IC ADC 24BIT HI SPEED 38QFN

LTC2449CUHF

Manufacturer Part NumberLTC2449CUHF
DescriptionIC ADC 24BIT HI SPEED 38QFN
ManufacturerLinear Technology
LTC2449CUHF datasheet
 


Specifications of LTC2449CUHF

Number Of Bits24Sampling Rate (per Second)8k
Data InterfaceMICROWIRE™, Serial, SPI™Number Of Converters1
Power Dissipation (max)40mWVoltage Supply SourceSingle Supply
Operating Temperature0°C ~ 70°CMounting TypeSurface Mount
Package / Case38-WFQFN, Exposed PadLead Free Status / RoHS StatusContains lead / RoHS non-compliant
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FEATURES
Up to 8 Differential or 16 Single-Ended Input
Channels
Up to 8kHz Output Rate
Up to 4kHz Multiplexing Rate
Selectable Speed/Resolution
2µV
Noise at 1.76kHz Output Rate
RMS
200nV
Noise at 13.8Hz Output Rate with
RMS
Simultaneous 50/60Hz Rejection
Guaranteed Modulator Stability and Lock-Up
Immunity for any Input and Reference Conditions
0.0005% INL, No Missing Codes
Autosleep Enables 20µA Operation at 6.9Hz
< 5µV Offset (4.5V < V
< 5.5V, – 40°C to 85°C)
CC
Differential Input and Differential Reference with
GND to V
Common Mode Range
CC
No Latency Mode, Each Conversion is Accurate Even
After a New Channel is Selected
Internal Oscillator—No External Components
LTC2445/LTC2449 Include MUXOUT/ADCIN for
External Buffering or Gain
Tiny QFN 5mm x 7mm Package
U
APPLICATIO S
High Speed Multiplexing
Weight Scales
Auto Ranging 6-Digit DVMs
Direct Temperature Measurement
High Speed Data Acquisition
U
TYPICAL APPLICATIO
Simple 24-Bit Variable Speed Data Acquisition System
CH0
CH1
CH7
16-CHANNEL
+
CH8
MUX
THERMOCOUPLE
CH15
COM
REF
GND
8-/16-Channel ∆Σ ADCs with
Selectable Speed/Resolution
DESCRIPTIO
®
The LTC
2444/LTC2445/LTC2448/LTC2449 are 8-/16-
channel (4-/8-differential) high speed 24-bit No Latency
∆Σ
TM
ADCs. They use a proprietary delta-sigma architec-
ture enabling variable speed/resolution. Through a simple
4-wire serial interface, ten speed/resolution combinations
6.9Hz/280nV
oscillator) can be selected with no latency between con-
version results or shift in DC accuracy (offset, full-scale,
linearity, drift). Additionally, a 2X speed mode can be
selected enabling output rates up to 7kHz (8kHz if an
external oscillator is used) with one cycle latency.
Any combination of single-ended or differential inputs can
be selected with a common mode input range from ground
to V
, independent of V
CC
speed mode the first conversion following a new speed,
resolution, or channel selection is valid. Since there is no
settling time between conversions, all 8 differential chan-
nels can be scanned at a rate of 500Hz. At the conclusion
of each conversion, the converter is internally reset elimi-
nating any memory effects between successive conver-
sions and assuring stability of the high order delta-sigma
modulator.
, LTC and LT are registered trademarks of Linear Technology Corporation.
No Latency ∆Σ is a trademark of Linear Technology Corporation.
4.5V TO 5.5V
1µF
+
REF
V
CC
= EXTERNAL OSCILLATOR
= INTERNAL OSCILLATOR
F
O
(SIMULTANEOUS 50Hz/60Hz
REJECTION AT 6.9Hz OUTPUT RATE)
SDI
VARIABLE SPEED/
SCK
RESOLUTION
4-WIRE
DIFFERENTIAL
SDO
SPI INTERFACE
24-BIT ∆Σ ADC
CS
LTC2448
2444 TA01
LTC2444/LTC2445/
LTC2448/LTC2449
24-Bit High Speed
U
to 3.5kHz/25µV
(4kHz with external
RMS
RMS
. While operating in the 1X
REF
LTC2444/LTC2448
Speed vs RMS Noise
100
V
= 5V
CC
V
= 5V
REF
+
V
= V
= 0V
IN
IN
2X SPEED MODE
NO LATENCY MODE
10
2.8µV AT 880Hz
280nV AT 6.9Hz
(50/60Hz REJECTION)
1
0.1
1
10
100
1000
CONVERSION RATE (Hz)
10000
2440 TA02
2444589fb
1

