LTC2439-1
8-/16-Channel
16-Bit No Latency
∆Σ™
ADC
FEATURES
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DESCRIPTION
The
LTC
®
2439-1
is a 16-channel (8-differential) micropower
16-bit ∆Σ analog-to-digital converter. It operates from 2.7V
to 5.5V and includes an integrated oscillator, 0.12LSB
INL and 1µV RMS noise. It uses delta-sigma technology
and provides single cycle settling time for multiplexed
applications. Through a single pin, the LTC2439-1 can be
configured for better than 87dB differential mode rejection
at 50Hz and 60Hz ±2%, or it can be driven by an external
oscillator for a user-defined rejection frequency. The
internal oscillator requires no external frequency setting
components.
The LTC2439-1 accepts any external differential reference
voltage from 0.1V to V
CC
for flexible ratiometric and remote
sensing measurement applications. It can be configured
to take 8 differential channels or 16 single-ended chan-
nels. The full-scale bipolar input range is from –0.5V
REF
to 0.5V
REF
. The reference common mode voltage, V
REFCM
,
and the input common mode voltage, V
INCM
, may be in-
dependently set between GND and V
CC
. The DC common
mode input rejection is better than 140dB.
The LTC2439-1 communicates through a flexible
4-wire digital interface that is compatible with SPI and
MICROWIRE protocols.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and No
Latency ∆Σ is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners.
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16-Channel Single-Ended or 8-Channel Differential
Inputs
Low Supply Current (200µA, 4µA in Autosleep)
Rail-to-Rail Differential Input/Reference
16-Bit No Missing Codes
1µV RMS Noise, 16-ENOBS Independent of V
REF
Very Low Transition Noise: Less Than 0.02LSB
Operates with a Reference as Low as 100mV with
1.5µV LSB Step Size
Guaranteed Modulator Stability and Lock-Up
Immunity for Any Input and Reference Conditions
Single Supply 2.7V to 5.5V Operation
Internal Oscillator—No External Components
Required
87dB Min, 50Hz and 60Hz Simultaneous Notch Filter
Pin Compatible with the 24-Bit LTC2418
28-Lead SSOP Packag
APPLICATIONS
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Direct Sensor Digitizer
Weight Scales
Direct Temperature Measurement
Gas Analyzers
Strain Gauge Transducers
Instrumentation
Data Acquisition
Industrial Process Control
TYPICAL APPLICATION
2.7V TO 5.5V
90
REF
+
Minimum Resolvable
Signal vs V
REF
MINIMUM RESOLVABLE SIGNAL (µV)
1µF
F
O
SDI
SCK
SDO
CS
19
20
18
17
16
80
70
60
50
40
30
20
10
5
4
3
V
REF
(V)
24361 TA02
*FOR V
REF
= 0.4V RESOLUTION IS LIMITED BY STEP SIZE
1
2
0
0
11
21 CH0
22 CH1
•
•
•
28 CH7
1 CH8
•
•
•
8 CH15
10 COM
12
15
REF
–
GND
9
V
CC
= EXTERNAL OSCILLATOR
= 50Hz and 60Hz REJECTION
THERMOCOUPLE
16-CHANNEL
MUX
+
–
DIFFERENTIAL
16-BIT ∆Σ ADC
4-WIRE
SPI INTERFACE
LTC2439-1
241418 TA01a
24391fb
For more information
www.linear.com/LTC2439-1
1
LTC2439-1
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW
CH8
CH9
CH10
CH11
CH12
CH13
CH14
CH15
V
CC
REF
+
1
2
3
4
5
6
7
8
9
11
28 CH7
27 CH6
26 CH5
25 CH4
24 CH3
23 CH2
22 CH1
21 CH0
20 SDI
19 F
O
18 SCK
17 SDO
16
CS
15 GND
Supply Voltage (V
CC
) to GND ....................... –0.3V to 7V
Analog Input Voltage to GND ........–0.3V to (V
CC
+ 0.3V)
Reference Input Voltage to GND ...–0.3V to (V
CC
+ 0.3V)
Digital Input Voltage to GND .........–0.3V to (V
CC
+ 0.3V)
