110 to select the SampleSet register.
8-bit binary word indicating desired sequence length. The equation is:
Sequence length = SEQ_LENGTH + 1
00000000 = Sequence length = 1
11111111 = Sequence length = 256
Coding: Straight binary
Maximum length: 256 ADC conversions
Unused.
30
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
CS
SCLK
1
16
1
1
DIN
ENTRY 1
DOUT
WRITE SampleSet REGISTER
DEFINE SEQ_LENGTH
ENTRY 2
ENTRY N = (SEQ_LENGTH)
LOAD SampleSet PATTERN
TIME BETWEEN CS FALLING AND
RISING EDGE DEPENDS IN SEQ_LENGTH
WRITE ADC MODE CONTROL
OR CONTINUE WITH ADDITIONAL
CONFIGURATION SETTINGS
Figure 10. SampleSet Timing Diagram
Applications Information
How to Program Modes
1) Configure the ADC (set the MSB on DIN to 1).
2) Program ADC mode control (set the MSB on DIN to 0)
to begin the conversion process or to control power
management features.
• If ADC mode control is written during a conversion
sequence, the ADC finishes the present conversion and at the next falling edge of CS initiates its
new instruction.
• If configuration data (MSB on DIN is a 1) is written
during a conversion sequence, the ADC finishes
the present conversion in the existing scan mode.
However, data on DOUT is not valid in following
frames until a new ADC mode control instruction
is coded.
Programming Sequence Flow Chart
See Figure 11 for programming sequence.
Layout, Grounding, and Bypassing
For best performance, use PCBs with a solid ground
plane. Ensure that digital and analog signal lines are
separated from each other. Do not run analog and digital
(especially clock) lines parallel to one another or digital
lines underneath the ADC package. Noise in the VDD,
Maxim Integrated
OVDD, and REF affects the ADC’s performance. Bypass
the VDD, OVDD, and REF to ground with 0.1FF and 10FF
bypass capacitors. Minimize capacitor lead and trace
lengths for best supply-noise rejection.
Choosing an Input Amplifier
It is important to match the settling time of the input
amplifier to the acquisition time of the ADC. The conver
sion results are accurate when the ADC samples the
input signal for an interval longer than the input signal’s
worst-case settling time. By definition, settling time is the
interval between the application of an input voltage step
and the point at which the output signal reaches and
stays within a given error band centered on the resulting steady-state amplifier output level. The ADC input
sampling capacitor charges during the sampling cycle,
referred to as the acquisition period. During this acquisition period, the settling time is affected by the input resistance and the input sampling capacitance. This error
can be estimated by looking at the settling of an RC time
constant using the input capacitance and the source
impedance over the acquisition time period. Figure 13
shows a typical application circuit. The MAX4430, offering a settling time of 37ns at 16-bit resolution, is an excellent choice for this application.
Table 15 lists serveral recommended operational amplifiers for MAX11321–MAX11328.
31
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
SELECT REFERENCE
EXTERNAL SINGLE-ENDED
EXTERNAL DIFFERENTIAL
SINGLE-ENDED
OR DIFFERENTIAL
SELECT ADC
CONFIGURATION REGISTER
SET REFSEL BIT TO 1
SELECT ADC
CONFIGURATION REGISTER
SET REFSEL BIT TO 0
FIGURE OUT NUMBER
OF CHANNELS TO USE (N)
FOR EACH ADC CHANNEL
SINGLE-ENDED
PSEUDODIFFERENTIAL
PSEUDO-DIFFERENTIAL
SELECT UNIPOLAR AND
REGISTER SET BIT PDIFF_COM
TO 1 FOR PSEUDODIFFERENTIAL SELECTION
SINGLE-ENDED
PSEUDODIFFERENTIAL
FULLYDIFFERENTIAL
SE, PsD/FD
SINGLE-ENDED
UNIPOLAR OR
BIPOLAR
BIPOLAR
SELECT UNIPOLAR AND
BIPOLAR REGISTER SET PER
CHANNEL UCH{X}/{X+1}
AND BCH{X}/{X+1} TO 0 FOR
SINGLE-ENDED SELECTION
SELECT BIPOLAR REGISTER
SET PER CHANNEL
