LINEAR TECHNOLOGY LTC2440 Product Specifications User Manual (1), (1)

LTC2440

24-Bit High Speed Differential Δ∑ ADC with

Selectable Speed/Resolution

FEATURES DESCRIPTION n Up to 3.5k Hz Output Rate

The LTC®2440 is a high speed 24-bit No Latency Δ∑TM

n Selectable Speed/Resolution

ADC with 5ppm INL and 5μV offset. It uses proprietary

n 2μVRMS Noise at 880Hz Output Rate

delta-sigma architecture enabling variable speed and reso-

n 200n VRMS Noise at 6.9Hz Output Rate with

lution with no latency. Ten speed/resolution combinations

Simultaneous 50/60Hz Rejection (6.9Hz/200n VRMS to 3.5k Hz/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, 200n VRMS, 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 3.5k Hz conversion speed but reading data at a 100Hz rate draws 240μA average

n High Speed Multiplexing

current (1.1m W) 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 fl exible 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. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. No Latency Δ∑ is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.

TYPICAL APPLICATION Speed vs RMS Noise Simple 24-Bit 2-Speed Acquisition System

VCC = 5V VREF = 5V 4.5V TO 5.5V + = VIN – = 0V VIN

VCC BUSY LTC2440 2μV AT 880Hz

f OREF+

REFERENCE VOLTAGE

0.1V TO VCC 200n V AT 6.9Hz

REF– SCK

VCC (50/60Hz REJECTION)

3-WIRE

IN+ SDO

ANALOG INPUT SPI INTERFACE 6.9Hz, 200n V NOISE, –0.5VREF TO 0.5VREF 50/60Hz REJECTION

IN– CS

10-SPEED SERIAL

PROGRAMMABLE

GND EXT 880Hz OUTPUT RATE,

2μV NOISE CONVERSION RATE (Hz)

2440 TA01

2440 TA01

2440 TA02

2440fc