Figure 2b: LTM9100 soft-starting, a 270V load with controlled 200mA inrush current


controlling, protecting, and monitoring high voltage power supplies up to 1000V DC (Figure 2a). A 5kVRMS


isolation barrier


separates the logic and digital interface from the switch controller driving an external N-channel MOSFET or IGBT switch. The isolation is needed for control circuit protection, operator safety, and breaking ground paths. The load is soft- started (Figure 2b) and the supply is protected from overload with a current- limited circuit breaker. Isolated 10-bit ADC measurements of load current and two voltage inputs are accessed via the I2


C/SMBus interface, enabling power, energy and thermal monitoring of the high voltage bus. The LTM9100 utilises Linear


Technology’s isolator µModule technology (Figure 3) to translate signals and power across an isolation barrier. Signals are encoded into pulses and passed across the isolation boundary using coreless transformers formed in the µModule substrate, resulting in an extremely robust bidirectional communication scheme. Uninterrupted communication is guaranteed for


common mode transients of 50kV/µs. The isolated side is powered by a fully integrated DC/DC converter, including the transformer, eliminating the need for external components. To guarantee a robust isolation barrier, each LTM9100 controller is production-tested to 6kVRMS


.


The LTM9100 will be recognised by the UL 1577 standard, saving months of certification time for the end equipment manufacturer. High distance through- insulation translates to a high ±20kV ESD level across the barrier. The µModule package integrates several components and technologies to deliver a cost-effective, advanced solution that minimises board space and improves electrical and thermal performance. Due to its isolated nature, the


LTM9100 is easily configured for high side, low side (ground return) and floating applications (Figure 4). The LTM9100 is versatile enough to control inrush current not just in hot-swappable cards, but also in AC transformers, motor drives, and inductive loads. Adjustable undervoltage and overvoltage lockout thresholds ensure that the load


Figure 4: LTM9100 in a high side (positive) or low side (negative) switching application


operates only when the input supply is in its valid range. The 22mm x 9mm x 5.16mm BGA package provides 14.6mm of creepage distance between the logic side and the isolated side.


Conclusion Traditionally, high voltage DC supplies are found in industrial environments, but other electronic systems are also moving towards higher voltages to lower costs and raise the efficiency of power distribution, especially in power-hungry systems. These supplies need a simple way to control inrush current, protect themselves and to monitor their usage. The first-of-its-kind LTM9100 delivers this simple and compact solution, beating discrete and relay based circuits by providing a certified ready-to-go solution, saving board area and multiple months of design time and certification effort. All the needed functionality, including digital telemetry and isolated power, is wrapped in a compact, surface mount, and low- profile BGA package.


www.linear.com Linear Technology,


Figure 3: Inside peek at Linear Technology’s isolator µModule technology www.cieonline.co.uk


now part of Analog Devices Tel: 01628 477066


Components in Electronics April 2017 9


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52