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AD7818AR-REEL

DIGITAL TEMP SENSOR-SERIAL

器件类别：传感器   

厂商名称：ADI(亚德诺半导体)

厂商官网：https://www.analog.com

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4-Channel/Single-Channel, 9 μs,
10-Bit ADCs with On-Chip Temperature Sensor
Data Sheet
FEATURES
10-bit ADC with 9 μs conversion time
1
AD7818
and 4
AD7817
single-ended analog input channels
On-chip temperature sensor
Resolution of 0.25°C
±2°C error from −40°C to +85°C
−55°C to +125°C operating range
Wide operating supply range: 2.7 V to 5.5 V
Inherent track-and-hold functionality
On-chip reference (2.5 V ± 1%)
Overtemperature indicator
Automatic power-down at the end of a conversion
Low power operation
4 μW at a throughput rate of 10 SPS
40 μW at a throughput rate of 1 kSPS
400 μW at a throughput rate of 10 kSPS
Flexible serial interface
REF
IN
AD7817/AD7818
FUNCTIONAL BLOCK DIAGRAMS
V
DD
AD7817
TEMP
SENSOR
V
IN1
V
IN2
V
IN3
V
IN4
MUX
REF
2.5V
OVERTEMP
REG
CHARGE
REDISTRIBUTION
DAC
CONTROL
LOGIC
B
A>B
A
DATA
OUT
OTI
D
OUT
SAMPLING
CAPACITOR
V
BALANCE
REG
CONTROL
D
IN
SCLK
RD/WR
01316-001
CLOCK
CS
AGND
DGND
BUSY
CONVST
Figure 1.
AD7817
Functional Block Diagram
V
DD
AD7818
TEMP
SENSOR
REF
2.5V
OVERTEMP
REG
CHARGE
REDISTRIBUTION
DAC
CONTROL
LOGIC
B
A>B
A
DATA
OUT
OTI
APPLICATIONS
Data acquisition systems with ambient temperature
monitoring
Industrial process control
Automotive
Battery charging applications
V
IN1
MUX
D
IN/OUT
SAMPLING
CAPACITOR
V
BALANCE
CONTROL
REG
CLOCK
GENERATOR
CONVST
SCLK
RD/WR
01316-002
AGND
Figure 2.
AD7818
Functional Block Diagram
GENERAL DESCRIPTION
The
AD7817/AD7818
are 10-bit, single- and 4-channel analog-to-
digital converters (ADCs) with an on-chip temperature sensor that
can operate from a single 2.7 V to 5.5 V power supply. Each
device contains a 9 μs successive approximation converter based
around a capacitor digital-to-analog converter (DAC), an on-
chip temperature sensor with an accuracy of ±2°C, an on-chip
clock oscillator, inherent track-and-hold functionality, and an
on-chip reference (2.5 V).
The on-chip temperature sensor of the
AD7817/AD7818
can
be accessed via Channel 0. When Channel 0 is selected and a
conversion is initiated, the resulting ADC code at the end of the
conversion gives a measurement of the ambient temperature with a
resolution of ±0.25°C. See the Temperature Measurement section.
The
AD7817/AD7818
have a flexible serial interface that allows
easy interfacing to most microcontrollers. The interface is
compatible with the Intel 8051, Motorola SPI and QSPI, and
National Semiconductors MICROWIRE protocols. For more
information, refer to the AD7817 Serial Interface section and
the AD7818 Serial Interface Mode section.
The
AD7817
is available in a narrow body, 0.15 inch, 16-lead
SOIC and a 16-lead TSSOP, and the
AD7818
comes in an 8-lead
SOIC and an 8-lead MSOP.
PRODUCT HIGHLIGHTS
1. The devices have an on-chip temperature sensor that allows
an accurate measurement of the ambient temperature to be
made. The measurable temperature range is −55°C to +125°C.
2. An overtemperature indicator is implemented by carrying out a
digital comparison of the ADC code for Channel 0 (temperature
sensor) with the contents of the on-chip overtemperature
register. The overtemperature indicator pin goes logic low
when a predetermined temperature is exceeded.
3. The automatic power-down feature enables the
AD7817
and
AD7818
to achieve superior power performance at slower
throughput rates, that is, 40 μW at 1 kSPS throughput rate.
Rev. E
Document Feedback
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 ©2012–2015 Analog Devices, Inc. All rights reserved.
Technical Support
www.analog.com
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.
AD7817/AD7818
TABLE OF CONTENTS
Features .............................................................................................. 1
 
