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 LTC2484 includes an on-chip temperature sensor and
oscillator. The LTC2484 can be configured to measure an
external signal or internal temperature sensor and reject
line frequencies. 50Hz, 60Hz or simultaneous 50Hz/60Hz
line frequency rejection can be selected as well as a 2x
speed-up mode.
The LTC2484 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 LTC2484 includes an on-chip trimmed oscil-
lator, eliminating the need for external crystals or oscil-
lators. Absolute accuracy and low drift are automatically
maintained through continuous, transparent, offset and
full-scale calibration.
L,
LT, LTC and LTM, Linear Technology and the Linear logo are registered trademarks and
No Latency
ΔΣ
and Easy Drive are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Patents pending.
Easy Drive Technology Enables Rail-to-Rail Inputs
with Zero Differential Input Current
Directly Digitizes High Impedance Sensors with
Full Accuracy
600nV RMS Noise
Integrated Temperature Sensor
GND to V
CC
Input/Reference Common Mode Range
Programmable 50Hz, 60Hz or Simultaneous
50Hz/60Hz Rejection Mode
2ppm INL, No Missing Codes
1ppm Offset and 15ppm Total Unadjusted Error
Selectable 2x Speed Mode (15Hz Using Internal
Oscillator)
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
80
V
CC
1μF
10k
SENSE
10k
SDI
SDO
LTC2484
V
IN–
GND
f
O
SCK
CS
2484 TA01
+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
0
–20
–40
–60
–80
1
10
100
1k
R
SOURCE
(Ω)
10k
100k
2484 TA02
+FS ERROR (ppm)
I
DIFF
= 0
1μF
V
IN
+
V
REF
V
CC
C
IN
= 1μF
4-WIRE
SPI INTERFACE
2484fb
1
LTC2484
ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW
SDI
V
CC
V
REF
IN
+
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
LTC2484C ............................................... 0°C to 70°C
LTC2484I ............................................ –40°C to 85°C
Storage Temperature Range.................. –65°C to 125°C
1
2
3
4
5
11
GND
10 f
O
9 SCK
8 GND
7 SDO
6
CS
IN
–
DD PACKAGE
10-LEAD (3mm 3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC2484CDD#PBF
LTC2484IDD#PBF
TAPE AND REEL
LTC2484CDD#TRPBF
LTC2484IDD#TRPBF
PART MARKING*
LBSS
LBSS
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.
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)
The
l
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
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)
T
A
= 27°C
l
l
l
l
l
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
MIN
24
TYP
2
1
0.5
10
MAX
10
2.5
25
UNITS
Bits
ppm of V
REF
ppm of V
REF
μV
nV/°C
ppm of V
REF
ppm of
V
REF
/°C
0.1
25
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
mV
mV/°C
Output Noise
Internal PTAT Signal
Internal PTAT Temperature Coefficient
0.6
420
1.4
2484fb
2
LTC2484
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
Offset Error
Offset Error Drift
Positive Full-Scale Error
Positive Full-Scale Error Drift
Negative Full-Scale Error
Negative Full-Scale Error Drift
Output Noise
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
= 5V, GND ≤ IN
–
= IN
+
≤ V
CC
(Note 13)
l
l
l
l
l
ELECTRICAL CHARACTERISTICS (2x SPEED)
MIN
24
TYP
2
1
0.5
100
MAX
10
2
25
UNITS
Bits
ppm of V
REF
ppm of V
REF
mV
nV/°C
ppm of V
REF
ppm of
V
REF
/°C
0.1
25
0.1
0.84
ppm of V
REF
ppm of
V
REF
/°C
μV
RMS
CONVERTER CHARACTERISTICS
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
