LTC2421.pdf 데이터시트 (총 30 페이지) - 파일 다운로드 LTC2421 데이타시트 다운로드

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LTC2421/LTC2422
1-/2-Channel 20-Bit µPower
No Latency ∆ΣTMADCs in MSOP-10
FEATURES
DESCRIPTIO
s 20-Bit ADCs in Tiny MSOP-10 Packages
s 1- or 2-Channel Inputs
s Single Supply 2.7V to 5.5V Operation
s Low Supply Current (200µA) and Auto Shutdown
s Automatic Channel Selection (Ping-Pong) (LTC2422)
s No Latency: Digital Filter Settles in a
Single Conversion Cycle
s 8ppm INL, No Missing Codes
s 4ppm Full-Scale Error
s 0.5ppm Offset
s 1.2ppm Noise
s Zero Scale and Full Scale Set for Reference
and Ground Sensing
s Internal Oscillator—No External Components Required
s 110dB Min, 50Hz/60Hz Notch Filter
s Reference Input Voltage: 0.1V to VCC
s Live Zero—Extended Input Range Accommodates
12.5% Overrange and Underrange
s Pin Compatible with LTC2401/LTC2402
U
APPLICATIO S
s Weight Scales
s Direct Temperature Measurement
s Gas Analyzers
s Strain Gauge Transducers
s Instrumentation
s Data Acquisition
s Industrial Process Control
The LTC®2421/LTC2422 are 1- and 2-channel 2.7V to 5.5V
micropower 20-bit analog-to-digital converters with an
integrated oscillator, 8ppm INL and 1.2ppm RMS noise.
These ultrasmall devices use delta-sigma technology and
a new digital filter architecture that settles in a single cycle.
This eliminates the latency found in conventional ∆Σ
converters and simplifies multiplexed applications.
Through a single pin, the LTC2421/LTC2422 can be
configured for better than 110dB rejection at 50Hz or
60Hz ±2%, or can be driven by an external oscillator for
a user defined rejection frequency in the range 1Hz to
120Hz. The internal oscillator requires no external fre-
quency setting components.
These converters accept an external reference voltage
from 0.1V to VCC. With an extended input conversion
range of –12.5% VREF to 112.5% VREF (VREF = FSSET
ZSSET), the LTC2421/LTC2422 smoothly resolve the off-
set and overrange problems of preceding sensors or
signal conditioning circuits.
The LTC2421/LTC2422 communicate through a 2- or
3-wire digital interface that is compatible with SPI and
MICROWIRETM 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.
TYPICAL APPLICATIO
2.7V TO 5.5V
1µF
REFERENCE VOLTAGE
ZSSET + 0.1V TO VCC
ANALOG INPUT RANGE
ZSSET – 0.12VREF TO
FSSET + 0.12VREF
(VREF = FSSET – ZSSET)
0V TO FSSET – 100mV
1
VCC
10
FO
LTC2422
2
FSSET
9
SCK
3
CH1
SDO 8
4
CH0
CS 7
56
ZSSET GND
VCC
= INTERNAL OSC/50Hz REJECTION
= EXTERNAL CLOCK SOURCE
= INTERNAL OSC/60Hz REJECTION
3-WIRE
SPI INTERFACE
24212 TA01
Pseudo Differential Bridge Digitizer
1
VCC
2 LTC2422
FSSET SCK 9
4
CH0
SDO 8
3
CH1
7
CS
2.7V TO 5.5V
3-WIRE
SPI INTERFACE
5
ZSSET
GND
6
10
FO
INTERNAL OSCILLATOR
60Hz REJECTION
24012TA02
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LTC2421/LTC2422
ABSOLUTE MAXIMUM RATINGS (Notes 1, 2)
Supply Voltage (VCC) to GND .......................– 0.3V to 7V
Analog Input Voltage to GND ....... – 0.3V to (VCC + 0.3V)
Reference Input Voltage to GND .. – 0.3V to (VCC + 0.3V)
Digital Input Voltage to GND ........ – 0.3V to (VCC + 0.3V)
Digital Output Voltage to GND ..... – 0.3V to (VCC + 0.3V)
Operating Temperature Range
LTC2421/LTC2422C ................................ 0°C to 70°C
LTC2421/LTC2422I ............................ – 40°C to 85°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
UW U
PACKAGE/ORDER INFORMATION
VCC 1
FSSET 2
VIN 3
NC 4
ZSSET 5
TOP VIEW
10 FO
9 SCK
8 SDO
7 CS
6 GND
MS10 PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 125°C, θJA = 130°C/W
ORDER PART NUMBER
LTC2421CMS
LTC2421IMS
MS10 PART MARKING
LTUX
LTUY
Consult factory for parts specified with wider operating temperature ranges.
