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Power monitor offers high-accuracy current sensing

Posted: 10 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:current/power monitor IC? I2C interface?

Texas Instruments Inc. has introduced a high-side measurement, bidirecTIonal current/power monitor IC with an I?C interface.

Using a zero-drift, auto-zeroing architecture, INA209 provides a high accuracy current sensing solution that offers one percent maximum accuracy over the -40C to 85C temperature range with 100?V maximum offset. The device provides monitoring and control of current, voltage and power in a variety of applications such as servers, telecommunications equipment, battery chargers, power management, automotive and test equipment.

How it works: INA209 monitors the drop across a shunt resistor and senses shunt bus voltage from 0V to 26V. An internal multiplier and calibration register provide direct data for current in amps and power in watts. The device operates from a single 3-5.5V supply.

The INA209 device features three levels of programmable watchdogs. The lowest level includes a programmable delay to ignore transient events. An intermediate level provides an output with no delay. A fully programmable fast analog path enables the highest level of warning for use in implementing immediate system shutdowns. In addition to the internal filtering for current and voltage measurements, the fast analog comparator also includes a filter for use in noisy environments, said TI.

Full scale readings as low as 40mV are available, keeping shunt dissipation to a minimum while a programmable gain amplifier function provides additional higher ranges. The ADC converts 12bit values in 530?s and offers combinations of lower resolution with higher speed as well as averaging (up to 128 samples). An external trigger line is available to trigger conversions at specific times.

The I?C interface includes a timeout to prevent bus lock-up and a high-speed mode to enable communications up to 3.4MHz. All features of the INA209 are software programmable.

INA209 is available in a TSSOP-16 package. Pricing starts at $3.50 in 1,000-piece quantities.

- Gina Roos

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