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
MIN
140
140
140
110
110
87
120
TYP
MAX
UNITS
dB
dB
dB
120
120
dB
dB
dB
140
120
120
120
dB
dB
dB
dB
ANALOG INPUT AND REFERENCE
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
SYMBOL
IN
+
IN
–
FS
LSB
V
IN
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
l
l
l
l
CONDITIONS
MIN
GND – 0.3V
GND – 0.3V
0.5V
REF
FS/2
24
–FS
0.1
TYP
MAX
V
CC
+ 0.3V
V
CC
+ 0.3V
UNITS
V
V
V
+FS
V
CC
V
V
2484fb
3
LTC2484
ANALOG INPUT AND REFERENCE
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
PARAMETER
IN
+
Sampling Capacitance
IN
–
Sampling Capacitance
V
REF
Sampling Capacitance
IN
+
DC Leakage Current
IN
–
DC Leakage Current
V
REF
DC Leakage Current
Sleep Mode, IN
+
= GND
Sleep Mode, IN
–
= GND
Sleep Mode, V
REF
= V
CC
l
l
l
SYMBOL
C
S
(IN
+
)
C
S
(IN
–
)
C
S
(V
REF
)
I
DC_LEAK
(IN
+
)
I
DC_LEAK
(IN
–
)
I
DC_LEAK
(V
REF
)
CONDITIONS
MIN
TYP
11
11
11
MAX
UNITS
pF
pF
pF
–10
–10
–100
1
1
1
10
10
100
nA
nA
nA
DIGITAL INPUTS AND DIGITAL OUTPUTS
The
l
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
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
I
O
= –800μA
I
O
= 1.6mA
I
O
= –800μA
I
O
= 1.6mA
l
l
l
l
l
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
CONDITIONS
2.7V ≤ V
CC
≤ 5.5V
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
UNITS
V
0.5
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
μA
pF
pF
V
V
V
V
μA
POWER REQUIREMENTS
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
PARAMETER
Supply Voltage
Supply Current
Conversion Mode (Note 12)
Sleep Mode (Note 12)
SYMBOL
V
CC
I
CC
CONDITIONS
l
l
l
MIN
2.7
TYP
160
1
MAX
5.5
250
2
UNITS
V
μA
μA
2484fb
4
LTC2484
TIMING CHARACTERISTICS
SYMBOL
f
EOSC
t
HEO
t
LEO
t
CONV_1
PARAMETER
External Oscillator Frequency Range
External Oscillator High Period
External Oscillator Low Period
Conversion Time for 1x Speed Mode
50Hz Mode
60Hz Mode
Simultaneous 50Hz/60Hz Mode
External Oscillator
50Hz Mode
60Hz Mode
Simultaneous 50Hz/60Hz Mode
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
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
l
l
l
l
l
l
MIN
10
0.125
0.125
157.2
131.0
144.1
78.7
65.6
72.2
TYP
MAX
4000
100
100
UNITS
kHz
μs
μs
ms
ms
ms
ms
ms
ms
ms
ms
kHz
kHz
160.3
163.5
133.6
136.3
146.9
149.9
41036/f
EOSC
(in kHz)
80.3
66.9
73.6
20556/f
EOSC
(in kHz)
38.4
f
EOSC
/8
81.9
68.2
75.1
t
CONV_2
Conversion Time for 2x Speed Mode
f
ISCK
D
ISCK
f
ESCK
t
LESCK
t
HESCK
t
DOUT_ISCK
t
DOUT_ESCK
t
1
t
2
t
3
t4
t
KQMAX
t
KQMIN
t
5
t
6
t
7
t
8
Internal SCK Frequency
Internal SCK Duty Cycle
External SCK Frequency Range
External SCK Low Period
External SCK High Period
Internal SCK 32-Bit Data Output Time
External SCK 32-Bit Data Output Time
CS↓
to SDO Low
CS↑
to SDO Hi-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↑
45
125
125
0.81
55
4000
%
kHz
ns
ns
0.83
0.85
256/f
EOSC
(in kHz)
32/f
ESCK
(in kHz)
200
200
200
200
ms
ms
ms
ns
ns
ns
ns
ns
ns
ns
0
0
0
50
15
50
(Note 10)
(Note 10)
(Note 5)
50
100
100
ns
ns
ns
(Note 5)
(Note 5)
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:
50Hz mode (internal oscillator) or f
EOSC
= 256kHz ±2%
(external oscillator).
Note 8:
60Hz mode (internal oscillator) or f
EOSC
= 307.2kHz ±2%
(external oscillator).
Note 9:
Simultaneous 50Hz/60Hz mode (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
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