INTERSIL ISL26322

12-bit, 250kSPS Low-power ADCs with Single-ended
and Differential Inputs and Multiple Input Channels
ISL26320, ISL26321, ISL26322,
ISL26323, ISL26324, ISL26325,
ISL26329
The ISL26320/21/22/23/24/25/29 family of sampling
SAR-type ADCs feature excellent linearity over supply and
temperature variations, and offer versions with 1-, 2-, 4- and
8-channel single-ended inputs, and 1-, 2- and 4-channel
differential inputs.
A proprietary input multiplexer and combination buffer amplifier
reduces the input drive requirements, resulting in lower cost and
reduced board space. Specified measurement accuracy is
maintained with input signals up to VDD.
Members of the ISL26320/21/22/23/24/25/29 family of
Low-Power ADCs offer pinout intercompatibility, differing only in
the analog inputs, to support quick replication of proven layouts
across multiple design platforms.
The serial digital interface is SPI compatible and is easily
interfaced to popular FPGAs and microcontrollers. Power
consumption is limited to 15mW at a sampling rate of 250kSPS,
and an operating current of just 8μA typical between
conversions, when configured for Auto Powerdown mode.
Features
• Pin-compatible Family Allows Easy Design Upgrades
• Excellent Differential Non-Linearity (0.7LSB max)
• Low THD: -86dB (typ)
• Simple SPI-compatible Serial Digital Interface
• Low 3mA Operating Current
• Power-down Current between Conversions 8μA (typ)
• +5.25V to +2.7V Supply
• Excellent ESD Survivability: 5kV HBM, 350V MM, 2kV CDM
Applications
• Industrial Process Control
• Energy Measurement
• Multichannel Data Acquisition Systems
• Pressure Sensors
• Flow Controllers
The ISL26320/21/22/23/24/25/29 feature up to 5kV Human
Body Model ESD survivability and are available in the popular
SOIC and TSSOP packages. Performance is specified for
operation over the full industrial temperature range (-40°C to
+125°C).
FIGURE 1. FUNCTIONAL BLOCK DIAGRAM
June 8, 2012
FN8273.0
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas Inc. 2012. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Application Block Diagram
Pin-Compatible Family
RESOLUTION
(Bits)
SPEED
(kHz)
ANALOG
INPUT
INPUT
CHANNELS
ISL26310
12
125
Differential
1
ISL26311
12
125
Single-Ended
1
ISL26312
12
125
Differential
2
ISL26313
12
125
Single-Ended
2
ISL26314
12
125
Differential
4
ISL26315
12
125
Single-Ended
4
ISL26319
12
125
Single-Ended
8
ISL26320
12
250
Differential
1
ISL26321
12
250
Single-Ended
1
ISL26322
12
250
Differential
2
ISL26323
12
250
Single-Ended
2
ISL26324
12
250
Differential
4
ISL26325
12
250
Single-Ended
4
ISL26329
12
250
Single-Ended
8
MODEL
2
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Ordering Information
DESCRIPTION
PART NUMBER
(Notes 1, 2, 3)
PART
MARKING
RESOLUTION
(Bits)
SPEED
(kHz)
INPUT
(SE/DIFF)
INPUT
CHANNELS
TEMP. RANGE
(°C)
PACKAGE
(Pb-Free)
PKG
DWG #
ISL26320FBZ
26320 FBZ
12
250
Diff
1
-40 to +125
8 Ld SOIC
M8.15
ISL26321FBZ
26321 FBZ
12
250
SE
1
-40 to +125
8 Ld SOIC
M8.15
ISL26322FVZ
26322 FVZ
12
250
Diff
2
-40 to +125
16 Ld TSSOP
M16.173
ISL26323FBZ
26323 FBZ
12
250
SE
2
-40 to +125
8 Ld SOIC
M8.15
ISL26324FVZ
26324 FVZ
12
250
Diff
4
-40 to +125
16 Ld TSSOP
M16.173
ISL26325FVZ
26325 FVZ
12
250
SE
4
-40 to +125
16 Ld TSSOP
M16.173
ISL26329FVZ
26329 FVZ
12
250
SE
8
-40 to +125
16 Ld TSSOP
M16.173
NOTES:
1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil
Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325,
ISL26329. For more information on MSL please see techbrief TB363.
