High-Side Power Monitor from Linear Technology

6th June 2008

ES Admin

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Linear Technology has introduced the LTC4151, a high side power monitor that measures current and input voltages from 7V to 80V. The LTC4151 utilizes an internal 12-bit ADC to continuously measure both high side current and input voltage to give a true power reading. The LTC4151 replaces prior solutions that use costly current sense amplifiers with a separate ADC, a hot-swap controller with an ADC, or an ADC with a floating ground.

These older implementations are in many cases limited by the ADC’s input voltage range (typically 5V or 10V), are much more expensive, require more board space, and are not reliable. The LTC4151’s simple, single-chip solution is ideal for 48V telecom equipment, advanced mezzanine cards (AMC), and blade servers used for measuring input power over a wide input range. The device is also appropriate for power monitoring in industrial applications running at 12V or 24V.

The maximum total unadjusted error (TUE) for the high-side current and voltage measurements is ±1.25% over the -40°C to +85°C industrial temperature range. A 2-wire I2C-compatible interface reports the LTC4151’s input power data, as well as a third low voltage input, which can be used to measure a voltage from a thermistor or a fuse. Data can be reported continuously or in a no-latency single snapshot mode, for applications that only need to measure input power occasionally. The LTC4151 features a dedicated shutdown pin to reduce power dissipation by 10x, while its counterpart, the LTC4151-1, features split I2C data pins with an inverted output to drive optoisolators.