AD7691_15 Datasheet, PDF (1/28 Pages) Analog Devices – 18-Bit, 1.5 LSB INL, 250 kSPS PulSAR

Data Sheet
18-Bit, 1.5 LSB INL, 250 kSPS PulSAR
Differential ADC in MSOP/LFCSP
AD7691
FEATURES
18-bit resolution with no missing codes
Throughput: 250 kSPS
INL: ±0.75 LSB typical, ±1.5 LSB maximum (±6 ppm of FSR)
Dynamic range: 102 dB typical at 250 kSPS
Oversampled dynamic range: 125 dB at1 kSPS
Noise-free code resolution: 20 bits at 1 kSPS
Effective resolution: 22.7 bits at 1 kSPS
SINAD: 101.5 dB typical at 1 kHz
THD: −125 dB typical at 1 kHz
True differential analog input range: ±VREF
0 V to VREF with VREF up to VDD on both inputs
No pipeline delay
Single-supply 2.3 V to 5 V operation with
1.8 V/2.5 V/3 V/5 V logic interface
Proprietary serial interface
SPI/QSPI/MICROWIRE™/DSP compatible
Ability to daisy-chain multiple ADCs
Optional busy indicator feature
Power dissipation
1.35 mW at 2.5 V/100 kSPS, 4 mW at 5 V/100 kSPS
1.4 μW at 2.5 V/100 SPS
Standby current: 1 nA
10-lead packages: MSOP (MSOP-8 size) and
3 mm × 3 mm LFCSP (SOT-23 size)
Pin-for-pin compatible with the18-bit AD7690 and
16-bit AD7693, AD7688, and AD7687
APPLICATIONS
Battery-powered equipment
Data acquisitions
Seismic data acquisition systems
Instrumentation
Medical instruments
1.5
POSITIVE INL = 0.43LSB
NEGATIVE INL = –0.62LSB
1.0
0.5
0
–0.5
–1.0
–1.5
0
65536
131072
196608
262144
CODE
Figure 1. Integral Nonlinearity vs. Code, 5 V
Rev. D
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APPLICATION DIAGRAM
+0.5V TO VDD +2.5V TO +5V
±10V, ±5V, ...
ADA4941
REF VDD ^VIO
IN+
SDI
SCK
IN–
GND
SDO
CNV
AD7691
Figure 2.
+1.8V TO VDD
3- OR 4-WIRE
INTERFACE
(SPI, DAISY CHAIN, CS)
Table 1. MSOP, LFCSP/SOT-23 14-/16-/18-Bit PulSAR® ADC
Type
18-Bit True
Differential
16-Bit True
Differential
16-Bit
Pseudo
Differential
14-Bit
Pseudo
Differential
100
kSPS
AD7684
AD7680
AD7683
AD7940
250
kSPS
AD7691
AD7687
AD7685
AD7694
AD7942
400 kSPS to
500 kSPS
AD7690
AD7688
AD7693
AD7686
AD7946
≥1000
kSPS
AD7982
AD7984
AD7980
ADC
Driver
ADA4941-1
ADA4841-x
ADA4941-1
ADA4841-x
ADA4841-x
ADA4841-1
GENERAL DESCRIPTION
The AD7691¹ is an 18-bit, charge redistribution, successive
approximation, analog-to-digital converter (ADC) that operates
from a single power supply, VDD, between 2.3 V and 5 V. It
contains a low power, high speed, 18-bit sampling ADC with no
missing codes, an internal conversion clock, and a versatile
serial interface port. On the CNV rising edge, it samples the
voltage difference between the IN+ and IN− pins. The voltages
on these pins swing in opposite phases between 0 V and REF.
The reference voltage, REF, is applied externally and can be set
up to the supply voltage.
The part’s power scales linearly with throughput.
The SPI-compatible serial interface also features the ability,
using the SDI input, to daisy-chain several ADCs on a single
3-wire bus and provides an optional busy indicator. It is compatible
with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate VIO supply.
The AD7691 is housed in a 10-lead MSOP or a 10-lead LFCSP
with operation specified from −40°C to +85°C.
1 _{Protected by U.S. Patent 6,703,961.}
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