5v analogue front ends with ΣΔ ADCs and sensor interfacing

Nisshinbo Micro Devices has released a series of industrial 5V analogue front end ICs with high-resolution ΣΔ converters, input multiplexers, programmable gain amplifiers and sensor excitation current sources.

NA2202 has 16bit resolution
NA2203 has 20bit resolution
NA2204 has 24bit resolution

“Microcontrollers with 5V operating voltage are still widely used in the industrial equipment market, according to the company. “In order to transmit sensor information as accurately as possible, analogue front-ends must operate at the same voltage as the microcontroller.”

In each case, the programmable amplifier can be set at gains from 1x to 128x and the current sources can be set to 0.1, 0.25. 0.5 or 1mA for resistance-based temperature detectors.

There are eight inputs, configurable as all single-ended or four differential pairs.

Analogue input range is almost all the way to both supplies, but varies depending on several factors – read the data sheet carefully.

The 2.048V internal reference voltage can be replaced with an external reference across two of the package pads.

Data is extracted and control commands sent in over an SPI bus.

Consumption is around 3mA, which can be reduced by three-quarters by entering the quarter-speed low-power mode.

Below this are a 140μA sleep mode (bias and regulator remain on) and a <1μA all-off ‘stand-by’ mode.

Packaging is 4 x 4 x 0.75mm.

	NA220x series
Supply	Analogue: +2.7 to +5.5V or ±2.5V Digital: +2.7 to +5.5V
Consumption	Analogue: 2.9mA (normal mode) 0.9mA (low-Power) Digital: 0.3mA
Inputs	four differential eight single-ended pseudo-differential
ΔΣADC	NA2202 16bit NA2203 20bit NA2204 24bit 3.125 to 9,600sample/s
Programmable amplifier	1 to 128V/V
Built-in reference	2.048V ±20 mV
GPIO	4 channels (shared pads)
Sensor excitation	Dual 0.1, 0.25, 0.5, or 1mA
Rejection	50Hz/60Hz
Calibration	Offset Voltage and gain
Interface	SPI (with CSB)
Error checksum	CRC8
Operating range	-40 to +125°C
Package	QFN4040-24-NB