eliminates dynamic input current errors and the shortcom-
ings of on-chip buffering through automatic cancellation of
differential input current. This allows large external source
impedances and rail-to-rail input signals to be directly
digitized while maintaining exceptional DC accuracy.
The LTC2497 includes an integrated oscillator. This device
can be configured to measure an external signal from com-
binations of 16 analog input channels operating in single-
ended or differential modes. It automatically rejects line
frequencies of 50Hz and 60Hz simultaneously.
The LTC2497 allows a wide, common mode input range
(0V to V
CC
), independent of the reference voltage. Any
combination of single-ended or differential inputs can be
selected and the first conversion, after a new channel is
selected, is valid. Access to the multiplexer output enables
optional external amplifiers to be shared between all
analog inputs and auto calibration continuously removes
their associated offset and drift.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No Latency ∆∑ and Easy Drive are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
n
n
n
n
n
n
n
n
n
n
n
Up to Eight Differential or 16 Single-Ended Inputs
Easy Drive
TM
Technology Enables Rail-to-Rail
Inputs with Zero Differential Input Current
Directly Digitizes High Impedance Sensors with
Full Accuracy
2-Wire I
2
C Interface with 27 Addresses Plus One
Global Address for Synchronization
600nV RMS Noise (0.02LSB Transition Noise)
GND to V
CC
Input/Reference Common Mode Range
Simultaneous 50Hz/60Hz Rejection
2ppm INL, No Missing Codes
1ppm Offset and 15ppm Full-Scale Error
No Latency: Digital Filter Settles in a Single Cycle,
Even After a New Channel Is Selected
Single Supply, 2.7V to 5.5V Operation (0.8mW)
Internal Oscillator
Tiny 5mm
×
7mm QFN Package
applicaTions
n
n
n
n
Direct Sensor Digitizer
Direct Temperature Measurement
Instrumentation
Industrial Process Control
Typical applicaTion
Easy Drive Data Acquisition System
2.7V TO 5.5V
CH0
CH1
•
•
•
CH7
CH8 16-CHANNEL
MUX
•
•
•
CH15
COM
MUXOUT/
ADCIN
+
+FS Error vs R
SOURCE
at IN
+
and IN
–
V
CC
= 5V
60 V
REF
= 5V
V
IN+
= 3.75V
V
–
= 1.25V
40
IN
f
O
= GND
20 T
A
= 25°C
0
–20
–40
C
IN
= 1mF
80
V
CC
REF
+
10µF
0.1µF
+FS ERROR (ppm)
IN
1.7k
SDA
SCL
2-WIRE
I
2
C INTERFACE
16-BIT ∆∑ ADC
WITH EASY DRIVE
IN
–
REF
–
MUXOUT/
ADCIN
f
O
OSC
2497 TA01
–60
–80
1
10
100
1k
R
SOURCE
( )
10k
100k
2497 TA01b
2497fb
For more information
www.linear.com/LTC2497
1
LTC2497
absoluTe MaxiMuM raTings
(Notes 1, 2)
pin conFiguraTion
TOP VIEW
GND
GND
GND
31 GND
30 REF
–
29 REF
+
28 V
CC
27 MUXOUTN
39
26 ADCINN
25 ADCINP
24 MUXOUTP
23 CH15
22 CH14
21 CH13
20 CH12
13 14 15 16 17 18 19
CH5
CH6
CH7
CH8
CH9
CH10
CH11
CA2
CA1
CA0
f
O
38 37 36 35 34 33 32
GND 1
SCL 2
SDA 3
GND 4
NC 5
GND 6
COM 7
CH0 8
CH1 9
CH2 10
CH3 11
CH4 12
Supply Voltage (V
CC
) ................................... –0.3V to 6V
Analog Input Voltage
(CH0-CH15, COM).....................–0.3V to (V
CC
+ 0.3V)
REF
+
, REF
–
................................–0.3V to (V
CC
+ 0.3V)
ADCINN, ADCINP,
MUXOUTP MUXOUTN ..............–0.3V to (V
CC
+ 0.3V)
Digital Input Voltage......................–0.3V to (V
CC
+ 0.3V)
Digital Output Voltage ...................–0.3V to (V
CC
+ 0.3V)
Operating Temperature Range
LTC2497C .................................................0ºC to 70ºC
LTC2497I ............................................. –40ºC to 85ºC
Storage Temperature Range ...................–65ºC to 150ºC
UHF PACKAGE
38-LEAD (5mm
×
7mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 34°C/W
EXPOSED PAD (PIN 39) IS GND, MUST BE SOLDERED TO PCB
orDer inForMaTion
LEAD FREE FINISH
