Texas Instruments ADS869 Series Manual

ADS869x 18-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with
1 Features
• 18-Bit ADCs with Integrated Analog Front-End
1
• 4-, 8-Channel MUX with Auto and Manual Scan
• Channel-Independent Programmable Inputs:
– ±10.24 V, ±5.12 V, ±2.56 V
– 10.24 V, 5.12 V
• 5-V Analog Supply: 1.65-V to 5-V I/O Supply
• Constant Resistive Input Impedance: 1 MΩ
• Input Overvoltage Protection: Up to ±20 V
• On-Chip, 4.096-V Reference with Low Drift
• Excellent Performance:
– 500-kSPS Aggregate Throughput
– DNL: ±0.5 LSB; INL: ±1.5 LSB
– Low Drift for Gain Error and Offset
– SNR: 93.5 dB; THD: –105 dB
– Low Power: 65 mW
• AUX Input → Direct Connection to ADC Inputs
• ALARM → High and Low Thresholds per Channel
• SPI™-Compatible Interface with Daisy-Chain
• Industrial Temperature Range: –40°C to 125°C
• TSSOP-38 Package (9.7 mm × 4.4 mm)
Block Diagram
AVDD
1 M:
AIN_0P
OVP
2nd-Order
PGA
AIN_0GND LPF
OVP
1 M:
V
B0
1 M:
AIN_1P OVP
2nd-Order
PGA
AIN_1GND
LPF
OVP
1 M:
V
B1
1 M:
AIN_2P OVP
2nd-Order
PGA
AIN_2GND
LPF
OVP
1 M:
V
B2
1 M:
AIN_3P
OVP
2nd-Order
PGA
AIN_3GND LPF
OVP
1 M:
V
B3
1 M:
AIN_4P
OVP
2nd-Order
PGA
AIN_4GND LPF
OVP
1 M:
V
B4
1 M:
AIN_5P OVP
2nd-Order
PGA
AIN_5GND
LPF
OVP
1 M:
V
B5
1 M:
AIN_6P OVP
2nd-Order
PGA
AIN_6GND
LPF
OVP
1 M:
V
B6
1 M:
AIN_7P
OVP
2nd-Order
PGA
AIN_7GND LPF
OVP
1 M:
V
B7
AUX_IN
Internal ADC Operating as 16-Bit ADC
AUX_GND
AGND
1
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.
Sample &
Product
Buy
Folder
Bipolar Input Ranges
DVDD
ADS8698
ADC
ADS8694
Driver
ADC
Driver
Digital
ADC
Logic
Driver
and
CS
Interface
SCLK
ADC
Driver
SDI
SDO
18-Bit
ADC
Driver SAR ADC
DAISY
REFSEL
ADC
Oscillator
Driver
RST / PD
ALARM
ADC
REFCAP
Driver
REFIO
ADC
Driver
4.096-V
Reference
DGND
REFGND
Tools &
Technical
Software
Documents
2 Applications
• Power Automation
• Protection Relays
• PLC Analog Input Modules
3 Description
The ADS8694 and ADS8698 are 4- and 8-channel,
integrated data acquisition systems based on a 18-bit
successive approximation (SAR) analog-to-digital
converter (ADC), operating at a throughput of
500 kSPS. The devices feature integrated analog
front-end circuitry for each input channel with
overvoltage protection up to ±20 V, a 4- or 8-channel
multiplexer with automatic and manual scanning
modes, and an on-chip, 4.096-V reference with low
temperature drift. Operating on a single 5-V analog
supply, each input channel on the devices can
support true bipolar input ranges of ±10.24 V,
±5.12 V, and ±2.56 V, as well as unipolar input
ranges of 0 V to 10.24 V and 0 V to 5.12 V. The gain
of the analog front-end for all input ranges is
accurately trimmed to ensure a high dc precision. The
input range selection is software-programmable and
independent for each channel. The devices offer a
1-MΩ constant resistive input impedance irrespective
of the selected input range.
The ADS8694 and ADS8698 offer a simple SPI-
compatible serial interface to the digital host and also
support daisy-chaining of multiple devices. The digital
supply operates from 1.65 V to 5.25 V, enabling
direct interface to a wide range of host controllers.
Device Information
PART NUMBER
ADS869x
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Gain Error versus Temperature
0.05
0.03
0.01
-0.01
-0.03
-0.05
±40 ±7
Support & Reference
Community
Design
ADS8694, ADS8698
SBAS686 – JULY 2015
(1)
PACKAGE BODY SIZE (NOM)
TSSOP (38) 9.70 mm × 4.40 mm
----- ± 2.5*V
REF
----- ] 1.25*V
REF
----- ] 0.625*V
----- + 2.5*V
REF
-----+1.25*V
REF
26 59 92
o
Free-Air temperature ( C)
REF
125
C027