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Pushbutton controller has voltage monitor, timer

Posted: 05 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:pushbutton controller? switching regulators? voltage monitors?

Linear Technology Corp. has introduced a pushbutton controller that integrates supervisory voltage monitors and timers for tracking a switching regulator's input and output voltages. LTC2953-1 combines dual input, output and pushbutton functions in a small 3-by-3mm DFN-12 package and is targeted for power path control, portable supervisors, PDAs and notebooks.

LTC2953-1 uses a power-fail input (PFI) comparator and under-voltage lockout (UVLO) comparator to trigger software and hardware control outputs when the input supply drops below two separate threshold voltages. An enable output forces the switching regulator's shutdown pin high when the input voltage drops below the UVLO threshold longer than an adjustable time period.

LTC2953-1 also monitors the regulator's output and triggers a reset signal when the output voltage dips below an adjustable threshold due to excessive loading. In addition to the input and output voltage comparators, this controller also includes a pushbutton input and software interrupt output.

Drawing only 14?A of supply current, LTC2953-1 operates over a wide 2.7-27V input supply range, serving single- or multi-battery applications as well as industrial supply lines that operate from 24V (10 percent tolerance). The rugged pushbutton input is designed to operate in noisy environments and can withstand ESD strikes up to 10kV, per the human body model.

A UVLO comparator latches power off and the reset output remains low until the supply monitor input has been in compliance for 200ms. The internal UVLO, PFI and voltage monitor comparators are accurate to 1.5 percent over the full temperature range. A single capacitor controls the adjustable power-down timer in order to allow the system time to perform all of the necessary housekeeping procedures before shutting down.

LTC2953-2 is a pin-compatible pushbutton controller with an active-low enable output. Both the LTC2953-1 and LTC2953-2 are available in commercial and industrial temperature grades.

Both the LTC2953-1 and LTC2953-2 devices are available now. Pricing starts at $2.30 each in quantities of 1,000.

- Gina Roos

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