ADS8684A Datasheet, PDF (1/80 Pages) Texas Instruments – 4- and 8-Channel, Single-Supply, SAR ADCs

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ADS8684A, ADS8688A
SBAS680 – JULY 2015
ADS868xA 16-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with
Bipolar Input Ranges
1 Features
•1 16-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, ±1.28 V, ±0.64 V
– 10.24 V, 5.12 V, 2.56 V, 1.28 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: ±0.75 LSB
– Low Drift for Gain Error and Offset
– SNR: 92 dB; THD: –102 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)
1 M:
AIN_0P
OVP
AIN_0GND
OVP
1 M:
1 M:
AIN_1P
OVP
AIN_1GND
OVP
1 M:
1 M:
AIN_2P
OVP
AIN_2GND
OVP
1 M:
1 M:
AIN_3P
OVP
AIN_3GND
OVP
1 M:
1 M:
AIN_4P
OVP
AIN_4GND
OVP
1 M:
1 M:
AIN_5P
OVP
AIN_5GND
OVP
1 M:
1 M:
AIN_6P
OVP
AIN_6GND
OVP
1 M:
1 M:
AIN_7P
OVP
AIN_7GND
OVP
1 M:
AUX_IN
AUX_GND
Block Diagram
AVDD
DVDD
PGA
2nd-Order
LPF
ADC
Driver
VB0
ADS8688A
ADS8684A
PGA
2nd-Order
LPF
ADC
Driver
VB1
PGA
2nd-Order
LPF
ADC
Driver
VB2
PGA
2nd-Order
LPF
ADC
Driver
VB3
PGA
2nd-Order
LPF
ADC
Driver
VB4
PGA
2nd-Order
LPF
ADC
Driver
VB5
PGA
2nd-Order
LPF
ADC
Driver
VB6
PGA
2nd-Order
LPF
ADC
Driver
VB7
Digital
Logic
and
Interface
CS
SCLK
SDI
16-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 ADS8684A and ADS8688A are 4- and 8-
channel, integrated data acquisition systems based
on a 16-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, ±2.56 V, ±1.28V and ±0.64V, as well as
unipolar input ranges of 0 V to 10.24 V, 0 V to 5.12 V,
0 V to 2.56 V and 0 V to 1.28 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 ADS8684A and ADS8688A 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)
ADS868xA
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
---- ± 2.5*V_REF, ---- “ 1.25*V_REF
---- “ 0.625*V_REF, ------“0.3125*V_REF
-------“0.156 V_REF, ---- + 2.5*V_REF
---- + 1.25*V_REF, ---- + 0.625*V_REF
---- + 0.3125*V_REF
-0.01
-0.03
-0.05
±40
±7
26
59
92
125
Free-Air Temperature (^oC)
C039
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.