Single-/Dual-/Triple-Voltage µP Supervisory Circuits with Independent Watchdog Output

The MAX6730A–MAX6735A single-/dual-/triple-voltage microprocessor (µP) supervisors feature a watchdog timer and manual reset capability. The MAX6730A–MAX6735A offer factory-set reset thresholds for monitoring voltages from +0.9V to +5V and an adjustable reset input for monitoring voltages down to +0.63V. The combination of these features significantly improves system reliability and accuracy when compared to separate ICs or discrete components.

The active-low reset output asserts and remains asserted for the reset timeout period after all the monitored voltages exceed their respective thresholds. Multiple factory-set reset threshold combinations reduce the number of external components required. The MAX6730A/MAX6731A monitor a single fixed voltage, the MAX6732A/MAX6733A monitor two fixed voltages, and the MAX6734A/MAX6735A monitor two fixed voltages and one adjustable voltage. All devices are offered with six minimum reset timeout periods ranging from 1.1ms to 1120ms.

The MAX6730A–MAX6735A feature a watchdog timer with an independent watchdog output. The watchdog timer prevents system lockup during code execution errors. A watchdog startup delay of 54s after reset asserts allows system initialization during power-up. The watchdog operates in normal mode with a 1.68s delay after initialization. The MAX6730A/MAX6732A/MAX6734A provide an active-low, open-drain watchdog output. The MAX6731A/MAX6733A/MAX6735A provide an active-low, push-pull watchdog output.

Other features include a manual reset input (MAX6730A/MAX6731A/MAX6734A/MAX6735A) and push-pull reset output (MAX6731A/MAX6733A/MAX6735A) or open-drain reset output (MAX6730A/MAX6732A/MAX6734A). The MAX6730A–MAX6733A are offered in a tiny 6-pin SOT23 package. The MAX6734A/MAX6735A are offered in an 8-pin, space-saving SOT23 package. All devices are fully specified over the extended -40°C to +125°C temperature range.

Applications

* Computers/Servers * Industrial Equipment * Multivoltage Systems * Portable Battery-Powered Equipment * Printers/Fax Machines * Set-Top Boxes * Telecom/Networking Equipment

* VCC1 (Primary Supply) Reset Threshold Voltages from +1.575V to +4.63V

* VCC2 (Secondary Supply) Reset Threshold Voltages from +0.79V to +3.08V

* Adjustable RSTIN Threshold for Monitoring Voltages Down to +0.63V (MAX6734A/MAX6735A Only)

* Six Reset Timeout Options

* Watchdog Timer with Independent Watchdog Output

* 35s (min) Initial Watchdog Startup Period

* 1.12s (min) Normal Watchdog Timeout Period

* Manual Reset Input (MAX6730A/MAX6731A/MAX6734A/MAX6735A)

* Guaranteed Reset Valid down to VCC1 or VCC2 = +0.8V

* Push-Pull Active-Low RESET or Open-Drain Active-Low RESET Output

* Immune to Short VCC Transients

* Low Supply Current: 14µA (typ) at +3.6V

* Small 6-Pin and 8-Pin SOT23 Packages