Cirrus Logic Inc. announced the addition of three high-precision analog-to-digital converters (ADCs) to its 552x Crystal family of industrial data acquisition ICs. The highly integrated 24-bit, Crystal ADCs (CS5522, CS5524 and CS5528) are capable of measuring ground referenced signals without external level-shifting components, improving the accuracy in industrial data acquisition while lowering system cost and complexity. As buffered, multi-channel single-supply devices, the new Crystal ADCs enable extremely precise measurements of temperature, pressure, voltage and current, and include all the capabilities needed to design complete signal acquisition solutions for industrial applications.

Capable of reliably performing over a wide range of extreme conditions, the new Crystal ADCs provide an ideal, low-cost solution for isolated and non-isolated industrial signal acquisition applications. The new entries combine two, four or eight channels, low power operation, the ability to handle negative input signals with a single power supply, stability over the full industrial temperature range, a simple interface, enhanced noise rejection and programmability.

"With the introduction of these devices, we continue to demonstrate our leadership in delivering cost-effective 24-bit conversion solutions," said Eric Broockman, vice president and general manager of the Crystal Semiconductor Products Division. "These Crystal products are excellent examples of how weıre providing 24-bit performance at 12-bit pricing, enabling critical industrial applications at a reasonable cost."

Each of the three new ADCs combine a low noise, low drift chopper stabilized instrumentation amplifier, a programmable gain stage and an on-chip charge pump drive to provide extremely precise voltage measurements, including full-scale bipolar and unipolar signals of 25mV, 55mV, 100mV, 1V, 2.5V and 5V. The new devices handle a reference input voltage of up to 5V directly from the supply, and include internal rough and fine charge buffers to ensure low input currents independent of input voltage. With superior voltage measurement features, these new industrial ADCs are ideal for thermocouple applications as well as bridge transducer digitizers, used in products such as panel meters, digital thermometers, weigh scales, electronic torque wrenches and other automatic manufacturing tools.

Electrical noise sources, common in industrial environments, are diminished with the implementation of the new ADCs into a system. The CS5522/24/28 trio rejects noise at 50 Hz and 60 Hzı3 Hz simultaneously. In addition, the new chips provide a 24-bit data word with up to 18 bits of noise-free resolution, providing a precise specification for data transfer.

Other features include:

It is no surprise to see more products that allow designs to be "dumbed down" to allow for their use in designs by engineers with little or no analog design experience. That is not a criticism of the designs or of the vendors: It is a necessity to accept that more engineers are having to design products that use technology only vaguely covered at college because of the lack of good analog education programs. This product is a little more unusual that some of the others, where we have seen programmable gain amplifiers used on board to move the incoming signals into the right range of voltage for the 10- or 12-bit converter. These products allow for that input optimization while offering 24-bit conversion as well and really are offered at near 12-bit prices. If I had been Cirrus I would have called this a data acquisition system rather than just an ADC.

I love the line frequency filtering and the output latch which could be extremely useful to shut down a process without having to have a microprocessor think about it.