LTC2497CUHF#PBF
LTC2497IUHF#PBF
TAPE AND REEL
LTC2497CUHF#TRPBF
LTC2497IUHF#TRPBF
PART MARKING*
2497
2497
PACKAGE DESCRIPTION
38-Lead (5mm
×
7mm) Plastic QFN
38-Lead (5mm
×
7mm) Plastic QFN
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard 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/
2497fb
2
For more information
www.linear.com/LTC2497
LTC2497
elecTrical characTerisTics
PARAMETER
Resolution (No Missing Codes)
Integral Nonlinearity
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
CONDITIONS
0.1V ≤ V
REF
≤ V
CC
, –FS ≤ V
IN
≤ +FS (Note 5)
5V ≤ V
CC
≤ 5.5V, V
REF
= 5V, V
IN(CM)
= 2.5V (Note 6)
2.7V ≤ V
CC
≤ 5.5V, V
REF
= 2.5V, V
IN(CM)
= 1.25V (Note 6)
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
+
= IN
–
≤ V
CC
(Note 13)
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
+
= IN
–
≤ V
CC
2.5V ≤ V
REF
≤ V
CC
, IN
+
= 0.75V
REF
, IN
–
= 0.25V
REF
2.5V ≤ V
REF
≤ V
CC
, IN
+
= 0.75V
REF
, IN
–
= 0.25V
REF
–
2.5V ≤ V
REF
≤ V
CC
REF
, IN = 0.75V
REF
2.5V ≤ V
REF
≤ V
CC
, IN
+
= 0.25V
REF
, IN
–
= 0.75V
REF
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
16
l
l
TYP
2
1
0.5
10
MAX
20
2.5
32
UNITS
Bits
ppm of V
REF
ppm of V
REF
µV
nV/°C
ppm of V
REF
ppm of V
REF
/°C
ppm of V
REF
ppm of V
REF
/°C
ppm of V
REF
ppm of V
REF
ppm of V
REF
µV
RMS
l
0.1
l
, IN
+
= 0.25V
32
0.1
15
15
15
0.6
5V ≤ V
CC
≤ 5.5V, V
REF
= 2.5V, V
IN(CM)
= 1.25V
5V ≤ V
CC
≤ 5.5V, V
REF
= 5V, V
IN(CM)
= 2.5V
2.7V ≤ V
CC
≤ 5.5V, V
REF
= 2.5V, V
IN(CM)
= 1.25V
2.7V < V
CC
< 5.5V, 2.5V ≤ V
REF
≤ V
CC
,
GND ≤ IN
+
= IN
–
≤ V
CC
(Note 12)
Output Noise
converTer characTerisTics
PARAMETER
Input Common Mode Rejection DC
Input Normal Mode Rejection 50Hz/60Hz ±2%
Reference Common Mode Rejection DC
Power Supply Rejection DC
Power Supply Rejection, 50Hz ±2%
Power Supply Rejection, 60Hz ±2%
CONDITIONS
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
MIN
l
l
l
TYP
MAX
UNITS
dB
dB
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
+
= IN
–
≤ V
CC
(Note 5)
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
+
= IN
–
≤ V
CC
(Notes 5, 9)
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
+
= IN
–
≤ V
CC
(Note 5)
V
REF
= 2.5V, IN
+
= IN
–
= GND
V
REF
= 2.5V, IN
+
= IN
–
= GND (Notes 7, 9)
V
REF
= 2.5V, IN
+
= IN
–
= GND (Notes 8, 9)
140
87
120
140
120
120
120
dB
dB
dB
dB
analog inpuT anD reFerence
SYMBOL
IN
+
IN
–
PARAMETER
Absolute/Common Mode IN
+
Voltage
(IN
+
Corresponds to the Selected Positive Input Channel)
Absolute/Common Mode IN
–
Voltage
(IN
–
Corresponds to the Selected Negative Input Channel
or COM)
Input Voltage Range (IN
+
– IN
–
)
Full Scale of the Input (IN
+
– IN
–
)
Least Significant Bit of the Output Code
Absolute/Common Mode REF
+
Voltage
Absolute/Common Mode REF
–
Voltage
Reference Voltage Range (REF
+
– REF
–
)
IN
+
Sampling Capacitance
IN
–
Sampling Capacitance
V
REF
Sampling Capacitance
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
MIN
GND – 0.3V
GND – 0.3V
TYP
MAX
V
CC
+ 0.3V
V
CC
+ 0.3V
+FS
UNITS
V
V
V
IN
FS
LSB
REF
+
REF
–
V
REF
CS(IN
+
)
CS(IN
–
)
CS(V
REF
)
Differential/Single-Ended
Differential/Single-Ended
l
l
l
l
l
l
–FS
0.5V
REF
FS/2
16
0.1
GND
0.1
11
11
11
V
V
V
CC
+
– 0.1V
REF
V
CC
V
V
V
pF
pF
pF
I
DC_LEAK(IN+)
IN
+
DC Leakage Current
Sleep Mode, IN
+
= GND
l
–10
1
10
nA
2497fb
For more information
www.linear.com/LTC2497
3
LTC2497
analog inpuT anD reFerence
I
DC_LEAK(IN–)
IN
–
DC Leakage Current
I
DC_
I
DC_
+
LEAK(REF )
–
LEAK(REF )
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
Sleep Mode, IN
–
= GND
Sleep Mode, REF
+
= V
CC
Sleep Mode, REF
–
= GND
l
l
l
–10
–100
–100
1
1
1
50
10
100
100
nA
nA
nA
ns
dB
REF
+
DC Leakage Current
REF
–
