Datasheet LTC2440 (Analog Devices)

LTC2440 24-Bit High Speed Differential ∆∑ ADC with Selectable Speed/Resolution
FEATURES DESCRIPTION
n
Up to 3.5kHz Output Rate (External fO)
The LTC®2440 is a high speed 24-bit No Latency ∆∑TM n
Selectable Speed/Resolution
ADC with 5ppm INL and 5µV offset. It uses a proprietary n
2µVRMS Noise at 880Hz Output Rate
delta-sigma architecture enabling variable speed and reso- n
200nVRMS Noise at 6.9Hz Output Rate with
lution with no latency. Ten speed/resolution combinations
Simultaneous 50/60Hz Rejection
(6.9Hz/200nVRMS to 3.5kHz/25µVRMS) are programmed n
0.0005% INL, No Missing Codes
through a simple serial interface. Alternatively, by tying a n
Autosleep Enables 20µA Operation at 6.9Hz
single pin HIGH or LOW, a fast (880Hz/2µVRMS) or ultralow n
<5µV Offset (4.5V < VCC < 5.5V, –40°C to 85°C)
noise (6.9Hz, 200nVRMS, 50/60Hz rejection) speed/reso- n
Differential Input and Differential Reference with
lution combination can be easily selected. The accuracy
GND to VCC Common Mode Range
(offset, full-scale, linearity, drift) and power dissipation n No Latency, Each Conversion is Accurate Even After are independent of the speed selected. Since there is no an Input Step latency, a speed/resolution change may be made between n Internal Oscillator—No External Components conversions with no degradation in performance. n Pin Compatible with the LTC2410 Following each conversion cycle, the LTC2440 automati- n 24-Bit ADC in Narrow 16-Lead SSOP Package cally enters a low power sleep state. Power dissipation may be reduced by increasing the duration of this sleep
APPLICATIONS
state. For example, running at the 3.5kHz conversion speed but reading data at a 100Hz rate draws 240µA average n High Speed Multiplexing current (1.1mW) while reading data at a 7Hz output rate n Weight Scales draws only 25µA (125µW).The LTC2440 communicates n Auto Ranging 6-Digit DVMs through a flexible 3-wire or 4-wire digital interface that is n Direct Temperature Measurement compatible with the LTC2410 and is available in a narrow n High Speed Data Acquisition 16-lead SSOP package. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and No Latency ∆∑ and SoftSpan are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION RMS Noise vs Speed Simple 24-Bit 2-Speed Acquisition System
100 VCC = 5V VREF = 5V 4.5V TO 5.5V V + – IN = VIN = 0V V 10 CC BUSY LTC2440 2µV AT 880Hz REFERENCE VOLTAGE REF+ fO 0.1V TO VCC 4 REF– SCK 200nV AT 6.9Hz V RMS NOISE (µV) 1 3-WIRE CC (50/60Hz REJECTION) ANALOG INPUT IN+ SDO SPI INTERFACE 6.9Hz, 200nV NOISE, –0.5VREF TO 0.5VREF 50/60Hz REJECTION IN– CS 10-SPEED SERIAL SDI PROGRAMMABLE 0.1 GND EXT 880Hz OUTPUT RATE, 1 10 100 1000 10000 2µV NOISE CONVERSION RATE (Hz) 2440 TA01 2440 TA01 2440 TA02 2440fe For more information www.linear.com/LTC2440 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Typical Performance Characteristics Pin Functions Typical Application Related Parts