LTC2415/LTC2415-1
24-Bit No Latency
∆Σ
TM
ADCs with Differential Input and
Differential Reference
DESCRIPTIO
The LTC
®
2415/2415-1 are micropower 24-bit differential
∆Σ
analog to digital converters with integrated oscillator,
2ppm INL, 0.23ppm RMS noise and a 2.7V to 5.5V supply
range. They use delta-sigma technology and provide
single cycle settling time for multiplexed applications.
Through a single pin, the LTC2415 can be configured for
better than 110dB input differential mode rejection at
50Hz or 60Hz
±2%,
or it can be driven by an external
oscillator for a user defined rejection frequency. The
LTC2415-1 can be configured for better than 87dB input
differential mode rejection over the range of 49Hz to
61.2Hz (50Hz and 60Hz
±2%
simultaneously). The inter-
nal oscillator requires no external frequency setting com-
ponents.
The converters accept any external differential reference
voltage from 0.1V to V
CC
for flexible ratiometric and
remote sensing measurement configurations. The full-
scale differential input range is from – 0.5V
REF
to 0.5V
REF
.
The reference common mode voltage, V
REFCM
, and the
input common mode voltage, V
INCM
, may be indepen-
dently set anywhere within the GND to V
CC
range of the
LTC2415/LTC2415-1. The DC common mode input rejec-
tion is better than 140dB.
The LTC2415/LTC2415-1 communicate through a flexible
3-wire digital interface which is compatible with SPI and
MICROWIRE
TM
protocols.
, LTC and LT are registered trademarks of Linear Technology Corporation.
No Latency
∆Σ
is a trademark of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
FEATURES
s
s
s
s
s
s
s
s
s
s
2× Speed Up Version of the LTC2410/LTC2413:
×
15Hz Output Rate, 50Hz or 60Hz Notch—LTC2415;
13.75Hz Output Rate, Simultaneous 50Hz/60Hz
Notch—LTC2415-1
Differential Input and Differential Reference with
GND to V
CC
Common Mode Range
2ppm INL, No Missing Codes
2.5ppm Gain Error
0.23ppm Noise
Single Conversion Settling Time for Multiplexed
Applications
Internal Oscillator—No External Components
Required
24-Bit ADC in Narrow SSOP-16 Package
(SO-8 Footprint)
Single Supply 2.7V to 5.5V Operation
Low Supply Current (200µA) and Auto Shutdown
APPLICATIO S
s
s
s
s
s
s
s
s
s
Direct Sensor Digitizer
Weight Scales
Direct Temperature Measurement
Gas Analyzers
Strain Gage Transducers
Instrumentation
Data Acquisition
Industrial Process Control
6-Digit DVMs
TYPICAL APPLICATIO S
V
CC
2.7V TO 5.5V
1µF
2
V
CC
F
O
14
V
CC
LTC2415/
LTC2415-1
REFERENCE
VOLTAGE
0.1V TO V
CC
ANALOG INPUT RANGE
–0.5V
REF
TO 0.5V
REF
3
4
5
6
REF
+
REF
–
IN
+
IN
–
GND
SDO
CS
12
11
SCK
13
= INTERNAL OSC/50Hz REJECTION (LTC2415)
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION (LTC2415)
= INTERNAL 50Hz/60Hz REJECTION (LTC2415-1)
BRIDGE
IMPEDANCE
100Ω TO 10k
5
6
3-WIRE
SPI INTERFACE
1, 7, 8, 9, 10, 15, 16
2415 TA01
U
U
U
1µF
3
REF
IN
+
2
+
V
CC
LTC2415/
LTC2415-1
F
O
14
12 SDO
13 SCK
11 CS
3-WIRE
SPI INTERFACE
IN
–
4
REF
–
GND
1, 7, 8
9, 10,
15, 16
2415 TA02
sn2415 24151fs
1
LTC2415/LTC2415-1
ABSOLUTE