DC Leakage Current
MUX Break-Before-Make
MUX Off Isolation
t
OPEN
QIRR
V
IN
= 2V
P-P
DC to 1.8MHz
120
i
2
c inpuTs anD DigiTal ouTpuTs
SYMBOL
V
IH
V
IL
V
IHA
V
ILA
R
INH
R
INL
R
INF
I
I
V
HYS
V
OL
t
OF
I
IN
C
CAX
PARAMETER
High Level Input Voltage
Low Level Input Voltage
High Level Input Voltage for Address Pins CA0, CA1, CA2,
and Pin f
O
Low Level Input Voltage for Address Pins CA0, CA1, CA2
The
l
denotes the specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
l
l
l
l
l
l
l
l
MIN
0.7V
CC
TYP
MAX
0.3V
CC
UNITS
V
V
V
0.95V
CC
0.05V
CC
10
10
2
–10
0.05V
CC
0.4
20 + 0.1C
B
250
1
10
10
V
kW
kW
MW
µA
V
V
ns
µA
pF
Resistance from CA0, CA1, CA2 to V
CC
to Set Chip Address
Bit to 1
Resistance from CA0, CA1, CA2 to GND to Set Chip Address
Bit to 0
Resistance from CA0, CA1, CA2 to GND or V
CC
to Set Chip
Address Bit to Float
Digital Input Current
Hysteresis of Schmidt Trigger Inputs
Low Level Output Voltage (SDA)
Output Fall Time V
IH(MIN)
to V
IL(MAX)
Input Leakage
External Capacitative Load on Chip Address Pins (CA0, CA1,
CA2) for Valid Float
(Note 5)
I = 3mA
Bus Load C
B
10pF to
400pF (Note 14)
0.1V
CC
≤ V
IN
≤ V
CC
l
l
l
l
l
power requireMenTs
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply 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
l
MIN
2.7
l
l
TYP
160
1
MAX
5.5
275
2
UNITS
V
µA
µA
Conversion Current (Note 11)
Sleep Mode (Note 11)
2497fb
4
For more information
www.linear.com/LTC2497
LTC2497
DigiTal inpuTs anD DigiTal ouTpuTs
SYMBOL
f
EOSC
t
HEO
t
LEO
t
CONV
PARAMETER
External Oscillator Frequency Range
External Oscillator High Period
External Oscillator Low Period
Conversion Time
Internal Oscillator
External Oscillator (Note 10)
CONDITIONS
(Note 16)
l
l
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)
MIN
10
0.125
0.125
144.1
146.9
41036/f
EOSC
(in kHz)
TYP
MAX
1000
100
100
149.9
UNITS
kHz
µs
µs
ms
ms
i
2
c TiMing characTerisTics
SYMBOL
f
SCL
t
HD(SDA)
t
LOW
t
HIGH
t
SU(STA)
t
HD(DAT)
t
SU(DAT)
t
r
t
f
t
SU(STO)
PARAMETER
SCL Clock Frequency
Hold Time (Repeated) Start Condition
Low Period of the SCL Pin
High Period of the SCL Pin
Set-Up Time for a Repeated Start Condition
Data Hold Time
Data Set-Up Time
Rise Time for SDA Signals
Fall Time for SDA Signals
Set-Up Time for Stop Condition
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3, 15)
CONDITIONS
l
l
l
l
l
l
l
MIN
0
0.6
1.3
0.6
0.6
0
100
20 + 0.1C
B
20 + 0.1C
B
0.6
TYP
MAX
400
UNITS
kHz
µs
µs
µs
µs
0.9
300
300
µs
ns
ns
ns
µs
(Note 14)
(Note 14)
l
l
l
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
REFCM
= V
REF
/2, F
S
= 0.5V
REF
V
IN
= IN
+
– IN
–
, V
IN(CM)
= (IN
+
– IN
–
)/2,
where IN
+
and IN
–
are the selected input channels.
Note 4:
Use internal conversion clock or external conversion clock source
with f
EOSC
= 307.2kHz 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
straight line passing through the actual endpoints of the transfer curve.
The deviation is measured from the center of the quantization band.
Note 7:
f
EOSC
= 256kHz ±2% (external oscillator).
Note 8:
f
EOSC
= 307.2kHz ±2% (external oscillator).
Note 9:
Simultaneous 50Hz/60Hz (internal oscillator) or f
EOSC
= 280kHz
±2% (external oscillator).
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 its internal oscillator.
Note 12:
The output noise includes the contribution of the internal
calibration operations.
Note 13:
Guaranteed by design and test correlation.
Note 14:
C
B
= capacitance of one bus line in pF (10pF ≤ C
B
≤ 400pF).
Note 15:
All values refer to V
IH(MIN)
and V
IL(MAX)
levels.
Note 16:
Refer to Applications Information section for performance versus
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