The MAX31914 is an ultra-low-power, eight-channel, industrial digital input-level translator that introduces the MAX31914's features, application range, reference design circuitry, and circuit analysis to help you reduce design time.
Introduction to MAX31914:
The MAX31914 level shifts and adjusts the sensor and 24V digital switch outputs to produce a 5V CMOS-compatible signal that the microcontroller can accept for industrial process control and building automation applications. The device provides a front-end interface circuit for a programmable logic controller (PLC) digital input module.
Signal level shifting, input current limiting, and low pass filtering are implemented. Compared to traditional discrete resistor divider schemes, input current limiting significantly reduces the power consumption of existing field power supplies. To achieve the lowest power consumption in its class, the IC uses patent-pending circuit technology to further reduce power consumption based on input current limiting. This special low-power mode of operation is automatically activated when on-chip low-pass filtering is selected.
An on-chip selectable low-pass filter allows for debounce and filtering of sensor inputs as needed. When no filtering is used, the IC can detect a short pulse of 0.75μs input from the field.
All eight input channels are converted to CMOS logic levels and output in parallel through eight output pins for direct or optical isolation of the interface to the controller ASIC or microprocessor.
The on-chip 5V regulator can be used to power external optocouplers, digital isolators, or other external 5V circuits.
For low-cost applications, Maxim Integrated offers a pin-compatible version of the device, the MAX31915, which does not include the patent-pending current-switching circuit in the MAX31914.
Key features of the MAX31914:
Flexible power options support 24V, 12V and 5V power systems
Wide field operation power range from 7V to 36V The device can be powered by a 5V power supply on the logic side. Low power consumption and low thermal dissipation. Very low quiescent current. High precision and stable input current limiter. Special ultra-low power operation mode. Switched current limiter configurability supports a wide range of standard and custom applications configurable to IEC 61131-2 input types 1, 2 and 3 or standard CMOS logic levels
0.5mA to 6mA configurable input current limit selectable input filtering and debounce 0, 25μs, 0.75ms and 3ms settings High integration reduces BOM count and board space
8 high-voltage input channels (up to 36V)
Eight CMOS logic outputs that simultaneously convert all input states to the controller's internal 5V regulator. On-chip over-temperature indication Internal field supply voltage monitor All input pins have high HBM ESD protection (15kV HBM)
MAX31914 application:
Programmable Logic Controller (PLC) Digital Input Module Programmable Logic Controller (PLC) Digital Input Module Process Automation
Internal block diagram of the MAX17532:
Figure 1 shows the internal block diagram of the MAX31914, showing the internal components.
The MAX17532 reference design circuit:
Figure 2 MAX31914 reference application circuit
MAX31914 Chinese data: Click to download the popular application circuit with schematic and source code. See: Appreciation immediately
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