Applications ....................................................................................... 1
 
Functional Block Diagrams ............................................................. 1
 
General Description ......................................................................... 1
 
Product Highlights ........................................................................... 1
 
Revision History ............................................................................... 2
 
Specifications..................................................................................... 3
 
Timing Characteristics ................................................................ 6
 
Absolute Maximum Ratings............................................................ 7
 
ESD Caution .................................................................................. 7
 
Pin Configurations and Function Descriptions ........................... 8
 
Terminology .................................................................................... 10
 
Control Byte .................................................................................... 11
 
Circuit Information .................................................................... 12
 
Data Sheet
Converter Details ....................................................................... 12
 
Typical Connection Diagram ................................................... 12
 
Analog Inputs ............................................................................. 12
 
On-Chip Reference .................................................................... 13
 
ADC Transfer Function ............................................................. 13
 
Temperature Measurement ....................................................... 14
 
Temperature Measurement Error Due to Reference Error... 14
 
Self-Heating Considerations ..................................................... 14
 
Operating Modes ........................................................................ 15
 
Power vs. Throughput................................................................ 17
 
AD7817 Serial Interface ............................................................. 17
 
AD7818 Serial Interface Mode ................................................. 18
 
Outline Dimensions ....................................................................... 19
 
Ordering Guide .......................................................................... 20
 
