EVAL-AD7686CB Analog Devices Inc, EVAL-AD7686CB Datasheet

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EVAL-AD7686CB

Manufacturer Part Number
EVAL-AD7686CB
Description
BOARD EVALUATION FOR AD7686
Manufacturer
Analog Devices Inc
Series
PulSAR®r
Datasheet

Specifications of EVAL-AD7686CB

Number Of Adc's
1
Number Of Bits
16
Sampling Rate (per Second)
500k
Data Interface
Serial
Inputs Per Adc
1 Differential
Input Range
±VREF
Power (typ) @ Conditions
15mW @ 500kSPS, 5 V
Voltage Supply Source
Single
Operating Temperature
-40°C ~ 85°C
Utilized Ic / Part
AD7686
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
FEATURES
16-bit resolution with no missing codes
Throughput: 500 kSPS
INL: ±0.6 LSB typical, ±2 LSB maximum (±0.003% of FSR)
SINAD: 92.5 dB @ 20 kHz
THD: −110 dB @ 20 kHz
Pseudo differential analog input range
No pipeline delay
Single-supply 5 V operation with
Serial interface SPI®-/QSPI™-/MICROWIRE™-/DSP-compatible
Daisy-chain multiple ADCs and busy indicator
Power dissipation
Standby current: 1 nA
10-lead MSOP (MSOP-8 size) and
Pin-for-pin-compatible with 10-lead MSOP/QFN PulSAR® ADCs
APPLICATIONS
Battery-powered equipment
Data acquisitions
Instrumentation
Medical instruments
Process controls
Rev. B
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
0 V to V
1.8 V/2.5 V/3 V/5 V logic interface
3.75 μW @ 5 V/100 SPS
3.75 mW @ 5 V/100 kSPS
3 mm × 3 mm, 10-lead QFN (LFCSP) (SOT-23 size)
–0.5
–1.0
–1.5
–2.0
2.0
1.5
1.0
0.5
0
0
REF
with V
Figure 1. Integral Nonlinearity vs. Code
16384
REF
up to VDD
32768
CODE
POSITIVE INL = +0.52LSB
NEGATIVE INL = –0.38LSB
49152
65535
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
Fax: 781.461.3113
Table 1. MSOP, QFN (LFCSP)/SOT-23
14-/16-/18-Bit PulSAR ADC
Type
18-Bit True
16-Bit True
16-Bit Pseudo
14-Bit Pseudo
GENERAL DESCRIPTION
The AD7686 is a 16-bit, charge redistribution, successive
approximation, analog-to-digital converter (ADC) that operates
from a single 5 V power supply, VDD. 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,
the AD7686 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. This device is
compatible with 1.8 V, 2.5 V, 3 V, or 5 V logic, using the separate
supply VIO.
The AD7686 is housed in a 10-lead MSOP or a 10-lead QFN
(LFCSP) with operation specified from −40°C to +85°C.
0 TO VREF
Differential
Differential
Differential
Differential
16-Bit, 500 kSPS PulSAR
FUNCTIONAL BLOCK DIAGRAM
100
kSPS
AD7684
AD7680
AD7683
AD7940
0.5V TO 5V
IN+
IN–
©2005–2007 Analog Devices, Inc. All rights reserved.
AD7686
GND
REF
250
kSPS
AD7691
AD7687
AD7685
AD7694
AD7942
VDD
ADC in MSOP/QFN
5V
Figure 2.
SDO
SCK
CNV
VIO
SDI
400 kSPS
to
500 kSPS
AD7690
AD7982
AD7688
AD7693
AD7686
AD7946
1.8V TO VDD
3- OR 4-WIRE INTERFACE
(SPI, DAISY CHAIN, CS)
1000
kSPS
AD7982
AD7980
AD7686
www.analog.com
ADC
Driver
ADA4941
ADA4841
ADA4941
ADA4841
ADA4841
ADA4841

Related parts for EVAL-AD7686CB

EVAL-AD7686CB Summary of contents

Page 1

FEATURES 16-bit resolution with no missing codes Throughput: 500 kSPS INL: ±0.6 LSB typical, ±2 LSB maximum (±0.003% of FSR) SINAD: 92 kHz THD: −110 kHz Pseudo differential analog input range ...

