Simplified Block Diagram
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- 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
- Industrial Equipment
- Multivoltage Systems
- Portable Battery-Powered Equipment
- Printers/Fax Machines
- Set-Top Boxes
- Telecom/Networking Equipment
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.