-0.05
-0.03
-0.01
0.01
0.03
0.05
±
40
±
7
26
59
92
125
Ga
in
(%
F
S
)
Free-Air Temperature (
o
C)
C026
-----
± 2.5*V
REF
-----
± 1.25*V
REF
----- ± 0.625*V
REF
------ +2.5*V
REF
------+1.25*V
REF
Mu
lti
p
le
x
e
r
Oscillator
CS
SCLK
SDI
SDO
DAISY
REFSEL
RST / PD
REFCAP
REFIO
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B0
AIN_0P
AIN_0GND
OVP
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B1
AIN_1P
AIN_1GND
OVP
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B2
AIN_2P
AIN_2GND
OVP
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B3
AIN_3P
AIN_3GND
OVP
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B4
AIN_4P
AIN_4GND
OVP
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B5
AIN_5P
AIN_5GND
OVP
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B6
AIN_6P
AIN_6GND
OVP
PGA
1 M
:
OVP
1 M
:
2nd-Order
LPF
ADC
Driver
V
B7
AIN_7P
AIN_7GND
OVP
AUX_IN
AUX_GND
16-bit
SAR ADC
Digital
Logic
&
Interface
4.096V
Reference
REFGND
DGND
AGND
DVDD
AVDD
A
d
d
iti
o
n
a
l
C
h
a
n
n
e
ls
i
n
A
D
S
8
6
8
8
ADS8688
ADS8684
SBAS582C – JULY 2014 – REVISED APRIL 2015
ADS868x 16-Bit, 500-kSPS, 4- and 8-Channel, Single-Supply, SAR ADCs with
Bipolar Input Ranges
1 Features
2 Applications
1
•
16-Bit ADCs with Integrated Analog Front-End
•
Power Automation
•
4-, 8-Channel MUX with Auto and Manual Scan
•
Protection Relays
•
Channel-Independent Programmable Input
•
PLC Analog Input Modules
Ranges:
3 Description
–
Bipolar: ±10.24 V, ±5.12 V, ±2.56 V
The ADS8684 and ADS8688 are 4- and 8-channel,
–
Unipolar: 10.24 V, 5.12 V
integrated data acquisition systems based on a 16-bit
•
5-V Analog Supply: 1.65-V to 5-V I/O Supply
successive
approximation
(SAR)
analog-to-digital
•
Constant Resistive Input Impedance: 1 M
Ω
converter
(ADC),
operating
at
a
throughput
of
500-kSPS. The devices feature integrated analog
•
Input Overvoltage Protection: Up to ±20 V
front-end
circuitry
for
each
input
channel
with
•
On-Chip, 4.096-V Reference with Low Drift
overvoltage protection up to ±20 V, a 4- or 8-channel
•
Excellent Performance:
multiplexer with automatic and manual scanning
modes, and an on-chip, 4.096-V reference with low
–
500-kSPS Aggregate Throughput
temperature drift. Operating on a single 5-V analog
–
DNL: ±0.5 LSB; INL: ±0.75 LSB
supply, each input channel on the devices can
–
Low Drift for Gain Error and Offset
support true bipolar input ranges of ±10.24 V,
±5.12 V, and ±2.56 V, as well as unipolar input
–
SNR: 92 dB; THD: –102 dB
ranges of 0 V to 10.24 V and 0 V to 5.12 V. The gain
–
Low Power: 65 mW
of the analog front-end for all input ranges is
•
AUX Input
→
Direct Connection to ADC Inputs
accurately trimmed to ensure a high dc precision. The
•
SPI™-Compatible Interface with Daisy-Chain
input range selection is software-programmable and
independent for each channel. The devices offer a
•
Industrial Temperature Range: –40°C to 125°C
1-M
Ω
constant resistive input impedance irrespective
•
TSSOP-38 Package (9.7 mm × 4.4 mm)
of the selected input range.
Simplified Block Diagram
The ADS8684 and ADS8688 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
PACKAGE
BODY SIZE (NOM)
ADS868x
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
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.
