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LTC2439-1
1
24391f
8-/16-Channel
16-Bit No Latency
TM
ADC
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
The LTC
2439-1 is a 16-channel (8-differential)
micropower 16-bit
analog-to-digital converter. It op-
erates from 2.7V to 5.5V and includes an integrated
oscillator, 0.12LSB INL and 1
V 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 differ-
ential mode rejection at 50Hz and 60Hz
2%, or it can be
driven by an external oscillator for a user-defined rejec-
tion 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 channels.
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 indepen-
dently 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
TM
protocols.
s
Direct Sensor Digitizer
s
Weight Scales
s
Direct Temperature Measurement
s
Gas Analyzers
s
Strain Gauge Transducers
s
Instrumentation
s
Data Acquisition
s
Industrial Process Control
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
16-Channel Single-Ended or 8-Channel Differential
Inputs
s
Low Supply Current (200
A, 4
A in Autosleep)
s
Rail-to-Rail Differential Input/Reference
s
16-Bit No Missing Codes
s
1
V RMS Noise, 16-ENOBS Independent of V
REF
s
Very Low Transition Noise: Less Than 0.02LSB
s
Operates with a Reference as Low as 100mV with
1.5
V LSB Step Size
s
Guaranteed Modulator Stability and Lock-Up
Immunity for Any Input and Reference Conditions
s
Single Supply 2.7V to 5.5V Operation
s
Internal Oscillator--No External Components
Required
s
87dB Min, 50Hz and 60Hz Simultaneous Notch Filter
s
Pin Compatible with the 24-Bit LTC2418
s
28-Lead SSOP Package
No Latency
is a trademark of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
Minimum Resolvable
Signal vs V
REF
SDI
SCK
SDO
CS
F
O
REF
+
V
CC
9
11
2.7V TO 5.5V
20
18
17
16
19
1
F
COM
REF
GND
10
THERMOCOUPLE
12
15
DIFFERENTIAL
16-BIT
ADC
+
241418 TA01a
4-WIRE
SPI INTERFACE
LTC2439-1
= EXTERNAL OSCILLATOR
= 50Hz and 60Hz REJECTION
CH0
CH1
21
22
CH7
CH8
28
1
CH15
8
16-CHANNEL
MUX
V
REF
(V)
0
*FOR V
REF
= 0.4V RESOLUTION IS LIMITED BY STEP SIZE
0
MINIMUM RESOLVABLE SIGNAL (
V)
10
30
40
50
2
4
5
90
24361 TA02
20
1
3
60
70
80
DESCRIPTIO
U
LTC2439-1
2
24391f
(Notes 1, 2)
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
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
ORDER PART
NUMBER
LTC2439-1CGN
LTC2439-1IGN
T
JMAX
= 125
C,
JA
= 110
C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TOP VIEW
GN PACKAGE
28-LEAD PLASTIC SSOP
28
27
26
25
24
23
22
21
20
19
18
17
16
15
CH8
CH9
CH10
CH11
CH12
CH13
CH14
CH15
V
CC
COM
REF
+
REF
NC
NC
CH7
CH6
CH5
CH4
CH3
CH2
CH1
CH0
SDI
F
O
SCK
SDO
CS
GND
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
0.1V
V
REF
V
CC
, 0.5 V
REF
V
IN
0.5 V
REF
, (Note 5)
q
16
Bits
Integral Nonlinearity
4.5V
V
CC
5.5V, REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V, (Note 6)
0.06
LSB
5V
V
CC
5.5V, REF
+
= 5V, REF
= GND, V
INCM
= 2.5V, (Note 6)
q
0.12
1.25
LSB
REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V, (Notes 6, 15)
0.30
LSB
Offset Error
2.5V
REF
+
V
CC
