Texas Instruments ADS8685W Handleiding
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ADS868xW 16-Bit, High-Speed, Single-Supply, SAR ADC Data Acquisition System
With Programmable, Bipolar Input Ranges
1 Features
•16-bit ADC with integrated analog front-end
•High speed:
–ADS8681W: 1MSPS
–ADS8685W: 500kSPS
–ADS8689W: 100kSPS
•Software programmable input ranges:
–Bipolar differential ranges: ±12.288V, ±10.24V,
±6.144V, ±5.12V, and ±2.56V
–Unipolar differential ranges: 0V–12.288V,
0V–10.24V, 0V–6.144V, and 0V–5.12V
•Analog supply (5V): 1.65V to 5V I/O supply
•Constant resistive input impedance ≥ 1MΩ
•Input bandwidth: 450kHz
•Input overvoltage protection: Up to ±20V
•On-chip, 4.096V reference with low drift
•Excellent performance:
–DNL: ±0.6LSB; INL: ±0.6LSB
–SNR: 80dB; THD: –105dB
•ALARM feature with high, low threshold
•multiSPI
™
interface with daisy-chain
•Temperature range: –40°C to +125°C
2 Applications
•Analog input modules
•Semiconductor tests
•Servo drive control modules
3 Description
The ADS8681W, ADS8685W, and ADS8689W are an
integrated data acquisition system family based on
a successive approximation (SAR) analog-to-digital
converter (ADC) topology. The devices feature a
high-speed, high-precision SAR ADC, integrated
differential analog front-end (AFE) input driver circuit.
The ADS868xW includes an overvoltage protection
circuit up to ±20V and an on-chip 4.096V reference
with extremely low temperature drift.
The devices operate on a single 5V analog supply,
but support true bipolar input ranges and unipolar
input ranges. The bipolar input ranges are ±12.288V,
±6.144V, ±10.24V, ±5.12V, and ±2.56V, and the
unipolar input ranges are from 0V to 12.288V, 10.24V,
6.144V, and 5.12V. The devices offer a high resistive
input impedance (≥ 1MΩ) irrespective of the selected
input range.
The multiSPI digital interface is backward-compatible
to the traditional SPI protocol. Additionally,
configurable features simplify interface to a wide
range of host controllers.
Package Information
PART NUMBERPACKAGE
(1)
PACKAGE SIZE
(2)
ADS868xWRUM (WQFN, 16)4mm × 4mm
(1)For more information, see the Mechanical, Packaging, and
Orderable Information.
(2)The package size (length × width) is a nominal value and
includes pins, where applicable.
Oscillator
CONVST/CS
PGA
1 M
OVP
1 M
OVP
LPF
ADC
Driver
V
BIAS
AIN_P
AIN_M
4.096-V
Reference
REFGND
DGNDAGND
DVDD
AVDD
Digital Logic
and Interface
REFIO
REFCAP
SCLK
SDI
SDO
16-Bit
SAR ADC
ADS868x
RVS
Block Diagram
ADS8681W, ADS8685W, ADS8689W
SBASAY5A – JUNE 2024 – REVISED MAY 2025
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
Table of Contents
1 Features............................................................................1
2 Applications.....................................................................1
3 Description.......................................................................1
4 Pin Configuration and Functions...................................3
5 Specifications..................................................................4
5.1 Absolute Maximum Ratings........................................4
5.2 ESD Ratings...............................................................4
5.3 Recommended Operating Conditions.........................5
5.4 Thermal Information....................................................5
5.5 Electrical Characteristics.............................................6
5.6 Timing Requirements................................................10
5.7 Switching Characteristics..........................................11
5.8 Timing Diagrams.......................................................12
5.9 Typical Characteristics..............................................15
6 Detailed Description......................................................21
6.1 Overview...................................................................21
6.2 Functional Block Diagram.........................................21
6.3 Feature Description...................................................22
6.4 Device Functional Modes..........................................34
6.5 Programming............................................................39
7 Register Maps................................................................47
7.1 Device Configuration and Register Maps.................47
8 Application and Implementation..................................55
8.1 Application Information.............................................55
8.2 Typical Application....................................................55
8.3 Power Supply Recommendations.............................58
8.4 Layout.......................................................................59
9 Device and Documentation Support............................61
9.1 Documentation Support............................................61
9.2 Receiving Notification of Documentation Updates....61
9.3 Support Resources...................................................61
9.4 Trademarks...............................................................61
9.5 Electrostatic Discharge Caution................................61
9.6 Glossary....................................................................61
10 Revision History..........................................................61
11 Mechanical, Packaging, and Orderable
Information....................................................................62
ADS8681W, ADS8685W, ADS8689W
SBASAY5A – JUNE 2024 – REVISED MAY 2025
www.ti.com
2Submit Document Feedback
Copyright © 2025 Texas Instruments Incorporated
Product Folder Links: ADS8681W ADS8685W ADS8689W
4 Pin Configuration and Functions
RVS
ALARM/SDO-1/GPO
SDO-0
CONVST/CS
SCLK
SDI
RST
AIN_M
AIN_P
AGND
REFIO
REFGND
REFCAP
AVDD
DGND
DVDD
Figure 4-1. RUM Package, 16-Pin WQFN (Top View)
Table 4-1. Pin Functions
NAMENO.TYPE
(1)
DESCRIPTION
AGND1PAnalog ground pin. Decouple with the AVDD pin.
AIN_M6AIAnalog input: negative. Decouple with the AIN_P pin.
AIN_P5AIAnalog input: positive. Decouple with the AIN_M pin.
ALARM/SDO-1/GPO12DO
Multifunction output pin. Active high alarm.
Data output 1 for serial communication. General-purpose output pin.
AVDD16PAnalog supply pin. Decouple with the AGND pin.
CONVST/CS9DI
Dual-functionality pin.
Active high logic: Conversion start input pin. A CONVST rising edge brings the device from acquisition
phase to conversion phase.
Active low logic: Chip-select input pin. The device takes control of the data bus when CS is low. The
SDO-x pins go to tri-state when CS is high.
DGND15PDigital ground pin. Decouple with the DVDD pin.
DVDD14PDigital supply pin. Decouple with the DGND pin.
REFCAP4AOADC reference buffer decoupling capacitor pin. Decouple with the REFGND pin.
REFGND3P
Reference ground pin. Short this pin to the analog ground plane. Decouple with the REFIO and
REFCAP pins.
REFIO2AIOInternal reference output and external reference input pin. Decouple with REFGND.
RST7DIActive-low logic input to reset the device.
RVS13DO
Multifunction output pin for serial interface, see the RESET State section.
With CS held high, RVS reflects the status of the internal ADCST signal.
With CS low, the status of RVS depends on the output protocol selection.
SCLK10DI
Serial communication: Clock input pin for the serial interface.
All system-synchronous data transfer protocols are timed with respect to the SCLK signal.
SDI8DI
Dual function: Data input pin for serial communication.
Chain data input during serial communication in daisy-chain mode.
SDO-011DOSerial communication: Data output 0.
(1)AI = analog input, AIO = analog input/output, DI = digital input, DO = digital output, and P = power supply.
www.ti.com
ADS8681W, ADS8685W, ADS8689W
SBASAY5A – JUNE 2024 – REVISED MAY 2025
Copyright © 2025 Texas Instruments Incorporated
Submit Document Feedback
3
Product Folder Links: ADS8681W ADS8685W ADS8689W
Product specificaties
| Merk: | Texas Instruments |
| Categorie: | Niet gecategoriseerd |
| Model: | ADS8685W |
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