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3.5- and 4.5-Digit Panel-Meter ADCs Feature 4-20mA Current Output

SUNNYVALE, CA-March 13, 2006-Maxim Integrated Products (NASDAQ: MXIM) introduces the MAX1365-MAX1368 stand-alone panel meters. These devices feature sigma-delta ADCs which digitize fully differential analog signals in the ±2V and ±200mV range and display the results with 3.5- or 4.5-digit resolution on a local LED display. The MAX1365-MAX1368 integrate a 4-20mA current transmitter to drive a remote panel-meter or other 4-20mA input. With their high performance, integrated LED display drivers, and integrated 4-20mA output, these panel meter ICs are ideal for industrial sensor applications.

The MAX1365-MAX1368 eliminate the need for sensitive and costly external components to achieve their high level of performance. Traditional panel meters based on dual-slope integrating ADC architectures rely on external capacitors to achieve specified performance. Additionally, they may require external clock sources and external references to complete the system. In contrast, each MAX1365-MAX1368 device includes a 20-bit sigma-delta ADC, an internal 2.048V reference and an internal oscillator, which means that they eliminate the need for precision external capacitors. They also integrate a common-cathode 7-segment LED display driver, ±15-bit DAC, and precision 4-20mA current transmitter in a 7mm x 7mm, 48-pin TQFP package. The current output is accurate to within ±0.5% (typ) gain error and ±10 µA (typ) offset error. A fourth-order SINC4 digital filter simultaneously rejects 100dB of both 50Hz and 60Hz noise. On-chip input buffers provide 100M input impedance on the fully differential analog and reference inputs. Transparent offset calibration automatically corrects offset errors.

The integrated LED display on the stand-alone 4.5-digit MAX1365 and 3.5-digit MAX1367 shows the analog measurement while the 4-20mA current output transmits a signal proportional to the analog inputs.

For ultimate flexibility, the MAX1366 (4.5 digit) and the MAX1368 (3.5 digit) ADCs provide a microcontroller interface which allows independent access and control of the ADC, LED display, and current output through a SPI™-/QSPI™-/MICROWIRE™-compatible interface. This independent operation allows pre-processing of the ADC results before they appear on the LED display. It also allows the 4-20 mA current output to be used independently of both the ADC results and the value shown on the LED display. Such flexibility makes the MAX1366/MAX1368 ideal for nonlinear measurements like thermocouples, or for multifunction microprocessor-based panel-meter products.

The MAX1365-MAX1368 operate off a 2.7V to 5.25V ADC/DAC supply, 4.75V to 5.25V V/I converter supply, and a 7V to 30V supply for the 4-20mA current loop output. The devices are available in a 7mm x 7mm, 48-pin TQFP package in the extended (-40° Celsius to +85° Celsius) temperature range. Prices start at $6.96 (1000-up, FOB USA).