Selectable Polarity Dual Supervisor Monitors Undervoltage or Overvoltage for Positive or Negative Supplies

Nov 17 2005 -MILPITAS, CA
  • Linear Technology introduces the LTC2909, a dual low voltage adjustable input supervisor intended for a variety of system monitoring applications. A single select pin chooses one of three possible polarity combinations for the adjustable inputs. The LTC2909 can monitor two supplies - positive, negative, or both - for UV, OV or one of each. It may also monitor a single supply (positive or negative) for UV and OV simultaneously. The adjustable trip thresholds are set with an external resistive divider network, giving users complete control over the trip point and tailoring the LTC2909 to the needs of specific designs.

    The low voltage threshold of 0.5V comes with an accuracy of ±1.5%, ensuring reliable reset operation without false triggering. A precision undervoltage lockout allows VCC to be used as an accurate third fixed 10% UV supply monitor. The common reset output delay can be configured to use a preset 200ms timeout, adjusted by an external capacitor or disabled.

    In addition to providing a highly versatile, precise solution for supply monitoring, the low quiescent current of 50µA and the tiny DFN package make the LTC2909 an ideal choice in low-voltage, space-limited applications. The onboard featured 6.5V shunt regulator, however, permits operation from a high voltage supply. Thus, the LTC2909 fits perfectly in small and portable appliances as well as in network servers and automotive applications.

    The IC is offered in 8-pin SOT-23 and 3mm × 2mm DFN packages and is specified over the commercial and industrial temperature ranges. Pricing begins at $1.55 each for 1,000 piece quantities.

    Summary of Features: LTC2909

    • Two Low Voltage Adjustable Inputs (0.5V)
    • Pin Selectable Input Polarity Allows Negative and OV Monitoring
    • Guaranteed Threshold Accuracy: ±1.5%
    • 6.5V Shunt Regulator for High Voltage Operation
    • Low 50µA Quiescent Current
    • Adjustable Reset Timeout Period
    • Ultralow Voltage Reset: VCC = 0.5V Guaranteed
    • Power Supply Glitch Immunity
    • Low Profile 8-Pin SOT-23 and (3mm × 2mm) DFN Packages


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