REVISION HISTORY
11/15—Rev. D to Rev. E
Changes to Title, Figure 1, and Figure 2 ........................................ 1
Change to Temperature Sensor (AD7818 Only) Parameter,
Table 1 ................................................................................................ 4
Change to Power Requirements (AD7818 Only) Parameter,
Table 1 ................................................................................................ 5
10/12—Rev. C to Rev. D
Deleted AD7816.................................................................. Universal
Changes to Format ............................................................. Universal
Deleted Figure 15; Renumbered Sequentially ............................ 14
Updated Outline Dimensions ....................................................... 19
Changes to Ordering Guide .......................................................... 20
9/04—Rev. B to Rev. C
Changes to Ordering Guide .............................................................6
Changes to Operating Modes Section and Figure 16 ................ 13
Changes to Figure 17...................................................................... 14
Changes to AD7817 Serial Interface, Read Operation Section
and Figure 20................................................................................... 15
Changes to Figure 21...................................................................... 16
Rev. E | Page 2 of 20
Data Sheet
SPECIFICATIONS
AD7817/AD7818
V
DD
= 2.7 V to 5.5 V, GND = 0 V, REF
IN
= 2.5 V, unless otherwise noted. The
AD7817
temperature sensor is specified with an external
2.5 V reference, and the
AD7818
temperature sensor is specified with an on-chip reference. For V
DD
= 2.7 V, T
A
= 85°C maximum and
temperature sensor measurement error = ±3°C.
Table 1.
Parameter
DYNAMIC PERFORMANCE (AD7817 ONLY)
Signal-to-(Noise + Distortion) Ratio
2
Total Harmonic Distortion
2
Peak Harmonic or Spurious Noise
2
Intermodulation Distortion
2
Second-Order Terms
Third-Order Terms
Channel-to-Channel Isolation
2
DC ACCURACY (AD7817 ONLY)
Resolution
Minimum Resolution for Which No
Missing Codes are Guaranteed
Relative Accuracy
2
Differential Nonlinearity
2
Gain Error
2
Gain Error Match
2
Offset Error
2
Offset Error Match
TEMPERATURE SENSOR (AD7817 ONLY)
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Temperature Resolution
REFERENCE INPUT (AD7817 ONLY)
3, 4
REF
IN
Input Voltage Range
3
Input Impedance
Input Capacitance
ON-CHIP REFERENCE (AD7817 ONLY)
5
Temperature Coefficient
3
CONVERSION RATE (AD7817 ONLY)
Track-and-Hold Acquisition Time
4
Conversion Time
Temperature Sensor
Channel 1 to Channel 4
A Version
1
B Version
1
S Version
1
Unit
Test Conditions/Comments
Sample rate = 100 kSPS, any channel,
f
IN
= 20 kHz
−75 dB typical
−75 dB typical
fa =19.9 kHz, fb = 20.1 kHz
58
–65
–65
–67
–67
–80
10
10
±1
±1
±2
±10
±1/2
±2
±1/2
58
−65
−65
−67
−67
−80
10
10
±1
±1
±2
±10
±1/2
±2
±1/2
58
−65
−65
−67
−67
−80
10
10
±1
±1
±2
+20/−10
±1/2
±2
±1/2
dB min
dB max
dB max
dB typ
dB typ
dB typ
Bits
f
IN
= 20 kHz
Any channel
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
LSB max
External reference
Internal reference
External reference V
REF
= 2.5 V
±2
±3
±2.25
±3
1/4
2.625
2.375
40
10
80
400
27
9
±1
±2
±2.25
±3
1/4
2.625
2.375
40
10
80
400
27
9
±2
±3
±2.25
±6
1/4
2.625
2.375
40
10
150
400
27
9
°C max
°C max
On-chip reference
°C max
°C max
°C/LSB
V max
V min
kΩ min
pF max
ppm/°C typ
ns max
μs max
μs max
Source Impedance < 10 Ω
2.5 V + 5%
2.5 V − 5%
Nominal 2.5 V
Rev. E | Page 3 of 20
AD7817/AD7818
Parameter
POWER REQUIREMENTS (AD7817 ONLY)
V
DD
I
DD
Normal Operation
Using External Reference
Power-Down (V
DD
= 5 V)
Power-Down (V
DD
= 3 V)
Auto Power-Down Mode
10 SPS Throughput Rate
1 kSPS Throughput Rate
10 kSPS Throughput Rate
Power-Down
DYNAMIC PERFORMANCE (AD7818 ONLY)
6
Signal-to-(Noise + Distortion) Ratio
2
Total Harmonic Distortion
2
Peak Harmonic or Spurious Noise
2
Intermodulation Distortion
2