3
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Pin Configurations
ISL26320
(8 LD SOIC)
TOP VIEW
ISL26321
(8 LD SOIC)
TOP VIEW
ISL26323
(8 LD SOIC)
TOP VIEW
ISL26322
(16 LD TSSOP)
TOP VIEW
ISL26324
(16 LD TSSOP)
TOP VIEW
ISL26325
(16 LD TSSOP)
TOP VIEW
ISL26329
(16 LD TSSOP)
TOP VIEW
4
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Pin Descriptions
PIN NUMBER
PIN NAME ISL26320 ISL26321
ISL26322
ISL26323 ISL26324 ISL26325 ISL26329
DESCRIPTION
VDD
1
1
1
1
1
1
1
GND
2
2
2, 4
2
2, 4
2, 4
2, 4
VREF
-
3
3
-
3
3
3
Reference Voltage Input
AIN0+
-
-
5
-
5
-
-
Differential Analog Input, Positive
AIN0-
-
-
6
-
6
-
-
Differential Analog Input, Negative
AIN1+
-
-
7
-
7
-
-
Differential Analog Input, Positive
AIN1-
-
-
8
-
8
-
-
Differential Analog Input, Negative
AIN2+
-
-
-
-
10
-
-
Differential Analog Input, Positive
AIN2-
-
-
-
-
9
-
-
Differential Analog Input, Negative
AIN3+
-
-
-
-
12
-
-
Differential Analog Input, Positive
AIN3-
-
-
-
-
11
-
-
Differential Analog Input, Negative
AIN0
-
4
-
3
-
5
5
Single-Ended Analog Input
AIN1
-
-
-
4
-
7
6
Single-Ended Analog Input
AIN2
-
-
-
-
-
10
7
Single-Ended Analog Input
AIN3
-
-
-
-
-
12
8
Single-Ended Analog Input
AIN4
-
-
-
-
-
-
9
Single-Ended Analog Input
AIN5
-
-
-
-
-
-
10
Single-Ended Analog Input
AIN6
-
-
-
-
-
-
11
Single-Ended Analog Input
AIN7
-
-
-
-
-
-
12
Single-Ended Analog Input
SDI
5
5
13
5
13
13
13
Serial Interface Data Input
SDO
6
6
14
6
14
14
14
Serial Interface Data Output
SCLK
7
7
15
7
15
15
15
Serial Interface Clock Input
CNV
8
8
16
8
16
16
16
Conversion Control Input
NC
-
-
9, 10, 11, 12
-
-
6, 8, 9, 11
-
No Connect
AIN+
3
-
-
-
-
-
-
Differential Analog Input, Positive
AIN-
4
-
-
-
-
-
-
Differential Analog Input, Negative
5
Positive Supply Voltage
Ground
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Absolute Maximum Ratings
Thermal Information
AIN+, AIN-, VREF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND-0.3 to VDD+0.3V
Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND-0.3 to VDD+0.3V
VDD. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 6V
GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GND-0.3 to +0.3V
ESD Rating
Human Body Model (Per MIL-STD-883 Method 3015.7) . . . . . . . . . . . 5000V
Machine Model (Per JESD22-A115). . . . . . . . . . . . . . . . . . . . . . . . . . 350V
Charged Device Model (Per JESD22-C101) . . . . . . . . . . . . . . . . . . . . . . 2000V
Latch-up (Tested per JESD-78B; Class 2, Level A) . . . . . . . . . . . . . . . . . . . . . . 100mA
Thermal Resistance (Typical)
θJA (°C/W) θJC (°C/W)
8 Ld SOIC (Notes 4, 5) . . . . . . . . . . . . . . . . .
98
48
16 Ld TSSOP (Notes 4, 5) . . . . . . . . . . . . . .
92
29
Maximum Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80mW
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . . . . . -65°C to +150°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +125°C
VDD to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.7V to +5.25V
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4. θJA is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
5. For θJC, the “case temp” location is taken at the package top center.
Electrical Specifications VREF = VDD V, VDD = 2.7V to 5V, VCM = VDD/2, SCLK = 20MHz and TA = -40°C to +125°C (typical performance
at +25°C), unless otherwise specified. Boldface limits apply over the operating temperature range, -40°C to +125°C.
SYMBOL
PARAMETER
TEST LEVEL OR NOTES
MIN
(Note 6)
TYP
MAX
(Note 6)
UNITS
VREF
V
ANALOG INPUTS
Number of Input Channels
Input Voltage Range
ISL26320, ISL26321
1
ISL26322
2
ISL26323
2
ISL26324, ISL26325
4
ISL26329
8
Differential Inputs (AINX+ - AINX-) is
-VREF (Min) and +VREF (Max)
AINX, Single-Ended Inputs
Common Mode Input Voltage Range
Differential Inputs
0
0
VREF/2 – 0.2
Average Input Current
CIN
Input Capacitance
Channel-Channel Crosstalk
fIN = 100kHz
VIN = FS, other channels = 0V
VREF/2
VREF
V
VREF/2 + 0.2
V
2.5
μA
4
pF
-86
dB
VOLTAGE REFERENCE
VREFEX
External Reference Input Voltage Range
IREFIN
CREFIN
2
2.5
VDD
V
Average Input Current
200
220
μA
Effective Input Capacitance
10
pF
DC ACCURACY
Resolution (No Missing Codes)
12
DNL
Differential Nonlinearity Error
-0.7
+0.7
LSB
INL
Integral Nonlinearity Error
-0.7
+0.7
LSB
-6
6
LSB
Gain Error
Bits
Gain Error Matching
-2
2
LSB
Offset Error
-6
6
LSB
6
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Electrical Specifications VREF = VDD V, VDD = 2.7V to 5V, VCM = VDD/2, SCLK = 20MHz and TA = -40°C to +125°C (typical performance