(Notes 1, 2)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
GND
V
CC
REF
+
REF
–
IN
+
IN
–
GND
GND
1
2
3
4
5
6
7
8
16 GND
15 GND
14 F
O
13 SCK
12 SDO
11 CS
10 GND
9
GND
Supply Voltage (V
CC
) to GND .......................– 0.3V to 7V
Analog Input Pins Voltage
to GND .................................... – 0.3V to (V
CC
+ 0.3V)
Reference Input Pins 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
LTC2415C/LTC2415-1C ........................... 0°C to 70°C
LTC2415I/LTC2415-1I ........................ – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART NUMBER
LTC2415CGN
LTC2415IGN
LTC2415-1CGN
LTC2415-1IGN
GN PART MARKING
2415
2415I
24151
24151I
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 95°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
The
q
denotes 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
CONDITIONS
0.1V
≤
V
REF
≤
V
CC
, –0.5 • V
REF
≤
V
IN
≤
0.5 • V
REF
, (Note 5)
q
ELECTRICAL CHARACTERISTICS
MIN
24
TYP
1
2
5
0.5
20
MAX
UNITS
Bits
ppm of V
REF
ppm of V
REF
ppm of V
REF
mV
nV/°C
5V
≤
V
CC
≤
5.5V, REF
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V, (Note 6)
5V
≤
V
CC
≤
5.5V, REF
+
= 5V, REF
–
= GND, V
INCM
= 2.5V, (Note 6)
q
+
= 2.5V, REF
–
= GND, V
REF
INCM
= 1.25V, (Note 6)
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
+
= IN
–
≤
V
CC
, (Note 14)
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
+
= IN
–
≤
V
CC
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
IN
+
= 0.75REF
+
, IN
–
= 0.25 • REF
+
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
IN
+
= 0.75REF
+
, IN
–
= 0.25 • REF
+
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
IN
+
= 0.25 • REF
+
, IN
–
= 0.75 • REF
+
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
IN
+
= 0.25 • REF
+
, IN
–
= 0.75 • REF
+
5V
≤
V
CC
≤
5.5V, REF
+
= 5V, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
, (Note 13)
q
q
q
14
2
Offset Error
Offset Error Drift
Positive Gain Error
Positive Gain Error Drift
Negative Gain Error
Negative Gain Error Drift
Output Noise
2.5
0.03
2.5
0.03
1.1
12
ppm of V
REF
ppm of V
REF
/°C
12
ppm of V
REF
ppm of V
REF
/°C
µV
RMS
CO VERTER CHARACTERISTICS
PARAMETER
Input Common Mode Rejection DC
CONDITIONS
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
q
TYP
140
MAX
UNITS
dB
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
130
sn2415 24151fs
2
U
W
U
U
W W
W
U
LTC2415/LTC2415-1
CO VERTER CHARACTERISTICS
PARAMETER
Input Common Mode Rejection
60Hz
±2%
(LTC2415)
Input Common Mode Rejection
50Hz
±2%
(LTC2415)
Input Normal Mode Rejection
60Hz
±2%
(LTC2415)
Input Normal Mode Rejection
50Hz
±2%
(LTC2415)
Input Common Mode Rejection
49Hz to 61.2Hz (LTC2415-1)
Input Normal Mode Rejection
49Hz to 61.2Hz (LTC2415-1)
Input Normal Mode Rejection
External Clock f
EOSC
/2560
±14%
(LTC2415-1)
Input Normal Mode Rejection
External Clock f
EOSC
/2560
±4%
(LTC2415-1)
Reference Common Mode
Rejection DC
Power Supply Rejection, DC
CONDITIONS
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
, (Note 7)
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