Digital Output Voltage to GND.......–0.3V to (V
CC
+ 0.3V)
Operating Temperature Range
LTC2439-1C ............................................. 0°C to 70°C
LTC2439-1I ..........................................–40°C to 85°C
Storage Temperature Range .................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
COM 10
REF
–
12
NC 13
NC 14
GN PACKAGE
28-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
ORDER INFORMATION
LEAD FREE FINISH
LTC2439-1CGN#PBF
LTC2439-1IGN#PBF
TAPE AND REEL
LTC2439-1CGN#TRPBF
LTC2439-1IGN#TRPBF
PART MARKING
LTC2439-1CGN
LTC2439-1IGN
PACKAGE DESCRIPTION
28-Lead Plastic SSOP
28-Lead Plastic SSOP
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on nonstandard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
PARAMETER
Resolution (No Missing Codes)
Integral Nonlinearity
CONDITIONS
0.1V ≤ V
REF
≤ V
CC
,
–
0.5 • V
REF
≤ V
IN
≤ 0.5 • V
REF
, (Note 5)
4.5V ≤ V
CC
≤ 5.5V, REF
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V, (Note 6)
5V ≤ V
CC
≤ 5.5V, REF
+
= 5V, REF
–
= GND, V
INCM
= 2.5V, (Note 6)
REF
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V, (Notes 6, 15)
2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
GND ≤ IN
+
= IN
–
≤ V
CC
, (Notes 12,15)
2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
GND ≤ IN
+
= IN
–
≤ V
CC
2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
IN
+
= 0.75REF
+
, IN
–
= 0.25 • REF
+
(Note 15)
2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
IN
+
= 0.75REF
+
, IN
–
= 0.25 • REF
+
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ELECTRICAL CHARACTERISTICS
MIN
16
TYP
0.06
0.12
0.30
5
10
0.16
0.03
MAX
UNITS
Bits
LSB
LSB
LSB
µV
nV/°C
1.25
20
Offset Error
Offset Error Drift
Positive Full-Scale Error
Positive Full-Scale Error Drift
1.25
LSB
ppm of V
REF
/°C
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2
For more information
www.linear.com/LTC2439-1
LTC2439-1
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
PARAMETER
Negative Full-Scale Error
Negative Full-Scale Error Drift
CONDITIONS
2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
IN
+
= 0.25 • REF
+
, IN
–
= 0.75 • REF
+
(Note 15)
2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
IN
+
= 0.25 • REF
+
, IN
–
= 0.75 • REF
+
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ELECTRICAL CHARACTERISTICS
MIN
TYP
0.16
0.03
MAX
1.25
UNITS
LSB
ppm of V
REF
/°C
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
PARAMETER
Total Unadjusted Error
CONDITIONS
5V ≤ V
CC
≤ 5.5V, REF
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V
5V ≤ V
CC
≤ 5.5V, REF
+
= 5V, REF
–
= GND, V
INCM
= 2.5V
REF
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V, (Note 6)
5V ≤ V
CC
≤ 5.5V, REF
+
= 5V, V
REF–
= GND,
GND ≤ IN
–
= IN
+
≤ 5V (Note 12)
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CONVERTER CHARACTERISTICS
MIN
TYP
0.20
0.20
1
MAX
UNITS
LSB
LSB
µV
RMS
dB
dB
dB
Output Noise
Input Common Mode Rejection DC 2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
GND ≤ IN
–
= IN
+
≤ V
CC
(Note 5)
Input Common Mode Rejection
49Hz to 61.2Hz
Input Normal Mode Rejection
49Hz to 61.2Hz
Reference Common Mode
Rejection DC
Power Supply Rejection, DC
Power Supply Rejection,
Simultaneous 50Hz/60Hz ±2%
2.5V ≤ REF
+
≤ V
CC
, REF
–
= GND,
GND ≤ IN
–
= IN
+
≤ V
CC
, (Note 5)
(Note 5)
2.5V ≤ REF
+
≤ V
CC
, GND ≤ REF
–
≤ 2.5V,
V
REF
= 2.5V, IN
–
= IN
+
= GND (Note 5)
REF
+
= 2.5V, REF
–
= GND, IN
–
= IN
+
= GND
REF
