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Digital optocouplers boast breakthrough features

Posted: 22 Nov 2004 ?? ?Print Version ?Bookmark and Share

Keywords:agilent technologies? digital optocoupler? acsl-6xx0?

Designed for a variety of consumer, computing, communications and industrial applications, Agilent Technologies Inc. bolsters its isolation products portfolio with the introduction of the industry's first line of 3.3V, 15Mbaud, multi-channel and bi-directional digital optocouplers.

By leveraging the company's patented manufacturing technology for stacking LEDs, Agilent was able to design the highly integrated parts necessary to develop multi-channel optocouplers. Available in dual, triple and quad channels, the company says this new product family can reduce part count, board space and system costs.

The integration of two, three and four optocouplers in a single package is achieved through stacking LED die and an insulating layer on a silicon substrate. With the insulating material between the LED and active circuitry, the optocoupler can provide safe, high-voltage insulation performance, which is key when providing electrical isolation of signal lines to protect low-voltage circuitry from high-voltage surges.

Gary Tay, business development manager for Agilent's Isolation Products Division says use of the stacking LED technology allows the company to integrate multi-channels in a single package for higher integration, and enables the use of a very thin package compared with traditional optocoupler packaging. Another key feature is the bi-directional functionality for two-way data transfer, which simplifies signal routing on printed-circuit boards. This saves the designer in the routing of the printed-circuit board by replacing two optocouplers with one bi-directional optocoupler with single routing, Tay said.

The ACSL-6xx0 series optocouplers provide minimum 10MBaud operating speeds, with 15MBaud typical performance. The devices are supplied in compact 8-pin (4.9-by-5.9-by-1.7mm for dual-channel) and 16-pin (9.9-by-5.9-by-1.7mm for triple- and quad-channel) thin SOIC packages to further reduce board-space requirements.

In addition to the higher integration, the new optocouplers boast a wide voltage supply range and wide operating temperature range. These devices feature high common-mode rejection of 10kV/?s minimum and operate from 3V to 5.5V supply voltages. The operating temperature range is -40C to 100C. These devices are pending safety regulatory approval. They are designed to meet the most widely accepted international safety regulations including UL1577 (2,500Vrms), CSA Component Acceptance Notice No. 5, and the newly established standard to replace VDE 0884, IEC/EN/DIN EN 60747-5-2.

A significant feature of the new optocouplers is the wide supply voltage range of 3V to 5.5V, which enable customers to use one part for both 3V and 5V applications, said Tay. And coupled with the wide operating temperature range, the devices can be used in a variety of consumer to industrial applications, he said. Key operating temperature ranges for current optocouplers in the market include 0C to 70C for less stringent consumer and computing applications, or -40C to 85C, which typically covers consumer and industrial applications. By moving to -40C to 100C, it covers nearly all of the industrial applications, superceding the other two ranges, Tay said. He also notes that the temperature range may extend up to 125C in the future for automotive applications. In computer systems, the ACSL series optocouplers provide the benefits of reduced part count and board space for parallel interfaces and serial interfaces such as RS232/485/422, SPI (serial peripheral interface), and the I?C bus. They offer the same benefits in industrial, test and measurement, and medical systems for PLCs, fieldbus interfaces and data acquisition, as well as in communications applications such as power-over-Ethernet (PoE) and networking boards, and for plasma display panels and other consumer appliances.

In this case, the ADC, a 24bit sigma delta or fast conversion type, converts the analog voltage to a digital number. The quad-channel and bi-directional ACSL-6410 provides a high CMR of 10kV/?s and electrical isolation of 2,500Vrms between the host system and the data acquisition circuitry and sensors. The power supply is isolated, typically via a transformer to isolate the AC line voltage from the DC voltages generated to power the data acquisition system.

Agilent is currently offering the dual and quad versions. Four other devices will be available in 3Q 2005. These include the ACSL-6300 (triple unidirectional channels), ACSL-6310 (triple bi-directional (2/1) channels), ACSL-6410 (quad bi-directional (3/1) channels), and ACSL-6420 (quad bi-directional (2/2) channels). Because of this new technology, there are additional possibilities for higher integration and higher value-added products in the future, Tay said.

The ACSL-6400 with quad unidirectional channels is priced at $4.14 each, and the ACSL-6210 with dual bi-directional channels is priced at $2.53 each, both in quantities of 10,000.

- Gina Roos

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