SBAS426H
August 2008 – March 2016
ADS1246
,
ADS1247
,
ADS1248
PRODUCTION DATA.
1
Features
2
Applications
3
Description
4
Revision History
5
Device Comparison Table
6
Pin Configuration and Functions
7
Specifications
7.1
Absolute Maximum Ratings
7.2
ESD Ratings
7.3
Recommended Operating Conditions
7.4
Thermal Information
7.5
Timing Requirements
7.6
Switching Characteristics
7.7
Typical Characteristics
8
Parameter Measurement Information
8.1
Noise Performance
9
Detailed Description
9.1
Overview
9.2
Functional Block Diagram
9.3
Feature Description
9.3.1
ADC Input and Multiplexer
9.3.2
Low-Noise PGA
9.3.2.1
PGA Common-Mode Voltage Requirements
9.3.2.2
PGA Common-Mode Voltage Calculation Example
9.3.2.3
Analog Input Impedance
9.3.3
Clock Source
9.3.4
Modulator
9.3.5
Digital Filter
9.3.6
Voltage Reference Input
9.3.7
Internal Voltage Reference
9.3.8
Excitation Current Sources
9.3.9
Sensor Detection
9.3.10
Bias Voltage Generation
9.3.11
General-Purpose Digital I/O
9.3.12
System Monitor
9.3.12.1
Power-Supply Monitor
9.3.12.2
External Voltage Reference Monitor
9.3.12.3
Ambient Temperature Monitor
9.4
Device Functional Modes
9.4.1
Power Up
9.4.2
Reset
9.4.3
Power-Down Mode
9.4.4
Conversion Control
9.4.4.1
Settling Time for Channel Multiplexing
9.4.4.2
Channel Cycling and Overload Recovery
9.4.4.3
Single-Cycle Settling
9.4.4.4
Digital Filter Reset Operation
9.4.5
Calibration
9.4.5.1
Offset Calibration Register: OFC[2:0]
9.4.5.2
Full-Scale Calibration Register: FSC[2:0]
9.4.5.3
Calibration Commands
9.4.5.3.1
System Offset and Self Offset Calibration
9.4.5.3.2
System Gain Calibration
9.4.5.4
Calibration Timing
9.5
Programming
9.5.1
Serial Interface
9.5.1.1
Chip Select (CS)
9.5.1.2
Serial Clock (SCLK)
9.5.1.3
Data Input (DIN)
9.5.1.4
Data Ready (DRDY)
9.5.1.5
Data Output and Data Ready (DOUT/DRDY)
9.5.1.6
SPI Reset
9.5.1.7
SPI Communication During Power-Down Mode
9.5.2
Data Format
9.5.3
Commands
9.5.3.1
WAKEUP (0000 000x)
9.5.3.2
SLEEP (0000 001x)
9.5.3.3
SYNC (0000 010x)
9.5.3.4
RESET (0000 011X)
9.5.3.5
RDATA (0001 001x)
9.5.3.6
RDATAC (0001 010x)
9.5.3.7
SDATAC (0001 011x)
9.5.3.8
RREG (0010 rrrr, 0000 nnnn)
9.5.3.9
WREG (0100 rrrr, 0000 nnnn)
9.5.3.10
SYSOCAL (0110 0000)
9.5.3.11
SYSGCAL (0110 0001)
9.5.3.12
SELFOCAL (0110 0010)
9.5.3.13
NOP (1111 1111)
9.5.3.14
Restricted Command (1111 0001)
9.6
Register Maps
9.6.1
ADS1246 Register Map
9.6.2
ADS1246 Detailed Register Definitions
9.6.2.1
BCS—Burn-out Current Source Register (offset = 00h) [reset = 01h]
9.6.2.2
VBIAS—Bias Voltage Register (offset = 01h) [reset = 00h]
9.6.2.3
MUX—Multiplexer Control Register (offset = 02h) [reset = x0h]
9.6.2.4
SYS0—System Control Register 0 (offset = 03h) [reset = 00h]
9.6.2.5
OFC—Offset Calibration Coefficient Registers (offset = 04h, 05h, 06h) [reset = 00h, 00h, 00h]
9.6.2.6
FSC—Full-Scale Calibration Coefficient Registers (offset = 07h, 08h, 09h) [reset = PGA dependent]
9.6.2.7
ID—ID Register (offset = 0Ah) [reset = x0h]
9.6.3
ADS1247 and ADS1248 Register Map
9.6.4
