The LTC2945 is a rail-to-rail system monitor that measures current, voltage, and power. It features an operating range of 2.7 to 80 V and includes a shunt regulator for supplies above 80 V to allow use with various input supply voltages. The current measurement range of 0 to 80 V is independent of the input supply. An onboard 0.75% accurate, 12-bit ADC measures load current, input voltage, and an auxiliary external voltage. A 24-bit power value is generated by digitally multiplying the measured 12-bit load current and input voltage data.

Minimum and maximum values are stored and an over-range alert with programmable thresholds minimizes the need for software polling. Data is reported via a standard I²C interface, and a shutdown mode reduces power consumption to 20 μA.

The LTC2945 I2C interface includes separate data input and output pins for use with standard or optoisolated I²C connections. The LTC2945-1 has an inverted data output for use with inverting opto-isolator configurations. Applications include telecom infrastructure, industrial, automotive, and consumer products.

Features include:

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

Linear Technology Corp., 1630 McCarthy Blvd., Milpitas, CA 95035. Phone: (408) 432-1900.