, (Note 8)
(Note 7)
(Note 8)
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
, (Note 7)
F
O
= GND
External Oscillator
q
q
q
q
q
q
q
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
140
140
110
110
140
87
87
140
140
TYP
MAX
UNITS
dB
dB
dB
dB
dB
dB
dB
Power Supply Rejection, 60Hz
±2%
REF
+
= 2.5V, REF
–
= GND, IN
–
= IN
+
= GND, (Note 7)
Power Supply Rejection, 50Hz
±2%
REF
+
= 2.5V, REF
–
= GND, IN
–
= IN
+
= GND, (Note 8)
A ALOG I PUT A D REFERE CE
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
SYMBOL
IN
+
IN
–
V
IN
REF
+
REF
–
V
REF
C
S
(IN
+
)
C
S
(IN
–
)
C
S
(REF
+
)
C
S
(REF
–
)
I
DC_LEAK
(IN
+
)
I
DC_LEAK
(IN
–
)
I
DC_LEAK
(REF
+
)
I
DC_LEAK
(REF
–
)
PARAMETER
Absolute/Common Mode IN
+
Voltage
Absolute/Common Mode IN
–
Voltage
Input Differential Voltage Range
(IN
+
– IN
–
)
Absolute/Common Mode REF
+
Voltage
Absolute/Common Mode REF
–
Voltage
Reference Differential Voltage Range
(REF
+
– REF
–
)
IN
+
Sampling Capacitance
IN
–
Sampling Capacitance
REF
+
Sampling Capacitance
REF
–
Sampling Capacitance
IN
+
DC Leakage Current
IN
–
DC Leakage Current
REF
+
DC Leakage Current
REF
–
DC Leakage Current
CS = V
CC
, IN
+
= GND
CS = V
CC
, IN
–
= GND
CS = V
CC
, REF
+
= 5V
CS = V
CC
, REF
–
= GND
q
q
q
q
U
U
U
U
External Oscillator
q
110
140
dB
2.5V
≤
REF
+
≤
V
CC
, GND
≤
REF
–
≤
2.5V,
V
REF
= 2.5V, IN
–
= IN
+
= GND
REF
+
= V
CC
, REF
–
= GND, IN
–
= IN
+
= GND
q
130
140
100
120
120
dB
dB
dB
dB
U
CONDITIONS
q
q
q
q
q
q
MIN
GND – 0.3V
GND – 0.3V
–V
REF
/2
0.1
GND
0.1
TYP
MAX
V
CC
+ 0.3V
V
CC
+ 0.3V
V
REF
/2
V
CC
V
CC
– 0.1V
V
CC
UNITS
V
V
V
V
V
V
pF
pF
pF
pF
18
18
18
18
–10
–10
–10
–10
1
1
1
1
10
10
10
10
nA
nA
nA
nA
sn2415 24151fs
3
LTC2415/LTC2415-1
DIGITAL I PUTS A D 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
(Note 9)
I
O
= –800µA
I
O
= 1.6mA
I
O
= –800µA (Note 10)
I
O
= 1.6mA (Note 10)
q
q
q
q
q
The
q
denotes 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
≤
3.3V
4.5V
≤
V
CC
≤
5.5V
2.7V
≤
V
CC
≤
5.5V
2.7V
≤
V
CC
≤
5.5V (Note 9)
2.7V
≤
V
CC
≤
3.3V (Note 9)
4.5V
≤
V
CC
≤
5.5V (Note 9)
2.7V
≤
V
CC
≤
5.5V (Note 9)
0V
≤
V
IN
≤
V
CC
0V
≤
V
IN
≤
V
CC
(Note 9)
q
q
q
q
q
q
POWER REQUIRE E TS
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply Current
Conversion Mode
Sleep Mode
The
q
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
q
4
U W
U
U
MIN
2.5
2.0
TYP
MAX
UNITS
V
V
0.8
0.6
2.5
2.0
0.8
0.6
–10
–10
10
10
V
CC
– 0.5
0.4
V
CC
– 0.5
0.4
–10
10
10
10
V
V
V
V
V
V
µA
µA
pF
pF
V
V
V
V
µA
MIN
2.7
TYP
MAX
5.5
UNITS
V
µA
µA
CS = 0V (Note 12)
CS = V
CC
(Note 12)
q
q
200
20
300
30
sn2415 24151fs
LTC2415/LTC2415-1
TI I G CHARACTERISTICS
SYMBOL
f
EOSC
t
HEO
t
LEO
t
CONV
PARAMETER
External Oscillator Frequency Range
External Oscillator High Period
External Oscillator Low Period
Conversion Time (LTC2415)
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
q
q
q
f
ISCK
D
ISCK
f
ESCK
t
LESCK
t
HESCK
t
DOUT_ISCK
t
DOUT_ESCK
t
1
t2
t3
t4
t
KQMAX
t
KQMIN
t
5
t
6
Note 1:
Absolute Maximum Ratings are those values beyond which the
life of the device may be impaired.
