MAXREFDES1152: Four-Channel Universal Analog Input Using the MAX11270


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The MAXREFDES1152 is a four-channel universal analog input that measures voltage or current signals. Each channel can be configured for voltage input at 0 to 10V or current input at 0 to 20mA. A 24V power supply can be switched out to power an external 2-Wire, 3-Wire, or 4-Wire sensor.

The MAXREFDES1152 provides a complete system solution for industry voltage and current measurement. The analog front end includes Beyond-the-Rails™ analog switches, and operational amplifiers are used to achieve voltage/ current input selection and signal conditions. The 24-bit MAX11270 analog-to-digital converter (ADC) is the heart of the system and achieves highly accurate measurements. The microcontroller communicates with the MAX11270 and the MAX7317 10-port I/O expander to control the analog front end and accept the ADC conversion results. The 24V field input power supply is isolated with the analog front end and with the microcontroller, which is powered by a USB power supply. This isolated design enhances system robustness in harsh industry applications.

The MAXREFDES1152 also integrates five Beyond-the- Rails single-pole/double throw (SPDT) analog switches (MAX14763); a dual Beyond-the-Rails 4:1 analog multiplexer (MAX14778); two ultraprecise, low-noise op amps (MAX44251); 2.75kVRMS data isolation (MAX14930 and MAX14932); an STMicroelectronics® STM32F1 microcontroller; a μp supervisory circuit (MAX6730); an FTDI Chip® USB-UART bridge; a high-efficiency iso-buck DC-DC converter (MAX17681); and isolated/regulated +5V and +3.3V power rails (two MAX16910s) and -5V power rail (MAX1697). The entire system typically operates at less than 500mW and fits into a 5cm × 10.6cm space. While targeted for industrial and PLC applications, the MAXREFDES1152 can be used in any application that requires high-accuracy analog-to-digital conversion.


  • Highly accurate measurements
  • 0 to +10V voltage inputs
  • 0 to 20mA current inputs
  • Four channels
  • Each channel can be configured for voltage or current input
  • 24V input protection
  • Isolated power and data
  • Board calibration
  • Connector provides 24V output
  • 24V output can enable or disable


Designed, Built, Tested

Board pictured here has been fully assembled and tested. Not available for sale.



PCB Layout

Bill of Materials

Test Results

Maxim Devices (1)

Part Number Name Product Family Order Design kits and evaluation modules
MAX11270 24-Bit, 10mW, 130dB SNR, 64ksps Delta-Sigma ADC with Integrated PGA Analog-to-Digital Converters Buy Now Design Kits

Maxim Devices (1)

Part Number Product Family
Analog-to-Digital Converters
24-Bit, 10mW, 130dB SNR, 64ksps Delta-Sigma ADC with Integrated PGA

Design Files (5)

Title Type Size Date
maxrefdes1152_pcb PDF 2MB 2019-07-09
maxrefdes1152_bom PDF 253KB 2019-07-09
maxrefdes1152_test_results PDF 285KB 2019-07-09
maxrefdes1152_schematic PDF 73KB 2019-07-09
maxrefdes1152-firmware ZIP 8MB 2019-08-13
Date Type


(PDF, 2MB)



(PDF, 253KB)



(PDF, 285KB)



(PDF, 73KB)



(ZIP, 8MB)

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