Voltage Supervisor with 27 Selectable Thresholds and Watchdog Timer

The LTC2917-A/LTC2917-B and LTC2918-A/LTC2918-B are low voltage single-supply monitors with selectable thresholds and an adjustable watchdog timer. The parts operate from 1.5V to 5.5V and consume a quiescent current of only 30µA.

Two three state inputs select one of nine internally programmed thresholds without the need for external resistors. For the LTC2917, an additional three state input determines the tolerance (–5%, –10%, –15%). The tolerance for the LTC2918 is fixed at –5%. Threshold accuracy is guaranteed at ±1.5% over the entire operating temperature range. Glitch filtering ensures reliable reset operation without false triggering.

The reset timeout and the watchdog timeout may be set with no external components, or adjusted using an external capacitor. A windowed watchdog feature is available for high-reliability applications (B1 versions). A separate manual reset input on the LTC2918-A/LTC2918-B allows a simple push button interface.

Operation to 125°C makes the LTC2917-A/LTC2917-B and LTC2918-A/LTC2918-B suitable for automotive ap- plications.

Applications

* Handheld Devices

* Cell Phone Base Stations

* Automotive Control Systems

* Network Servers

* Optical Networking Systems

* 9 Selectable Supply Voltages

* 12V, 5V, 3.3V, 2.5V, 1.8V, 1.5V, 1.2V, 1V, +ADJ (0.5V)

* 3 Selectable Tolerances

* –5%, –10%, –15% (LTC2917)

* Manual Reset Input (LTC2918)

* 1.5V to 5.5V Supply Operation

* Adjustable Watchdog Timeout

* Windowed Watchdog Timeout for Higher Reliability Applications (LTC2917-B, LTC2918-B)

* 6.2V Shunt Regulator for High Voltage Operation

* Guaranteed Operation to 125°C

* Guaranteed Threshold Accuracy: ±1.5%

* Low Quiescent Current: 30µA Typical

* Power Supply Glitch Immunity

* Guaranteed RST for VCC ≥ 0.8V

* 10-Lead MSOP Packages and (3mm × 2mm) DFN Packages