analog-to-digital converter with patented Easy Drive
technology. The patented sampling scheme eliminates
dynamic input current errors and the shortcomings of on-
chip buffering through automatic cancellation of differential
input current. This allows large external source impedances
and input signals with rail-to-rail input range to be directly
digitized while maintaining exceptional DC accuracy.
The LTC2482 allows a wide common mode input range
(0V to V
CC
) independent of the reference voltage. The
reference can be as low as 100mV or can be tied directly
to V
CC
. The noise level is 600nV RMS independent of
V
REF
. This allows direct digitization of low level signals
with 16-bit accuracy. The LTC2482 includes an on-chip
trimmed oscillator, eliminating the need for external crystals
or oscillators and provides 87dB rejection of 50Hz and
60Hz line frequency noise. Absolute accuracy and low
drift are automatically maintained through continuous,
transparent, offset and full-scale calibration.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. No Latency
ΔΣ
and Easy Drive are trademarks of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
Easy Drive
™
Technology Enables Rail-to-Rail
Inputs with Zero Differential Input Current
Directly Digitizes High Impedance Sensors with
Full Accuracy
600nV RMS Noise, Independent of V
REF
Operates with a Reference as Low as 100mV with
16-Bit Resolution
GND to V
CC
Input/Reference Common Mode Range
Simultaneous 50Hz/60Hz Rejection Mode
2ppm INL, No Missing Codes
1ppm Offset and 15ppm Total Unadjusted Error
No Latency: Digital Filter Settles in a Single Cycle
Single Supply 2.7V to 5.5V Operation
Internal Oscillator
Available in a Tiny (3mm
×
3mm) 10-Lead
DFN Package
APPLICATIONS
n
n
n
n
n
n
n
Direct Sensor Digitizer
Weight Scales
Direct Temperature Measurement
Strain Gauge Transducers
Instrumentation
Industrial Process Control
DVMs and Meters
TYPICAL APPLICATION
V
CC
0.1μF
10k
SENSE
V
IN–
10k
0.1μF
GND
f
O
I
DIFF
= 0
V
REF
LTC2482
V
CC
1μF
+FS ERROR (ppm)
80
+FS Error vs R
SOURCE
at IN
+
and IN
–
V
CC
= 5V
60 V
REF
= 5V
V
IN+
= 3.75V
–
40 V
IN
= 1.25V
f
O
= GND
20 T
A
= 25°C
C
IN
= 1μF
0
–20
–40
–60
–80
1
10
100
1k
R
SOURCE
(Ω)
10k
100k
2482 TA02
V
IN+
SDO
SCK
CS
2482 TA01
3-WIRE
SPI INTERFACE
2482fc
1
LTC2482
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PIN CONFIGURATION
TOP VIEW
*GND
V
CC
V
REF
IN
+
IN
–
1
2
3
4
5
11
10 f
O
9 SCK
8 GND
7 SDO
6 CS
Supply Voltage (V
CC
) to GND ...................... –0.3V to 6V
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
LTC2482C ............................................... 0°C to 70°C
LTC2482I ............................................ –40°C to 85°C
Storage Temperature Range.................. –65°C to 125°C
DD PACKAGE
10-LEAD (3mm 3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 160°C/W
EXPOSED PAD (PIN #) IS GND, MUST BE SOLDERED TO PCB
*PIN 1 MAY BE DRIVEN WITH A DIGITAL SIGNAL IN ORDER TO
REMAIN PIN COMPATIBLE WITH THE LTC2480/LTC2482
ORDER INFORMATION
LEAD FREE FINISH
LTC2482CDD#PBF
LTC2482IDD#PBF
TAPE AND REEL
LTC2482CDD#TRPBF
LTC2482IDD#TRPBF
PART MARKING*
LBSQ
LBSQ
PACKAGE DESCRIPTION
10-Lead (3mm
×
3mm) Plastic DFN
10-Lead (3mm
×
3mm) Plastic DFN
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/
ELECTRICAL CHARACTERISTICS (NORMAL SPEED)
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
0.1 ≤ 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 14)
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
, IN
+
= 0.75V
REF
, IN
–
= 0.25V
REF
2.5V ≤ V
REF
≤ V
CC
, IN
+
= 0.75V
REF
, IN
–
= 0.25V
REF
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
5V ≤ V
CC
≤ 5.5V, V
REF
= 5V, GND ≤ IN
–
= IN
+
≤ V
CC
(Note 13)
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
l
l
l
l
TYP
2
1
0.5
10
MAX
20
5
32
UNITS
Bits
ppm of V
REF
ppm of V
REF
μV
nV/°C
ppm of V
REF
ppm of
V
REF
/°C
16
0.1
l
32
0.1
15
ppm of V
REF
ppm of
V
REF
/°C
ppm of V
REF
ppm of V
REF
ppm of V
REF
μV
RMS
Output Noise
0.6
2482fc
2
LTC2482
CONVERTER CHARACTERISTICS
PARAMETER
Input Common Mode Rejection DC
Input Common Mode Rejection, 50Hz ±2%
Input Common Mode Rejection, 60Hz ±2%
Input Normal Mode Rejection, 50Hz ±2%
Input Normal Mode Rejection, 60Hz ±2%
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
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
