LTC2436-1
1
24361f
The LTC
2436-1 is a 2-channel differential input mi-
cropower 16-bit No Latency
TM
analog-to-digital con-
verter with an integrated oscillator. It provides 0.5LSB
INL and 800nV RMS noise independent of V
REF
. The two
differential channels convert alternately with a channel
identification included in the conversion result. It uses
delta-sigma technology and provides single conversion
settling of the digital filter. Through a single pin, the
LTC2436-1 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 LTC2436-1 communicates through a flexible 3-wire
digital interface which is compatible with SPI and
MICROWIRE
TM
protocols.
s
Direct Sensor Digitizer
s
Weight Scales
s
Direct Temperature Measurement
s
Gas Analyzers
s
Strain-Gage Transducers
s
Instrumentation
s
Data Acquisition
s
Industrial Process Control
, LTC and LT are registered trademarks of Linear Technology Corporation.
s
2-Channel Differential Input with Automatic
Channel Selection (Ping-Pong)
s
Low Supply Current: 200
A, 4
A in Autosleep
s
Differential Input and Differential Reference with
GND to V
CC
Common Mode Range
s
0.12LSB INL, No Missing Codes
s
0.16LSB Full-Scale Error and 0.006LSB Offset
s
800nV RMS Noise, Independent of V
REF
s
No Latency: Digital Filter Settles in a Single Cycle and
Each Channel Conversion is Accurate
s
Internal Oscillator--No External Components
Required
s
87dB Min, 50Hz and 60Hz Notch Filter
s
Narrow SSOP-16 Package
s
Single Supply 2.7V to 5.5V Operation
s
Pin Compatible with the 24-Bit LTC2412
2-Channel Differential Input
16-Bit No Latency
ADC
No Latency
is a trademark of Linear Technology Corporation.
MICROWIRE is a trademark of National Semiconductor Corporation.
Effective Resolution vs V
REF
DESCRIPTIO
U
FEATURES
APPLICATIO S
U
TYPICAL APPLICATIO
U
V
CC
REF
+
F
O
CH0
+
CH0
SCK
REF
CH1
+
SDO
GND
CS
1
14
4
13
3
5
THERMOCOUPLE
6
CH1
7
12
8, 9, 10, 15, 16
11
24361 TA01
2
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/SIMULTANEOUS
50Hz/60Hz REJECTION
3-WIRE
SPI INTERFACE
1
F
(100mV)
4.9k
100
5V REF
LTC2436-1
V
REF
(V)
0
*COMBINES EFFECTS OF PEAK-TO-PEAK NOISE
AND 16-BIT STEP SIZE (V
REF
/2
16
)
0
EFFECTIVE RESOLUTION (
V)*
10
30
40
50
2
4
5
90
24361 TA02
20
1
3
60
70
80
LTC2436-1
2
24361f
(Notes 1, 2)
ORDER PART NUMBER
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
LTC2436-1C ............................................ 0
C to 70
C
LTC2436-1I ........................................ 40
C to 85
C
Storage Temperature Range ................. 65
C to 150
C
Lead Temperature (Soldering, 10 sec).................. 300
C
T
JMAX
= 125
C,
JA
= 110
C/W
LTC2436-1CGN
LTC2436-1IGN
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Resolution (No Missing Codes)
0.1V
V
REF
V
CC
, 0.5 V
REF
V
IN
0.5 V
REF
, (Note 5)
q
16
Bits
Integral Nonlinearity
5V
V
CC
5.5V, REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V, (Note 6)
0.06
LSB
5V
V
CC
5.5V, REF
+
= 5V, REF
= GND, V
INCM
= 2.5V, (Note 6)
q
0.12
3
LSB
REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V, (Note 6)
0.30
LSB
Offset Error
2.5V
REF
+
V
CC
, REF
= GND,
q
0.006
1
LSB
GND
IN
+
= IN
V
CC
, (Note 13)
