AD7687_15 Datasheet, PDF (1/28 Pages) Analog Devices – 16-Bit, 1.5 LSB INL, 250 kSPS PulSAR

Data Sheet
16-Bit, 1.5 LSB INL, 250 kSPS PulSAR
Differential ADC in MSOP
AD7687
FEATURES
16-bit resolution with no missing codes
Throughput: 250 kSPS
INL: ±0.4 LSB typ, ±1.5 LSB max (±23 ppm of FSR)
Dynamic range: 96.5 dB
S/(N + D): 95.5 dB at 20 kHz
THD: −118 dB at 20 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 5.5 V operation with
1.8 V/2.5 V/3 V/5 V logic interface
Proprietary serial interface: SPI-/QSPI™-/MICROWIRE™-/DSP-
compatible¹
Daisy-chain multiple ADCs and BUSY indicator
Power dissipation
1.35 mW at 2.5 V/100 kSPS, 4 mW at 5 V/100 kSPS, and
1.4 µW at 2.5 V/100 SPS
Standby current: 1 nA
10-lead MSOP (MSOP-8 size) and
3 mm × 3 mm LFCSP (SOT-23 size)
Pin-for-pin compatible with AD7685, AD7686, and AD7688
APPLICATIONS
Battery-powered equipment
Data acquisitions
Instrumentation
Medical instruments
Process controls
1.5
1.0
POSITIVE INL = +0.32LSB
NEGATIVE INL = –0.41LSB
0.5
0
–0.5
–1.0
–1.5
0
16384
32768
CODE
49152
Figure 1. Integral Nonlinearity vs. Code
65535
TYPICAL APPLICATION CIRCUIT
0.5V TO 5V 2.5 TO 5V
VREF
0
VREF
0
REF VDD ^VIO
SDI
IN+
AD7687 ^SCK
IN–
SDO
GND
CNV
1.8V TO VDD
3- OR 4-WIRE INTERFACE
(SPI, DAISY CHAIN, CS)
Figure 2.
Table 1. MSOP, LFCSP/SOT-23 16-Bit PulSAR™ ADC
Type
100 kSPS 250 kSPS 500 kSPS
True Differential
AD7684
AD7687
AD7688
Pseudo
AD7683
AD7685
AD7686
Differential/Unipolar
AD7694
Unipolar
AD7680
GENERAL DESCRIPTION
The AD7687 is a 16-bit, charge redistribution, successive
approximation, analog-to-digital converter (ADC) that operates
from a single power supply, VDD, between 2.3 V to 5.5 V. It
contains a low power, high speed, 16-bit sampling ADC with no
missing codes, an internal conversion clock, and a versatile
serial interface port. The part also contains a low noise, wide
bandwidth, short aperture delay track-and-hold circuit. On the
CNV rising edge, it samples the voltage difference between IN+
and IN− pins. The voltages on these pins usually swing in
opposite phase between 0 V to REF. The reference voltage, REF,
is applied externally and can be set up to the supply voltage.
Its 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
supply VIO.
The AD7687 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.}
Rev. C
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