The MAXREFDES163# is one of the world’s smallest industrial magnetic sensor solutions that uses a RedRock™ RR120 TMR integrated digital magnetic sensor and the MAX14839, an industrial sensor output.
The reference design PCB dimension is just 15mm long x 10mm wide, with the width determined by the size of the M12 connector.
Design files can be found on the Design Resources tab. The board is also available for purchase.
Figure 1 shows the MAXREFDES163# reference design system block diagram. Also refer to the schematic Design Resources tab for circuit details. The MAXREFDES163# uses a robust, industry-standard M12 connector providing a simple connection of the binary sensor to any IO-Link® master. Alternatively, the sensor can be connected to an industrial digital input module compatible with 24V sensors. Pin 1 connects to the 24V power supply, pin 3 connects to the ground, pin 4 connects to the output from the MAX14839, and pin 2 is not connected.
The MAX14839 is a 24V, 100mA driver for industrial binary sensors. This device is pin-programmable and integrates the common high-voltage circuitry needed for industrial binary sensors into a single-device solution. The MAX14839 features multiple configuration options that are user-selectable during operation. The device's output can be pin-configured for high-side (pnp), low-side (npn), or push-pull operation. Refer the MAX14839 IC data sheet for configuration details. Additionally, the device allows the user to configure the logic for sensors that are normally open (NO) or normally closed (NC). Resistors R2 and R3 on the MAXREFDES163# allow these options to be configured.
By default, the MAXREFDES163# has MAX14839 pins PP, NO, and NPN all connected to ground, meaning that the MAX14839 is configured for pnp and normally-closed operation ("PNP NC" mode). The output from the TMR sensor connects to the MAX14839’s DIN pin. Because the MAX14839 can be configured, sensor manufacturers can create a variety of sensor configurations, while stocking all the same material.
The two integrated LED drivers in the MAX14839 provide visual feedback of the sensor's state. A red LED indicates FAULT and a yellow LED indicates the DO status. In addition, a green LED indicates when 24V DC power is present.
The MAX14839 features an integrated 3.3V linear regulator that provides the power supply for the RedRock RR120 TMR integrated digital magnetic sensor. For more information on the RedRock 120, visit Coto Technology's website.
The sensor's output is normally high, meaning the MAX14839's output DO is off. When a magnetic field of sufficient strength (30 gauss) is placed near the sensor, its output switches low, causing the MAX14839's output DO to be on, or high. When the magnetic field strength falls below 15G, the sensor’s output switches back to high, or off. See Table 1.
The MAX14839 delivers the robust design necessary in industrial applications. Integrated transient protection meets the IEC 61000-4-5 standard and protects surges up to ±1kV/500Ω. The DO, VCC, and GND interface pins are protected against reverse-polarity connection, short circuits, and high ESD. Overcurrent protection guards the MAX14839 from damage due to overheating during overcurrent fault conditions. The FAULT\ output signals thermal overload and overcurrents.
Table 1. MAXREFDES163# Truth Table
(From the Sensor)
|MODE||DO STATUS||LEDs (Status LED)|
|L||L||L||L (Magnetic Force = 30G)||PNP NC||On (High)||On|
|L||L||L||H||PNP NC||Off (High Impedance||Off|
L = low, H = high, NC = normally closed.
Figure 1. MAXREFDES163# reference design block diagram.
Quick Start Guide
The MAXREFDES163# can be connected to a digital input module or to an IO-Link Master to verify operation. This quick start guide shows both examples to demonstrate the flexibility of this design for industrial control applications.
Note: Software items appear in bold.
Required Equipment for Digital Input Module
- IO-Link to pigtail cable (not supplied)
- Digital input module (our example uses MAX14914PMB, not supplied)
- USB2PMB2 adapter with Munich_GUI EV KIT SOFTWARE and USB cable (not supplied)
- 24V DC supply (not supplied)
Procedure for Digital Input Module
- Connect the MAXREFDES163# M12 male connector to an IO-Link cable with an M12 female connector.
- Strip the wires at the other end of the cable and connect to the MAX14914PMB board. With a standard IO-Link cable, the brown wire connects to +24V, the black wire connects to the DI input of the MAX14914PMB, and the blue wire connects to GND. See Figure 2.
- The MAX14914PMB plugs into the USB2PMB2 adapter, which connects via a USB cable to a PC.
- Connect the 24V DC supply to MAX14914PMB. This supply is also used to power the MAXREFDES163#.
- Open the Munich_GUI and in the Device tab select MAX14914PMB. Use the Setting button DI_ENA to configure the MAX14914 as a digital input (see Figure 3a). When the RR120 sensor is not triggered (by a magnet), the MAX14914’s DOI_LVL\ output is off or low.
- Moving a magnet over the MAXREFDES163# triggers the RR120 sensor and the MAX14914's DOI_LVL\ output is high, as shown in the Munich GUI – MAX14914PMB screenshot in Figure 3b.
The Figure 4 timing diagram captures the response time for this system. The RR120 data sheet has a typical 30ms operating time specification. The MAX14839 propagation delay is 5s typ and 20s max. The MAX14914 propagation delay from DOI to DOI_LVL\ is 0.9s typ and 8s max. Therefore, the MAX14839 impact is negligible compared to the RR120 TMR sensor’s operating and release times.
Figure 2. MAXREFDES163# connected to MAX14914PMB and USB2PMB2.
Figure 3a. Munich GUI – MAX14914PMB showing MAX14914 digital input with sensor off.
Figure 3b. Munich GUI – MAX14914PMB showing MAX14914 digital input with sensor on.
Figure 4. MAXREFDES163# response time to magnetic force.
Required Equipment for IO-Link Master
- IO-Link cable (not supplied)
- MAXREFDES145# 8-port IO-Link Master with USB cable (not supplied)
- TEConcept GmbH IO-Link Control Tool (not supplied)
- 24V DC supply (not supplied)
Procedure for IO-Link Master
An IO-Link Master supports legacy binary sensors as well as an IO-Link Sensor using the same M12 connector. The IO-Link Master IC determines if the sensor is IO-Link compatible or not. If it is not compatible, the IO-Link Master treats the sensor as a binary sensor, which MAXREFDES163# is. Therefore, the IO-Link Master does not require an IODD file to work with the MAXREFDES163#.
- Connect the MAXREFDES163# to a port on the MAXREFDES145# with an IO-Link cable with M12 connectors. In this example, we use Port 1.
- Connect MAXREFDES145# to the PC with the USB cable.
- Connect the 24V DC supply to the MAXREFDES145#.
- Connect the IO-Link cable with the MAXREFDES163# to Port 1 of the MAXREFDES145#.
- Open the TEConcept IO-Link Control Tool, select FTDI USB-SPI, and hit CONNECT.
- Within the tool select Port 1 and specify Digital Input mode. In the Device Control box press Power ON and note how the red LED for Port 1 of the MAXREFDES145# and the green LED on MAXREFDES163# are illuminated. See Figure 5.
- When there is no magnet near the sensor, the IO-Link Master reads the DI as off. See Figure 6a for the GUI screenshot.
- Moving a magnet over the MAXREFDES163# triggers the RR120 sensor, and the IO-Link Master reads the DI as on. See Figure 6b for the GUI screenshot.
Figure 5. MAXREFDES163# connected to MAXREFDES145#.
Figure 6a. TEConcept IO-Link Control Tool GUI showing MAXREFDES163# with sensor off.
Figure 6b. TEConcept IO-Link Control Tool GUI showing MAXREFDES163# with sensor on.
IO-Link is a registered trademark of PROFIBUS.
RedRock is a registered trademark of Coto Technology, Inc.
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