Offset Error Drift
2.5V
REF
+
V
CC
, REF
= GND,
10
nV/
C
GND
IN
+
= IN
V
CC
Positive Full-Scale Error
2.5V
REF
+
V
CC
, REF
= GND,
q
0.16
3
LSB
IN
+
= 0.75REF
+
, IN
= 0.25 REF
+
Positive Full-Scale Error Drift
2.5V
REF
+
V
CC
, REF
= GND,
0.03
ppm of V
REF
/
C
IN
+
= 0.75REF
+
, IN
= 0.25 REF
+
Negative Full-Scale Error
2.5V
REF
+
V
CC
, REF
= GND,
q
0.16
3
LSB
IN
+
= 0.25 REF
+
, IN
= 0.75 REF
+
Negative Full-Scale Error Drift
2.5V
REF
+
V
CC
, REF
= GND,
0.03
ppm of V
REF
/
C
IN
+
= 0.25 REF
+
, IN
= 0.75 REF
+
Total Unadjusted Error
5V
V
CC
5.5V, REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V
0.20
3
LSB
5V
V
CC
5.5V, REF
+
= 5V, REF
= GND, V
INCM
= 2.5V
0.20
3
LSB
REF
+
= 2.5V, REF
= GND, V
INCM
= 1.25V, (Note 6)
0.25
3
LSB
Output Noise
5V
V
CC
5.5V, REF
+
= 5V, REF
= GND,
0.8
V
RMS
GND
IN
= IN
+
V
CC
, (Note 13)
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Notes 3, 4)
GN PART MARKING
24361
24361I
TOP VIEW
GN PACKAGE
16-LEAD PLASTIC SSOP
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
CC
REF
+
REF
CH0
+
CH0
CH1
+
CH1
GND
GND
GND
F
O
SCK
SDO
CS
GND
GND
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
ELECTRICAL CHARACTERISTICS
LTC2436-1
3
24361f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
IN
+
Absolute/Common Mode IN
+
Voltage
q
GND 0.3
V
CC
+ 0.3
V
IN
Absolute/Common Mode IN
Voltage
q
GND 0.3
V
CC
+ 0.3
V
V
IN
Input Differential Voltage Range
q
V
REF
/2
V
REF
/2
V
(IN
+
IN
)
REF
+
Absolute/Common Mode REF
+
Voltage
q
0.1
V
CC
V
REF
Absolute/Common Mode REF
Voltage
q
GND
V
CC
0.1
V
V
REF
Reference Differential Voltage Range
q
0.1
V
CC
V
(REF
+
REF
)
C
S
(IN
+
)
IN
+
Sampling Capacitance
18
pF
C
S
(IN
)
IN
Sampling Capacitance
18
pF
C
S
(REF
+
)
REF
+
Sampling Capacitance
18
pF
C
S
(REF
)
REF
Sampling Capacitance
18
pF
I
DC_LEAK
(IN
+
)
IN
+
DC Leakage Current
CS = V
CC
= 5V, IN
+
= GND
q
10
1
10
nA
I
DC_LEAK
(IN
)
IN
DC Leakage Current
CS = V
CC
= 5V, IN
= 5.5V
q
10
1
10
nA
I
DC_LEAK
(REF
+
)
REF
+
DC Leakage Current
CS = V
CC
= 5V, REF
+
= 5.5V
q
10
1
10
nA
I
DC_LEAK
(REF
)
REF
DC Leakage Current
CS = V
CC
= 5V, REF
= GND
q
10
1
10
nA
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Note 3)
The
q
denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
C. (Notes 3, 4)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Common Mode Rejection DC
2.5V
REF
+
V
CC
, REF
= GND,
q
130
140
dB
GND
IN
= IN
+
V
CC
(Note 5)
Input Common Mode Rejection
2.5V
REF
+
V
CC
, REF
= GND,
q
140
dB
49Hz to 61.2Hz
GND
IN
= IN
+
V
CC
, (Notes 5, 7)
Input Normal Mode Rejection
(Note 5, 7)
q
87
dB
49Hz to 61.2Hz
Reference Common Mode
2.5V
REF
+
V
CC
, GND
REF
2.5V,
q
130
140
dB
Rejection DC
V
REF
= 2.5V, IN
= IN
+
= GND (Note 5)
Power Supply Rejection, DC
REF
+
= 2.5V, REF
= GND, IN
= IN
+
= GND
120
dB
Power Supply Rejection,
REF
+
= 2.5V, REF
= GND, IN
= IN
+
= GND, (Note 7)
120
dB
Simultaneous 50Hz/60Hz
2%
CO VERTER CHARACTERISTICS
U
A ALOG I PUT A D REFERE CE
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LTC2436-1
4
24361f
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
CC
Supply Voltage
q
2.7
5.5
V
I
CC
Supply Current
Conversion Mode
CS = 0V (Note 14)