–
= IN
+
≤ V
CC
(Note 5)
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
–
= IN
+
≤ V
CC
(Note 5)
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, 7)
2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
–
= IN
+
≤ V
CC
(Notes 5, 8)
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 (Note 7)
V
REF
= 2.5V, IN
–
= IN
+
= GND (Note 8)
l
l
l
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. (Notes 3, 4)
MIN
140
140
140
110
110
87
120
140
120
120
120
120
120
TYP
MAX
UNITS
dB
dB
dB
dB
dB
dB
dB
dB
dB
dB
ANALOG INPUT AND REFERENCE
SYMBOL
IN
+
IN
–
FS
LSB
V
IN
V
REF
C
S
(IN
+
)
C
S
(IN
–
)
C
S
(V
REF
)
I
DC_LEAK
(IN
+
)
I
DC_LEAK
(IN
–
)
I
DC_LEAK
(V
REF
)
PARAMETER
Absolute/Common Mode IN
+
Voltage
Absolute/Common Mode IN
–
Voltage
Full Scale of the Differential Input (IN
+
– IN
–
)
Least Significant Bit of the Output Code
Input Differential Voltage Range (IN
+
– IN
–
)
Reference Voltage Range
IN
+
Sampling Capacitance
IN
–
Sampling Capacitance
V
REF
Sampling Capacitance
IN
+
DC Leakage Current
IN
–
DC Leakage Current
V
REF
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
MIN
GND – 0.3V
GND – 0.3V
l
l
l
l
TYP
MAX
V
CC
+ 0.3V
V
CC
+ 0.3V
UNITS
V
V
V
0.5V
REF
FS/2
16
–FS
0.1
11
11
11
+FS
V
CC
V
V
pF
pF
pF
Sleep Mode, IN
+
= GND
Sleep Mode, IN
–
= GND
Sleep Mode, V
REF
= V
CC
l
l
l
–10
–10
–100
1
1
1
10
10
100
nA
nA
nA
2482fc
3
LTC2482
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
Low Level Input Voltage;
CS,
f
O
High Level Input Voltage, SCK
Low Level Input Voltage, SCK
Digital Input Current;
CS,
f
O
Digital Input Current, SCK
Digital Input Capacitance;
CS,
f
O
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
I
O
= –800μA
I
O
= 1.6mA
I
O
= –800μA
I
O
= 1.6mA
l
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)
CONDITIONS
2.7V ≤ V
CC
≤ 5.5V (Note 16)
2.7V ≤ V
CC
≤ 5.5V
2.7V ≤ V
CC
≤ 5.5V (Note 10)
2.7V ≤ V
CC
≤ 5.5V (Note 10)
0V ≤ V
IN
≤ V
CC
0V ≤ V
IN
≤ V
CC
(Note 10)
l
l
l
l
l
l
MIN
V
CC
– 0.5
TYP
MAX
0.5
UNITS
V
V
V
V
μA
μA
pF
pF
V
V
CC
– 0.5
0.5
–10
–10
10
10
V
CC
– 0.5
0.4
V
CC
– 0.5
0.4
–10
10
10
10
V
V
V
μA
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
250
2
UNITS
V
μA
μA
Conversion Mode (Note 12)
Sleep Mode (Note 12)
2482fc
4
LTC2482
TIMING CHARACTERISTICS
SYMBOL
f
EOSC
t
HEO
t
LEO
t
CONV_1
f
ISCK
D
ISCK
f
ESCK
t
LESCK
t
HESCK
t
DOUT_ISCK
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 24-Bit Data Output Time
Simultaneous 50Hz/60Hz
External Oscillator
Internal Oscillator (Note 10)
External Oscillator (Notes 10, 11)
(Note 10)
(Note 10)
(Note 10)
(Note 10)
Internal Oscillator (Notes 10, 12)
External Oscillator (Notes 10, 11)
(Note 10)
l
l
l
l
l
l
l
l
l
l
l
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)
CONDITIONS
(Note 15)
l
l
l
l
l
MIN
10
0.125
0.125
144.1
TYP
MAX
4000
100
100
UNITS
kHz
μs
μs
ms
ms
kHz
kHz
146.9
41036/f
EOSC
(in kHz)
38.4
f
EOSC
/8
149.9
45
125
125
0.61
0.625
192/f
EOSC
(in kHz)
24/f
ESCK
(in kHz)
0
0
0
50
55
4000
%
kHz
ns
ns
0.64
ms
ms
ms
ns
ns
ns
ns
ns
ns
ns
t
DOUT_ESCK
External SCK 24-Bit Data Output Time
t
1
t
2
t
3
t
4
t
KQMAX
t
KQMIN
t
5
t
6
CS↓
to SDO Low
CS↑ to SDO Hi-Z
CS↓
to SCKØ
CS↓
to SCK≠
SCK↓ to SDO Valid
SDO Hold After SCK↓
SCK Set-Up Before
CS↓
SCK Hold After
CS↓
200
200
200
200
(Note 10)
(Note 10)
(Note 5)
15
50
50
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
REFCM
= V
REF
/2, FS = 0.5V
REF
V
IN
= IN
+
– IN
–
, V
IN(CM)
= (IN
+
+ IN
–
)/2
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 rejection (internal oscillator) or
f
EOSC
= 280kHz ±2% (external oscillator).
Note 10:
The SCK can be configured in external SCK mode or internal SCK
mode. In external SCK mode, the SCK pin is used as digital input and the
driving clock is f
ESCK
. In internal SCK mode, the SCK pin is used as digital
output and the output clock signal during the data output is f
ISCK
.
Note 11:
The external oscillator is connected to the f
O
pin. The external
oscillator frequency, f
EOSC
, is expressed in kHz.
Note 12:
The converter uses the internal oscillator.
Note 13:
The output noise includes the contribution of the internal
calibration operations.
Note 14:
Guaranteed by design and test correlation.
Note 15:
Refer to Applications Information section for performance vs
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