at +25°C), unless otherwise specified. Boldface limits apply over the operating temperature range, -40°C to +125°C. (Continued)
SYMBOL
PARAMETER
TEST LEVEL OR NOTES
Offset Error Matching
PSRR
MIN
(Note 6)
TYP
-2
Power Supply Rejection Ratio
MAX
(Note 6)
UNITS
2
LSB
70
dB
DYNAMIC PERFORMANCE
SNR
Signal-to-Noise
Notes: VIN = FS-0.1dB, fIN = 10kHz
Differential Inputs
73.4
dB
Single-Ended Inputs
73.4
dB
SINAD
Signal-to-Noise + Distortion
Notes: VIN = FS-0.1dB, fIN = 10kHz
Differential Inputs
73.1
dB
Single-Ended Inputs
73.1
dB
THD
Total Harmonic Distortion
Notes: VIN = FS-0.1dB, fIN = 10kHz
Differential Inputs
-86
dB
Single-Ended Inputs
-86
dB
SFDR
Spurious-free Dynamic Range
Notes: VIN = FS-0.1dB
fIN = 20kHz
96
dB
BW
-3dB Input Bandwidth
2.5
MHz
tAD
Sampling Aperture Delay
12
ns
tjit
Sampling Aperture Jitter
25
ps
POWER SUPPLY REQUIREMENTS
VDD
Supply Voltage
IDD
Supply Current
PD
Power Consumption
IPD
Istby
2.7
5.25
V
3
3.5
mA
Normal Operation
15
17.5
mW
Power-down Current
Auto Power-Down Mode
8
50
μA
Standby Mode Current
Auto Sleep Mode
0.4
mA
DIGITAL INPUTS
VIH
0.7 VDD
V
VIL
0.2 VDD
VOH
IOH = -1mA
VOL
IOL = 1mA
IIH, IIL
VDD-0.4
Input Leakage Current
V
V
-100
Serial Clock Frequency
0.2 VDD
V
100
nA
20
MHz
TIMING SPECIFICATIONS (Note 7)
tSCLK
SCLK Period (in RAC Mode)
50
tSCLK
SCLK Period (in RSC, RDC Modes)
50
tDATA
Safe Data Transfer Time After Conversion
State Begins
tCSB_SCLK CSB Falling Low to SCLK Rising Edge
ns
100
ns
1.6
μs
40
ns
tSDI_SU
SDI Setup Time with Respect to Positive
Edge of SCLK
10
ns
tSDI_H
SDI Hold Time with Respect to Positive
Edge of SCLK
10
ns
tSDO_V
SDOUT Valid Time with Respect to
Negative Edge of SCLK
tSDOZ_D
SDOUT to High Impedance State After CNV Note 8
Rising Edge (or last SCLK falling edge)
tACQ
Acquisition Time when Fully Powered Up
7
25
85
400
ns
ns
ns
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Electrical Specifications VREF = VDD V, VDD = 2.7V to 5V, VCM = VDD/2, SCLK = 20MHz and TA = -40°C to +125°C (typical performance
at +25°C), unless otherwise specified. Boldface limits apply over the operating temperature range, -40°C to +125°C. (Continued)
SYMBOL
PARAMETER
TEST LEVEL OR NOTES
MIN
(Note 6)
TYP
MAX
(Note 6)
UNITS
tACQ
Acquisition Time in Auto Sleep Mode
1.7
μs
tACQ
Acquisition time in Auto Power Down
Mode
150
μs
tSCLKH
SCLK High Time
20
ns
tSCLKL
SCLK Low Time
20
ns
tCNV
CNV Pulse Width
100
ns
NOTES:
6. Compliance to datasheet limits is assured by one or more methods: production test, characterization and/or design.
7. The device may become nonresponsive if the minimum acquisition times are not met in their respective modes, requiring a power cycle to restore
normal operation.
8. Transition time to high impedance state is dominated by RC loading on the SDOUT pin. Specified value is measured using equivalent loading shown
in Figure 2.
FIGURE 2. EQUIVALENT LOAD CIRCUIT FOR DIGITAL OUTPUT TESTING
8
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Typical Performance Characteristics
TA = +25°C, VDD = 5V, VREF = 5V, fSAMPLE = 250kHz, fSCLK = 20MHz,
1.00
1.00
0.75
0.75
0.50
0.50
0.25
0.25
INL (LSBs)
DNL (LSBs)
unless otherwise specified.
0
-0.25
0
-0.25
-0.50
-0.50
-0.75
-0.75
-1.00
-2000
-1000
0
1000
2000
-1.00
-2000
-1000
0
FIGURE 3. DIFFERENTIAL NONLINEARITY (DNL) vs CODE
1.0
0.8
POSITIVE DNL
0.6
0.6
0.4
0.4
0.2
0.2
INL
DNL
0.8
0.0
-0.2
-0.4
-0.4
-0.6
POSITIVE INL
0.0
-0.2
-0.6
NEGATIVE DNL
-0.8
-20
0
20
40
60
80
100
NEGATIVE INL
-0.8
-1.0
-40
120
-20
0
20
TEMPERATURE (°C)
80
100
120
0.0
2.7V
-0.1
1.5
-0.2
1.0
OFFSET ERROR (LSB)
GAIN ERROR (LSB)
60
FIGURE 6. INL DISTRIBUTION vs TEMPERATURE
2.0
0.5
2.7V
3.3V
-0.5
-1.0
-20
0
20
5.25V
40
-0.4
3.3V
5.0V
5.25V
-0.5
-0.6
-0.7
60
-0.9
80
100
120
TEMPERATURE (°C)
FIGURE 7. GAIN ERROR vs SUPPLY VOLTAGE AND TEMPERATURE
9
-0.3
-0.8
5.0V
-1.5
-2.0
-40
40
TEMPERATURE (°C)
FIGURE 5. DNL DISTRIBUTION vs TEMPERATURE
0.0
2000
FIGURE 4. INTEGRAL NONLINEARITY (INL) vs CODE
1.0
-1.0
-40
1000
CODE
CODE
-1.0
-40
-20
0
20
40
60
80
100
120
TEMPERATURE (°C)
FIGURE 8. OFFSET ERROR vs SUPPLY VOLTAGE AND TEMPERATURE
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Typical Performance Characteristics
unless otherwise specified. (Continued)
4.0
3.5
20
SUPPLY CURRENT (mA)
APERTURE DELAY (ns)
25
TA = +25°C, VDD = 5V, VREF = 5V, fSAMPLE = 250kHz, fSCLK = 20MHz,
15
10
5
3.0
5.25V
5.0V
2.5
2.0
1.5
1.0
3.3V
2.7V
0.5
0
2.7
3.2
3.7
4.2
4.7
0.0
-40
5.2
-20
0
SUPPLY VOLTAGE
FIGURE 9. APERTURE DELAY vs SUPPLY VOLTAGE
20
40
60
TEMPERATURE (°C)
80
100
120
FIGURE 10. SUPPLY CURRENT vs VOLTAGE AND TEMPERATURE
2.5
50
45
