LTC2436-1
2-Channel Differential Input
16-Bit No Latency
∆Σ
ADC
FEATURES
s
s
s
DESCRIPTIO
s
s
s
s
s
s
s
s
s
2-Channel Differential Input with Automatic
Channel Selection (Ping-Pong)
Low Supply Current: 200µA, 4µA in Autosleep
Differential Input and Differential Reference with
GND to V
CC
Common Mode Range
0.12LSB INL, No Missing Codes
0.16LSB Full-Scale Error and 0.006LSB Offset
800nV RMS Noise, Independent of V
REF
No Latency: Digital Filter Settles in a Single Cycle and
Each Channel Conversion is Accurate
Internal Oscillator—No External Components
Required
87dB Min, 50Hz and 60Hz Notch Filter
Narrow SSOP-16 Package
Single Supply 2.7V to 5.5V Operation
Pin Compatible with the 24-Bit LTC2412
The LTC
®
2436-1 is a 2-channel differential input mi-
cropower 16-bit No Latency
∆Σ
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.
, 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
s
s
s
s
s
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
4
V
CC
EFFECTIVE RESOLUTION (µV)*
F
O
14
REF
+
CH0
+
LTC2436-1
CH0
–
REF
–
CH1
+
CH1
–
GND
24361 TA01
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/SIMULTANEOUS
50Hz/60Hz REJECTION
50
40
30
20
10
0
0
5
4
3
2
V
REF
(V)
24361 TA02
*COMBINES EFFECTS OF PEAK-TO-PEAK NOISE
AND 16-BIT STEP SIZE (V
REF
/2
16
)
1
5
THERMOCOUPLE
3
6
7
8, 9, 10, 15, 16
SCK
SDO
CS
13
12
11
3-WIRE
SPI INTERFACE
U
Effective Resolution vs V
REF
90
80
70
60
U
U
24361f
1
LTC2436-1
ABSOLUTE
(Notes 1, 2)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW
V
CC
REF
+
REF
–
CH0
+
CH0
–
CH1
+
CH1
–
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 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
ORDER PART NUMBER
LTC2436-1CGN
LTC2436-1IGN
GN PART MARKING
24361
24361I
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
PARAMETER
Resolution (No Missing Codes)
Integral Nonlinearity
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
0.06
0.12
0.30
0.006
10
MAX
UNITS
Bits
LSB
LSB
LSB
LSB
nV/°C
0.1V
≤
V
REF
≤
V
CC
, –0.5 • V
REF
≤
V
IN
≤
0.5 • V
REF
, (Note 5)
16
3
1
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 13)
q
q
q
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
0.16
0.03
0.16
0.03
0.20
0.20
0.25
0.8
3
ppm of V
REF
/°C
3
LSB
ppm of V
REF
/°C
3
3
3
LSB
LSB
LSB
µV
RMS
Output Noise
2
U
LSB
24361f
W
U
U
W W
W
LTC2436-1
CO VERTER CHARACTERISTICS
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
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
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
TYP
140
MAX
UNITS
dB
dB
dB
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)
130
140
87
130
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
18
18
18
18
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
–10
–10
–10
–10
1
1
1
1
10
10
10
10
nA
nA
nA
nA
24361f
3
LTC2436-1
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
24361f
LTC2436-1
TI I G CHARACTERISTICS
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
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
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).
UW
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 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.
24361f
5
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