SPI/digital or I2C uModule isolator provides three isolated power rails

September 18, 2012 // By Paul Buckley
Linear Technology Corporation has introduced a 6-channel SPI/Digital or I2C digital µModule isolator with triple rail regulated power for 3.3 V and 5 V systems.

In industrial systems applications, ground potentials can vary widely, often exceeding the tolerable range, which can interrupt communications or even destroy components.

The LTM2883 breaks ground loops by electrically separating communications signals, isolating the logic level interface on each side of an internal inductive isolation barrier that withstands a large common-mode voltage range up to 2,500VRMS. The LTM2883’s low EMI isolated DC-DC converter powers the communications interface and provides adjustable 5 V, +12.5 V, and -12.5 V supply outputs, ideal for powering data converters in data acquisition systems. With 2,500 VRMS of galvanic isolation, onboard secondary power and a communications interface operating at up to 20 Mbps, the LTM2883 requires no external components and provides a simple µModule solution for isolated data communications.

The LTM2883 is available in two communications interface versions. The LTM2883-I is I2C compliant at up to 400 kHz with bidirectional serial data (SDA) plus clock (SCL) and three additional isolated CMOS logic signals that operate at up to 20 Mbps. The LTM2883-S is SPI compliant and offers a total of six CMOS digital isolator communication channels. All channels operate at up to 20 Mbps and include three forward direction signals (/CS, SCK and SDI) and three reverse direction signals (SDO, DO1 and DO2). When configured for SPI communications, the maximum clock rate is 8 MHz for unidirectional communication or 4 MHz for round-trip bidirectional operation.

An onboard 2 MHz DC-DC converter powers the LTM2883 and allows each of the three isolated power supply outputs to source up to 20 mA over the full operating temperature range. A logic supply pin provides direct interfacing with low voltage microcontrollers down to 1.62 V, and an ON pin enables the LTM2883 to be shut down using less than 10 µA. Additional features include uninterrupted communications for common mode transients greater than 30 kV/µs and rugged ±10 kV ESD HBM across the isolation barrier.

Availability and Pricing

The LTM2883 is