VCC 1
FSSET 2
CH1 3
CH0 4
ZSSET 5
TOP VIEW
10 FO
9 SCK
8 SDO
7 CS
6 GND
MS10 PACKAGE
10-LEAD PLASTIC MSOP
TJMAX = 125°C, θJA = 130°C/W
ORDER PART NUMBER
LTC2422CMS
LTC2422IMS
MS10 PART MARKING
LTUZ
LTVA
CONVERTER CHARACTERISTICS The q denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VREF = FSSET – ZSSET. (Notes 3, 4)
PARAMETER
Resolution
No Missing Codes Resolution
Integral Nonlinearity
Offset Error
Offset Error Drift
Full-Scale Error
Full-Scale Error Drift
Total Unadjusted Error
Output Noise
Normal Mode Rejection 60Hz ±2%
Normal Mode Rejection 50Hz ±2%
Power Supply Rejection, DC
Power Supply Rejection, 60Hz ±2%
Power Supply Rejection, 50Hz ±2%
CONDITIONS
0.1V FSSET VCC, ZSSET = 0V (Note 5)
FSSET = 2.5V, ZSSET = 0V (Note 6)
FSSET = 5V, ZSSET = 0V (Note 6)
2.5V FSSET VCC, ZSSET = 0V
2.5V FSSET VCC, ZSSET = 0V
2.5V FSSET VCC, ZSSET = 0V
2.5V FSSET VCC, ZSSET = 0V
FSSET = 2.5V, ZSSET = 0V
FSSET = 5V, ZSSET = 0V
VIN = 0V (Note 13)
(Note 7)
(Note 8)
FSSET = 2.5V, ZSSET = 0V, VIN = 0V
FSSET = 2.5V, ZSSET = 0V, VIN = 0V, (Notes 7, 15)
FSSET = 2.5V, ZSSET = 0V, VIN = 0V, (Notes 8, 15)
MIN TYP MAX
q 20
q 20
q 4 10
q 8 20
q 0.5 10
0.04
q 4 10
0.04
8
16
6
q 110
130
q 110
130
100
110
110
UNITS
Bits
Bits
ppm of VREF
ppm of VREF
ppm of VREF
ppm of VREF/°C
ppm of VREF
ppm of VREF/°C
ppm of VREF
ppm of VREF
µVRMS
dB
dB
dB
dB
dB
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LTC2421/LTC2422
A ALOG I PUT A D REFERE CE The q denotes specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VREF = FSSET – ZSSET. (Note 3)
SYMBOL
VIN
FSSET
ZSSET
CS(IN)
CS(REF)
IIN(LEAK)
IREF(LEAK)
PARAMETER
Input Voltage Range
Full-Scale Set Range
Zero-Scale Set Range
Input Sampling Capacitance
Reference Sampling Capacitance
Input Leakage Current
Reference Leakage Current
CONDITIONS
(Note 14)
CS = VCC
VREF = 2.5V, CS = VCC
MIN TYP MAX
UNITS
q ZSSET – 0.12VREF FSSET + 0.12VREF
q 0.1 + ZSSET
VCC
q0
FSSET – 0.1
1
V
V
V
pF
1.5 pF
q
–100 1
100
nA
q
– 100
1
100
nA
DIGITAL I PUTS A D DIGITAL OUTPUTS The q denotes specifications which apply over the full
operating temperature range, otherwise specifications are at TA = 25°C. (Note 3)
SYMBOL
VIH
VIL
VIH
VIL
IIN
IIN
CIN
CIN
VOH
VOL
VOH
VOL
IOZ
PARAMETER
High Level Input Voltage
CS, FO
Low Level Input Voltage
CS, FO
High Level Input Voltage
