Datasheet LTC2444, LTC2445, LTC2448, LTC2449 (Analog Devices)

LTC2444/LTC2445/ LTC2448/LTC2449 24-Bit High Speed 8-/16-Channel ∆∑ ADCs with Selectable Speed/Resolution
FeaTures DescripTion
n
Up to 8 Differential or 16 Single-Ended Input Channels
The LTC®2444/LTC2445/LTC2448/LTC2449 are 8-/16- n
Up to 8kHz Output Rate (External fO)
channel (4-/8-differential) high speed 24-bit No Latency n
Up to 4kHz Multiplexing Rate (External fO)
∆Σ™ ADCs. They use a proprietary delta-sigma architec- n
Selectable Speed/Resolution
ture enabling variable speed/resolution. Through a simple n
2µVRMS Noise at 1.76kHz Output Rate
4-wire serial interface, ten speed/resolution combinations n
200nVRMS Noise at 13.8Hz Output Rate with
6.9Hz/280nVRMS to 3.5kHz/25µVRMS (4kHz with external
Simultaneous 50Hz/60Hz Rejection
oscillator) can be selected with no latency between con- n
Guaranteed Modulator Stability and Lock-Up
version results or shift in DC accuracy (offset, full-scale,
Immunity for any Input and Reference Conditions
linearity, drift). Additionally, a 2X speed mode can be n
0.0005% INL, No Missing Codes
selected enabling output rates up to 7kHz (8kHz if an n
Autosleep Enables 20µA Operation at 6.9Hz
external oscillator is used) with one cycle latency. n
<5µV Offset (4.5V < VCC < 5.5V, –40°C to 85°C)
Any combination of single-ended or differential inputs n
Differential Input and Differential Reference with GND to V
can be selected with a common mode input range from
CC Common Mode Range
ground to V n No Latency Mode, Each Conversion is Accurate Even CC, independent of VREF. While operating in After a New Channel is Selected the 1X speed mode the first conversion following a new speed, resolution, or channel selection is valid. Since n Internal Oscillator—No External Components there is no settling time between conversions, all 8 dif- n LTC2445/LTC2449 Include MUXOUT/ADCIN for External Buffering or Gain ferential channels can be scanned at a rate of 500Hz. At the conclusion of each conversion, the converter is n Tiny QFN 5mm × 7mm Package internally reset eliminating any memory effects between
applicaTions
successive conversions and assuring stability of the high order delta-sigma modulator. n High Speed Multiplexing L n , LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and Weight Scales No Latency ∆∑ and SoftSpan are trademarks of Linear Technology Corporation. All other n trademarks are the property of their respective owners. Auto Ranging 6-Digit DVMs n Direct Temperature Measurement n High Speed Data Acquisition
Typical applicaTion LTC2444/LTC2448 RMS Noise vs Speed Simple 24-Bit Variable Speed Data Acquisition System
4.5V TO 5.5V 100 VCC = 5V VREF = 5V 1µF V + – IN = VIN = 0V 2X SPEED MODE REF+ V CH0 CC = EXTERNAL OSCILLATOR NO LATENCY MODE CH1 10 FO = INTERNAL OSCILLATOR (SIMULTANEOUS 50Hz/60Hz • 2.8µV AT 880Hz • REJECTION AT 6.9Hz OUTPUT RATE) • CH7 SDI 16-CHANNEL VARIABLE SPEED/ 280nV AT 6.9Hz CH8 MUX + SCK (50/60Hz REJECTION) THERMOCOUPLE RESOLUTION 4-WIRE RMS NOISE (µV) • 1 • – DIFFERENTIAL SDO SPI INTERFACE • 24-BIT ∆∑ ADC CS CH15 COM 0.1 1 10 100 1000 10000 REF– CONVERSION RATE (Hz) GND LTC2448 2440 TA01b 2444 TA01a 2444589fc For more information www.linear.com/LTC2444 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Analog Input and Reference Digital Inputs and Digital Outputs Power Requirements Timing Characteristics Pin Functions Functional Block Diagram Test Circuit Applications Information Package Description Revision History Typical Application Related Parts