LTC2496
16-Bit 8-/16-Channel
ΔΣ
ADC with Easy Drive
Input Current Cancellation
FEATURES
■
■
DESCRIPTION
The LTC
®
2496 is a 16-channel (8-differential) 16-bit No
Latency
ΔΣ™
ADC with Easy Drive™ technology. The pat-
ented 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 LTC2496 includes an integrated oscillator. This device
can be configured to measure an external signal (from
combinations of 16 analog input channels operating in
single ended or differential modes). It automatically rejects
line frequencies of 50Hz and 60Hz, simultaneously.
The LTC2496 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.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
■
■
■
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■
■
■
■
■
■
Up to 8 Differential or 16 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 (0.02 LSB 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
QFN 5mm
×
7mm Package
APPLICATIONS
■
■
■
■
Direct Sensor Digitizer
Direct Temperature Measurement
Instrumentation
Industrial Process Control
TYPICAL APPLICATION
Data Acquisition System
2.7V TO 5.5V
0.1μF
10μF
+FS ERROR (ppm)
80
+FS Error vs R
SOURCE
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
F
0
CH0
CH1
•
•
•
CH7
CH8 16-CHANNEL
MUX
•
•
•
CH15
COM
MUXOUT/
ADCIN
REF
+
V
CC
IN
+
16-BIT
ΔΣ
ADC
WITH EASY-DRIVE
IN
–
REF
–
SDI
SCK
SDO
CS
4-WIRE
SPI INTERFACE
MUXOUT/
ADCIN
OSC
2496 TA01a
–80
1
10
100
1k
R
SOURCE
(Ω)
10k
100k
2498 TA01b
2496fa
1
LTC2496
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
PACKAGE/ORDER INFORMATION
TOP VIEW
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
SDO
SCK
SDI
CS
F
O
38 37 36 35 34 33 32
GND 1
NC 2
GND 3
GND 4
GND 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 to CH15, COM)
.................................................–0.3V to (V
CC
+ 0.3V)
Reference Input Voltage
.................................................–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
LTC2496C ................................................ 0°C to 70°C
LTC2496I ............................................. –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
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 PART NUMBER
LTC2496CUHF
LTC2496IUHF
QFN PART MARKING*
2496
2496
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
PARAMETER
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
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
●
●
TYP
2
1
0.5
10
MAX
20
5
32
UNITS
Bits
ppm of V
REF
ppm of V
REF
μV
nV/ºC
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
2496fa
Resolution (No Missing Codes) 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)
●
●
0.1
32
0.1
15
15
15
0.6
Output Noise
2
LTC2496
CONVERTER CHARACTERISTICS
PARAMETER
Input Common Mode Rejection DC
Input Common Mode Rejection 60Hz ±2%
Input Common Mode Rejection 50Hz ±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 (Notes 7, 9)
V
REF
= 2.5V, IN
+
= IN
–
= GND (Notes 8, 9)
●
●
●
●
●
●
●
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
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
–
V
IN
FS
LSB
REF
+
REF
–
V
REF
CS(IN
+
)
CS(IN
–
)
CS(V
REF
)
I
DC_LEAK
(IN
+
)
I
DC_LEAK
(IN
–
)
PARAMETER
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
●
●
●
●
●
●
TYP
MAX
V
CC
+ 0.3V
V
CC
+ 0.3V
+FS
UNITS
V
V
V
V
Absolute/Common Mode IN
+
Voltage
(IN
+
Corresponds to the Selected Positive Input Channel)
Absolute/Common Mode IN
–
Voltage
(IN
–
Corresponds to the Selected Positive 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
●
●
●
●
–FS
0.5 V
REF
FS/2
16
0.1
GND
0.1
11
11
11
–10
–10
–100
–100
1
1
1
1
50
120
V
CC
REF
+
– 0.1V
V
CC
V
V
V
pF
pF
pF
10
10
100
100
nA
nA
nA
nA
ns
dB
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
2496fa
3
LTC2496
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 (
⎯
C
⎯
S, 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)
(Notes 10, 17)
I
O
= –800μA
I
O
= 1.6mA
I
O
= –800μA (Notes 10, 17)
I
O
= 1.6mA (Notes 10, 17)
●
●
●
●
●
The
●
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
2.7V ≤ V
CC
≤ 5.5V
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)
●
●
●
●
●
●
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
●
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
1
MAX
5.5
275
2
UNITS
V
μA
μA
Conversion Current (Note 12)
Sleep Mode (Note 12)
DIGITAL INPUTS AND DIGITAL OUTPUTS
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
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
External SCK 24-Bit Data Output Time
Simultaneous 50/60Hz
External Oscillator
CONDITIONS
(Note 16)
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
4000
100
100
UNITS
kHz
μs
μs
ms
ms
kHz
kHz
10
0.125
0.125
144.1
146.9
41036/f
EOSC
(in kHz)
38.4
f
EOSC
/8
149.9
Internal Oscillator (Note 10)
External Oscillator (Notes 10, 11)
(Note 10)
(Note 10)
(Note 10)
(Note 10)
Internal Oscillator
External Oscillator
(Note 10)
●
●
●
●
●
45
125
125
0.61
0.625
192/f
EOSC
(in kHz)
24/f
ESCK
(in kHz)
55
4000
%
kHz
ns
ns
0.64
ms
ms
ms
2496fa
4
LTC2496
DIGITAL INPUTS AND DIGITAL OUTPUTS
SYMBOL
t
1
t
2
t
3
t
4
t
KQMAX
t
KQMIN
t
5
t
6
t
7
t
8
PARAMETER
⎯
CS
↓
to SDO Low
⎯
⎯
CS
↑
to SDO High Z
⎯
⎯
CS
↓
to SCK↓
⎯
⎯
C
⎯
S
↓
to SCK↑
SCK↓ to SDO Valid
SDO Hold After SCK↓
SCK Set-Up Before
⎯
C
⎯
S
↓
SCK Hold After
⎯
C
⎯
S
↓
SDI Setup Before SCK↑
SDI Hold After SCK↑
(Note 5)
(Note 5)
(Note 5)
Internal SCK Mode
External SCK Mode
CONDITIONS
●
●
●
●
●
●
●
●
●
●
The
●
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
MIN
0
0
0
50
200
15
50
50
100
100
TYP
MAX
200
200
200
UNITS
ns
ns
ns
ns
ns
ns
ns
ns
ns
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, 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:
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 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 is in internal SCK mode of operation such that the
SCK pin is used as a digital output.
2496fa
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