This post was last edited by yang_alex on 2018-10-11 13:38 The TLP3547 evaluation board sample I received was well packaged, in a small plastic box, plus a manual. This way the sample is not easily damaged by bumps.
In order to be compatible with the traditional relay package, the TLP3547 evaluation board uses a solution made of two small boards spliced together, which converts the DIP8 package into the four pins below. The two on the left are the "coil" terminals, and the two on the right are the "normally open contact" packages. The advantage is that the original PCB design can be used without changing the design. However, it will be more compact and reasonable to re-layout the wiring in the new design.
Here, pay attention to the comparison between the evaluation board pins and the device pins. Fortunately, the manufacturer provided a schematic diagram of the evaluation board with the evaluation board sample:
Main performance of TLP3547: TLP3547 is a 5A drive current photorelay launched by Toshiba. It adopts DIP8 package and is mainly used to replace mechanical relays in industrial applications.
There are 3 ways to connect the TLP3547 load end: Connection method 1: Can connect to AC or DC. Of course, the voltage range is limited. Different models are different, please refer to the device manual for details.
Access method 3: Only DC can be connected. The load current can be increased by connecting MOSFET in parallel. However, it should be noted that the parallel MOSFET does not have the function of automatic current sharing, so the current load should not be too large, and sufficient margin should be left. Pay attention to the direction of DC load current.
1. LED side, that is, "coil side" VF: Test tool: The multimeter measurement result VF is about 1.74V. The input voltage is 3.3V, so the voltage on the drive resistor is about 1.56V. The drive resistor on the evaluation board is 150 ohms, so IF is about 10mA. The drive power consumption is 3.3VX 10 mA = 33mW. Compared with mechanical relays, the drive power consumption is much smaller, and the drive circuit only needs one resistor, so the cost of the drive circuit will also be reduced a lot. 2. Switching time delay test. Use an oscilloscope to connect the test circuit according to the manual. Set the driving voltage to 3.3V (obtained from a development board), connect the positive pole of the driving to pin 1 of the evaluation board, and connect the ground to pin 2 of the evaluation board. The load is a mobile power bank charging, with an approximate current of 1.04A and a voltage of 5.25V. Connect the positive power input terminal to pin 3 of the evaluation board, and the positive input terminal of the mobile power bank to pin 4 of the evaluation board. For the convenience of oscilloscope measurement, the ground of the driving development board, the ground of the charger output, and the ground of the mobile power bank are connected together.
Summary: 1. Compared with traditional mechanical relays, it has obvious advantages in volume, and it is more space-saving to replace signal relays and low-power relays. 2. The switch drive is faster than the mechanical type, with less jitter and less drive power. 3. From the parameter point of view, the repeated switching life is higher than that of mechanical relays.
A few additional points: 1. From the perspective of drive delay (refer to the oscilloscope test above), a 100HZ square wave at the load end can be obtained. If it is higher, there will be some problems. 2. If it is used for signal isolation, optocouplers can meet the requirements, and there is no need to use photorelays. 3. It would be better if the photorelay could support higher current and higher AC voltage (change the package and use MOSFET with higher current and higher voltage resistance).
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