SCK
Low Level Input Voltage
SCK
Digital Input Current
CS, FO
Digital Input Current
SCK
Digital Input Capacitance
CS, FO
Digital Input Capacitance
SCK
High Level Output Voltage
SDO
Low Level Output Voltage
SDO
High Level Output Voltage
SCK
Low Level Output Voltage
SCK
High-Z Output Leakage
SDO
CONDITIONS
2.7V VCC 5.5V
2.7V VCC 3.3V
4.5V VCC 5.5V
2.7V VCC 5.5V
2.7V VCC 5.5V (Note 9)
2.7V VCC 3.3V (Note 9)
4.5V VCC 5.5V (Note 9)
2.7V VCC 5.5V (Note 9)
0V VIN VCC
0V VIN VCC (Note 9)
(Note 9)
IO = – 800µA
IO = 1.6mA
IO = – 800µA (Note 10)
IO = 1.6mA (Note 10)
MIN
q 2.5
2.0
q
q 2.5
2.0
q
q –10
TYP MAX UNITS
V
V
0.8 V
0.6 V
V
V
0.8 V
0.6 V
10 µA
q –10
10 µA
10 pF
10 pF
q VCC – 0.5
q
V
0.4 V
q VCC – 0.5
q
V
0.4 V
q –10
10 µA
POWER REQUIRE E TS The q denotes specifications which apply over the full operating temperature range,
otherwise specifications are at TA = 25°C. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
VCC Supply Voltage
ICC Supply Current
Conversion Mode
Sleep Mode
CS = 0V (Note 12)
CS = VCC (Note 12)
q 2.7
q
q
5.5
200 300
20 30
V
µA
µA
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LTC2421/LTC2422
WU
TI I G CHARACTERISTICS The q denotes specifications which apply over the full operating temperature
range, otherwise specifications are at TA = 25°C. (Note 3)
SYMBOL
fEOSC
tHEO
tLEO
tCONV
fISCK
DISCK
fESCK
tLESCK
tHESCK
tDOUT_ISCK
tDOUT_ESCK
t1
t2
t3
t4
tKQMAX
tKQMIN
t5
t6
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 24-Bit Data Output Time
External SCK 24-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
CONDITIONS
FO = 0V
FO = VCC
External Oscillator (Note 11)
Internal Oscillator (Note 10)
External Oscillator (Notes 10, 11)
(Note 10)
(Note 9)
(Note 9)
(Note 9)
Internal Oscillator (Notes 10, 12)
External Oscillator (Notes 10, 11)
(Note 9)
(Note 10)
(Note 9)
(Note 5)
MIN TYP MAX UNITS
q 2.56
307.2
kHz
q 0.5
390 µs
q 0.5
390 µs
q 130.86 133.53 136.20
q 157.03 160.23 163.44
q 20510/fEOSC (in kHz)
19.2
fEOSC/8
45 55
ms
ms
ms
kHz
kHz
%
q 2000 kHz
q 250
ns
q 250
ns
q 1.23
1.25 1.28
q 192/fEOSC (in kHz)
q 24/fESCK (in kHz)
q0
150
ms
ms
ms
ns
q0
150 ns
q0
150 ns
q 50
ns
q 200 ns
q 15
ns
q 50
ns
q 50 ns
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: VCC = 2.7 to 5.5V unless otherwise specified. Input source
resistance = 0.
