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Rail-to-Rail 80V Power Monitor Measures Current & Voltage with ±0.75% Accuracy

Nov 7 2012 - MILPITAS, CA
  • Linear Technology Corporation introduces the LTC2945, a wide range I2C system monitor that monitors the current, voltage and power of any 0V to 80V rail. In many cases, prior power monitoring solutions are limited to 3V to 5V supplies and monitor voltages less than 36V, requiring additional circuitry to monitor higher voltages. The LTC2945 has flexible power supply options, deriving power from a 4V to 80V monitored supply, a 2.7V to 80V secondary supply, or from the on-board shunt regulator. These supply options eliminate the need for a separate buck regulator, shunt regulator or inefficient resistive divider while monitoring any 0V to 80V rail. The LTC2945 is a simple, single-IC solution that uses an internal Delta Sigma ADC and multiplier to provide 12-bit current and voltage measurements and 24-bit power readings.


    The LTC2945’s wide operating range is ideal for many applications, especially for 48V telecom equipment, advanced mezzanine cards (AMC) and blade servers. The on-board shunt regulator provides support for supplies greater than 80V and negative supply monitoring. The LTC2945 measures current and voltage either continuously or on-demand, calculates power and stores all of this information along with minimum and maximum values in I2C accessible registers. Measurements are made with only ±0.75% of total unadjusted error (TUE) over the entire temperature range. If any parameter exceeds the user-programmable limits, the LTC2945 flags an alert register and pin per the SMBus alert response protocol. The 400kHz I2C interface features nine device addresses, a stuck bus reset timer and a split SDA pin that simplifies I2C opto-isolation. The LTC2945-1 version offers an inverted data output I2C pin for use with inverting opto-isolator configurations.


    The LTC2945 and LTC2945-1 are offered in commercial and industrial versions, supporting operating temperature ranges from 0°C to 70°C and –40°C to 85°C, respectively. Both versions are available today in RoHS compliant, 12-pin 3mm × 3mm QFN and 12-lead MSOP packages. Pricing starts at $3.57 each in 1,000 piece quantities. Please visit www.linear.com/products/power_monitors for more product selection and information.


    Summary of Features: LTC2945


    • Rail-to-Rail Input Range: 0V to 80V
    • Wide Input Supply Range: 2.7V to 80V
    • Shunt Regulator for Supplies >80V
    • I2C Interface
    • ΔΣ ADC with Less than ±0.75% TUE
    • 12-Bit Resolution for Current & Voltages
    • Internal Multiplier Calculates 24-Bit Power Value
    • Additional ADC Input Monitors an External Voltage
    • Minimum & Maximum Values Stored
    • Continuous Scan & Snapshot Modes
    • Shutdown Mode with IQ < 80µA
    • Split SDA for Opto-Isolation
    • Available in 12-pin 3mm ×< 3mm QFN & 12-Lead MSOP Packages

    Wide Range Power Monitor with Onboard ADC, I2C & Shunt Regulator

    LTC2945 PR Image

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  • About Analog Devices
  • Innovation, performance, and excellence are the cultural pillars on which Analog Devices has built one of the longest standing, highest growth companies within the technology sector. Acknowledged industry-wide as the world leader in data conversion and signal conditioning technology, Analog Devices serves over 60,000 customers, representing virtually all types of electronic equipment. Analog Devices is headquartered in Norwood, Massachusetts, with design and manufacturing facilities throughout the world. Analog Devices is included in the S&P 500 Index.
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