Second-Order Terms
Third-Order Terms
Channel-to-Channel Isolation
2
DC ACCURACY (AD7818 ONLY)
6
Resolution
Minimum Resolution for Which No
Missing Codes are Guaranteed
Relative Accuracy
2
Differential Nonlinearity
2
Gain Error
2
Offset Error
2
TEMPERATURE SENSOR (AD7818 ONLY)
6
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Measurement Error
Ambient Temperature 25°C
T
MIN
to T
MAX
Temperature Resolution
ON-CHIP REFERENCE (AD7818 ONLY)
5
Temperature Coefficient
3
CONVERSION RATE (AD7818 ONLY)
6
Track-and-Hold Acquisition Time
4
Conversion Time
Temperature Sensor
Channel 1
A Version
1
5.5
2.7
2
1.75
10
4
6.4
48.8
434
12
B Version
1
5.5
2.7
2
1.75
10
4
6.4
48.8
434
12
S Version
1
5.5
2.7
2
1.75
12.5
4.5
6.4
48.8
434
13.5
Unit
V max
V min
mA max
mA max
μA max
μA max
μW typ
μW typ
μW typ
μW max
Data Sheet
Test Conditions/Comments
For specified performance
Logic inputs = 0 V or V
DD
1.6 mA typical
2.5 V external reference connected
5.5 μA typical
2 μA typical
V
DD
= 3 V
See the Power vs. Throughput
section for description of power
dissipation in auto power-down mode
Typically 6 μW
Sample rate = 100 kSPS, any channel,
f
IN
= 20 kHz
−75 dB typical
−75 dB typical
fa = 19.9 kHz, fb = 20.1 kHz
57
–65
–67
–67
–67
–80
10
10
±1
±1
±10
±4
dB min
dB max
dB typ
dB typ
dB typ
dB typ
Bits
Bits
LSB max
LSB max
LSB max
LSB max
f
IN
= 20 kHz
Any channel
Internal reference V
REF
= 2.5 V
±2
±3
±2
±3
1/4
30
400
27
9
°C max
°C max
On-chip reference
°C max
°C max
°C/LSB
Nominal 2.5 V
ppm/°C typ
ns max
μs max
μs max
Source impedance < 10 Ω
Rev. E | Page 4 of 20
Data Sheet
Parameter
POWER REQUIREMENTS (AD7818 ONLY)
6
V
DD
I
DD
Normal Operation
Using External Reference
Power-Down (V
DD
= 5 V)
Power-Down (V
DD
= 3 V)
Auto Power-Down Mode
10 SPS Throughput Rate
1 kSPS Throughput Rate
10 kSPS Throughput Rate
Power-Down
ANALOG INPUTS (AD7817/AD7818)
7
Input Voltage Range
Input Leakage
Input Capacitance
LOGIC INPUTS (AD7817/AD7818)
4
Input High Voltage, V
INH
Input Low Voltage, V
INL
Input High Voltage, V
INH
Input Low Voltage, V
INL
Input Current, I
IN
Input Capacitance, C
IN
LOGIC OUTPUTS (AD7817/AD7818)
4
Output High Voltage, V
OH
A Version
1
5.5
2.7
2
1.75
10.75
4.5
6.4
48.8
434
13.5
V
REF
0
±1
10
2.4
0.8
2
0.4
±3
10
V
REF
0
±1
10
2.4
0.8
2
0.4
±3
10
V
REF
0
±1
10
2.4
0.8
2
0.4
±3
10
B Version
1
S Version
1
Unit
V max
V min
mA max
mA max
μA max
μA max
μW typ
μW typ
μW typ
μW max
V max
V min
μA min
pF max
V min
V max
V min
V max
μA max
pF max
AD7817/AD7818
Test Conditions/Comments
For specified performance
Logic inputs = 0 V or V
DD
1.3 mA typical
2.5 V internal reference connected
6 μA typ
2 μA typ
V
DD
= 3 V
See the Power vs. Throughput section
for description of power dissipation
in auto power-down mode
Typically 6 μW
V
DD
= 5 V ±10%
V
DD
= 5 V ±10%
V
DD
= 3 V ±10%
V
DD
= 3 V ±10%
Typically 10 nA, V
IN
= 0 V to V
DD
4
2.4
Output Low Voltage, V
OL
0.4
0.2
±1
15
4
2.4
0.4
0.2
±1
15
4
2.4
0.4
0.2
±1
15
V min
V min
V max
V max
μA max
pF max
I
SOURCE
= 200 μA
V
DD
= 5 V ± 10%
V
DD
= 3 V ± 10%
I
SINK
= 200 μA
V
DD
= 5 V ± 10%
V
DD
= 3 V ± 10%
High Impedance Leakage Current
High Impedance Capacitance
1
2
The B Version and the S Version only apply to the
AD7817.
The A Version applies to the
AD7817
or the
AD7818
(as stated in specification).
See Terminology.
3
The accuracy of the temperature sensor is affected by reference tolerance. The relationship between the two is explained in the Temperature Measurement Error Due
to Reference Error section.
4
Sample tested during initial release and after any redesign or process change that may affect this parameter.
5
On-chip reference shuts down when external reference is applied.
6
These specifications are typical for
AD7818
at temperatures above 85°C and with V
DD
greater than 3.6 V.
7
This refers to the input current when the part is not converting. Primarily due to the reverse leakage current in the ESD protection diodes.
Rev. E | Page 5 of 20
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