SHUTDOWN CURRENT (μA)
SUPPLY CURRENT (mA)
2.0
1.5
NORMAL MODE
AUTO POWER DOWN MODE
1.0
AUTO SLEEP MODE
0.5
40
35
5.25V
30
25
5.0V
20
15
3.3V
10
5
0.0
100
1k
10k
SAMPLE RATE (Sps)
0
-40
100k
FIGURE 11. SUPPLY CURRENT vs SAMPLING RATE (VDD = 5V)
-20
0
20
40
60
TEMPERATURE (°C)
80
100
120
FIGURE 12. SHUTDOWN CURRENTS vs VOLTAGE AND TEMPERATURE
-80
75
5.25V
5.0V
74
-82
73
-84
THD (dB)
SNR/SINAD (dB)
2.7V
72
5.25V
5.0V
-86
3.3V
2.7V
-88
71
70
-40
2.7V
-20
0
20
40
60
TEMPERATURE (°C)
80
100
120
FIGURE 13. SNR AND SINAD vs SUPPLY VOLTAGE AND TEMPERATURE
10
-90
-40
-20
0
20
40
60
TEMPERATURE (°C)
80
3.3V
100
120
FIGURE 14. THD vs SUPPLY VOLTAGE AND TEMPERATURE
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Typical Performance Characteristics
TA = +25°C, VDD = 5V, VREF = 5V, fSAMPLE = 250kHz, fSCLK = 20MHz,
unless otherwise specified. (Continued)
0
75
-10
SNR
-20
-30
SINAD
THD (dB)
SNR/SINAD (dB)
70
65
-40
-50
-60
-70
60
-80
-90
55
100
1k
10k
100k
INPUT FREQUENCY (Hz)
-100
100
1M
1k
FIGURE 15. SNR AND SINAD vs INPUT FREQUENCY
1M
FIGURE 16. THD vs INPUT FREQUENCY
70,000
0
SNR = 73.6dB
THD = -87.6dB
SINAD = 73.4dB
SFDR = 89.1dB
ENOB = 11.4
-20
-40
60,000
65,536
CODES
50,000
-60
HITS
AMPLITUDE (dB)
10k
100k
INPUT FREQUENCY (Hz)
-80
40,000
30,000
-100
20,000
-120
10,000
-140
-160
0
25000
50000
75000
FREQUENCY (Hz)
FIGURE 17. SINGLE-TONE FFT
11
100000
125000
0
0
CODES
-3
-2
-1
0
CODES
0
1
2
3
CODE
FIGURE 18. SHORTED INPUT HISTOGRAM
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Circuit Description
The ISL26320/21/22/23/24/25/29 family of 12-bit ADCs are
low-power Successive Approximation-type (SAR) ADCs with 1-,
2-, 4-, or 8-channels and a choice of single-ended or differential
inputs. The high-impedance buffered input simplifies interfacing
to sensors and external circuitry.
The entire ISL26320/21/22/23/24/25/29 family follows the
same base pinout and differs only in the analog input pins,
allowing the user to replicate the basic board layout across
multiple platforms with a minimum redesign effort.
The simple serial digital interface is compatible with popular
FPGAs and microcontrollers and allows direct conversion control
by the CNV pin.
Functional Description
The ISL26320/21/22/23/24/25/29 devices are SAR
(Successive Approximation Register) analog-to-digital converters
that use capacitor-based charge redistribution as their
conversion method.
These devices include an on-chip power-on reset (POR) circuit to
initialize the internal digital logic when power is applied. An
on-chip oscillator provides the master clock for the conversion
logic. The CNV signal controls when the converter enters into its
signal acquisition time (CNV = 0), and when it begins the
conversion sequence after the signal has been captured
(CNV = 1). The converters include a configuration register that
can be accessed via the serial port. The configuration register
has various bits to indicate which channel (where applicable) is
selected, to activate the auto-power-down feature where the ADC
is shut down between conversions, or to output the configuration
register contents along with the data conversion word whenever
a conversion word is read from the serial port. The serial port
supports three different modes of reading the conversion data.
These will be discussed later in this data sheet.
FIGURE 19. ARCHITECTURAL BLOCK DIAGRAM, DIFFERENTIAL INPUT
12
Figures 19 and 20 illustrate simplified representations of the
converter analog section for differential and single-ended inputs,
respectively. During the acquisition phase (CNV = 0) the input
signal is presented to the Cs samples capacitors. To properly
sample the signal, the CNV signal must remain low for the
specified time. When CNV is taken high (CNV = 1), the switches
that connect the sampling capacitors to the input are opened
and the control logic begins the successive approximation
sequence to convert the captured signal into a digital word. The
conversion sequence timing is determined by the on-chip
oscillator.
ADC Transfer Function
The ISL26320, the ISL26322, and the ISL26324 feature
differential inputs with output data coding in two's complement
format (see Table 1). The size of one LSB in these devices is
(2*VREF)/4096. Figure 21 illustrates the ideal transfer function
for these devices.
The ISL26321, ISL26323, ISL26325, and ISL26329 feature
single-ended inputs with output coding in binary format (see
Table 2). The size of one LSB in these devices is VREF/4096.
Figure 22 illustrates the ideal transfer function for these devices.
