Rail-to-Rail 80 Volt Power Monitor Measures Current And Voltage with ±0.75 Percent Accuracy

Linear Technology Corp. has  introduced the LTC2945, a wide range I²C system monitor that monitors the current, voltage and power of any 0 V to 80 V rail. In many cases, prior power monitoring solutions are limited to 3 V to 5 V supplies and monitor voltages less than 36 V, requiring additional circuitry to monitor higher voltages. The LTC2945 has flexible power supply options, deriving power from a 4 V to 80 V  monitored supply, a 2.7 V to 80 V secondary supply, or from the onboard shunt regulator. These supply options eliminate the need for a separate buck regulator, shunt regulator or inefficient resistive divider while monitoring any 0 V to 80 V 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 well suited for many applications, especially for 48 V telecom equipment, advanced mezzanine cards (AMC) and blade servers. The onboard shunt regulator provides support for supplies greater than 80 V 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 ±0.75 percent 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 400 kHz 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 3 mm by 3 mm QFN and 12-lead MSOP packages. Pricing starts at $3.57 each in 1,000 piece quantities.

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