Note 4: Internal Conversion Clock source with the FO pin tied
to GND or to VCC or to external conversion clock source with
fEOSC = 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: FO = 0V (internal oscillator) or fEOSC = 153600Hz ±2%
(external oscillator).
Note 8: FO = VCC (internal oscillator) or fEOSC = 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 fESCK 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 CLOAD = 20pF.
Note 11: The external oscillator is connected to the FO pin. The external
oscillator frequency, fEOSC, is expressed in kHz.
Note 12: The converter uses the internal oscillator.
FO = 0V or FO = VCC.
Note 13: The output noise includes the contribution of the internal
calibration operations.
Note 14: VREF = FSSET – ZSSET. The minimum input voltage is limited
to – 0.3V and the maximum to VCC + 0.3V.
Note 15: VCC (DC) = 4.1V, VCC (AC) = 2.8VP-P.
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TYPICAL PERFOR A CE CHARACTERISTICS
LTC2421/LTC2422
Total Unadjusted Error (3V Supply)
10
VCC = 3V
8 VREF = 2.5V
6
4
2
0
–2
–4
–6 TA = –55°C, –45°C, 25°C, 90°C
–8
–10
0
0.5 1.0 1.5 2.0
INPUT VOLTAGE (V)
2.5
24212 G01
Positive Extended Input Range
Total Unadjusted Error (3V Supply)
10
VCC = 3V
8 VREF = 2.5V
6
4
2
0
–2
–4
–6 TA = –55°C, –45°C, 25°C, 90°C
–8
–10
2.50 2.55 2.60 2.65 2.70 2.75 2.80
INPUT VOLTAGE (V)
24212 G04
Negative Extended Input Range
Total Unadjusted Error (5V Supply)
10
VCC = 5V
8 VREF = 5V
6
4
2
TA = 25°C
TA = 90°C
TA = –45°C
TA = –55°C
0
–2
–4
–6
–8
–10
0
–0.05 –0.10 –0.15 –0.20 –0.25 –0.30
INPUT VOLTAGE (V)
24212 G07
INL (3V Supply)
10
VCC = 3V
8 VREF = 2.5V
6
4
2
0
–2
–4
TA = –55°C, –45°C, 25°C, 90°C
–6
–8
–10
0
0.5 1.0 1.5 2.0
INPUT VOLTAGE (V)
2.5
24212 G02
Total Unadjusted Error (5V Supply)
10
VCC = 5V
8 VREF = 5V
6
4
2
0
–2
–4
TA = –55°C, –45°C, 25°C, 90°C
–6
–8
–10
0
1 2 34
INPUT VOLTAGE (V)
5
24212 G05
Positive Extended Input Range
Total Unadjusted Error (5V Supply)
10
VCC = 5V
8 VREF = 5V
6
4
2
0
–2
–4
TA = –55°C
–6
–8 TA = 90°C TA = 25°C
TA = –45°C
–10
5.00 5.05 5.10 5.15 5.20 5.25 5.30
INPUT VOLTAGE (V)
24212 G08
Negative Extended Input Range
Total Unadjusted Error (3V Supply)
10
VCC = 3V
8 VREF = 2.5V
6
TA = 90°C
TA = 25°C
4 TA = –45°C
2
0
–2 TA = –55°C
–4
–6
–8
–10
0
–0.05 –0.10 –0.15 –0.20 –0.25 –0.30
INPUT VOLTAGE (V)
24212 G03
INL (5V Supply)
10
VCC = 5V
8 VREF = 5V
6
4
2
0
–2
–4
TA = –55°C, –45°C, 25°C, 90°C
–6
–8
–10
0
1 2 34
INPUT VOLTAGE (V)
5
24212 G06
Offset Error vs Reference Voltage
150
VCC = 5V
TA = 25°C
120
90
60
30
0
01 2 345
REFERENCE VOLTAGE (V)
24212 G09
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