BCH{X}/{X+1} TO 1
FOR BIPOLAR FULLY
DIFFERENTIAL
SELECT RANGE REGISTER SET PER CHANNEL
PAIR RANGE{X}/{X+1} TO 1 QVREF+
1
UNIPOLAR
SELECT UNIPOLAR
REGISTER SET PER
CHANNEL UCH{X}/{X+1}
TO 1 FOR UNIPOLAR
RANGE SELECT
0
FOR EACH ADC CHANNEL
SELECT RANGE REGISTER SET PER CHANNEL
PAIR RANGE{X}/{X+1} TO 0 QVREF+/2
NEXT CHANNEL
SEE FIGURE 12
Figure 11. ADC Programming Sequence
Maxim Integrated
32
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
INTERNAL
YES
REPEAT
AVERAGE
INTERNAL/EXTERNAL
CLOCK
NO
EXTERNAL
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 0001
SET CHSEL[3:0] TO CHANNEL NUMBER
SELECT THE PM[1:0] BITS
YES
YES
NO
MANUAL
NO
ADC CONFIGURATION REGISTER
SET AVG ON BIT TO 1
SET NAVG[1:0] TO N
ADC CONFIGURATION REGISTER
SET NSCAN[1:0] FOR SCAN COUNT
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 0010
SET CHSEL[3:0] TO CHANNEL NUMBER
SELECT THE RIGHT SWCNV BIT
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 0100
SET CHSEL[3:0] TO CHANNEL NUMBER
STANDARD-EXT
YES
NO
YES
AVERAGE
STANDARD-INT
NO
YES
NO
ADC CONFIGURATION REGISTER
SET AVG ON BIT TO 1
SET NAVG[1:0] TO N
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 0011
SET CHSEL[3:0] TO CHANNEL NUMBER
SELECT THE RIGHT SWCNV BIT
UPPER-INT
YES
AVERAGE
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 0110
SET CHSEL[3:0] TO CHANNEL NUMBER
UPPER-EXT
YES
NO
NO
YES
NO
ADC CONFIGURATION REGISTER
SET AVG ON BIT TO 1
SET NAVG[1:0] TO N
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 0101
SET CHSEL[3:0] TO CHANNEL NUMBER
SELECT THE RIGHT SWCNV BIT
CUSTOM-INT
NO
YES
AVERAGE
NO
SET CUSTOM Scan0 REGISTER
SET CUSTOM Scan1 REGISTER
CUSTOM-EXT
YES
NO
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 1000
SET CHSEL[3:0] TO CHANNEL NUMBER
YES
ADC CONFIGURATION REGISTER
SET AVGON BIT TO 1
SET NAVG[1:0] TO N
SET CUSTOM Scan0 REGISTER
SET CUSTOM Scan1 REGISTER
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 0111
SET CHSEL[3:0] TO CHANNEL NUMBER
SELECT THE RIGHT SWCNV BIT
SampleSet REGISTER
SET SEQ_DEPTH[7:0] TO SET
CHANNEL CAPTURE DEPTH
SampleSet
YES
FOLLOW SampleSet REGISTER WITH
CHANNEL PATTERN OF THE SAME SIZE
AS SEQUENCE DEPTH
ADC MODE CONTROL REGISTER
SET SCAN[3:0] TO 1001
SET CHSEL[3:0] TO CHANNEL NUMBER
Figure 12. ADC Mode Select Programming Sequence
Maxim Integrated
33
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Choosing a Reference
For devices using an external reference, the choice of the
reference determines the output accuracy of the ADC.
An ideal voltage reference provides a perfect initial accuracy and maintains the reference voltage independent
of changes in load current, temperature, and time. The
following parameters need to be considered in selecting
a reference:
U Initial voltage accuracy
U Temperature drift
U Current source capability
U Current sink capability
U Quiescent current
U Noise. See Table 16.
+5V
0.1µF
10µF
VDD
100pF
VOVDD
VDD
0.1µF
500I
500I
INPUT 1
0.1µF
AGND
4
5
3
2
AIP
AIN
AIN0
COG
CAPACITOR
-5V
0.1µF
470pF
AIN1
10µF
COG
470pF
CAPACITOR
INPUT 2
10µF
0.1µF
SCLK
SCLK
DOUT
MISO
CPU
AIN15
REF
+5V
10µF
AOP
AON
MAX11321–MAX11328
10I
1
MAX4430
VDC
OVDD
10µF
GND
CS
SS
DIN
MOSI
10µF
+5V
100pF
7
6
500I
500I
INPUT 2
4
0.1µF
5
MAX4430
VDC
3
2
10I
1
4
3
IN
OUTF
2
1µF
OUTS
GNDS
GND
MAX6126
NR
0.1µF
1
0.1µF
-5V
0.1µF
10µF
Figure 13. Typical Application Circuit
Maxim Integrated
34
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Definitions
Integral Nonlinearity
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line can be either a best-straight-line fit or a line
drawn between the end points of the transfer function,
once offset and gain errors have been nulled. The static
linearity parameters for the MAX11321–MAX11328 are
measured using the end-points method.
