Optoelectronics

Vishay has created a fast opto-coupler that can operate at 25Mbit/s. Called VOIH72A, is has a digital buffering on the input and output. “The component combines a maximum pulse distortion of only 6ns, a maximum supply current of 2mA and a supply voltage range of 2.7 to 5.5V, and is fast enough to support bus systems such as SPI, as ...

Toshiba has released a “high-speed” low-voltage photo-relay “particularly suitable for the pin electronics of semiconductor testers”, it said. High-speed? “Turn-on switching time is below 80μs,” according to Toshiba. “Compared to the previous generation – TLP3450 – this represents a 40% improvement.” It has a single normally-open ‘contact’, consisting of back-to-back mosfets making it suitable for switching ac or dc signals. ...

Würth Elektronik has created a range of opto-isilated triacs for controlling light AC loads and larger triacs. They are called WL-OCTR, and come in a choice of packages: through hole DIP-4 or DIP-6, or surface-mount SOP-4. Through-hole parts offer 5kV breakdown between input and output, which drops to 3.75kC for surface mount. DIP parts can also be supplied with legs ...

Novosense Microelectronics has created a pair of isolated digital input chips suitable for 24V industrial control applications that only need power on the output side. 4-channel NSI8604 (SSOP16 package) and 8-channel NSI8608 (SSOP20) provide input/output isolation when converting voltages in the range of -60V to 60V to logic signals. (The third digit is a capital ‘i’, not a numerical ‘1’). ...

Vishay has introduced a photovoltaic mosfet gate driver qualified to AEC-Q102 for automotive use. Called VOMDA1271, “the component is available in a SOP-4 housing. The driver is the only one of its kind in this package size with an isolation voltage of 3.750 V [sic] and a typical open-circuit output voltage of 8.5V”, according to component distributor Rutronik, which is ...

Toshiba has added over-temperature and over-voltage protection features to an 80V 1.4A photo-relay, all inside a 4pin DIP package. Called TLP241BP, it can switch ac or dc though its single isolate 280mΩ (max) output switch – implemented as a pair of back to back mosfets – and handle pulses up to 4.2A (100ms, 1/10 duty). Output leakage is 1μA max ...

Littelfuse has introduced an optically isolated photovoltaic gate driver for mosfets and IGBTs. Essentially, photovoltaic gate drivers are opto-isolated relays without the internal output mosfets, allowing mosfets to be picked appropriate to the load. They are not fast, but they allow a microcontroller to switch a large load on and off across a huge potential difference. This one is called ...

In adding an alternative cutter drive motor (‘spindle’) to an existing cnc machine, an electrically isolated pwm to analogue converter is needed. The machine uses a ‘grbl’ controller, which has an Arduino-based circuit that includes multiple outputs, including a powerful 24V pwm signal that is generally used to drive a 60-80W spindle motor. Update: See a constant current approach to ...

Würth Elektronik has released a detailed and thoughtful app note on using opto-couplers, particularly ‘817’ types. AN0007a* ‘Understanding phototransistor optocouplers’ goes deep into analogue and digital uses, covering performance variations due to process, temperature voltage, current and parasitics, and appropriate design behaviour. “An essential aspect for the development of robust applications involving optocouplers is not only to understand and integrate ...

After announcing 60V opto-mosfet relays last week, this week Panasonic has revealed a 600V type in a 2.65 x 4.45 x1.8mm package. AQY206GV’s 8Ω mosfet (15Ωmax) will switch 600V, and 150mA (450mA pulsed), with a maximum dissipation of 350mW. Its SSOP package is rated for 1,500Vrms isolation, and the whole device will work up to +105°C ambient. Maximuturn on and ...