Ultra-Low-Voltage µP Reset Circuits and Voltage Detectors

The MAX6841–MAX6845 microprocessor (µP) supervisory circuits monitor ultra-low-voltage power supplies in µP and digital systems. They provide excellent circuit reliability at low cost by eliminating external components and adjustments when used with +0.9V to +1.5V systems. Factory-trimmed reset thresholds are available for the MAX6841/MAX6842. The MAX6843/MAX6844/MAX6845 provide a RESET IN input, allowing the user to externally adjust the reset threshold. The MAX6841–MAX6845 family features a debounced manual reset input (active-low MR). The reset comparator is designed to ignore fast transients on VCC.

The MAX6841–MAX6845 assert a reset signal whenever the VCC supply voltage declines below a preset or adjustable threshold or whenever manual reset (active-low MR) is asserted. Reset remains asserted for a fixed timeout delay after VCC has risen above the reset threshold and when manual reset is deasserted. Five timeout periods are available for each part: 150µs (voltage detector version), 1.5ms, 30ms, 210ms, and 1.68s (typ).

The MAX6841/MAX6843 have an active-low push-pull reset output. The MAX6841/MAX6842/MAX6844 have an active-high push-pull reset output, and the MAX6842/MAX6845 have an active-low open-drain reset output. The active-low open-drain reset output requires a pullup resistor that can be connected to a voltage from 0 to VCC.

The low supply current (5.7µA) and small package (SOT23-5) make the MAX6841–MAX6845 ideal for use in portable equipment.

Applications

* Computers * Controllers * Critical µP and µC Power Monitoring * Intelligent Instruments * Portable Battery-Powered Equipment * Servers and Workstations * Telecom/Networking Equipment * Wireless Base Stations

* Factory-Set Reset Threshold Voltages for Monitoring Supplies from 0.9V to 1.5V (MAX6841/MAX6842)

* Adjustable Threshold RESET IN (MAX6843/MAX6844/MAX6845)

* Low Power Consumption: 5.7µA (typ)

* ±2.5% Reset Threshold Accuracy Over Temperature

* Five Timeout Periods: 150µs (Voltage Detector Version), 1.5ms, 30ms, 210ms, and 1.68s

* Available in Three Output Configurations

* Push-Pull active-low RESET

* Push-Pull RESET

* Open-Drain active-low RESET

* Guaranteed Reset Valid to VCC = 0.55V (Active Low)

* Manual Reset Input

* Immune to Short VCC Transients

* Space-Saving 5-Pin SOT23 Package