FIGURE 20. ARCHITECTURAL BLOCK DIAGRAM, SINGLE-ENDED
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
FIGURE 21. IDEAL TRANSFER CHARACTERISTICS, DIFFERENTIAL INPUT
FIGURE 22. IDEAL TRANSFER CHARACTERISTICS, SINGLE-ENDED INPUT
Analog Inputs
Some members of the ISL26320/21/22/23/24/25/29 family
feature a fully differential input with a nominal full-scale range
equal to twice the applied VREF voltage. Those devices with
differential inputs have a nominal full scale range equal to twice
the applied VREF voltage. Each input swings VREF volts (peak-topeak), 180° out of phase from one another for a total differential
input of 2*VREF (refer to Figures 23 and 24).
FIGURE 23. DIFFERENTIAL INPUT SIGNALING
Differential signaling offers several benefits over a single-ended
input, such as:
• Doubling of the full-scale input range (and therefore the
dynamic range)
• Improved even order harmonic distortion
• Better noise immunity due to common mode rejection
Figure 24 shows the relationship between the reference voltage
and the full-scale differential input range for two different values
of VREF. Note that the common-mode input voltage must be
maintained within ±200mV of VREF/2 for differential inputs.
FIGURE 24. RELATIONSHIP BETWEEN VREF AND FULL-SCALE
RANGE FOR DIFFERENTIAL INPUTS
Those devices with singled-ended inputs have a groundreferenced peak-to-peak input voltage span equal to the
reference voltage.
13
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Voltage Reference Input
An external reference voltage must be supplied to the VREF pin
to set the full-scale input range of the converter. The VREF input
on these devices can accept voltages ranging from 2V (nominal)
to VDD, however, they are specified with VREF at a voltage of 5V
with VDD at 5V. Note that exceeding VDD by more than 100mV
can forward bias the ESD protection diodes and degrade
measurement accuracy due to leakage current. A lower value
voltage reference must be used if the device is operated with
VDD at voltages lower than 5V. If the VREF pin is tied to the VDD
pin, the VREF pin should be decoupled with a local 1μF ceramic
capacitor as described in a later paragraph.
Figures 27 and 28 illustrate possible voltage reference options
for these ADCs. Figure 27 uses the precision ISL21090 voltage
reference, which exhibits exceptionally low drift and low noise.
The ISL21090 must be powered from a supply greater than 4.7V.
Figure 28 illustrates the ISL21010 voltage reference used with
these ADCs. The ISL21010 series voltage references have higher
noise and drift than the ISL21090 devices, but operate at lower
supply voltages. Therefore, these devices can readily be used
when these SAR ADCs operate with VDD at voltages less than 5V.
FIGURE 25. RELATIONSHIP BETWEEN VREF AND FULL-SCALE
RANGE FOR SINGLE-ENDED INPUTS
Input Multiplexer
The input of the multiplexer connects the selected analog input
pins to the ADC input. A proprietary sampling circuit significantly
reduces the input drive requirements, resulting in lower overall
cost and board space in addition to improved performance. Note
that the input capacitance is only 2-3pF during the Sampling
phase, changing to 40pF during the Settling phase, resulting in
an average input current of 2.5μA and an effective input
capacitance of only 4pF. See Figure 26.
AC
ERROR
INPUT VOLTAGE
TOTAL
DC
ERROR ERROR
SETTLING ERROR AND NOISE
OFFSET ERROR
The outputs of ISL21090 or the ISL21010 devices should be
decoupled with a 1μF ceramic capacitor. A 1μF, 6.3 V, X7R, 0603
(1608 metric) MLCC type capacitor is recommended for its high
frequency performance. The trace length from the VREF pin to
this capacitor and the voltage reference output should be as
short as possible.
The ISL26320 and ISL26323 devices (packaged in 8 pin SOIC
packages) derive their voltage reference from the VDD pin. To
achieve best performance, the VDD pin of these devices should
be bypassed with the 1μF ceramic capacitor mentioned above.
Power-Down/Standby Modes
In order to reduce power consumption between conversions, a
number of user-selectable modes can be utilized by setting the
appropriate bits in the Configuration Register.
Auto Power-down (PD0 = 0) reduces power consumption by
shutting down all portions of the device except the oscillator and
digital interface after completion of a conversion. There is a short
recovery period after CNV is asserted Low (150μs with external
reference).
In Auto Sleep mode (PD1 = 1), the device will automatically enter
the low-power Sleep mode at the end of the current conversion.
Recovery from this mode involves only 2.1μs and may offer an
alternative to Power-down mode in some applications.
Sampling Phase
Output Data Format
Settling Phase
FIGURE 26. INPUT SAMPLING OPERATION
The converter output word is delivered in two’s complement
format in differential input mode, and straight binary in
single-ended input mode of operation respectively, all MSB-first.
Input exceeding the specified full-scale voltage results in a clipped
output which will not return to in-range values until after the input
signal has returned to the specified allowable voltage range.
Data must be read prior to the completion of the current
conversion to avoid conflict and loss of data, due to overwriting of
the new conversion data into the output register.
