FEATURES
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LTC2486
16-Bit 2-/4-Channel
ΔΣ
ADC
with PGA and Easy Drive
Input Current Cancellation
DESCRIPTION
The LTC
®
2486 is a 4-channel (2-channel differential),
16-bit, No Latency
ΔΣ™
ADC with 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 rail-to-
rail input signals to be directly digitized while maintaining
exceptional DC accuracy.
The LTC2486 includes programmable gain, a high accuracy
temperature sensor, and an integrated oscillator. This de-
vice can be configured to measure an external signal (from
combinations of 4 analog input channels operating in single
ended or differential modes) or its internal temperature sen-
sor. It can be programmed to reject line frequencies of 50Hz,
60Hz, or simultaneous 50Hz/60Hz, provide a programmable
gain from 1 to 256 in 8 steps, and configured to double its
output rate. The integrated temperature sensor offers 1/2°C
resolution and 2°C absolute accuracy.
The LTC2486 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
selection is valid.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
No Latency
∆Σ
and Easy Drive are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Up to 2 Differential or 4 Single-Ended Inputs
Easy Drive Technology Enables Rail-to-Rail Inputs
with Zero Differential Input Current
Directly Digitizes High Impedance Sensors with
Full Accuracy
600nV RMS Noise
Programmable Gain from 1 to 256
Integrated High Accuracy 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 Full-Scale Error
2x Speed Mode/Reduced Power Mode (15Hz Using
Internal Oscillator and 80µA at 7.5Hz Output)
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 4mm
×
3mm DFN Package
APPLICATIONS
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Direct Sensor Digitizer
Direct Temperature Measurement
Instrumentation
Industrial Process Control
TYPICAL APPLICATION
Data Acquisition System with Temperature Compensation
2.7V TO 5.5V
0.1µF
10µF
ABSOLUTE ERROR (°C)
5
4
Absolute Temperature Error
CH0
CH1
REF
+
V
CC
3
2
1
0
–1
–2
–3
–4
4-CHANNEL
MUX
CH2
CH3
COM
TEMPERATURE
SENSOR
IN
+
16-BIT
∆Σ
ADC
WITH EASY-DRIVE
IN
–
REF
–
SDI
SCK
SDO
CS
4-WIRE
SPI INTERFACE
F
O
OSC
2486 TA01a
–5
–55
–30
–5
20
45
70
TEMPERATURE (°C)
95
120
2486 TA01b
2486f
1
LTC2486
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PACKAGE/ORDER INFORMATION
F
O
SDI
SCK
CS
SDO
GND
COM
1
2
3
4
5
6
7
15
14 REF
–
13 REF
+
12 V
CC
11 CH3
10 CH2
9 CH1
8 CH0
Supply Voltage (V
CC
) ................................... –0.3V to 6V
Analog Input Voltage
(CH0 to CH3, COM) ..................–0.3V to (V
CC
+ 0.3V)
REF
+
, REF
–
................................–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
LTC2486C ................................................ 0°C to 70°C
LTC2486I ............................................. –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
DE PACKAGE
14-LEAD (4mm
×
3mm) PLASTIC DFN
T
JMAX
= 125°C,
θ
JA
= 37°C/W
EXPOSED PAD (PIN 15) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER
LTC2486CDE
LTC2486IDE
DE PART MARKING*
2486
2486
Order Options
Tape and Reel: Add #TR
Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Lead Free Part Marking:
http://www.linear.com/leadfree/
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is identified by a label on the shipping container.
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
0.1V ≤ 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 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
+
= 0.25V
REF
, IN
–
= 0.75V
REF
2.5V ≤ V
REF
≤ V
CC
, IN
+
= 0.25V
REF
, IN
–
= 0.75V
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
5.5V < V
CC
< 2.7V, 2.5V ≤ V
REF
≤ V
CC
,
GND ≤ IN
+
= IN
–
≤ V
CC
(Note 13)
T
A
= 27°C (Note 14)
●
●
●
●
The
●
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
16
2
1
0.5
10
32
0.1
●
TYP
MAX
20
5
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
32
0.1
15
15
15
0.6
27.8
1
28.0
93.5
256
28.2
Output Noise
Internal PTAT Signal
Internal PTAT Temperature Coefficient
Programmable Gain
mV
µV/°C
2486f
2
LTC2486
ELECTRICAL CHARACTERISTICS (2X 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
Output Noise
Programmable Gain
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 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
+
= 0.25V
REF
, IN
–
= 0.75V
REF
2.5V ≤ V
REF
≤ V
CC
, IN
+
= 0.25V
REF
, IN
–
= 0.75V
REF
2.7V ≤ V
CC
≤ 5.5V, 2.5V ≤ V
REF
≤ V
CC
, GND ≤ IN
+
= IN
–
≤ V
CC
●
●
●
●
●
●
The
●
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
16
2
1
0.2
100
32
0.1
32
0.1
0.85
1
128
20
2
TYP
MAX
UNITS
Bits
ppm of V
REF
ppm of V
REF
mV
nV/°C
ppm of V