, REF
= GND,
q
5
20
V
GND
IN
+
= IN
V
CC
, (Notes 12,15)
Offset Error Drift
2.5V
REF
+
V
CC
, REF
= GND,
10
nV/
C
GND
IN
+
= IN
V
CC
Positive Full-Scale Error
2.5V
REF
+
V
CC
, REF
= GND,
q
0.16
1.25
LSB
IN
+
= 0.75REF
+
, IN
= 0.25 REF
+
(Note 15)
Positive Full-Scale Error Drift
2.5V
REF
+
V
CC
, REF
= GND,
0.03
ppm of V
REF
/
C
IN
+
= 0.75REF
+
, IN
= 0.25 REF
+
Negative Full-Scale Error
2.5V
REF
+
V
CC
, REF
= GND,
q
0.16
1.25
LSB
IN
+
= 0.25 REF
+
, IN
= 0.75 REF
+
(Note 15)
Negative Full-Scale Error Drift
2.5V
REF
+
V
CC
, REF
= GND,
0.03
ppm of V
REF
/
C
IN
+
= 0.25 REF
+
, IN
= 0.75 REF
+
Total Unadjusted Error
5V
V
CC
5.5V, REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V
0.20
LSB
5V
V
CC
5.5V, REF
+
= 5V, REF
= GND, V
INCM
= 2.5V
0.20
LSB
REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V, (Note 6)
0.25
LSB
Output Noise
5V
V
CC
5.5V, REF
+
= 5V, V
REF
= GND,
1
V
RMS
GND
IN
= IN
+
5V (Note 12)
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Notes 3, 4)
ELECTRICAL CHARACTERISTICS
LTC2439-1
3
24391f
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Common Mode Rejection DC
2.5V
REF
+
V
CC
, REF
= GND,
q
130
140
dB
GND
IN
= IN
+
V
CC
(Note 5)
Input Common Mode Rejection
2.5V
REF
+
V
CC
, REF
= GND,
q
140
dB
49Hz to 61.2Hz
GND
IN
= IN
+
V
CC
, (Note 5)
Input Normal Mode Rejection
(Note 5)
q
87
dB
49Hz to 61.2Hz
Reference Common Mode
2.5V
REF
+
V
CC
, GND
REF
2.5V,
q
130
140
dB
Rejection DC
V
REF
= 2.5V, IN
= IN
+
= GND (Note 5)
Power Supply Rejection, DC
REF
+
= 2.5V, REF
= GND, IN
= IN
+
= GND
120
dB
Power Supply Rejection,
REF
+
= 2.5V, REF
= GND, IN
= IN
+
= GND
120
dB
Simultaneous 50Hz/60Hz
2%
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Notes 3, 4)
CO VERTER CHARACTERISTICS
U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
IN
+
Absolute/Common Mode IN
+
Voltage
q
GND 0.3
V
CC
+ 0.3
V
IN
Absolute/Common Mode IN
Voltage
q
GND 0.3
V
CC
+ 0.3
V
V
IN
Input Differential Voltage Range
q
V
REF
/2
V
REF
/2
V
(IN
+
IN
)
REF
+
Absolute/Common Mode REF
+
Voltage
q
0.1
V
CC
V
REF
Absolute/Common Mode REF
Voltage
q
GND
V
CC
0.1
V
V
REF
Reference Differential Voltage Range
q
0.1
V
CC
V
(REF
+
REF
)
C
S
(IN
+
)
IN
+
Sampling Capacitance
18
pF
C
S
(IN
)
IN
Sampling Capacitance
18
pF
C
S
(REF
+
)
REF
+
Sampling Capacitance
18
pF
C
S
(REF
)
REF
Sampling Capacitance
18
pF
I
DC_LEAK
(IN
+
)
IN
+
DC Leakage Current
CS = V
CC
= 5.5V, IN
+
= GND
q
100
1
100
nA
I
DC_LEAK
(IN
)
IN
DC Leakage Current
CS = V
CC
= 5.5V, IN
= 5V
q
100
1
100
nA
I
DC_LEAK
(REF
+
)
REF
+
DC Leakage Current
CS = V
CC
= 5.5V, REF
+
= 5V
q
100
1
100
nA
I
DC_LEAK
(REF
)
REF
DC Leakage Current
CS = V
CC
= 5.5V, REF
= GND
q
100
1
100
nA
Off Channel to On Channel Isolation
DC
140
dB
(R
IN
= 100
)
1Hz
140
dB
f
S
= 15,3600Hz
140
dB
t
OPEN
MUX Break-Before-Make Interval
2.7V
V
CC
5.5V
100
ns
I
S(OFF)
Channel Off Leakage Current
Channel at V
CC
and GND
q
100
1
100
nA
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Note 3)
A ALOG I PUT A D REFERE CE
U
U
U
U
LTC2439-1
4