14
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
5V
+
BULK
0.1μF
0.1μF
1 DNC
DNC
8
2 VIN
DNC
7
3 COMP VOUT
6
4 GND
5
TRIM
ISL2631X
ISL2632X
2.5V
VDD
VREF
1μF (see text)
ISL21090
FIGURE 27. PRECISION VOLTAGE REFERENCE FOR +5V SUPPLY
+2.7V TO +3.6V
OR +5V
+
VIN
1
VOUT
2
GND
3
BULK
0.1μF
0.1μF
ISL2631X VDD
ISL2632X
VREF
1.25, 2.048 OR 2.5V
ISL21010
1μF (see text)
FIGURE 28. VOLTAGE REFERENCE FOR +2.7V TO +3.6V, OR FOR +5V SUPPLY
+2.7V TO +5V
BULK
1μF (see text)
ISL26320
ISL26323
VDD
FIGURE 29. VOLTAGE REFERENCE FOR ISL26320/ISL26323 IS DERIVED FROM VDD
TABLE 1. OUTPUT CODES - DIFFERENTIAL
Input Voltage
Two’s Complement (12-bit)
>(VFS-1.5 LSB)
7FF
VFS-1.5 LSB
7FF
...
7FE
000
…
FFF
-0.5 LSB
801
…
800
-VFS +0.5 LSB
NOTE: VFS in the table above equals the voltage between AIN+ and AIN-.
Differential full scale is equal to 2* VREF.
15
TABLE 2. OUTPUT CODES - SINGLE-ENDED
Input Voltage
Binary (12 bit)
>AIN-1.5 LSB
FFF
AIN-1.5 LSB
FFF
…
FFE
0.5 LSB
001
…
000
<0.5 LSB
000
NOTE: Single-ended full scale is equal to VREF.
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Serial Digital Interface
The ISL26320/21/22/23/24/25/29 family utilizes an SPIcompatible interface to set the device configuration and read
conversion data. This flexible interface provides 3 modes of
operation: Reading After Conversion (RAC), Reading During
Conversion (RDC), and Reading Spanning Conversions (RSC),
with an additional option providing an End of Conversion (EOC)
indication on the SDO output in all 3 modes. The choice of
operating mode is determined by the timing of the signals on the
serial interface.
The interface consists of the data clock (SCLK), serial digital
input (SDI), serial digital output (SDO), and the conversion control
input (CNV). From the Idle state (after completion of a prior
conversion), a High-to-Low transition on CNV indicates the
beginning of input signal acquisition, with the Conversion then
initiated by a subsequent Low-to-High transition. When CNV is
Low, input data presented to SDI is latched on the rising edge of
SCLK. Output data will be present at SDO on the falling edge of
SCLK. SDO is in the high-impedance state whenever CNV is High,
and activity on SCLK should be avoided during this time to avoid
corruption of the conversion process. SCLK should be Low when
CNV is High.
During the Nth conversion, output data indicates the conversion
data and configuration settings for the N-1th conversion, while
the current configuration settings apply to the N+1th conversion.
In order to minimize errors due to digital noise coupling, there
should be no activity on the serial interface after the specified
tDATA period. Data should be read before the conversion is
completed to avoid the newer results being overwritten resulting
in a permanent loss of data.
Reading After Conversion Mode Without EOC
In this mode, data transfer always occurs during the Acquisition
phase, supporting the widest variety of interface data rates.
Figure 30 depicts a timing waveform in this mode. From Idle, the
device enters the Acquisition phase when CNV is taken Low. SDO
emerges High from a high-impedance state, waiting for an SCLK
to present the MSB of the current output data word. The
configuration settings can be updated using SDI and at the same
time previous conversion results can be read from SDO. After the
communication is completed or the required acquisition time
(tACQ) has elapsed – whichever is later – CNV transitions High
indicating the start of conversion. CNV must be held High
continuously for a minimum of 3.6μs (at 250kSPS) so that the
conversion is completed without enabling EOC. Subsequently
CNV may be asserted Low at any time so that the next
Acquisition phase can begin. This method is suitable for hosts
which operate with lower frequency SCLK.
Reading During Conversion Mode
Without EOC
From Idle, the user initiates the input signal Acquisition mode by
taking CNV Low, and then initiates a conversion after tACQ by
pulsing CNV High. After the conversion starts, data is exchanged
on the serial interface while CNV is held Low (as shown in
Figure 31). CNV must also be asserted High before tDATA to avoid
enabling EOC. This method is ideal for hosts with high SCLK
communication rates to operate the device at the highest
conversion rates.
At the end of conversion the device enters the Idle state. After the
host is certain that the conversion is completed (3.6μs after
conversion is initiated at 250kSPS) a new acquisition can be
initiated by pulling CNV Low which will initiate the Acquisition state.
Reading Spanning Conversion Mode
Without EOC
In applications desiring slower interface data rates and while still
maintaining maximum possible throughput, RSC mode can be
used to transfer data during both the Acquisition and Conversion
phases, as shown in Figure 32.
Data exchange begins during the Acquisition phase until CNV is
asserted High to initiate a conversion and SDO returns to the
high-impedance state, interrupting the exchange. After CNV is
returned Low, SDO will return to the state prior to the CNV pulse
in order to avoid data loss. Once again data exchange occurs
when CNV is Low. CNV must be asserted High before tDATA in
order to avoid enabling EOC.
At the end of conversion the device enters the Idle state. After
the host is certain that the conversion is completed (3.6μs after
conversion is initiated at 250kSPS) a new acquisition can be
initiated by pulling CNV Low, which will take the device back to
Acquisition state from Idle state.
Note that when using slower SPI rates the data transfer time can
exceed the minimum acquisition time, which will limit the
conversion throughput to less than the maximum specified rate.
For example, a 12-bit data transfer takes 12μs with a 1MHz SPI
clock. This adds to the 3.6μs conversion time for an effective
throughput of 64ksps.