LTC2449CUHF Summary of contents

  • Page 1

    ... LTC and LT are registered trademarks of Linear Technology Corporation. No Latency ∆Σ trademark of Linear Technology Corporation. 4.5V TO 5.5V 1µF ...

  • Page 2

    ... ADCINN 25 ADCINP 24 MUXOUTP CH7 QFN PART MARKING* 21 CH6 2445 UHF PACKAGE = 125°C, θ = 34°C/W JA TOP VIEW ORDER PART NUMBER 31 GND – 30 REF LTC2449CUHF + REF 29 LTC2449IUHF MUXOUTN ADCINN ADCINP 24 MUXOUTP 23 CH15 22 CH14 21 CH13 QFN PART MARKING* 20 CH12 2449 UHF PACKAGE = 125°C, θ ...

  • Page 3

    ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T PARAMETER CONDITIONS 0.1V ≤ V Resolution (No Missing Codes) Integral Nonlinearity V = 5V, REF CC + REF = 2.5V, REF 2.5V ≤ REF Offset Error GND ≤ IN 2.5V ≤ ...

  • Page 4

    LTC2444/LTC2445/ LTC2448/LTC2449 U U DIGITAL I PUTS A D DIGITAL OUTPUTS operating temperature range, otherwise specifications are at T SYMBOL PARAMETER V High Level Input Voltage IH CS Low Level Input Voltage IL CS ...

  • Page 5

    CHARACTERISTICS range, otherwise specifications are at T SYMBOL PARAMETER D Internal SCK Duty Cycle ISCK f External SCK Frequency Range ESCK t External SCK Low Period LESCK t External SCK High Period HESCK t Internal ...

  • Page 6

    LTC2444/LTC2445/ LTC2448/LTC2449 CTIO S GND – 0. 0.3V. Within these limits, the two CC + – selected inputs (IN and IN ) provide a bipolar input range + – ...

  • Page 7

    CTIO AL BLOCK DIAGRA V CC GND + REF – REF CH0 CH1 • • MUX • CH15 COM TEST CIRCUITS SDO 1.69k C Hi Hi-Z OH ...

  • Page 8

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Initially, the LTC2444/LTC2445/LTC2448/LTC2449 per- form a conversion. Once the conversion is complete, the device enters the sleep state. While in this sleep state, power consumption is reduced below 10µA. The part ...

  • Page 9

    U U APPLICATIO S I FOR ATIO LTC2448/LTC2449 convert the bipolar differential input + – + signal – IN (where IN and IN IN input channels), from – – 0.5 • – where ...

  • Page 10

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO SCK SDI 1 0 BIT 31 BIT 30 Hi-Z SDO EOC “0” BUSY Figure 3. SDI Speed/Resolution, Channel Selection, and Data Output Timing first falling edge of SCK. ...

  • Page 11

    U U APPLICATIO S I FOR ATIO external SCK mode is selected by tying EXT (Pin 3) LOW for external SCK and HIGH for internal SCK. Serial Data Output (SDO) The serial data output pin, SDO (Pin 37), provides the ...

  • Page 12

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Table 3. Channel Selection for the LTC2448/LTC2449 MUX ADDRESS ODD/ SGL SIGN – ...

