LTC2440 Delta Sigma ADC

Analog Devices' LTC2440 is a high-speed 24-bit no latency ΔΣ ADC with 5 ppm INL and 5 µV offset. It uses proprietary ΔΣ architecture enabling variable speed and resolution with no latency. Ten speed / resolution combinations (6.9 Hz / 200 nVR MS to 3.5 kHz / 25 µVRMS) are programmed through a simple serial interface. Alternatively, by tying a single pin HIGH or LOW, a fast (880 Hz / 2 µVRMS) or ultra low noise (6.9 Hz, 200 nVRMS, 50 / 60 Hz rejection) speed/resolution combination can be easily selected. The accuracy (offset, full-scale, linearity, drift) and power dissipation are independent of the speed selected. Since there is no latency, a speed/resolution change may be made between conversions with no degradation in performance.

Following each conversion cycle, the LTC2440 automatically enters a low-power sleep state. Power dissipation may be reduced by increasing the duration of this sleep state. For example, running at the 3.5 kHz conversion speed but reading data at a 100 Hz rate draws 240 µA average current (1.1 mW) while reading data at a 7 Hz output rate draws only 25 µA (125 µW).The LTC2440 communicates through a flexible 3-wire or 4-wire digital interface that is compatible with the LTC2410 and is available in a narrow 16-lead SSOP package.

Features

Up to 3.5 kHz output rate Selectable speed/resolution 2 µVRMS noise at 880 Hz output rate 200 nVRMS noise at 6.9 Hz output rate with simultaneous 50 / 60 Hz rejection 0.0005% INL, no missing codes Autosleep enables 20 µA operation at 6.9 Hz < 5µV offset (4.5 V < VCC < 5.5 V, -40°C to 85°C) Differential input and differential reference with GND to VCC common mode range No latency, each conversion is accurate even after an input step Internal oscillator, no external components Pin compatible with the LTC2410 24-bit ADC in narrow 16-Lead SSOP package

Applications
High speed multiplexing Weight scales Auto ranging 6-digit DVMs Direct temperature measurement High-speed data acquisition