Page 2

... CS Mode 4-Wire, No Busy Indicator....................................... 19 CS Mode 4-Wire with Busy Indicator ..................................... 20 Chain Mode, No Busy Indicator .............................................. 21 Chain Mode with Busy Indicator............................................. 22 Application Hints ........................................................................... 23 Layout .......................................................................................... 23 Evaluating Performance ............................................................ 23 True 16-Bit Isolated Application Example .............................. 24 Outline Dimensions ....................................................................... 25 Ordering Guide .......................................................................... 26 4/06—Rev Rev. A Updated Format..................................................................Universal Updated Outline Dimensions....................................................... 25 Changes to Ordering Guide .......................................................... 26 4/05— ...

Page 3

SPECIFICATIONS VDD = 4 5.5 V, VIO = 2 VDD, V Table 2. Parameter Conditions RESOLUTION ANALOG INPUT Voltage Range IN+ − IN− Absolute Input Voltage IN+ IN− Analog Input CMRR f = 200 kHz IN ...

Page 4

AD7686 VDD = 4 5.5 V, VIO = 2 VDD, V Table 3. Parameter Conditions REFERENCE Voltage Range Load Current 500 kSPS, REF = 5 V SAMPLING DYNAMICS −3 dB Input Bandwidth Aperture Delay VDD = ...

Page 5

TIMING SPECIFICATIONS −40°C to +85°C, VDD = 4 5.5 V, VIO = 2 5 VDD + 0.3 V, whichever is the lowest, unless otherwise stated. See Figure 3 and Figure 4 for load conditions. ...

Page 6

AD7686 ABSOLUTE MAXIMUM RATINGS Table 5. Parameter Rating Analog Inputs 1 1 IN+ , IN− GND − 0 VDD + 0 ±130 mA REF GND − 0 VDD + 0.3 V Supply Voltages VDD, ...

Page 7

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS REF 1 10 VDD 2 9 AD7686 IN TOP VIEW (Not to Scale) IN– GND 5 6 Figure 5. 10-Lead MSOP Pin Configuration Table 6. Pin Function Descriptions 1 Pin No. ...

Page 8

AD7686 TERMINOLOGY Integral Nonlinearity Error (INL) INL refers to the deviation of each individual code from a line drawn from negative full scale through positive full scale. The point used as negative full scale occurs ½ LSB before the first ...

Page 9

TYPICAL PERFORMANCE CHARACTERISTICS 2.0 POSITIVE INL = +0.52LSB NEGATIVE INL = –0.38LSB 1.5 1.0 0.5 0 –0.5 –1.0 –1.5 –2.0 0 16384 32768 CODE Figure 7. Integral Nonlinearity vs. Code 250000 202719 200000 150000 100000 50000 30770 27583 0 0 ...

Page 10

AD7686 100 2.3 2.7 3.1 3.5 3.9 4.3 REFERENCE VOLTAGE (V) Figure 13. SNR, SINAD, and ENOB vs. Reference Voltage 100 –55 –35 – TEMPERATURE (°C) Figure 14. SNR ...

Page 11

VDD 750 500 250 VIO 0 4.50 4.75 5.00 5.25 SUPPLY (V) Figure 19. Operating Currents vs. Supply 1000 750 500 250 VDD + VIO 0 –55 –35 – TEMPERATURE (°C) Figure 20. Power-Down Currents ...

Page 12

AD7686 THEORY OF OPERATION IN+ REF GND IN– CIRCUIT INFORMATION The AD7686 is a fast, low power, single-supply, precise 16-bit ADC using a successive approximation architecture. The AD7686 is capable of converting 500,000 samples per second (500 kSPS) and powers ...

