45V LDO has diagnostics for industrial and hi-rel

Linear Technology has introduced a 45V LDO that indicates over-load and low-load (open circuit), die temperature and allows an associated microcontroller to calculate power dissipation in both the regulator and the load.

Called LT3055, the basic specs are 2-45V in, 0.6-40V at up to 500mA out, and 350mV drop-out at max current.

“A single capacitor at the REF/BYP pin provides programmable low noise operation 25µV_RMS across 10Hz to 100kHz, and also reference soft start functionality, preventing output voltage overshoot at turn-on,” said Linear. “Output voltage tolerance is +/-2% over line, load and temperature.”

Diagnostics come from:

A resistor at the I_MAX pin programmes current limit, accurate to ±10% over the full temperature range.

A resistor at the I_MIN pin programmes a minimum output current detector, “useful for identifying open-circuit conditions”, said Linear.

A current monitor function sources current equal to 1/500th of output current, “allowing the user to measure output current or calculate the device’s power dissipation”.

Logic fault pins Fault1 and Fault2 (open collector), assert low if the LT3055 is in current limit (Fault2), is operating below minimum output current (Fault1) or is in thermal limit (both).

PwrGd (open collector) indicates output regulation.

The Temp pin indicates die temperature with 250mV for 25°C, and a slope of 10mV/°C.

In-built protection includes reverse input, reverse output, reverse current, internal default current limiting and thermal limiting.

With reverse input “the device protects both itself and the load. No reverse current flows into the regulator and no reverse voltage appears at the load,” said Linear. “In battery back-up applications where the output is held up by a back-up battery and the input is pulled to ground, the LT3055 acts like it has a diode in series with its output and prevents reverse current flow.”

A 3.3µF ceramic output capacitor is needed (4.7µF below 1.2V).

Quiescent current is 65µA (operating), and <1µA in shutdown.

Application are expected in active antennas, industrial products, battery-powered systems, and high reliability power supplies requiring diagnostic and protection.

Packages are 3x4mm 16-lead DFN (-40 to 125°C) and 16-lead MSOP (-40 to 125°C, -55 to 150°C, or -40°C to 150°C).

Now, where have I heard that 3055 number before….