LTC2433-1
Differential Input
16-Bit No Latency
∆Σ
ADC
FEATURES
s
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s
s
s
DESCRIPTIO
s
s
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s
16-Bit Differential ADC in a Tiny MSOP
Low Supply Current: 200µA, 4µA in Autosleep
Rail-to-Rail Differential Input/Reference
0.12LSB INL, No Missing Codes
0.16LSB Full-Scale Error and 5
µ
V Offset
1.45
µ
V RMS Noise, Independent of V
REF
Very Low Transition Noise: <0.02LSB
Operates with a Reference as Low as 100mV with
16-Bit Resolution
Internal Oscillator—No External Components
Required
87dB Min, Simultaneous 50Hz and 60Hz Notch Filter
Single Supply 2.7V to 5.5V Operation
Pin Compatible with the 20/24-Bit LTC2431/LTC2411
Available in 10-Lead MSOP Package
The LTC
®
2433-1 is a differential input micropower 16-bit
No Latency
∆Σ
TM
analog-to-digital converter with an inte-
grated oscillator. It provides 0.12LSB INL and 1.45µV
RMS noise independent of V
REF
. It uses delta-sigma
technology and provides single conversion settling of the
digital filter. Through a single pin, the LTC2433-1 can be
configured for better than 87dB input differential mode
rejection at 50Hz and 60Hz
±2%,
or it can be driven by an
external oscillator for a user defined rejection frequency.
The internal oscillator requires no external frequency
setting components.
The converter accepts 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 – 0.5 • V
REF
to 0.5 •
V
REF
. The reference common mode voltage, V
REFCM
, and
the input common mode voltage, V
INCM
, may be indepen-
dently set anywhere between GND and V
CC
. The DC
common mode input rejection is better than 140dB.
The LTC2433-1 communicates 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.
APPLICATIO S
s
s
s
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s
s
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Direct Sensor Digitizer
Weight Scales
Direct Temperature Measurement
Gas Analyzers
Strain-Gage Transducers
Instrumentation
Data Acquisition
Industrial Process Control
TYPICAL APPLICATIO
5V REF
1µF
4.9k
(100mV)
100Ω
1
2
V
CC
+
Minimum Resolvable Signal vs V
REF
90
MINIMUM RESOLVABLE SIGNAL (µV)*
80
70
60
50
40
30
20
10
0
0
5
4
3
2
V
REF
(V)
24331 TA02
*FOR V
REF
≥
0.5V THE RESOLUTION
IS LIMITED BY STEP SIZE
1
24331fa
F
O
10
REF
4
IN
+
LTC2433-1
5
9
SCK
IN
–
3
6
REF
–
GND
SDO
CS
8
7
24331 TA01
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/SIMULTANEOUS
50Hz/60Hz REJECTION
3-WIRE
SPI INTERFACE
U
U
U
1
LTC2433-1
ABSOLUTE
(Notes 1, 2)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
LTC2433-1CMS
LTC2433-1IMS
Supply Voltage (V
CC
) to GND .......................– 0.3V to 7V
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
LTC2433-1C ............................................ 0°C to 70°C
LTC2433-1I ........................................ – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART NUMBER
TOP VIEW
V
CC
REF
+
REF
–
IN
+
IN
–
1
2
3
4
5
10
9
8
7
6
F
O
SCK
SDO
CS
GND
MS10 PACKAGE
10-LEAD PLASTIC MSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
MS PART MARKING
LTAEY
LTAEZ
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, 6)
PARAMETER
Resolution (No Missing Codes)
Integral Nonlinearity (Note 15)
CONDITIONS
0.1V
≤
V
REF
≤
V
CC
, –0.5 • V
REF
≤
V
IN
≤
0.5 • V
REF
, (Note 5)
q
ELECTRICAL CHARACTERISTICS
MIN
16
TYP
0.06
0.12
0.30
5
20
MAX
UNITS
Bits
LSB
LSB
LSB
µV
nV/°C
5V
≤
V
CC
≤
5.5V, REF
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V, (Note 6)
q
5V
≤
V
CC
≤
5.5V, REF
+
= 5V, REF
–
= GND, V
INCM
= 2.5V, (Note 6)
+
= 2.5V, REF
–
= GND, V
REF
INCM
= 1.25V, (Note 6)
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
+
= IN
–
≤
V
CC
, (Note 13)
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
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V
5V
≤
V
CC
≤
5.5V, REF
+
= 5V, REF
–
= GND, V
INCM
= 2.5V
REF
+
= 2.5V, REF
–
= GND, V
INCM
= 1.25V, (Note 6)
5V
≤
V
CC
≤
5.5V, REF
+
= 5V, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
, (Note 12)
q
q
q
1.25
20
Offset Error (Note 15)
Offset Error Drift
Positive Full-Scale Error (Note 15)
Positive Full-Scale Error Drift
Negative Full-Scale Error (Note 15)
Negative Full-Scale Error Drift
