Small Photorelay with High ON-State Current and High-Speed Switching

Toshiba Electronic Devices & Storage Corporation ("Toshiba") has launched “TLP3640A,” a photorelay for factory automation (FA), building automation (BA), and other industrial equipment. Volume shipments start today.

In factory automation and building automation, switches are used to turn on and off other externally connected equipment. The typical used switches are mechanical relays. However, mechanical relays, which control metal contacts through electromagnetic force generated by a coil, have problems such as highly power consumption, wear of metal contacts and noise caused by driving.

Replacing mechanical relays with photorelays can solve these problems. A photorelay is an optical isolator that has an LED on the input side and a MOSFET with gate-driving elements (photodiode arrays) on the output side. The coil and metal contacts of mechanical relays correspond to the same role as the LED and MOSFET of photorelays, respectively. Therefore, photorelays work in the same way as mechanical relays.

The photorelays have the following features.

1. Long life: No mechanical contacts, so there is no limit to the number of contact times on the output side.
2. Low power consumption: Power consumption of input side is low due to LED drive.
3. Silent: No sound occurs when the output switches.
4. Small package: Small mounting area and low height.

The new product, TLP3640A uses Toshiba's proprietary chip-on-chip technology^[1] developed in small photorelays and allows an ON-state current rating of 1A and OFF-state output terminal voltage rating of 60V in the SO4 package smaller than Toshiba’s existing product, TLP3122A^[2]. In addition, the switching speed has been increased and the operating temperature range has been extended. With these features, TLP3640A helps high-density mounting of relays on various industrial equipment, high-speed operation of equipment, and flexibility in design.

1. Small package
2. Large ON-state current rating
3. High-speed operation
4. High temperature operation

The new product’s package is a small SO4 package, and despite being 30% smaller in area compared to Toshiba’s existing product TLP3122A, it offers ON-state current rating of 1A by optimizing the internal structure design. This contributes to improving the design margin.
For example, when the required on-current for the product is less than 1A, the number of units per area for Toshiba’s existing product TLP3122A would be three units (width 3.7mm×3=11.1mm), whereas the new product would be four units (width 2.6mm×4=10.4mm), allowing for more products to be placed.

Relay switches used in the interfaces of various industrial equipment may require faster operation. Some small signal relays have a few milliseconds of contact switching times. The new product, TLP3640A features a turn-on time/turn-off time of up to 0.5ms/0.2ms maximum by improving the characteristics of LED and photodiode arrays, enabling faster switching than Toshiba’s existing product TLP3122A^[3]. The new product is suitable for analog interface sections in programmable logic controllers and gain switches in measuring instruments, in which high-speed operation is required.

As equipment becomes smaller, thermal designs and component selection may become more difficult. While general small signal relays and Toshiba’s existing product TLP3122 have a maximum operating temperature rating of 85°C, the new TLP3640A features 110°C by optimizing its internal structure. This helps operate in high-temperature environments required for FA equipment and industrial robots.

• For Factory Automation (FA) Control equipment
• For programmable logic controller (PLC)
• For the security system
• For measuring instruments
• Replacement of mechanical relays

• Isolators/Solid State Relays

• What is a photorelay?

• How to replace mechanical relays with photorelays (PDF: 1.9MB)

• Programmable Logic Controller

• Package

• Isolators/Solid State Relays