inates 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 LTC2495 includes programmable gain, a high accuracy
temperature sensor, and an integrated oscillator. This device
can be configured to measure an external signal (from com-
binations of 16 analog input channels operating in single-
ended or differential modes) or its internal temperature
sensor. The integrated temperature sensor offers 1/2°C
resolution and 2°C absolute accuracy. The LTC2495 can
be configured to provide a programmable gain from 1 to
256 in 8 steps.
The LTC2495 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 en-
ables optional external amplifiers to be shared between all
analog inputs and auto calibration continuously removes
their associated offset and drift.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
No Latency
DS
and Easy Drive are trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
n
n
n
n
n
n
n
n
n
n
n
n
n
n
Up to Eight Differential or 16 Single-Ended Inputs
Easy Drive
TM
Technology Enables Rail-to-Rail
Inputs with Zero Differential Input Current
Directly Digitizes High Impedance Sensors with
Full Accuracy
2-Wire I
2
C Interface with 27 Addresses Plus One
Global Address for Synchronization
600nV RMS Noise
Programmable Gain from 1 to 256
Integrated High Accuracy Temperature Sensor
GND to V
CC
Input/Reference Common Mode Range
Programmable 50Hz, 60Hz, or Simultaneous
50Hz/60Hz Rejection Mode
2ppm INL, No Missing Codes
1ppm Offset and 15ppm Full-Scale Error
2x Speed/Reduced Power Mode (15Hz Using Internal
Oscillator and 80µA at 7.5Hz Output)
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
Tiny 5mm
×
7mm QFN Package
applications
n
n
n
n
Direct Sensor Digitizer
Direct Temperature Measurement
Instrumentation
Industrial Process Control
typical application
Data Acquisition System with Temperature Compensation
2.7V TO 5.5V
CH0
CH1
•
•
•
CH7 16-CHANNEL
MUX
CH8
•
•
•
CH15
COM
TEMPERATURE
SENSOR
MUXOUT/
ADCIN
IN
+
REF
+
16-BIT
∆Σ
ADC
WITH EASY DRIVE
IN
–
REF
–
1.7k
SDA
SCL
f
O
OSC
2495 TA01
Built-In High Performance Temperature Sensor
5
4
3
0.1µF
10µF
ABSOLUTE ERROR (°C)
V
CC
2
1
0
–1
–2
–3
–4
–5
–55
–30
–5
20
45
70
TEMPERATURE (°C)
95
120
2495 TA02
2-WIRE
I
2
C INTERFACE
MUXOUT/
ADCIN
2495fe
For more information
www.linear.com/LTC2495
1
LTC2495
absolute MaxiMuM ratings
(Notes 1, 2)
pin conFiguration
TOP VIEW
GND
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
CA2
CA1
CA0
f
O
38 37 36 35 34 33 32
GND 1
SCL 2
SDA 3
GND 4
NC 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-CH15, COM).....................–0.3V to (V
CC
+ 0.3V)
REF
+
, REF
–
...............................–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
LTC2495C ................................................ 0°C to 70°C
LTC2495I .............................................–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 inForMation
LEAD FREE FINISH
LTC2495CUHF#PBF
LTC2495IUHF#PBF
TAPE AND REEL
LTC2495CUHF#TRPBF
LTC2495IUHF#TRPBF
PART MARKING*
2495
2495
PACKAGE DESCRIPTION
38-Lead (5mm
×
7mm) Plastic QFN
38-Lead (5mm
×
7mm) Plastic QFN
TEMPERATURE RANGE
0°C to 70°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
electrical characteristics (norMal speeD)
PARAMETER
Resolution (No Missing Codes)
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
CONDITIONS
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 13)
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
l
l
l
l
l
The
l
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
16
2
1
0.5
10
32
0.1
32
0.1
20
5
TYP
MAX
UNITS
Bits
ppm of V
REF
ppm of V
REF
µV
nV/°C
ppm of V
REF
ppm of V
REF
/°C
ppm of V
REF
ppm of V
REF
/°C