Total Unadjusted Error
0.16
0.04
0.16
0.04
0.20
0.20
0.25
1.45
1.25
ppm of V
REF
/°C
1.25
LSB
ppm of V
REF
/°C
LSB
LSB
LSB
µV
RMS
Output Noise
24331fa
2
U
LSB
W
U
U
W W
W
LTC2433-1
CO VERTER CHARACTERISTICS
The
q
denotes 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
49Hz to 61.2Hz
Input Normal Mode Rejection
49Hz to 61.2Hz
Reference Common Mode
Rejection DC
Power Supply Rejection, DC
Power Supply Rejection,
Simultaneous 50Hz/60Hz
±2%
CONDITIONS
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
(Note 5)
2.5V
≤
REF
+
≤
V
CC
, REF
–
= GND,
GND
≤
IN
–
= IN
+
≤
V
CC
, (Notes 5, 7)
(Note 5, 7)
2.5V
≤
REF
+
≤
V
CC
, GND
≤
REF
–
≤
2.5V,
V
REF
= 2.5V, IN
–
= IN
+
= GND (Note 5)
REF
+
= 2.5V, REF
–
= GND, IN
–
= IN
+
= GND
REF
+
= 2.5V, REF
–
= GND, IN
–
= IN
+
= GND, (Note 7)
q
q
q
q
A ALOG I PUT A D REFERE CE
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
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
q
q
q
U
U
U
U
MIN
130
140
87
130
TYP
140
MAX
UNITS
dB
dB
dB
140
120
120
dB
dB
dB
U
MIN
GND – 0.3
GND – 0.3
–V
REF
/2
0.1
GND
0.1
TYP
MAX
V
CC
+ 0.3
V
CC
+ 0.3
V
REF
/2
V
CC
V
CC
– 0.1
V
CC
UNITS
V
V
V
V
V
V
pF
pF
pF
pF
6
6
6
6
CS = V
CC
= 5V, IN
+
= GND
CS = V
CC
= 5V, IN
–
= 5.5V
CS = V
CC
= 5V, REF
+
= 5.5V
CS = V
CC
= 5V, REF
–
= GND
q
q
q
q
–100
–100
–100
–100
1
1
1
1
100
100
100
100
nA
nA
nA
nA
24331fa
3
LTC2433-1
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 8)
I
O
= –800µA
I
O
= 1.6mA
I
O
= –800µA (Note 9)
I
O
= 1.6mA (Note 9)
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 8)
2.7V
≤
V
CC
≤
3.3V (Note 8)
4.5V
≤
V
CC
≤
5.5V (Note 8)
2.7V
≤
V
CC
≤
5.5V (Note 8)
0V
≤
V
IN
≤
V
CC
0V
≤
V
IN
≤
V
CC
(Note 8)
q
q
q
q
q
q
POWER REQUIRE E TS
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply Current
Conversion Mode
Sleep 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
µA
CS = 0V (Note 14)
CS = V
CC
(Notes 11, 14)
CS = V
CC
, 2.7V
≤
V
CC
≤
3.3V
(Notes 11, 14)
q
q
200
4
2
300
13
24331fa
LTC2433-1
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
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
t
1
t2
t3
t4
t
KQMAX
t
KQMIN
t
5
t
6
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 19-Bit Data Output Time
External SCK 19-Bit Data Output Time
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 9)
(Note 8)
F
O
= 0V
External Oscillator (Note 10)
Internal Oscillator (Note 9)
External Oscillator (Notes 9, 10)
(Note 9)
(Note 8)
(Note 8)
(Note 8)
Internal Oscillator (Notes 9, 11)
External Oscillator (Notes 9, 10)
(Note 8)
q
q
q
q
q
q
q
q
q
q
q
q
q
q
q
TI I G CHARACTERISTICS
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
= 2.7V 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 an external conversion clock source
with f
EOSC
= 139,800Hz 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 precise analog input voltage. Maximum specifications are limited by
the LSB step size (V
REF
/2
16
) and the single shot measurement. Typical
specifications are measured from the center of the quantization band.
Note 7:
F
O
= GND (internal oscillator) or f
EOSC
= 139,800Hz
±2%
(external oscillator).
Note 8:
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.
UW
CONDITIONS
q
q
q
q
q
MIN
2.56
0.25
0.25
143.8
TYP
MAX
2000
390
390
UNITS
kHz
µs
µs
ms
ms
kHz
kHz
146.7
149.6
20510/f
EOSC
(in kHz)
17.5
f
EOSC
/8
45
250
250
1.06
55
2000
%
kHz
ns
ns
1.09
1.11
152/f
EOSC
(in kHz)
19/f
ESCK
(in kHz)
200
200
200
220
ms
ms
ms
ns
ns
ns
ns
ns
ns
ns
0
0
0
50
15
50
50
ns
Note 9:
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 10:
The external oscillator is connected to the F
O
pin. The external
oscillator frequency, f
EOSC
, is expressed in kHz.
Note 11:
The converter uses the internal oscillator.
F
O
= 0V.
Note 12:
1.45µV RMS noise is independent of V
REF
. Since the noise
performance is limited by the quantization, lowering V
REF
improves the
effective resolution.
Note 13:
Guaranteed by design and test correlation.
Note 14:
The low sleep mode current is valid only when CS is high.
Note 15:
These parameters are guaranteed by design over the full
supply and temperature range. Automated testing procedures are
limited by the LSB step size (V
REF
/65,536).
24331fa
5