24391f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IH
High Level Input Voltage
2.7V
V
CC
5.5V
q
2.5
V
CS, F
O
, SDI
2.7V
V
CC
3.3V
2.0
V
V
IL
Low Level Input Voltage
4.5V
V
CC
5.5V
q
0.8
V
CS, F
O
, SDI
2.7V
V
CC
5.5V
0.6
V
V
IH
High Level Input Voltage
2.7V
V
CC
5.5V (Note 8)
q
2.5
V
SCK
2.7V
V
CC
3.3V (Note 8)
2.0
V
V
IL
Low Level Input Voltage
4.5V
V
CC
5.5V (Note 8)
q
0.8
V
SCK
2.7V
V
CC
5.5V (Note 8)
0.6
V
I
IN
Digital Input Current
0V
V
IN
V
CC
q
10
10
A
CS, F
O
, SDI
I
IN
Digital Input Current
0V
V
IN
V
CC
(Note 8)
q
10
10
A
SCK
C
IN
Digital Input Capacitance
10
pF
CS, F
O
, SDI
C
IN
Digital Input Capacitance
(Note 8)
10
pF
SCK
V
OH
High Level Output Voltage
I
O
= 800
A
q
V
CC
0.5
V
SDO
V
OL
Low Level Output Voltage
I
O
= 1.6mA
q
0.4
V
SDO
V
OH
High Level Output Voltage
I
O
= 800
A (Note 9)
q
V
CC
0.5
V
SCK
V
OL
Low Level Output Voltage
I
O
= 1.6mA (Note 9)
q
0.4
V
SCK
I
OZ
Hi-Z Output Leakage
q
10
10
A
SDO
DIGITAL I PUTS A D DIGITAL OUTPUTS
U
U
The
q
denotes specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25
C. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Supply Voltage
q
2.7
5.5
V
I
CC
Supply Current
Conversion Mode
CS = 0V (Note 11)
q
200
300
A
Sleep Mode
CS = V
CC
(Note 11)
q
4
15
A
Sleep Mode
CS = V
CC
, 2.7V
V
CC
3.3V (Note 11, 14)
2
A
POWER REQUIRE E TS
W
U
The
q
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25
C. (Note 3)
LTC2439-1
5
24391f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
EOSC
External Oscillator Frequency Range
q
2.56
2000
kHz
t
HEO
External Oscillator High Period
q
0.25
390
s
t
LEO
External Oscillator Low Period
q
0.25
390
s
t
CONV
Conversion Time
F
O
= 0V
q
143.8
146.7
149.6
ms
External Oscillator (Note 10)
q
20510/f
EOSC
(in kHz)
ms
f
ISCK
Internal SCK Frequency
Internal Oscillator (Note 9)
17.5
kHz
External Oscillator (Notes 9, 10)
f
EOSC
/8
kHz
D
ISCK
Internal SCK Duty Cycle
(Note 9)
q
45
55
%
f
ESCK
External SCK Frequency Range
(Note 8)
q
2000
kHz
t
LESCK
External SCK Low Period
(Note 8)
q
250
ns
t
HESCK
External SCK High Period
(Note 8)
q
250
ns
t
DOUT_ISCK
Internal SCK 19-Bit Data Output Time
Internal Oscillator (Notes 9, 11)
q
1.06
1.09
1.11
ms
External Oscillator (Notes 9, 10)
q
152/f
EOSC
(in kHz)
ms
t
DOUT_ESCK
External SCK 19-Bit Data Output Time
(Note 7)
q
19/f
ESCK
(in kHz)
ms
t
1
CS
to SDO Low
q
0
200
ns
t2
CS
to SDO High Z
q
0
200
ns
t3
CS
to SCK
(Note 9)
q
0
200
ns
t4
CS
to SCK
(Note 8)
q
50
ns
t
KQMAX
SCK
to SDO Valid
q
220
ns
t
KQMIN
SDO Hold After SCK
(Note 5)
q
15
ns
t
5
SCK Set-Up Before CS
q
50
ns
t
6
SCK Hold After CS
q
50
ns
t
7
SDI Setup Before SCK
(Note 5)
q
100
ns
t
8
SDI Hold After SCK
(Note 5)
q
100
ns
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25
C. (Note 3)
TI I G CHARACTERISTICS
U
W
Note 1: Absolute Maximum Ratings are those values beyond which the
life of the device may be impaired.
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: 1
V 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 proceedures are
limited by the LSB Step Size (V
REF
/2
16
).
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