REF
ppm of V
REF
/°C
ppm of V
REF
ppm of V
REF
/°C
µV
RMS
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
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
MIN
●
●
●
●
●
●
●
TYP
MAX
UNITS
dB
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
(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 (Notes 7, 9)
V
REF
= 2.5V, IN
+
= IN
–
= GND (Notes 8, 9)
140
140
140
110
110
87
120
140
120
120
120
120
120
dB
dB
dB
dB
dB
dB
dB
2486f
3
LTC2486
ANALOG INPUT AND REFERENCE
SYMBOL
IN
+
IN
–
V
IN
FS
LSB
REF
+
REF
–
V
REF
C
S(IN+)
C
S(IN–)
C
S(VREF)
I
DC_LEAK(IN+)
I
DC_LEAK(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)
Input Differential Voltage Range (IN
+
– IN
–
)
Full Scale of the Differential 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
IN
+
DC Leakage Current
IN
–
DC Leakage Current
Sleep Mode, IN
+
= GND
Sleep Mode, IN
–
= GND
Sleep Mode, REF
+
= V
CC
Sleep Mode, REF
–
= GND
V
IN
= 2V
P-P
DC to 1.8MHz
●
●
●
●
●
●
●
●
●
●
The
●
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
–FS
0.5V
REF
/Gain
FS/2
16
0.1
GND
0.1
11
11
11
–10
–10
–100
–100
1
1
1
1
50
120
10
10
100
100
V
CC
REF
+
– 0.1V
V
CC
V
V
V
pF
pF
pF
nA
nA
nA
nA
ns
dB
TYP
MAX
V
CC
+ 0.3V
V
CC
+ 0.3V
+FS
UNITS
V
V
V
V
I
DC_LEAK(REF+)
REF
+
DC Leakage Current
I
DC_LEAK(REF–)
REF
–
DC Leakage Current
t
OPEN
QIRR
MUX Break-Before-Make
MUX Off Isolation
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 (
⎯
C
⎯
S, F
O
, SDI)
Low Level Input Voltage (
⎯
C
⎯
S, 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 (
⎯
C
⎯
S, 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)
CONDITIONS
2.7V ≤ V
CC
≤ 5.5V
2.7V ≤ V
CC
≤ 5.5V
The
●
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
MIN
●
●
●
●
●
●
TYP
MAX
0.5
UNITS
V
V
V
V
µA
µA
pF
pF
V
V
CC
– 0.5
V
CC
– 0.5
0.5
–10
–10
10
10
10
10
2.7V ≤ V
CC
≤ 5.5V (Notes 10, 15)
2.7V ≤ V
CC
≤ 5.5V (Notes 10, 15)
0V ≤ V
IN
≤ V
CC
0V ≤ V
IN
≤ V
CC
(Notes 10, 15)
(Notes 10, 15)
I
O
= –800µA
I
O
= 1.6mA
I
O
= –800µA (Notes 10, 17)
I
O
= 1.6mA (Notes 10, 17)
●
●
●
●
●
V
CC
– 0.5
0.4
V
CC
– 0.5
0.4
–10
10
V
V
V
µA
POWER REQUIREMENTS
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply Current
The
●
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
●
MIN
2.7
●
●
●
TYP
160
200
1
MAX
5.5
275
300
2
UNITS
V
µA
µA
µA
2486f
Conversion Current (Note 12)
Temperature Measurement (Note 12)
Sleep Mode (Note 12)
4
LTC2486
DIGITAL INPUTS AND DIGITAL OUTPUTS
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 50/60Hz Mode
External Oscillator
50Hz Mode
60Hz Mode
Simultaneous 50/60Hz Mode
External Oscillator
Internal Oscillator (Notes 10, 17)
External Oscillator (Notes 10, 11, 15)
(Notes 10, 17)
(Notes 10, 11, 15)
(Notes 10, 11, 15)
(Notes 10, 11, 15)
Internal Oscillator (Notes 10, 17)
External Oscillator (Notes 10, 11, 15)
(Notes 10, 11, 15)
●
●
●
●
●
●
●
The
●
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
(Note 16)
●
●
●
●
●
●
●
●
●
MIN
10
0.125
0.125
157.2
131
144.1
78.7
65.6
72.2
TYP
MAX
4000
50
50
UNITS
kHz
µs
µs
ms
ms
ms
ms
ms
ms
ms
ms
kHz
kHz
160.3
133.6
146.9
41036/f
EOSC
(in kHz)
80.3
66.9
73.6
20556/f
EOSC
(in kHz)
38.4
f
EOSC
/8
163.5
136.3
149.9
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
t
4
t
KQMAX
t
KQMIN
t
5
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 24-Bit Data Output Time
External SCK 24-Bit Data Output Time
⎯
CS
↓
to SDO Low
⎯
⎯
C
⎯
S
↑
to SDO High Z
⎯
CS
↓
to SCK↓
⎯
⎯
C
⎯
S
↓
to SCK↑
SCK↓ to SDO Valid
SDO Hold After SCK↓
⎯ ⎯
SCK Set-Up Before CS
↓
SDI Setup Before SCK↑
SDI Hold After SCK↑
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
ns
ns
200
200
200
200
Internal SCK Mode
External SCK Mode
(Note 5)
(Note 5)
(Note 5)
●
●
●
●
●
●
●
15
50
100
100
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:
Unless otherwise specified:
V
CC
= 2.7V to 5.5V
V
REFCM
= V
REF
/2, F
S
= 0.5V
REF
/Gain
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 other wise 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 a digital input and the
driving clock is f
ESCK
. In the internal SCK mode, the SCK pin is used as a
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 its 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:
The converter is in external SCK mode of operation such that the
SCK pin is used as a digital input. The frequency of the clock signal driving
SCK during the data output is f
ESCK
and is expressed in Hz.
Note 16:
Refer to Applications Information section for performance vs
data rate graphs.
Note 17:
The converter in internal SCK mode of operation such that the
SCK pin is used as a digital output.
2486f
5
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