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Analog Angle Article

Power-supply monitor/controller is bridge between analog supply and digital oversight

Milpitas, CA—We hear a lot about digital power supplies, with a processor as the core of the control loop, but many applications are not ready for–or comfortable with–that approach, whether due to cost, familiarity, performance, reliability, or other reasons The LTC2978 from Linear Technology Corp. extends digital control and insight to analog supplies, so designers can get some of the benefits of digital control and interfacing while retaining the architecture of a conventional analog supply, Figure 1 .



Using analog and digital blocks to control an analog-only supply

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The IC can be used with a power-supply subsystem to allow adjustment of output voltage and as well as implement protection, monitoring, and diagnostics. The internal EEPROM is accessible via the PMBus interface, so users can configure their supplies, assess fault situations and data, implement responses, and check supply performance. Further, the LTC2978 includes a menu of supervisory, margining, and sequencing functions to extend its power-management umbrella.

The LTC2978 is an eight-channel device, and can be cascaded with other LTC2978 ICs for up to 72 channels. It includes a sequencer and a differential, 15-bit sigma-delta A/D converter (12.5 μV resolution, 0.25% accuracy); as well as a 10-bit dual-range margin/trim D/A converter. Each channel has a programmable overvoltage/undervoltage supervisor. The 9×9 mm IC also includes an internal temperature sensor and a programmable watchdog timer, Figure 2 .



Key functions of the LTC2978

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In operation, the LTC2978 as a smart supervisor/manager for the supply while connected to the load, Figure 3 , and also provides fault data logging.



Use of LTC2978 Monitor/Controller with power supply and load

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To establish and monitor thee the IC's functions, users connect a PC via vendor-available interface circuitry and invoke LTC's LTpowerPlay™ graphical user interface (even analog-IC vendors have to provide GUIs in the 21st century;)—Bill Schweber.

Price, package, and availability : The 64-lead LTC2978 is housed in a 9×9mm QFN package and is priced at $10.95 in 1000-piece lots; it is available immediately from stock.

For more information , contact Linear Technology Corp., http://www.linear.com.

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