LTC's rail-to-rail 80-V power monitor measures current and voltage with ±0.75% accuracy

Linear Technology has introduced the LTC2945, a wide range I²C system monitor that monitors the current, voltage, and power of any 0- to 80-V rail. In many cases, prior power monitoring ICs are limited to 3- to 5-V 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 4 to 80-V monitored supply, a 2.7- 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- to 80-V rail. The LTC2945 is a simple, single IC 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, AMCs (advanced mezzanine cards), and blade servers. The onboard 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 TUE (total unadjusted error) 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° to 70 °C and -40 to 85 °C, respectively. Both versions are available today in RoHS compliant, 12-pin 3- x 3-mm QFN and 12-lead MSOP packages. Pricing starts at $3.57 each in 1,000 piece quantities. Summary of Features: LTC2945

• Rail-to-rail input range: 0 to 80 V
• Wide input supply range: 2.7 to 80 V
• Shunt regulator for supplies > 80 V
• I²C interface
• ?? ADC with < ±0.75% TUE
• 12-bit resolution for current and voltages
• Internal multiplier calculates 24-bit power value
• Additional ADC input monitors an external voltage
• Minimum & maximum values stored
• Continuous scan and snapshot modes
• Shutdown mode with I_Q < 80 μA
• Split SDA for opto-isolation
• Available in 12-pin 3- x 3-mm QFN and 12-lead MSOP packages