AD7685_15 Datasheet, PDF (1/28 Pages) Analog Devices – 16-Bit, 250 kSPS PulSAR

Data Sheet
FEATURES
16-bit resolution with no missing codes
Throughput: 250 kSPS
INL: ±0.6 LSB typical, ±2 LSB maximum (±0.003% of FSR)
SINAD: 93.5 dB at 20 kHz
THD: −110 dB at 20 kHz
Pseudo differential analog input range
0 V to VREF with VREF up to VDD
No pipeline delay
Single-supply operation 2.3 V to 5.5 V with
1.8 V to 5 V logic interface
Proprietary serial interface: SPI-/QSPI™-/MICROWIRE™-/DSP-
compatible
Daisy-chain multiple ADCs, BUSY indicator
Power dissipation
1.4 µW at 2.5 V/100 SPS
1.35 mW at 2.5 V/100 kSPS, 4 mW at 5 V/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 10-lead MSOP/PulSAR® ADCs
APPLICATIONS
Battery-powered equipment
Medical instruments
Mobile communications
Personal digital assistants (PDAs)
Data acquisition
Instrumentation
Process controls
2.0
POSITIVE INL = +0.33LSB
NEGATIVE INL = –0.50LSB
1.5
1.0
0.5
0
–0.5
–1.0
–1.5
–2.0
0
16384
32768
CODE
49152
Figure 1. Integral Nonlinearity vs. Code
65536
Rev. D
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16-Bit, 250 kSPS PulSAR
ADC in MSOP
AD7685
TYPICAL APPLICATION CIRCUIT
0.5V TO VDD 2.5V TO 5V
0 TO VREF
REF VDD ^VIO
SDI
IN+
AD7685 ^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 14-/16-/18-Bit PulSAR ADC
Type
100
kSPS
250
kSPS
400 kSPS
to
1000
500 kSPS kSPS
ADC
Driver
18-Bit True
AD7691 AD7690 AD7982 ADA4941
Differential
AD7982
ADA4841
16-Bit True
AD7684 AD7687 AD7688
ADA4941
Differential
AD7693
ADA4841
16-Bit Pseudo AD7680 AD7685 AD7686 AD7980 ADA4841
Differential AD7683 AD7694
14-Bit Pseudo AD7940 AD7942 AD7946
ADA4841
Differential
GENERAL DESCRIPTION
The AD7685¹ 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 an analog input IN+ between 0 V to REF with
respect to a ground sense IN−. The reference voltage, REF, is
applied externally and can be set up to the supply voltage.
Power dissipation 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 or 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 AD7685 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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