In reality, there are other noise sources besides quantization noise, including thermal noise, reference noise, clock
jitter, etc. Therefore, SNR is computed by taking the ratio
of the RMS signal to the RMS noise, which includes all
spectral components minus the fundamental, the first five
harmonics, and the DC offset.
Total Harmonic Distortion
Total harmonic distortion (THD) is expressed as:
THD
=
Differential Nonlinearity
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of 1 LSB. A DNL
error specification of 1 LSB or less guarantees no missing codes and a monotonic transfer function.
Signal-to-Noise Ratio
Signal-to-noise ratio is the ratio of the amplitude of the
desired signal to the amplitude of noise signals at a
given point in time. The larger the number, the better. The
theoretical minimum analog-to-digital noise is caused by
quantization error and results directly from the ADC’s
resolution (N bits):
V 2 + V32 + V42 + V52
20 × log 2
V1
where V1 is the fundamental amplitude, and V2 through V5
are the amplitudes of the 2nd- through 5th-order harmonics.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio of the
RMS amplitude of the fundamental (maximum signal
component) to the RMS value of the next largest distortion component.
Full-Power Bandwidth
Full-power bandwidth is the frequency at which the input
signal amplitude attenuates by 3dB for a full-scale input.
SNR = (6.02 x N + 1.76) dB
Table 15. Recommended Input Amplifiers
REFERENCE
CHANNELS
TYPICAL APPLICATION
MAX4430
1
Dual supply, low noise, low distortion, high bandwidth
MAX4432
2
Dual supply, low noise, low distortion, high bandwidth
MAX4454
4
Low power, single, supply, low cost
MAX4418
4
Low noise, low power, high bandwidth
MAX44263
2
Low power, precision, CMOS input, rail-to-rail I/O
Table 16. Recommended References
REFERENCE
TYPICAL APPLICATION
MAX6126
Ultra-high precision, ultra-low noise, wide temperature range
MAX6033
Ultra-high precision, low noise, low power, wide temperature range
MAX6043
High precision, wide temperature range
MAX6129B
MAX6003
Maxim Integrated
Low cost, ultra-low power
Low cost, low power
35
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Full-Linear Bandwidth
Full-linear bandwidth is the frequency at which the
signal-to-noise plus distortion (SINAD) is more than 70dB
(MAX11322/MAX11325/MAX11328).
Intermodulation Distortion
Any device with nonlinearities creates distortion products
when two sine waves at two different frequencies (f1 and
f2) are input into the device. Intermodulation distortion
(IMD) is the total power of the IM2 to IM5 intermodulation
products to the Nyquist frequency relative to the total
input power of the two input tones, f1 and f2. The individual input tone levels are at -6dBFS.
Ordering Information
PIN-PACKAGE
BITS
SPEED (Msps)
NO. OF CHANNELS
MAX11321ATJ+
PART
32 TQFN-EP*
10
1
4
MAX11322ATJ+
32 TQFN-EP*
12
1
4
MAX11324ATJ+
32 TQFN-EP*
10
1
8
MAX11325ATJ+
32 TQFN-EP*
12
1
8
MAX11327ATJ+
32 TQFN-EP*
10
1
16
MAX11328ATJ+
32 TQFN-EP*
12
1
16
Note: All devices are specified over the -40°C to +125°C temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Package Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
Maxim Integrated
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
32 TQFN-EP
T3255+5
21-0140
90-0013
36
MAX11321–MAX11328
1Msps, 10-/12-Bit, 4-/8-/16-Channel ADCs with
Post-Mux External Signal Conditioning Access
Revision History
REVISION
NUMBER
REVISION
DATE
0
9/12
DESCRIPTION
Initial release
PAGES
CHANGED
—
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied.
Maxim reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical
Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
©
2012 Maxim Integrated
37
The Maxim logo and Maxim Integrated are trademarks of Maxim Integrated Products, Inc.