Note 2:
All voltage values are with respect to GND.
Note 3:
V
CC
= 2.7 to 5.5V unless otherwise specified.
V
REF
= REF
+
– REF
–
, V
REFCM
= (REF
+
+ REF
–
)/2;
V
IN
= IN
+
– IN
–
, V
INCM
= (IN
+
+ IN
–
)/2.
Note 4:
F
O
pin tied to GND or to V
CC
or to external conversion clock
source with f
EOSC
= 153600Hz 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
O
= 0V (internal oscillator) or f
EOSC
= 153600Hz
±2%
(external oscillator).
UW
MIN
2.56
0.25
0.25
65.43
78.52
71.3
TYP
MAX
2000
390
390
UNITS
kHz
µs
µs
ms
ms
ms
ms
ms
kHz
kHz
kHz
F
O
= 0V
F
O
= V
CC
External Oscillator (Note 11)
F
O
= 0V
External Oscillator (Note 11)
Internal Oscillator (Note 10), LTC2415
Internal Oscillator (Note 10), LTC2415-1
External Oscillator (Notes 10, 11)
(Note 10)
(Note 9)
(Note 9)
(Note 9)
q
q
q
q
q
66.77
68.1
80.12
81.72
10278/f
EOSC
(in kHz)
74.3
10278/f
EOSC
(in kHz)
19.2
17.5
f
EOSC
/8
72.8
Conversion Time (LTC2415-1)
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
q
q
q
q
45
250
250
1.64
1.80
55
2000
%
kHz
ns
ns
Internal Oscillator (Notes 10, 12), LTC2415
q
Internal Oscillator (Notes 10, 12), LTC2415-1
q
q
External Oscillator (Notes 10, 11)
q
q
q
1.67
1.70
1.83
1.86
256/f
EOSC
(in kHz)
32/f
ESCK
(in kHz)
200
200
200
220
ms
ms
ms
ms
ns
ns
ns
ns
ns
ns
ns
External SCK 32-Bit Data Output Time (Note 9)
CS
↓
to SDO Low Z
CS
↑
to SDO High Z
CS
↓
to SCK
↓
CS
↓
to SCK
↑
SCK
↓
to SDO Valid
SDO Hold After SCK
↓
SCK Set-Up Before CS
↓
SCK Hold After CS
↓
(Note 5)
(Note 10)
(Note 9)
0
0
0
50
15
50
q
q
q
q
q
q
50
ns
Note 8:
F
O
= V
CC
(internal oscillator) or f
EOSC
= 128000Hz
±2%
(external oscillator).
Note 9:
The converter is in external SCK mode of operation such that
the SCK pin is used as digital input. The frequency of the clock signal
driving SCK during the data output is f
ESCK
and is expressed in kHz.
Note 10:
The converter is in internal SCK mode of operation such that
the SCK pin is used as digital output. In this mode of operation the
SCK pin has a total equivalent load capacitance C
LOAD
= 20pF.
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.
F
O
= 0V or F
O
= V
CC
.
Note 13:
The output noise includes the contribution of the internal
calibration operations.
Note 14:
Refer to Offset Accuracy and Drift in the Applications
Information section.
sn2415 24151fs
5
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