16
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
FIGURE 30. TIMING DIAGRAM FOR READING AFTER CONVERSION MODE, WITHOUT EOC
FIGURE 31. TIMING DIAGRAM FOR READING DURING CONVERSION MODE, WITHOUT EOC
FIGURE 32. TIMING DIAGRAM FOR READING SPANNING CONVERSION MODE, WITHOUT EOC
17
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Reading After Conversion Mode, with EOC
Reading Spanning Conversion Mode, with EOC
In this mode (Figure 33), after CNV is asserted Low to start input
acquisition, a data exchange is executed by SCLK during the
Acquisition period. CNV is asserted High briefly to initiate a
Conversion, forcing SDO to a high-impedance state. SDO returns
HIGH when CNV is asserted Low during the entire conversion period.
After initiating an Acquisition by bringing CNV Low, the user
begins exchanging data as previously mentioned, until CNV is
asserted High to initiate a conversion and SDO returns to a
high-impedance state, interrupting the exchange. And, after CNV
is returned Low, SDO will return to the state prior to the CNV
pulse in order to avoid losing data interrupted by the conversion
pulse. See Figure 35. The user should take care to observe the
tDATA period in order to minimize the effects of digital noise on
sensitive portions of conversion. After completion of the data
exchange, an additional pulse on SCLK forces SDO to a
high-impedance state. At the end of conversion, the device
asserts SDO Low indicating the end of conversion. The device
then returns to Idle, waiting for a pulse on CNV to initiate a new
Acquisition cycle.
At the end of conversion, the device asserts SDO Low to indicate
that the conversion is complete. This may be used as an interrupt
to start the Acquisition phase. It should be noted (as indicated in
Figure 33) that an additional pulse on CNV is required at the end
of conversion to take the part back to Acquisition from Idle state.
As discussed in the “Reading After Conversion Mode Without
EOC” section, the acquisition time (tACQ) may limit the
conversion throughput at slower SPI clock rates.
Reading During Conversion Mode, with EOC
From Idle, a falling edge on CNV initiates the Acquisition mode,
and then a rising edge initiates a Conversion. After the
conversion is initiated, CNV is asserted Low once again. Data
exchange across SDI and SDO can proceed while CNV is Low,
again observing the requirements of the tDATA period in order to
minimize the effects of digital noise on sensitive portions of the
conversion. In this mode, an additional pulse is required on SCLK
after the completion of the data exchange, to transition SDO to
the high-impedance state. Later, SDO is asserted low by the
device indicating end of conversion. The device then returns to
Idle. The falling edge of SDO may be used as an interrupt to start
the Acquisition phase. See Figure 34.
Accessing the Configuration Register During
Data Readback
The Configuration Register contains the channel address of the
current conversion data. The contents can be accessed during a
normal data output sequence by continuing to clock data from
SDO if the register readback mode is enabled. Both 12-bit output
data words and the 16-bit configuration word are output in 28
SCLK periods, as shown in Figure 36, which demonstrates an
example sequence. Note that SDO goes into the high-impedance
state when CNV is High. The Configuration Register can be read
during any Read Sequence by generating the additional SCLKs,
with the restriction that the sequence must be completed prior to
the end of the current conversion. This will prevent loss of data
due to overwriting of the new conversion data into the output and
configuration registers.
FIGURE 33. TIMING DIAGRAM FOR READING AFTER CONVERSION MODE WITH EOC ON SDO OUTPUT
18
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
FIGURE 34. TIMING DIAGRAM FOR READING DURING CONVERSION MODE WITH EOC ON SDO OUTPUT
FIGURE 35. TIMING DIAGRAM FOR READING SPANNING CONVERSIONS MODE WITH EOC ON SDO OUTPUT
FIGURE 36. TIMING DIAGRAM FOR READING AFTER CONVERSION WITH REGISTER READBACK, WITHOUT EOC
19
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Device Configuration Registers
Power Management Modes
The Input Multiplexer Channel Select and power management
features are controlled by loading the appropriate bits into the
16-bit Configuration Register through the serial port, MSB-first,
as shown below. The first two Load bits LD1-LD0 must be set to
“11” in order to perform a Register update: any other setting will
leave the Register unchanged. Changes to the Configuration
Register will be implemented internally immediately following
the completion of the current conversion, or require a dummy
conversion in order to take effect. Also, in the case of all power
management features, a recovery time will be incurred when
returning to normal operation, as indicated.
In all SPI interface modes (RAC, RDC, etc.) the device has three
states of operation: Acquisition, Conversion and Idle. Power
management modes decide the state of the ADC in Idle mode
and are selected by the PM bits in the Configuration Register as
shown in Table 3 and Table 4.
TABLE 3. CONFIGURATION REGISTER
BIT 15
(MSB)
14
13
12
11
10
9
8
LD1
LD0
ADDR2
ADDR1
ADDR0
PM1
PM0
Unused
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
(LSB)
RGRD
Unused
TABLE 4. CONFIGURATION REGISTER 2
BIT(S)
DESCRIPTION
15:14 Register Load word, set to “11” to update registers,
otherwise previous settings are retained.
In the default mode (Continuous Operation) the ADC is fully
powered in the Idle state and can be taken back to the
Acquisition state instantaneously. In this mode the ADC can be
operated with maximum throughput and hence is ideally suitable
for applications where the ADC is operated continuously.
In Auto Sleep Mode the ISL263XX will be in a sleep state
consuming less than 0.4mA. However, it should be noted that the
requirements on tACQ are more stringent in Auto Sleep mode
since the device must wake up and then perform the Acquisition.
In Auto Power Down Mode (as selected by PM bits) the ADC will be in
power-down condition during the Idle period, consuming less than
5μA of current. Wake-up time takes 150μs. The acquisition time
(tACQ) must be increased to account for this delay.
