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Micromodule Isolator Produces Over 100 mA

14 December 2016

LTM2887 μModule®?isolator. Source: Linear Technology LTM2887 μModule®?isolator. Source: Linear Technology Linear Technology Corporation has introduced the LTM2887, a six-channel SPI/Digital or I²C μModule® isolator with dual-rail regulated power that targets low-voltage components, including newer DSPs and microprocessors. Two well-regulated adjustable supply rails (up to 5 V) deliver more than 100 mA of load current over the isolation barrier, with up to 62% efficiency. The voltages may be adjusted to as low as 0.6 V for the auxiliary supply, while the isolated logic supply may be as low as 1.8 V for SPI interfaces. Each supply provides a precise current limit adjustment pin and the ability to adjust the voltage using external resistors.

In industrial system applications, ground potentials can vary widely—often exceeding the tolerable range, interrupting communications or even destroying components. The LTM2887 breaks ground loops by electrically isolating the logic level interface on each side of an internal isolation barrier. This inductively coupled barrier withstands very large ground differential voltages up to 2,500 VRMS.

A low EMI isolated DC/DC converter powers the LTM2887 and provides the isolated power to the communications interface and output rails. A separate logic supply pin provides direct interfacing with low-voltage microcontrollers down to 1.62 V, and an ON pin enables the LTM2887 to be shut down and use less than 10 μA. The LTM2887 provides uninterrupted communications for common mode transients greater than 30 kV/μs and rugged ±10 kV ESD (HBM) protection across the isolation barrier.

The LTM2887 is available in two communications interface versions. The LTM2887-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 up to 10 MHz. The LTM2887-S is SPI compliant and offers six CMOS digital isolator communication channels. All channels operate at up to 10 MHz 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.

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