+
= 2.5V, REF
–
= GND, IN
–
= IN
+
= GND
130
140
87
130
140
140
120
120
dB
dB
dB
ANALOG INPUT AND REFERENCE
SYMBOL
IN
+
IN
–
V
IN
REF
+
REF
–
V
REF
C
S
(IN
+
)
C
S
(IN
–
)
C
S
(REF
+
)
C
S
(REF
–
)
I
DC_LEAK
(IN
+
)
I
DC_LEAK
(IN
–
)
I
DC_LEAK
(REF
+
)
I
DC_LEAK
(REF
–
)
PARAMETER
Absolute/Common Mode IN
+
Voltage
Absolute/Common Mode IN
–
Voltage
Input Differential Voltage Range (IN
+
– IN
–
)
Absolute/Common Mode REF
+
Voltage
Absolute/Common Mode REF
–
Voltage
Reference Differential Voltage Range
(REF
+
– REF
–
)
IN
+
Sampling Capacitance
IN
–
Sampling Capacitance
REF
+
Sampling Capacitance
REF
–
Sampling Capacitance
IN
+
DC Leakage Current
IN
–
DC Leakage Current
REF
+
DC Leakage Current
REF
–
DC Leakage Current
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
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MIN
GND – 0.3
GND – 0.3
–V
REF
/2
0.1
GND
0.1
TYP
MAX
V
CC
+ 0.3
V
CC
+ 0.3
V
REF
/2
V
CC
V
CC
– 0.1
V
CC
UNITS
V
V
V
V
V
V
pF
pF
pF
pF
18
18
18
18
CS
= V
CC
= 5.5V, IN
+
= GND
CS
= V
CC
= 5.5V, IN
–
= 5V
CS
= V
CC
= 5.5V, REF
+
= 5V
CS
= V
CC
= 5.5V, REF
–
= GND
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–100
–100
–100
–100
1
1
1
1
100
100
100
100
nA
nA
nA
nA
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For more information
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3
LTC2439-1
ANALOG INPUT AND REFERENCE
SYMBOL
PARAMETER
Off Channel to On Channel Isolation
(R
IN
= 100Ω)
t
OPEN
I
S(OFF)
MUX Break-Before-Make Interval
Channel Off Leakage Current
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
DC
1Hz
f
S
= 15,3600Hz
2.7V ≤ V
CC
≤ 5.5V
Channel at V
CC
and GND
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MIN
TYP
140
140
140
100
MAX
UNITS
dB
dB
dB
ns
–100
1
100
nA
DIGITAL INPUTS AND DIGITAL OUTPUTS
SYMBOL
V
IH
V
IL
V
IH
V
IL
I
IN
I
IN
C
IN
C
IN
V
OH
V
OL
V
OH
V
OL
I
OZ
PARAMETER
High Level Input Voltage
CS,
F
O
, SDI
Low Level Input Voltage
CS,
F
O
, SDI
High Level Input Voltage
SCK
Low Level Input Voltage
SCK
Digital Input Current
CS,
F
O
, SDI
Digital Input Current
SCK
Digital Input Capacitance
CS,
F
O
, SDI
Digital Input Capacitance
SCK
High Level Output Voltage
SDO
Low Level Output Voltage
SDO
High Level Output Voltage
SCK
Low Level Output Voltage
SCK
Hi-Z Output Leakage
SDO
(Note 8)
I
O
= –800µA
I
O
= 1.6mA
I
O
= –800µA (Note 9)
I
O
= 1.6mA (Note 9)
CONDITIONS
2.7V ≤ V
CC
≤ 5.5V
2.7V ≤ V
CC
≤ 3.3V
4.5V ≤ V
CC
≤ 5.5V
2.7V ≤ V
CC
≤ 5.5V
The
l
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
MIN
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TYP
MAX
UNITS
V
V
2.5
2.0
0.8
0.6
2.5
2.0
0.8
0.6
–10
–10
10
10
10
10
V
V
V
V
V
V
µA
µA
pF
pF
V
2.7V ≤ V
CC
≤ 5.5V (Note 8)
2.7V ≤ V
CC
≤ 3.3V (Note 8)
4.5V ≤ V
CC
≤ 5.5V (Note 8)
2.7V ≤ V
CC
≤ 5.5V (Note 8)
0V ≤ V
IN
≤ V
CC
0V ≤ V
IN
≤ V
CC
(Note 8)
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V
CC
– 0.5
0.4
V
CC
– 0.5
0.4
–10
10
V
V
V
µA
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply Current
Conversion Mode
Sleep Mode
Sleep Mode
CS
= 0V (Note 11)
CS
= V
CC
(Note 11)
CS
= V
CC
, 2.7V ≤ V
CC
≤ 3.3V (Note 11, 14)
CONDITIONS
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POWER REQUIREMENTS
MIN
2.7
TYP
MAX
5.5
UNITS
V
µA
µA
µA
200
4
2
300
15
24391fb
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For more information
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LTC2439-1
TIMING CHARACTERISTICS
SYMBOL
f
