MAX1401EAI+ Maxim Integrated Products, MAX1401EAI+ Datasheet

IC ADC 18BIT LP 28-SSOP

MAX1401EAI+

Manufacturer Part Number
MAX1401EAI+
Description
IC ADC 18BIT LP 28-SSOP
Manufacturer
Maxim Integrated Products
Datasheet

Specifications of MAX1401EAI+

Number Of Bits
18
Sampling Rate (per Second)
480
Data Interface
QSPI™, Serial, SPI™
Number Of Converters
1
Power Dissipation (max)
750µW
Voltage Supply Source
Analog and Digital
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
28-SSOP
Number Of Adc Inputs
5
Architecture
Delta-Sigma
Conversion Rate
4.8 KSPs
Resolution
18 bit
Input Type
Voltage
Interface Type
Serial
Voltage Reference
External
Supply Voltage (max)
3 V
Maximum Power Dissipation
21.45 mW
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Input Signal Type
Pseudo-Differential, Differential
Minimum Operating Temperature
- 40 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
The MAX1401 18-bit, low-power, multichannel, serial-
output ADC uses a sigma-delta modulator with a digital
decimation filter to achieve true 16-bit accuracy. The
user-selectable decimation factor of the digital filter
allows the conversion resolution to be reduced in
exchange for a higher output data rate. The device
achieves true 16-bit performance at an output data rate of
up to 480sps. In addition, the modulator sampling
frequency may be optimized for either lowest power
dissipation or highest throughput rate. The MAX1401
operates from +3V.
This device offers three fully differential input channels
that can be independently programmed with a gain
between +1V/V and +128V/V. Furthermore, it can com-
pensate an input-referred DC offset (such as system off-
set) up to 117% of the selected full-scale range. These
three differential channels may also be configured to
operate as five pseudo-differential input channels. Two
additional, fully differential system-calibration channels
are provided for gain and offset error correction. External
access is provided to the multiplexer (mux) output to
facilitate additional signal processing.
The MAX1401 can be configured to sequentially scan all
signal inputs and provide the results through the serial
interface with minimum communications overhead. When
used with a 2.4576MHz or 1.024MHz master clock, the
digital decimation filter can be programmed to produce
zeros in its frequency response at the line frequency
and associated harmonics, ensuring excellent line rejec-
tion without the need for further postfiltering.
The MAX1401 is available in a 28-pin SSOP package.
SPI and QSPI are trademarks of Motorola, Inc.
19-1480; Rev 1; 7/02
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX1401CAI
MAX1401EAI
Portable Industrial Instruments
Portable Weigh Scales
Loop-Powered Systems
Pressure Transducers
PART
________________________________________________________________ Maxim Integrated Products
-40°C to +85°C
TEMP RANGE
0°C to +70°C
Ordering Information
General Description
+3V, 18-Bit, Low-Power, Multichannel,
Applications
Oversampling (Sigma-Delta) ADC
28 SSOP
28 SSOP
PIN-PACKAGE
o 18-Bit Resolution, Sigma-Delta ADC
o 16-Bit Accuracy with No Missing Codes to 480sps
o Access to the Mux Output/ADC Input
o Low Quiescent Current
o 3 Fully Differential or 5 Pseudo-Differential Signal
o 2 Additional Fully Differential Calibration
o Programmable Gain and Offset
o Fully Differential Reference Inputs
o Converts Continuously or On Command
o Automatic Channel Scanning and Continuous
o Operates with Analog and Digital Supplies
o SPI™/QSPI™-Compatible 3-Wire Serial Interface
o 28-Pin SSOP Package
Input Channels
Channels/Auxiliary Input Channels
Data Output Mode
from +2.7V to +3.6V
TOP VIEW
250µA (operating mode)
2µA (power-down mode)
MUXOUT+
MUXOUT-
CLKOUT
ADCIN+
ADCIN-
RESET
CLKIN
AGND
AIN1
AIN2
AIN3
AIN4
CS
V+
10
11
12
13
14
1
2
3
4
5
6
7
8
9
MAX1401
SSOP
Pin Configuration
28
27
26
25
24
23
22
21
20
19
18
17
16
15
SCLK
DIN
DOUT
INT
V
DGND
CALOFF+
CALOFF-
REFIN+
REFIN-
CALGAIN+
CALGAIN-
AIN6
AIN5
DD
Features
1

Related parts for MAX1401EAI+

MAX1401EAI+ Summary of contents

Page 1

... MAX1401EAI -40°C to +85°C SPI and QSPI are trademarks of Motorola, Inc. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. Oversampling (Sigma-Delta) ADC o 18-Bit Resolution, Sigma-Delta ADC ...

