Accurate optical coupling analogue isolation amp includes ΔΣ ADC

September 14, 2015 // By Graham Prophet
For current sensing and voltage sensing in power converters, these photocouplers achieve high accuracy through the inclusion of a delta sigma analogue-to-digital converter (ADC). The TLP7820 and TLP7920 are analogue output type devices; digital output variants will be added.

Target applications include servo amplifiers, inverters, power sources and photovoltaic inverters. Factory automation equipment, such as servo amplifiers and inverters, now operates with such a high degree of precision that it requires extremely accurate feedback to the microcontroller on status of the phase current of the motor or the variation of the bus voltage. To meet these requirements, Toshiba has equipped its newest photocouplers with a delta sigma ADC at the input side that enables the devices to achieve a high level of linearity (0.02% @NL200, typical).

TLP7820 and TLP7920 provide a guaranteed common mode transient immunity of 20 kV/ µsec (typical @VCM=1 kV, Ta=25˚C), which enables stable operation in electrically noisy environments and suits them for motor control applications. Isolation is through an optical barrier with a guaranteed isolation voltage of 5 kVrms (minimum). Operating temperature range is -40 to +105˚C. A choice of two package types is available: TLP7920 is supplied in an industry-standard DIP8 package; TLP7820 comes in a new SO8L package, which is more compact, taking up 30% less board space and featuring a 40% lower profile.

Toshiba Electronics Europe;