AD7690_15 Datasheet, PDF (1/24 Pages) Analog Devices – 18-Bit, 1.5 LSB INL, 400 kSPS PulSAR

Data Sheet
18-Bit, 1.5 LSB INL, 400 kSPS PulSAR^®
Differential ADC in MSOP/LFCSP
AD7690
FEATURES
18-bit resolution with no missing codes
Throughput: 400 kSPS
INL: ±0.75 LSB typical, ±1.5 LSB maximum (±6 ppm of FSR)
Dynamic range: 102 dB at 400 kSPS
Oversampled dynamic range: 125 dB at 1 kSPS
Noise-free code resolution: 20 bits at 1 kSPS
Effective resolution: 22.7 bits at 1 kSPS
SINAD: 101.5 dB at 1 kHz
THD: −125 dB 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 5 V operation with
1.8 V/2.5 V/3 V/5 V logic interface
Proprietary serial interface
SPI/QSPI/MICROWIRE™/DSP compatible
Daisy-chain multiple ADCs and busy indicator
Power dissipation
4.25 μW at 100 SPS
4.25 mW at 100 kSPS
Standby current: 1 nA
10-lead package: MSOP (MSOP-8 size) and
3 mm × 3 mm LFCSP (SOT-23 size)
Pin-for-pin compatible with LFCSP/MSOP PulSAR ADCs
APPLICATIONS
Battery-powered equipment
Data acquisition
Seismic data acquisition systems
DVMs
Instrumentation
Medical instruments
1.5
POSITIVE INL = +0.42LSB
NEGATIVE INL = –0.6LSB
1.0
0.5
0
–0.5
–1.0
–1.5
0
65536
131072
196608
CODE
Figure 1. Integral Nonlinearity vs. Code
262144
Rev. C
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APPLICATION EXAMPLE
+2.5V TO +5V +5V
±10V, ±5V, ...
ADA4941-1
REF VDD ^VIO
IN+
SDI
SCK
IN–
GND
SDO
CNV
AD7690
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
100
kSPS
250
kSPS
400 kSPS
to
1000
500 kSPS kSPS
ADC
Driver
18-Bit True
Differential
AD7691 AD7690 AD7982 ADA4941
AD7982
ADA4841
16-Bit True AD7684 AD7687 AD7688
Differential
AD7693
ADA4941
ADA4841
16-Bit Pseudo AD7680 AD7685 AD7686 AD7980 ADA4841
Differential AD7683 AD7694
14-Bit Pseudo AD7940 AD7942 AD7946
Differential
ADA4841
GENERAL DESCRIPTION
The AD7690¹ is an 18-bit, successive approximation, analog-to-
digital converter (ADC) that operates from a single power supply,
VDD. 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 phase between 0 V
and REF. The reference voltage, REF, is applied externally and
can be set up to the supply voltage.
The power of the AD7690 scales linearly with the 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 AD7690 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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