Page 2

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC ABSOLUTE MAXIMUM RATINGS V+ to AGND, DGND .................................................-0. AGND, DGND ...............................................-0.3V to +6V DD AGND to DGND.....................................................-0.3V to +0.3V Analog Inputs to AGND................................-0.3V to (V+ + 0.3V) Analog Outputs ...

Page 3

Low-Power, Multichannel, ELECTRICAL CHARACTERISTICS (continued) (V+ = +2.7V to +3.6V +2.7V to +3.6V otherwise noted. Typical values are at T PARAMETER SYMBOL OFFSET DAC Offset DAC Range (Note 8) Offset DAC Resolution Offset DAC ...

Page 4

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC ELECTRICAL CHARACTERISTICS (continued) (V+ = +2.7V to +3.6V +2.7V to +3.6V otherwise noted. Typical values are PARAMETER SYMBOL AIN and REFIN Input Sampling f S Frequency ...

Page 5

Low-Power, Multichannel, ELECTRICAL CHARACTERISTICS (continued) (V+ = +2.7V to +3.6V +2.7V to +3.6V otherwise noted. Typical values are at T PARAMETER SYMBOL ANALOG POWER-SUPPLY CURRENT (Measured with digital inputs at either DGND or V ...

Page 6

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC ELECTRICAL CHARACTERISTICS (continued) (V+ = +2.7V to +3.6V +2.7V to +3.6V otherwise noted. Typical values are PARAMETER SYMBOL POWER DISSIPATION ( +3.3V, digital ...

Page 7

Low-Power, Multichannel, Note 16: These specifications apply to CLKOUT only when driving a single CMOS load. Note 17: The burn-out currents require a 500mV overhead between the analog input voltage and both V+ and AGND to operate correctly. ...

Page 8

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC TIMING CHARACTERISTICS (continued) (V+ = +2.7V to +3.6V +2.7V to +3.6V, AGND = DGND unless otherwise noted.) (Notes 21, 22, 23) MAX PARAMETER SYMBOL SERIAL-INTERFACE WRITE OPERATION ...

Page 9

Low-Power, Multichannel, (V+ = +3V +3V +1.25V, REFIN- = AGND REFIN+ DIFFERENTIAL NONLINEARITY 15 480sps GAIN = +1V/V 10 262, 144 pts -10 -15 -1.0 -0.5 DIFFERENTIAL INPUT VOLTAGE ...

Page 10

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC (V+ = +3V +3V +1.25V, REFIN- = AGND REFIN+ V SUPPLY CURRENT vs. TEMPERATURE DD (240sps OUTPUT DATA RATE UNBUFFERED) 450 400 350 300 250 200 150 ...

Page 11

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC PIN NAME Clock Input. A crystal can be connected across CLKIN and CLKOUT. Alternatively, drive CLKIN with a 1 CLKIN CMOS-compatible clock at a nominal frequency of 2.4576MHz or 1.024MHz, and leave CLKOUT ...

Page 12

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC PIN NAME Negative Gain Calibration Input. Used for system gain calibration. It forms the negative input of a fully differential input pair with CALGAIN+. Normally these inputs are connected to reference voltages in ...

Page 13

Low-Power, Multichannel, _______________Detailed Description Circuit Description The MAX1401 is a low-power, multichannel, serial- output, sigma-delta ADC designed for applications with a wide dynamic range, such as weigh scales and pres- sure transducers. The functional diagram in Figure 2 ...

Page 14

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC Serial Digital Interface The serial digital interface provides access to eight on- chip registers (Figure 3). All serial-interface commands begin with a write to the communications register (COMM). On power-up, system reset, or ...

Page 15

Low-Power, Multichannel, Selecting Clock Polarity The serial interface can be operated with the clock idling either high or low. This is compatible with Motorola’s SPI interface operated in CPOL = 1, CPHA = 1 mode or CPOL = ...

Page 16

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC FSYNC: (Default = 0) Filter Sync Bit. When FSYNC = 0, conversions are automatically performed at a data rate determined by CLK, FS1, FS0, MF1, and MF0 bits. When FSYNC = 1, the ...

Page 17

Low-Power, Multichannel, channels, selection of either calibration mode (01 or 10) will cause the scanning sequence to be extended to include a conversion on both the CALGAIN+/CALGAIN- input pair and the CALOFF+/CALOFF- input pair. The exact sequence depends ...

