LTC2439-1
8-/16-Channel
16-Bit No Latency
∆Σ
TM
ADC
FEATURES
s
s
s
s
s
s
s
DESCRIPTIO
s
s
s
s
s
s
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
1
µ
V 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 Package
The LTC
®
2439-1 is a 16-channel (8-differential)
micropower 16-bit
∆Σ
analog-to-digital converter. It op-
erates 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 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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
No Latency
∆Σ
is a trademark of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
APPLICATIO S
s
s
s
s
s
s
s
s
Direct Sensor Digitizer
Weight Scales
Direct Temperature Measurement
Gas Analyzers
Strain Gauge Transducers
Instrumentation
Data Acquisition
Industrial Process Control
TYPICAL APPLICATIO
21 CH0
22 CH1
•
•
•
28 CH7
1 CH8
•
•
•
8 CH15
10 COM
12 REF
–
15
GND
2.7V TO 5.5V
REF
+
V
CC
F
O
MINIMUM RESOLVABLE SIGNAL (µV)
11
9
19
1µF
= EXTERNAL OSCILLATOR
= 50Hz and 60Hz REJECTION
THERMOCOUPLE
16-CHANNEL
MUX
+
–
DIFFERENTIAL
16-BIT
∆Σ
ADC
SDI
SCK
SDO
CS
20
18
17
16
4-WIRE
SPI INTERFACE
LTC2439-1
241418 TA01a
U
Minimum Resolvable
Signal vs V
REF
90
80
70
60
50
40
30
20
10
0
5
4
3
V
REF
(V)
24361 TA02
*FOR V
REF
= 0.4V RESOLUTION IS LIMITED BY STEP SIZE
1
2
0
U
U
24391f
1
LTC2439-1
ABSOLUTE
(Notes 1, 2)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
CH8
CH9
CH10
CH11
CH12
CH13
CH14
CH15
V
CC
1
2
3
4
5
6
7
8
9
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
ORDER PART
NUMBER
LTC2439-1CGN
LTC2439-1IGN
COM 10
REF
+
11
REF
–
12
NC 13
NC 14
GN PACKAGE
28-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Nonlinearity
CONDITIONS
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
q
q
q
TYP
0.06
0.12
0.30
5
10
MAX
UNITS
Bits
LSB
LSB
LSB
µV
nV/°C
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
+
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
+
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)
16
1.25
20
Offset Error
Offset Error Drift
Positive Full-Scale Error
Positive Full-Scale Error Drift
Negative Full-Scale Error
Negative Full-Scale Error Drift
Total Unadjusted Error
q
0.16
0.03
1.25
ppm of V
REF
/°C
1.25
LSB
ppm of V
REF
/°C
LSB
LSB
LSB
µV
RMS
24391f
q
0.16
0.03
0.20
0.20
0.25
1
Output Noise
2
U
LSB
W
U
U
W W
W
LTC2439-1
CO VERTER CHARACTERISTICS
PARAMETER
Input Common Mode Rejection DC
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%
CONDITIONS
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
q
q
q
q
A ALOG I PUT A D REFERE CE
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
Off Channel to On Channel Isolation
(R
IN
= 100Ω)
t
OPEN
I
S(OFF)
MUX Break-Before-Make Interval
Channel Off Leakage Current
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
q
q
q
q
q
q
U
U
U
U
TYP
140
MAX
UNITS
dB
dB
dB
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
(Note 5)
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
120
120
dB
dB
dB
U
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
DC
1Hz
f
S
= 15,3600Hz
2.7V
≤
V
CC
≤
5.5V
Channel at V
CC
and GND
q
q
q
q
q
–100
–100
–100
–100
1
1
1
1
140
140
140
100
100
100
100
100
nA
nA
nA
nA
dB
dB
dB
ns
–100
1
100
nA
24391f
3
LTC2439-1
DIGITAL I PUTS A D 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)
q
q
q
q
q
The
q
denotes specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
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
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)
q
q
q
q
q
q
POWER REQUIRE E TS
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply Current
Conversion Mode
Sleep Mode
Sleep Mode
The
q
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
q
4
U W
U
U
MIN
2.5
2.0
TYP
MAX
UNITS
V
V
0.8
0.6
2.5
2.0
0.8
0.6
–10
–10
10
10
V
CC
– 0.5
0.4
V
CC
– 0.5
0.4
–10
10
10
10
V
V
V
V
V
V
µA
µA
pF
pF
V
V
V
V
µA
MIN
2.7
TYP
MAX
5.5
UNITS
V
µA
µA
µA
CS = 0V (Note 11)
CS = V
CC
(Note 11)
CS = V
CC
, 2.7V
≤
V
CC
≤
3.3V (Note 11, 14)
q
q
200
4
2
300
15
24391f
LTC2439-1
TI I G 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
t2
t3
t4
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
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)
q
q
q
q
q
q
q
q
q
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
q
q
q
q
q
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).
UW
MIN
2.56
0.25
0.25
143.8
TYP
MAX
2000
390
390
UNITS
kHz
µs
µs
ms
ms
kHz
kHz
146.7
149.6
20510/f
EOSC
(in kHz)
17.5
f
EOSC
/8
45
250
250
1.06
55
2000
%
kHz
ns
ns
1.09
1.11
152/f
EOSC
(in kHz)
19/f
ESCK
(in kHz)
200
200
200
220
ms
ms
ms
ns
ns
ns
ns
ns
ns
ns
External SCK 19-Bit Data Output Time (Note 7)
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)
0
0
0
50
15
50
q
q
q
q
q
q
q
q
50
100
100
ns
ns
ns
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 proceedures are
limited by the LSB Step Size (V
REF
/2
16
).
24391f
5
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