  • Page 13

    U U APPLICATIO S I FOR ATIO Table 4. Channel Selection for the LTC2444/LTC2445 (Bit A2 Should Always Be 0) MUX ADDRESS ODD/ SGL SIGN * ...

  • Page 14

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Table 5. LTC2444/LTC2445/LTC2448/LTC2449 Speed/Resolution Selection OSR3 OSR2 OSR1 OSR0 TWOX INTERNAL EXTERNAL ...

  • Page 15

    U U APPLICATIO S I FOR ATIO Speed Multiplier Mode In addition to selecting the speed/resolution, a speed multiplier mode is used to double the output rate while maintaining the selected resolution. The last bit of the 5-bit speed/resolution control ...

  • Page 16

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO External Serial Clock, Single Cycle Operation (SPI/MICROWIRE Compatible) This timing mode uses an external serial clock to shift out the conversion result and a CS signal to monitor and control the ...

  • Page 17

    U U APPLICATIO S I FOR ATIO As described above, CS may be pulled LOW at any time in order to monitor the conversion status on the SDO pin. Typically, CS remains LOW during the data output state. However, the ...

  • Page 18

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO External Serial Clock, 2-Wire I/O This timing mode utilizes a 2-wire serial I/O interface. The conversion result is shifted out of the device by an exter- nally generated serial clock (SCK) ...

  • Page 19

    U U APPLICATIO S I FOR ATIO Internal Serial Clock, Single Cycle Operation This timing mode uses an internal serial clock to shift out the conversion result and a CS signal to monitor and control the state of the conversion ...

  • Page 20

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO If CS remains LOW longer than t EOCtest edge of SCK will occur and the conversion result is serially shifted out of the SDO pin. The data output cycle begins on ...

  • Page 21

    U U APPLICATIO S I FOR ATIO Internal Serial Clock, 2-Wire I/O, Continuous Conversion This timing mode uses a 2-wire, all output (SCK and SDO) interface. The conversion result is shifted out of the device by an internally generated serial ...

  • Page 22

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Normal Mode Rejection and Antialiasing One of the advantages delta-sigma ADCs offer over con- ventional ADCs is on-chip digital filtering. Combined with a large oversampling ratio, the LTC2444/LTC2445/ LTC2448/LTC2449 significantly simplify ...

  • Page 23

    U U APPLICATIO S I FOR ATIO grounded set by the on-chip oscillator 1.8MHz ±5% (over supply and temperature variations OSR of 32,768, the first NULL latency ...

  • Page 24

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Reduced Power Operation In addition to adjusting the speed/resolution of the LTC2444/LTC2445/LTC2448/LTC2449, the speed/reso- lution/power dissipation may also be adjusted using the automatic sleep mode. During the conversion cycle, the LTC2444/LTC2445/LTC2448/LTC2449 ...

  • Page 25

    U U APPLICATIO S I FOR ATIO Input Bandwidth and Frequency Rejection The combined effect of the internal SINC the digital and analog autocalibration circuits determines the LTC2444/LTC2445/LTC2448/LTC2449 input band- width and rejection characteristics. The digital filter’s response can be ...

  • Page 26

    LTC2444/LTC2445/ LTC2448/LTC2449 U U APPLICATIO S I FOR ATIO Example amplifier (e.g. LT1219) driving the input of an LTC2444/LTC2445/LTC2448/LTC2449 has wideband noise of 33nV/√Hz, band-limited to 1.8MHz, the total noise entering the ADC input is: 33nV/√Hz • √1.8MHz ...

  • Page 27

    ... DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. U UHF Package 38-Lead Plastic QFN (5mm × ...

  • Page 28

    ... LTC2430/LTC2431 2-Channel, Differential Input, 16-Bit, No Latency ∆Σ ADC LTC2436-1 LTC2440 1-Channel, Differential Input, High Speed/Low Noise, 24-Bit, No Latency ∆Σ ADC SoftSpan is a trademark of Linear Technology Corporation. Linear Technology Corporation 28 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 ● ...