q
200
300
A
Sleep Mode
CS = V
CC
(Notes 11, 14)
q
4
13
A
Sleep Mode
CS = V
CC
, 2.7V
V
CC
3.3V
2
A
(Notes 11, 14)
The
q
denotes specifications which apply over the full operating temperature range,
otherwise specifications are at T
A
= 25
C. (Note 3)
The
q
denotes specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25
C. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IH
High Level Input Voltage
2.7V
V
CC
5.5V
q
2.5
V
CS, F
O
2.7V
V
CC
3.3V
2.0
V
V
IL
Low Level Input Voltage
4.5V
V
CC
5.5V
q
0.8
V
CS, F
O
2.7V
V
CC
5.5V
0.6
V
V
IH
High Level Input Voltage
2.7V
V
CC
5.5V (Note 8)
q
2.5
V
SCK
2.7V
V
CC
3.3V (Note 8)
2.0
V
V
IL
Low Level Input Voltage
4.5V
V
CC
5.5V (Note 8)
q
0.8
V
SCK
2.7V
V
CC
5.5V (Note 8)
0.6
V
I
IN
Digital Input Current
0V
V
IN
V
CC
q
10
10
A
CS, F
O
I
IN
Digital Input Current
0V
V
IN
V
CC
(Note 8)
q
10
10
A
SCK
C
IN
Digital Input Capacitance
10
pF
CS, F
O
C
IN
Digital Input Capacitance
(Note 8)
10
pF
SCK
V
OH
High Level Output Voltage
I
O
= 800
A
q
V
CC
0.5
V
SDO
V
OL
Low Level Output Voltage
I
O
= 1.6mA
q
0.4
V
SDO
V
OH
High Level Output Voltage
I
O
= 800
A (Note 9)
q
V
CC
0.5
V
SCK
V
OL
Low Level Output Voltage
I
O
= 1.6mA (Note 9)
q
0.4
V
SCK
I
OZ
Hi-Z Output Leakage
q
10
10
A
SDO
DIGITAL I PUTS A D DIGITAL OUTPUTS
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POWER REQUIRE E TS
W
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LTC2436-1
5
24361f
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, IN
+
and IN
are defined as the selected positive
(CH0
+
or CH1
+
) and negative (CH0
or CH1
) input respectively.
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).
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
f
EOSC
External Oscillator Frequency Range
q
2.56
2000
kHz
t
HEO
External Oscillator High Period
q
0.25
390
s
t
LEO
External Oscillator Low Period
q
0.25
390
s
t
CONV
Conversion Time
F
O
= 0V
q
143.8
146.7
149.6
ms
External Oscillator (Note 10)
q
20510/f
EOSC
(in kHz)
ms
f
ISCK
Internal SCK Frequency
Internal Oscillator (Note 9)
17.5
kHz
External Oscillator (Notes 9, 10)
f
EOSC
/8
kHz
D
ISCK
Internal SCK Duty Cycle
(Note 9)
q
45
55
%
f
ESCK
External SCK Frequency Range
(Note 8)
q
2000
kHz
t
LESCK
External SCK Low Period
(Note 8)
q
250
ns
t
HESCK
External SCK High Period
(Note 8)
q
250
ns
t
DOUT_ISCK
Internal SCK 19-Bit Data Output Time
Internal Oscillator (Notes 9, 11)
q
1.06
1.09
1.11
ms
External Oscillator (Notes 9, 10)
q
152/f
EOSC
(in kHz)
ms
t
DOUT_ESCK
External SCK 19-Bit Data Output Time
(Note 8)
q
19/f
ESCK
(in kHz)
ms
t
1
CS
to SDO Low Z
q
0
200
ns
t2
CS
to SDO High Z
q
0
200
ns
t3
CS
to SCK
(Note 9)
q
0
200
ns
t4
CS
to SCK
(Note 8)
q
50
ns
t
KQMAX
SCK
to SDO Valid
q
220
ns
t
KQMIN
SDO Hold After SCK
(Note 5)
q
15
ns
t
5
SCK Set-Up Before CS
q
50
ns
t
6
SCK Hold After CS
q
50
ns
The
q
denotes specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25
C. (Note 3)
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.
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: 800nV 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.
TI I G CHARACTERISTICS
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