2495fe
2
For more information
www.linear.com/LTC2495
LTC2495
electrical characteristics (norMal speeD)
PARAMETER
Total Unadjusted Error
CONDITIONS
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
2.7V < V
CC
< 5.5V, 2.5V ≤ V
REF
≤ V
CC
,
GND ≤ IN
+
= IN
–
≤ V
CC
(Note 12)
T
A
= 27°C (Note 13)
l
The
l
denotes the specifications which
apply over the full operating temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
TYP
15
15
15
0.6
27.8
1
28.0
93.5
256
28.2
MAX
UNITS
ppm of V
REF
ppm of V
REF
ppm of V
REF
µV
RMS
mV
µV/°C
Output Noise
Internal PTAT Signal
Internal PTAT Temperature Coefficient
Programmable Gain
electrical characteristics (2x speeD)
PARAMETER
Resolution (No Missing Codes)
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
Output Noise
Programmable Gain
CONDITIONS
0.1V ≤ V
REF
≤ V
CC
, –FS ≤ V
IN
≤ +FS (Note 5)
The
l
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Notes 3, 4)
MIN
16
l
l
TYP
2
1
0.2
100
MAX
20
2
32
UNITS
Bits
ppm of V
REF
ppm of V
REF
mV
nV/°C
ppm of V
REF
ppm of V
REF
/°C
ppm of V
REF
ppm of V
REF
/°C
µV
RMS
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 13)
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
= 5V, GND ≤ IN
+
= IN
–
≤ V
CC
l
0.1
l
32
0.1
0.85
l
1
128
converter characteristics
PARAMETER
Input Common Mode Rejection DC
Input Common Mode Rejection 50Hz ±2%
Input Common Mode Rejection 60Hz ±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%, 60Hz ±2%
CONDITIONS
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
MIN
l
l
l
l
l
l
l
TYP
MAX
UNITS
dB
dB
dB
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, 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, 8, 9)
140
140
140
110
110
87
120
140
120
120
120
120
dB
dB
dB
dB
dB
dB
analog input anD reFerence
SYMBOL
IN
+
IN
–
PARAMETER
The
l
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
UNITS
V
V
2495fe
Absolute/Common Mode IN
+
Voltage
(IN
+
Corresponds to the Selected Positive Input Channel)
Absolute/Common Mode IN
–
Voltage
(IN
–
Corresponds to the Selected Negative Input Channel or COM)
For more information
www.linear.com/LTC2495
3
LTC2495
analog input anD reFerence
SYMBOL
V
IN
FS
LSB
REF
+
REF
–
V
REF
CS(IN
+
)
CS(IN
–
)
CS(V
REF
)
I
DC_LEAK(IN+)
I
DC_LEAK(IN–)
PARAMETER
Input Voltage Range (IN
+
– IN
–
)
Full-Scale of the 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
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
Differential/Single-Ended
Differential/Single-Ended
l
l
l
l
l
l
MIN
–FS
0.5V
REF
/Gain
FS/2
16
0.1
GND
0.1
TYP
MAX
+FS
UNITS
V
V
V
CC
+
– 0.1V
REF
V
CC
11
11
11
V
V
V
pF
pF
pF
–10
–10
–100
–100
1
1
1
1
50
120
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
i
2
c inputs anD Digital outputs
SYMBOL PARAMETER
V
IH
V
IL
V
IHA
V
ILA
R
INH
R
INL
R
INF
I
I
V
HYS
V
OL
t
OF
I
IN
C
CAX
High Level Input Voltage
Low Level Input Voltage
The
l
denotes the specifications which apply over the full
operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
l
l
l
l
l
l
l
l
MIN
0.7V
CC
TYP
MAX
0.3V
CC
0.05V
CC
UNITS
V
V
V
V
kW
kW
MW
Low Level Input Voltage for Address Pins CA0, CA1, CA2 and Pin f
O
High Level Input Voltage for Address Pins CA0, CA1, CA2
Resistance from CA0, CA1, CA2 to V
CC
to Set Chip Address Bit to 1
Resistance from CA0, CA1, CA2 to GND to Set Chip Address Bit to 0
Resistance from CA0, CA1, CA2 to GND or V
CC
to Set Chip Address Bit
to Float
Digital Input Current (f
O
)
Hysteresis of Schmitt Trigger Inputs
Low Level Output Voltage (SDA)
Output Fall Time V
IH(MIN)
to V
IL(MAX)
Input Leakage (SDA/SCL)
External Capacitative Load on Chip Address Pins (CA0, CA1, CA2) for
Valid Float
(Note 5)
I = 3mA
Bus Load C
B