ADS1247 and ADS1248 Detailed Register Definitions
9.6.4.1
MUX0—Multiplexer Control Register 0 (offset = 00h) [reset = 01h]
9.6.4.2
VBIAS—Bias Voltage Register (offset = 01h) [reset = 00h]
9.6.4.3
MUX1—Multiplexer Control Register 1 (offset = 02h) [reset = x0h]
9.6.4.4
SYS0—System Control Register 0 (offset = 03h) [reset = 00h]
9.6.4.5
OFC—Offset Calibration Coefficient Register (offset = 04h, 05h, 06h) [reset = 00h, 00h, 00h]
9.6.4.6
FSC—Full-Scale Calibration Coefficient Register (offset = 07h, 08h, 09h) [reset = PGA dependent]
9.6.4.7
IDAC0—IDAC Control Register 0 (offset = 0Ah) [reset = x0h]
9.6.4.8
IDAC1—IDAC Control Register 1 (offset = 0Bh) [reset = FFh]
9.6.4.9
GPIOCFG—GPIO Configuration Register (offset = 0Ch) [reset = 00h]
9.6.4.10
GPIODIR—GPIO Direction Register (offset = 0Dh) [reset = 00h]
9.6.4.11
GPIODAT—GPIO Data Register (offset = 0Eh) [reset = 00h]
10
Application and Implementation
10.1
Application Information
10.1.1
Serial Interface Connections
10.1.2
Analog Input Filtering
10.1.3
External Reference and Ratiometric Measurements
10.1.4
Establishing a Proper Common-Mode Input Voltage
10.1.5
Isolated (or Floating) Sensor Inputs
10.1.6
Unused Inputs and Outputs
10.1.7
Pseudo Code Example
10.1.8
Channel Multiplexing Example
10.1.9
Power-Down Mode Example
10.2
Typical Applications
10.2.1
Ratiometric 3-Wire RTD Measurement System
10.2.1.1
Design Requirements
10.2.1.2
Detailed Design Procedure
10.2.1.2.1
Topology
10.2.1.2.2
RTD Selection
10.2.1.2.3
Excitation Current
10.2.1.2.4
Reference Resistor RREF
10.2.1.2.5
PGA Setting
10.2.1.2.6
Common-Mode Input Range
10.2.1.2.7
Input and Reference Low-Pass Filters
10.2.1.2.8
Register Settings
10.2.1.3
Application Curves
10.2.2
K-Type Thermocouple Measurement (-200°C to +1250°C) with Cold-Junction Compensation
10.2.2.1
Design Requirements
10.2.2.2
Detailed Design Procedure
10.2.2.2.1
Biasing Resistors
10.2.2.2.2
Input Filtering
10.2.2.2.3
PGA Setting
10.2.2.2.4
Cold-Junction Measurement
10.2.2.2.5
Calculated Resolution
10.2.2.2.6
Register Settings
10.3
Do's and Don'ts
11
Power-Supply Recommendations
11.1
Power-Supply Sequencing
11.2
Power-Supply Decoupling
12
Layout
12.1
Layout Guidelines
12.2
Layout Example
13
Device and Documentation Support
13.1
Documentation Support
13.1.1
Related Documentation
13.2
Related Links
13.3
Community Resources
13.4
Trademarks
13.5
Electrostatic Discharge Caution
13.6
Glossary
14
Mechanical, Packaging, and Orderable Information
パッケージ・オプション
メカニカル・データ(パッケージ|ピン)
PW|28
MPDS364
サーマルパッド・メカニカル・データ
5 Device Comparison Table
PRODUCT
RESOLUTION (Bits)
NUMBER OF INPUTS
VOLTAGE REFERENCE
EXCITATION CURRENT SOURCES
PACKAGE
ADS1146
16
1 Differential
External
No
TSSOP-16
ADS1147
16
4-Input Multiplexer
Internal or External
Yes
TSSOP-20
ADS1148
16
8-Input Multiplexer
Internal or External
Yes
TSSOP-28
VQFN-32
ADS1246
24
1 Differential
External
No
TSSOP-16
ADS1247
24
4-Input Multiplexer
Internal or External
Yes
TSSOP-20
ADS1248
24
8-Input Multiplexer
Internal or External
Yes
TSSOP-28