EOSC
t
HEO
t
LEO
t
CONV
f
ISCK
D
ISCK
f
ESCK
t
LESCK
t
HESCK
t
DOUT_ISCK
t
DOUT_ESCK
t
1
t
2
t
3
t
4
t
KQMAX
t
KQMIN
t
5
t
6
t
7
t
8
PARAMETER
External Oscillator Frequency Range
External Oscillator High Period
External Oscillator Low Period
Conversion Time
Internal SCK Frequency
Internal SCK Duty Cycle
External SCK Frequency Range
External SCK Low Period
External SCK High Period
Internal SCK 19-Bit Data Output Time
External SCK 19-Bit Data Output Time
CS
↓
to SDO Low
CS
↑
to SDO High Z
CS
↓
to SCK
↓
CS
↓
to SCK
↑
SCK
↓
to SDO Valid
SDO Hold After SCK
↓
SCK Set-Up Before
CS
↓
SCK Hold After
CS
↓
SDI Setup Before SCK↑
SDI Hold After SCK↑
(Note 5)
(Note 5)
(Note 5)
(Note 9)
(Note 8)
F
O
= 0V
External Oscillator (Note 10)
Internal Oscillator (Note 9)
External Oscillator (Notes 9, 10)
(Note 9)
(Note 8)
(Note 8)
(Note 8)
Internal Oscillator (Notes 9, 11)
External Oscillator (Notes 9, 10)
(Note 7)
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l
l
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
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l
l
MIN
2.56
0.25
0.25
TYP
MAX
2000
390
390
UNITS
kHz
µs
µs
ms
ms
kHz
kHz
143.8
146.7
149.6
20510/f
EOSC
(in kHz)
17.5
f
EOSC
/8
45
250
250
1.06
1.09
1.11
152/f
EOSC
(in kHz)
19/f
ESCK
(in kHz)
0
0
0
50
220
15
50
50
100
100
200
200
200
55
2000
%
kHz
ns
ns
ms
ms
ms
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
All voltage values are with respect to GND.
Note 3:
V
CC
= 2.7V to 5.5V unless otherwise specified.
V
REF
= REF
+
– REF
–
, V
REFCM
= (REF
+
+ REF
–
)/2; V
IN
= IN
+
– IN
–
,
V
INCM
= (IN
+
+ IN
–
)/2, IN
+
and IN
–
are defined as the selected positive and
negative input respectively.
Note 4:
F
O
pin tied to GND or to V
CC
or to external conversion clock source
with f
EOSC
= 153600Hz unless otherwise specified.
Note 5:
Guaranteed by design, not subject to test.
Note 6:
Integral nonlinearity is defined as the deviation of a code from
a precise analog input voltage. Maximum specifications are limited by
the LSB step size (V
REF
/2
16
) and the single shot measurement. Typical
specifications are measured from the center of the quantization band.
Note 7:
F
O
= GND (internal oscillator) or f
EOSC
= 139800Hz ±2% (external
oscillator).
Note 8:
The converter is in external SCK mode of operation such that the
SCK pin is used as digital input. The frequency of the clock signal driving
SCK during the data output is f
ESCK
and is expressed in kHz.
Note 9:
The converter is in internal SCK mode of operation such that the
SCK pin is used as digital output. In this mode of operation the SCK pin
has a total equivalent load capacitance C
LOAD
= 20pF.
Note 10:
The external oscillator is connected to the F
O
pin. The external
oscillator frequency, f
EOSC
, is expressed in kHz.
Note 11:
The converter uses the internal oscillator.
F
O
= 0V or F
O
= V
CC
.
Note 12:
1µV RMS noise is independent of V
REF
. Since the noise
performance is limited by the quantization, lowering V
REF
improves the
effective resolution.
Note 13:
Guaranteed by design and test correlation.
Note 14:
The low sleep mode current is valid only when
CS
is high.
Note 15:
These parameters are guaranteed by design over the full supply
and temperature range. Automated testing procedures are limited by the
LSB Step Size (V
REF
/2
16
).
24391fb
For more information
www.linear.com/LTC2439-1
5
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