10pF to
400pF (Note 14)
0.1V
CC
≤ V
IN
≤ 0.9 • V
CC
0.95V
CC
10
10
2
–10
0.05V
CC
0.4
20 + 0.1C
B
250
1
10
10
µA
V
V
ns
µA
pF
l
l
l
l
l
power requireMents
SYMBOL
V
CC
I
CC
PARAMETER
Supply Voltage
Supply Current
The
l
denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at T
A
= 25°C. (Note 3)
CONDITIONS
l
MIN
2.7
l
l
l
TYP
160
200
1
MAX
5.5
275
300
2
UNITS
V
µA
µA
µA
2495fe
Conversion Current (Note 11)
Temperature Measurement (Note 11)
Sleep Mode (Note 11)
4
For more information
www.linear.com/LTC2495
LTC2495
Digital inputs anD Digital outputs
SYMBOL
f
EOSC
t
HEO
t
LEO
t
CONV_1
PARAMETER
External Oscillator Frequency Range
External Oscillator High Period
External Oscillator Low Period
Conversion Time for 1x Speed Mode
50Hz Mode
60Hz Mode
Simultaneous 50Hz/60Hz Mode
External Oscillator (Note 10)
50Hz Mode
60Hz Mode
Simultaneous 50Hz/60Hz Mode
External Oscillator (Note 10)
CONDITIONS
(Note 16)
l
l
l
l
l
l
l
l
l
The
l
denotes the specifications which apply over the
full operating temperature range, otherwise specifications are at T
A
= 25°C. (Note 3)
MIN
10
0.125
0.125
157.2
131
144.1
78.7
65.6
72.2
160.3
133.6
146.9
41036/f
EOSC
(in kHz)
80.3
66.9
73.6
TYP
MAX
1000
100
100
163.5
136.3
149.9
81.9
68.2
75.1
UNITS
kHz
µs
µs
ms
ms
ms
ms
ms
ms
ms
ms
t
CONV_2
Conversion Time for 2x Speed Mode
20556/f
EOSC
(in kHz)
i
2
c tiMing characteristics
SYMBOL
f
SCL
t
HD(SDA)
t
LOW
t
HIGH
t
SU(STA)
t
HD(DAT)
t
SU(DAT)
t
r
t
f
t
SU(STO)
t
BUF
PARAMETER
SCL Clock Frequency
Hold Time (Repeated) START Condition
LOW Period of the SCL Pin
HIGH Period of the SCL Pin
Set-Up Time for a Repeated START Condition
Data Hold Time
Data Set-Up Time
Rise Time for SDA Signals
Fall Time for SDA Signals
Set-Up Time for STOP Condition
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. (Note 3, 15)
CONDITIONS
l
l
l
l
l
l
l
MIN
0
0.6
1.3
0.6
0.6
0
100
20 + 0.1C
B
20 + 0.1C
B
0.6
1.3
TYP
MAX
400
UNITS
kHz
µs
µs
µs
µs
0.9
300
300
µs
ns
ns
ns
µs
µs
(Note 14)
(Note 14)
l
l
l
l
Bus Free Time Between a Second START Condition
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:
Unless otherwise specified: V
CC
= 2.7V to 5.5V
V
REFCM
= V
REF
/2, F
S
= 0.5V
REF
/Gain
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 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:
50Hz mode (internal oscillator) or f
EOSC
= 256kHz ±2% (external oscillator).
Note 8:
60Hz mode (internal oscillator) or f
EOSC
= 307.2kHz ±2% (external oscillator).
Note 9:
Simultaneous 50Hz/60Hz mode (internal oscillator) or f
EOSC
=
280kHz ±2% (external oscillator).
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 its internal oscillator.
Note 12:
The output noise includes the contribution of the internal
calibration operations.
Note 13:
Guaranteed by design and test correlation.
Note 14:
C
B
= capacitance of one bus line in pF (10pF ≤ C
B
≤ 400pF).
Note 15:
All values refer to V
IH(MIN)
and V
IL(MAX)
levels.
Note 16:
Refer to Applications Information section for Performance vs
语音作为自然的人机接口，可以使车载导航系统实现更安全、更人性化的操作。通过国内外车载导航系统的功能对比可知，支持语音交互是车载导航系统的一个发展趋势。另外，市场信息服务公司J.D Power and Associates的调研数据也表明，56％的消费者更倾向于选择声控的导航系统。因此，开发车载语音导航系统是很有意义的。目前，国内已经具备开发车载语音导航系统的技术基础，特别是文语转换TTS技术...[详细]
中风发生时，一切都是以秒来计算的。延误治疗可能导致大脑重大损伤。伦敦大学医学院的一位博士Alistair McEwan已经获得行为医学研究所(Action Medical Research)的同意，为急救人员开发一种无线诊断系统来减少时间延误。感谢抗血栓药物，一些病人在病情发作的三个小时之内可以完全恢复。但出血也会导致中风。医生在治疗之前需要确定发病原因，因为不适当的服用抗血栓药物会加重损害。...[详细]
据国外媒体报道，英特尔将处理器价格最高下调31%，但降价整体来说是有限的。 根据英特尔7月20日的新定价单来看，Core 2 Duo E8500(3.16GHz)价格降幅最高，从266美元下调至183美元，降幅达31%；Core 2 Duo E7200 (2.53GHz)次之，从133美元下调至113美元，降幅15%。 其他降价处理器还有四核Q6600(2.4GHz)，从224美...[详细]
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