“Today, the industrial revolution that is redefining manufacturing with the application of intelligent information, communication technology and the Internet of Things (IoT) is gradually taking shape around the world, which the German government calls: “Industry 4.0”.
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1 Introduction
Today, the industrial revolution that is redefining manufacturing with the application of intelligent information, communication technology and the Internet of Things (IoT) is gradually taking shape around the world, which the German government calls: “Industry 4.0”.
The basic principle of “Industry 4.0” is to build an intelligent network of automatic mutual control between upstream and downstream of the entire value chain by connecting machines, workpieces and control systems. By integrating information communication, sensors and robotics to build the Internet of Things, the concept of Industry 4.0 can improve the level of intelligence in industrial manufacturing.
In the field of sensor technology, IO-Link is the world’s first standardized input and output communication technology (IEC 61131-9) for sensors and actuators, so we think this standard may be selected as the standard communication interface for Industry 4.0.
This powerful point-to-point communication is based on proven three-wire communication technology for sensors and actuators without any additional requirements for wires. Therefore, IO-Link is not Fieldbus fieldbus technology, but an upgraded evolution of existing mature sensor and actuator communication technology.
ST’s L6362A, although specially designed to be compatible with the IO-Link communication protocol and Industry 4.0, can still be used as a standard general-purpose transceiver.
Figure 1: L6362A DFN 3×3 12L tiny package
This product is a three-wire digital interface sensor drive solution that is energy efficient, compact and affordable, and meets all the requirements of modern sensors and actuators: remote service, standardization, functional verification, diagnostics and monitoring.
This article will mainly introduce the L6362A product, focusing on describing the product features, advantages and working methods.
2. L6362A product features and advantages
Product Features
As shown in Figure 2, the L6362A monolithically integrates a 3.3V/5V linear regulator; the SEL pin has an output voltage selection function; the maximum output current is 12mA. The voltage regulator also drives the internal logic unit, and drives the on-chip output stage (typically 1Ω) with extremely low on-resistance Rds(on) through the transparent transmission interface in the logic unit. The output stage (high and low sides) can be configured through the levels of the IN1 and IN2 pins, and the push-pull configuration can be achieved by connecting OUTH and OUTL externally to the device. When the EN pin is set to a low logic level, the output stage is turned off. The Inductor achieves fast demagnetization in the high-side configuration; in the push-pull configuration, slow demagnetization is effective because the low-side switch is turned on. The high-speed transmission performance of the output stage enables the communication speed to reach the COM3 (230.4 kbps) level.
Figure 2: L6362A block diagram
The product has self-protection features: cut-off current limiting (non-dissipative short-circuit protection), thermal shutdown, active voltage clamping, right-side pin polarity return protection, undervoltage lockout protection and EN60947-5-2 and IEC61000- 4-5 standard surge protection. The so-called non-dissipative short-circuit protection is an innovative circuit patent technology that minimizes the power dissipation when the output stage is shorted to ground; avoiding thermal shutdown intervention in most cases.
Figure 3: Current characteristics when the chip is off
Figure 4: Thermal shutdown intervention after cut-off cycle
The EN (thermal shutdown) and OL (current limit) pins enable diagnostic functions, and the host microcontroller can also detect IO-Link wake-up request events through the OL pin.
product advantages
The Rds(on) on-resistance of L6362A is the lowest among the products of the same level, which is less than one tenth of that of the main competitive products, which helps to reduce the total power loss and achieve extremely low power dissipation. It can be inserted in high-density IP modules. Inside the slot, there are no overheating issues.
The chip provides designers with a transparent transmission interface, which facilitates the development of simple and economical communication solutions. The wide transmission speed range up to COM3 guarantees high-frequency communication.
Suitable for developing IO-link applications as well as general-purpose transceivers or simple line drivers, the L6362A’s versatility is an important advantage of this product, eg “jolly” can outperform any slot. In addition, the connection to the output stage is very easy, allowing for a great degree of flexibility and customization.
The product features excellent all-round protection, high reliability and long-lasting durability.
3. Drive capacitive and inductive loads
STEVAL-IFP017V3 (Figure 5) is a special evaluation board for L6362A developed by STMicroelectronics, which provides a simple application tool for customers to test the working performance of this product. Next, we use this evaluation board to analyze the driving ability of L6362A products to large capacitive and large inductive loads.
Figure 5: STEVAL-IFP017V3 demo board for testing the RC and inductive load drive capability of the L6362A
Charging Resistor-Capacitive Loads
When the ambient temperature is Ta=25°C, the high-side, low-side, and push-pull configurations of the chip are used to charge a 25μF resistive-capacitive load connected in parallel with a 100Ω resistor, and the Vcc voltage is between 18V and 30V.
When using the L6362A to charge a large capacitor, the main risk is that the cut-off protection function may shut down the output stage. When this phenomenon occurs, the capacitor is charged through the parallel resistor. To avoid this phenomenon, the input stage must be driven with a pulse train whose duration is less than the off-time (Figure 6).
Figure 6: RC charging waveforms
As shown in Figure 6, the RC load connected to the L6362A is charged with a voltage of Vcc=24V and two pulse signals with a duration of 3.5ms (the green line represents Vin, the red line represents Vload, and the blue line represents Iload).
If Vcc=30V, three pulse signals are required to achieve the same result. When driving capacitors higher than 25µF, the number of pulse signals must be increased.
Large inductance demagnetization
In the process of repeated demagnetization of a large inductor, two main risks must be considered: 1. The huge electric energy generated by the discharge of the inductor may cause the device to burn out or burn; 2. The power stage junction temperature rises too quickly, which may trigger the thermal shutdown of the device itself. interrupt function.
In order to test whether the chip works normally when demagnetized, use the STEVAL-IFP017V3 evaluation board to drive a large inductor of 1.9H, and do not connect any freewheeling diodes outside the chip. Test conditions: Vcc=24V, Tamb=25°C, output current 300mA, frequency 2Hz, duty cycle 50%, push-pull configuration. The heat sink used for the test is 5mm2.
No abnormality was found in the experiment: the maximum package temperature reached 39.6°C. The test is then repeated at Tamb = 105°C to verify that thermal shutdown occurs.
Figure 7: 1.9H inductor demagnetization; Iout=300mA, Tamb=105°C
Figure 7 shows the charging waveform (green line represents Vin; red line represents Vload; blue line represents Iload).
4 Conclusion
The L6362A is an ideal transceiver for connecting digital sensors and actuators, intelligent enough to implement complex solutions compatible with the IO-Link communication protocol, and a simple general-purpose I/O system solution.
This product has many advantages, such as the industry’s lowest Rds(on) resistance, DFN miniature package, the highest power stage in the market, ultra-large capacitive and inductive drive capability, and low product price.
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