The power management modes provide a high degree of
flexibility in trading average power consumption versus the
required throughput. Significant power savings can be achieved
by operating in either Auto Sleep Mode or Auto Power-Down
mode depending on the throughput requirements.
13:11 Multiplexer Channel Select word ADDR2:0.
000H: Channel AIN0 (single-ended input devices) or AIN0+/AIN0(differential input devices)
001H: Channel AIN1 or AIN1+/AIN1010H: Channel AIN2 or AIN2+/AIN2011H: Channel AIN3 or AIN3+/AIN3100H: Channel AIN4
101H: Channel AIN5
110H: Channel AIN6
111H: Channel AIN7
10:9 Power Management Configuration Control
00H: Auto Power-Down mode. Device will go into Power-down
mode automatically at the end of the next conversion cycle.
01H: Continuous Operation mode (default). Device remains fully
powered at all times.
1xH: Auto Sleep Mode. Device will enter reduced-power Sleep
mode automatically at the end of the next conversion cycle. A "1"
in PM1 overrides the setting in PM0.
8
Unused
7
Register readback mode. "1" means register readback is enabled
resulting in configuration settings to be output along with
conversion results. "0" (default) mode of operation register
settings are not output.
6:0
Unused
20
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make sure you
have the latest Rev.
DATE
June 8, 2012
REVISION
CHANGE
FN8273.0 Initial Release.
Products
Intersil Corporation is a leader in the design and manufacture of high-performance analog semiconductors. The Company's products
address some of the industry's fastest growing markets, such as, flat panel displays, cell phones, handheld products, and notebooks.
Intersil's product families address power management and analog signal processing functions. Go to www.intersil.com/products for a
complete list of Intersil product families.
For a complete listing of Applications, Related Documentation and Related Parts, please see the respective device information page on
intersil.com: ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329 .
To report errors or suggestions for this datasheet, please go to: www.intersil.com/askourstaff
FITs are available from our website at: http://rel.intersil.com/reports/sear
For additional products, see www.intersil.com/product_tree
Intersil products are manufactured, assembled and tested utilizing ISO9000 quality systems as noted
in the quality certifications found at www.intersil.com/design/quality
Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time
without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be
accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see www.intersil.com
21
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Package Outline Drawing
M16.173
16 LEAD THIN SHRINK SMALL OUTLINE PACKAGE (TSSOP)
Rev 2, 5/10
A
1
3
5.00 ±0.10
SEE DETAIL "X"
9
16
6.40
PIN #1
I.D. MARK
4.40 ±0.10
2
3
0.20 C B A
1
8
B
0.65
0.09-0.20
END VIEW
TOP VIEW
1.00 REF
- 0.05
H
C
1.20 MAX
SEATING
PLANE
0.90 +0.15/-0.10
GAUGE
PLANE
0.25 +0.05/-0.06 5
0.10 M C B A
0.10 C
0°-8°
0.05 MIN
0.15 MAX
SIDE VIEW
0.25
0.60 ±0.15
DETAIL "X"
(1.45)
NOTES:
1. Dimension does not include mold flash, protrusions or gate burrs.
(5.65)
Mold flash, protrusions or gate burrs shall not exceed 0.15 per side.
2. Dimension does not include interlead flash or protrusion. Interlead
flash or protrusion shall not exceed 0.25 per side.
3. Dimensions are measured at datum plane H.
4. Dimensioning and tolerancing per ASME Y14.5M-1994.
5. Dimension does not include dambar protrusion. Allowable protrusion
shall be 0.08mm total in excess of dimension at maximum material
condition. Minimum space between protrusion and adjacent lead
(0.65 TYP)
(0.35 TYP)
TYPICAL RECOMMENDED LAND PATTERN
is 0.07mm.
6. Dimension in ( ) are for reference only.
7. Conforms to JEDEC MO-153.
22
FN8273.0
June 8, 2012
ISL26320, ISL26321, ISL26322, ISL26323, ISL26324, ISL26325, ISL26329
Package Outline Drawing
M8.15
8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE
Rev 4, 1/12
DETAIL "A"
1.27 (0.050)
0.40 (0.016)
INDEX
6.20 (0.244)
5.80 (0.228)
AREA
0.50 (0.20)
x 45°
0.25 (0.01)
4.00 (0.157)
3.80 (0.150)
1
2
8°
0°
3
0.25 (0.010)
0.19 (0.008)
SIDE VIEW “B”
TOP VIEW
2.20 (0.087)
SEATING PLANE
5.00 (0.197)
4.80 (0.189)
1.75 (0.069)
1.35 (0.053)
1
8
2
7
0.60 (0.023)
1.27 (0.050)
3
6
4
5
-C-
1.27 (0.050)
0.51(0.020)
0.33(0.013)
SIDE VIEW “A
0.25(0.010)
0.10(0.004)
5.20(0.205)
TYPICAL RECOMMENDED LAND PATTERN
NOTES:
1. Dimensioning and tolerancing per ANSI Y14.5M-1994.
2. Package length does not include mold flash, protrusions or gate burrs.
Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006
inch) per side.
3. Package width does not include interlead flash or protrusions. Interlead
flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
4. The chamfer on the body is optional. If it is not present, a visual index
feature must be located within the crosshatched area.
5. Terminal numbers are shown for reference only.
6. The lead width as measured 0.36mm (0.014 inch) or greater above the
seating plane, shall not exceed a maximum value of 0.61mm (0.024 inch).
7. Controlling dimension: MILLIMETER. Converted inch dimensions are not
necessarily exact.
8. This outline conforms to JEDEC publication MS-012-AA ISSUE C.
23
FN8273.0
June 8, 2012