Page 13

Transfer Functions The ideal transfer characteristic for the AD7686 is shown in Figure 25 and Table 7. 111...111 111...110 111...101 000...010 000...001 000...000 –FSR –FSR + 1 LSB –FSR + 0.5 LSB +FSR – 1.5 LSB ANALOG INPUT Figure 25. ...

Page 14

AD7686 ANALOG INPUT Figure 27 shows an equivalent circuit of the input structure of the AD7686. The two diodes, D1 and D2, provide ESD protection for the analog inputs IN+ and IN−. Care must be taken to ensure that the ...

Page 15

DRIVER AMPLIFIER CHOICE Although the AD7686 is easy to drive, the driver amplifier should meet the following requirements: • The noise generated by the driver amplifier needs to be kept as low as possible to preserve the SNR and transition ...

Page 16

AD7686 The AD7686 powers down automatically at the end of each conversion phase and, therefore, the power scales linearly with the sampling rate, as shown in Figure 31. This makes the part ideal for low sampling rates (even a few ...

Page 17

CS MODE 3-WIRE, NO BUSY INDICATOR This mode is most often used when a single AD7686 is connected to an SPI-compatible digital host. The connection diagram is shown in Figure 33, and the corresponding timing is provided in Figure 34. ...

Page 18

AD7686 CS MODE 3-WIRE WITH BUSY INDICATOR This mode is generally used when a single AD7686 is connected to an SPI-compatible digital host having an interrupt input. The connection diagram is shown in Figure 35, and the correspond- ing timing ...

Page 19

CS MODE 4-WIRE, NO BUSY INDICATOR This mode is generally used when multiple AD7686s are connected to an SPI-compatible digital host. A connection diagram example using two AD7686 devices is shown in Figure 37, and the corresponding timing is given ...

Page 20

AD7686 CS MODE 4-WIRE WITH BUSY INDICATOR This mode is usually used when a single AD7686 is connected to an SPI-compatible digital host, which has an interrupt input, and when it is desired to keep CNV, which is used to ...

Page 21

CHAIN MODE, NO BUSY INDICATOR This mode can be used to daisy-chain multiple AD7686s on a 3-wire serial interface. This feature is useful for reducing component count and wiring connections, for example, in isolated multiconverter applications or for systems with ...

Page 22

AD7686 CHAIN MODE WITH BUSY INDICATOR This mode can be used to daisy-chain multiple AD7686s on a 3-wire serial interface while providing a busy indicator. This feature is useful for reducing component count and wiring connections, for example, in isolated ...

Page 23

... Figure 45 and Figure 46. EVALUATING PERFORMANCE Other recommended layouts for the AD7686 are outlined in the documentation of the evaluation board (EVAL-AD7686CB). The evaluation board package includes a fully assembled and tested evaluation board, documentation, and software for controlling the board from a PC via the universal evaluation ...

Page 24

AD7686 TRUE 16-BIT ISOLATED APPLICATION EXAMPLE In applications where high accuracy and isolation are required, such as power monitoring, motor control, and some medical equipment, the circuit shown in Figure 47, using the AD7686 and the ADuM1402C digital isolator, provides ...

Page 25

OUTLINE DIMENSIONS INDEX ARE A 1.50 BSC SQ 0.80 0.75 0.70 SEATING PLANE 3.10 3.00 2. 5.15 3.10 4.90 3.00 4.65 2. PIN 1 0.50 BSC 0.95 0.85 1.10 MAX 0.75 0.15 0.33 SEATING 0.23 0.05 ...

Page 26

... LSB max 1 AD7686CRMZRL7 ±2 LSB max 2 EVAL-AD7686CB 1, 2 EVAL-AD7686CBZ EVAL-CONTROL BRD2 3 3 EVAL-CONTROL BRD3 RoHS Compliant Part, # denotes RoHS Compliant product may be top or bottom marked. 2 This board can be used as a standalone evaluation board or in conjunction with the EVAL-CONTROL BRDx for evaluation/demonstration purposes. ...

Page 27

NOTES Rev Page AD7686 ...

Page 28

AD7686 NOTES ©2005–2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D02969-0-3/07(B) Rev Page ...

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