Page 18

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC Table 4. SCAN Mode Scanning Sequences (SCAN = 1) DIFF M1 M0 SEQUENCE AIN1–AIN6, AIN2–AIN6, AIN3–AIN6 AIN4–AIN6, AIN5–AIN6 AIN1–AIN6, AIN2–AIN6, AIN3–AIN6 AIN4–AIN6, AIN5–AIN6, CALOFF, CALGAIN AIN1–AIN6, AIN2–AIN6, ...

Page 19

Low-Power, Multichannel, Analog Inputs AIN1 to AIN6 Inputs AIN1 and AIN2 map to transfer-function register 1, regardless of scanning mode (SCAN = 1) or single- ended vs. differential (DIFF) modes. Likewise, AIN3 and AIN4 inputs always map to ...

Page 20

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC Table 8. Transfer-Function Register Mapping—Normal Mode ( SCAN DIFF ...

Page 21

Low-Power, Multichannel, Table 10. Transfer-Function Register Mapping—Gain-Calibration Mode ( SCAN DIFF ...

Page 22

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC Table 11. Channel ID Tag Codes CID2 CID1 CID0 ...

Page 23

Low-Power, Multichannel, External Access to Mux Outputs The MAX1401 provides access to the switching-net- work output and the modulator input with the MUXOUT and ADCIN pins. This allows the user to share a single high-performance amplifier for additional ...

Page 24

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC Table 13c Values for Less than 16-Bit Gain Error in Unbuffered (BUFF = 0) EXT EXT Mode; 4x Modulator Sampling Frequency (MF1, MF0 = 10 ); X2CLK = 0; f ...

Page 25

Low-Power, Multichannel, Table 14 Values for Less than 16-Bit Gain Error in Buffered (BUFF = 1) EXT EXT Mode; All Modulator Sampling Frequencies (MF1, MF0 = XX); X2CLK = 0; f 2.4576MHz PGA GAIN C ...

Page 26

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC Table 15. Modulator Operating Frequency, Sampling Frequency, and 16-Bit Data Output Rates CLKIN FREQUENCY, f (MHz) CLKIN X2CLK = 0 X2CLK = 1 DEFAULT 1.024 2.048 1.024 2.048 1.024 2.048 1.024 2.048 2.4576 ...

Page 27

Low-Power, Multichannel, Table 16b. Noise vs. Gain and Output Data Rate—Buffered Mode 2.4576MHz CLKIN OUTPUT -3dB DATA FREQ. RATE (Hz) (sps 13.1 5.72 3.21 60 15.7 6.29 3.57 300 78.6 80.6 39.8 157.2 ...

Page 28

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC The noise shown in Tables 16a and 16b is composed of device noise and quantization noise. The device noise is relatively low but becomes the limiting noise source for high gain settings. The ...

Page 29

Low-Power, Multichannel, The on-chip digital filter processes the 1-bit data stream from the modulator using a SINC ter. The SINC filters are conceptually simple, efficient, and extremely flexible, especially where variable reso- lution and data rates are required. ...

Page 30

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC input can four-times the output data period. For a synchronized step input (using the FSYNC func- tion or the internal scanning logic), the settling time is three-times the output data ...

Page 31

Low-Power, Multichannel, /* Assumptions: ** The MAX140X's CS pin is tied to ground ** The MAX140X's INT pin drives a falling-edge-triggered interrupt ** MAX140X's DIN is driven by MOSI, DOUT drives MISO, and SCLK drives SCLK */ /* ...

Page 32

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC V DD P3.0 8051 P3.1 Figure 13. MAX1401 to 8051 Interface Listing 2. Bit-Banging SPI Replacement 32 ______________________________________________________________________________________ Bit-Banging Interface (80C51, PIC16C54) Any microcontroller can use general-purpose I/O pins to interface to the ...

Page 33

Low-Power, Multichannel, Strain-Gauge Operation Connect the differential inputs of the MAX1401 to the bridge network of the strain gauge. In Figure 14, the analog positive supply voltage powers the bridge net- work and the MAX1401 along with its ...

Page 34

Low-Power, Multichannel, Oversampling (Sigma-Delta) ADC THERMOCOUPLE R JUNCTION AIN1 SWITCHING NETWORK R AIN2 C C +3V +1.25V REFIN+ REFIN- AGND Figure 15. Thermocouple Application with MAX1401 ISOLATION BARRIER V+ SENSOR 4 4 SPI SPI GND Figure 16. 4–20mA ...

Page 35

Low-Power, Multichannel, Grounding and Layout For best performance, use printed circuit boards with separate analog and digital ground planes. Wire-wrap boards are not recommended. Design the printed circuit board so the analog and digi- tal sections are separated ...

Page 36

... 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. 36 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products ...

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