ADS8694 Datasheet, PDF (1/77 Pages) Texas Instruments – 4- and 8-Channel, Single-Supply, SAR ADCs

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ADS8694, ADS8698
SBAS686 – JULY 2015
ADS869x 18-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with
Bipolar Input Ranges
1 Features
•1 18-Bit ADCs with Integrated Analog Front-End
• 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
DVDD
1 M:
AIN_0P
OVP
AIN_0GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB0
1 M:
AIN_1P
OVP
AIN_1GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB1
1 M:
AIN_2P
OVP
AIN_2GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB2
1 M:
AIN_3P
OVP
AIN_3GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB3
1 M:
AIN_4P
OVP
AIN_4GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB4
1 M:
AIN_5P
OVP
AIN_5GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB5
1 M:
AIN_6P
OVP
AIN_6GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB6
1 M:
AIN_7P
OVP
AIN_7GND
OVP
1 M:
PGA
2nd-Order
LPF
ADC
Driver
VB7
AUX_IN
AUX_GND ^{Internal ADC Operating as 16-Bit ADC}
ADS8698
ADS8694
Digital
Logic
and
Interface
CS
SCLK
SDI
18-Bit
SAR ADC
SDO
DAISY
Oscillator
REFSEL
RST / PD
ALARM
REFCAP
REFIO
4.096-V
Reference
AGND
DGND
REFGND
1
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⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
ADS869x
TSSOP (38)
9.70 mm × 4.40 mm
(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
----- ± 2.5*V_REF
----- ] 1.25*V_REF
----- ] 0.625*V_REF
----- + 2.5*V_REF
-----+1.25*V_REF
±7
26
59
92
125
Free-Air temperature (^oC)
C027
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.