An overvoltage detector which suppresses glitches is constructed from the LTC®1541 micropower op amp + comparator + voltage reference and LTC6994-1 TimerBlox® delay block/debouncer. In this circuit, the LTC1541 comparator detects power rail overvoltage conditions (including glitches). The built-in op amp inverts this signal and drives the LTC6994-1 which debounces the active low overvoltage signal to suppress glitches shorter than a given delay period. The delay period is set by a single resistor at the SET pin. The supply of LTC1541 and LTC6994-1 can be Vin or 2.5V - 5.5V voltage source. The accuracy of the circuit depends on the LTC1541 variations of the Vref, Vtrip, Vhysteresis and Vos voltages.
The LTC6994 is a programmable delay block with a range of 1µs to 33.6 seconds. The LTC6994 is part of the TimerBlox family of versatile silicon timing devices. A single resistor, RSET, programs an internal master oscillator frequency, setting the LTC6994’s time base. The input-to-output delay is determined by this master oscillator and an internal clock divider, NDIV, programmable to eight settings from 1 to 221. The output follows the input after delaying the rising and/or falling transitions. The LTC6994-1 will delay the rising or falling edge. For easy configuration of the LTC6994, download the TimerBlox Designer Tool. The LTC6994 is available in 6-pin ThinSOT and DFN packages.
The LTC1541/LTC1542 combine a micropower amplifier, comparator and bandgap reference in an 8-pin package. The part operates from a single 2.5V to 12.6V or dual ±1.25V to ±6.3V supply with a typical supply current of 5µA. Both the op amp and comparator feature a common mode input voltage range that extends from the negative supply to within 1.3V of the positive supply. The op amp output stage swings from rail-to-rail. The comparator's inverting input is internally connected to the reference output. The LTC1541is available in DFN, MSOP and SO packages.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
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