Dual-Voltage µP Supervisory Circuits with Sequenced Reset Outputs

Active: In Production.

The MAX6391/MAX6392 microprocessor (µP) supervisory circuits provide sequenced logic reset outputs for multicomponent or dual-voltage systems. Each device can monitor two supply voltages and time-sequence two reset outputs to control the order in which system components are turned on and off. The MAX6391/MAX6392 increase system reliability and reduce circuit complexity and cost compared to separate ICs or discrete components.

The MAX6391/MAX6392 monitor V_CC as the master reset supply. Both active-low RESET1 and active-low RESET2 are asserted whenever V_CC drops below the selected factory-fixed reset threshold voltage. RESET1 remains asserted as long as V_CC is below the threshold and deasserts 140ms (min) after V_CC exceeds the thresholds.

RESET IN2 is monitored as the secondary reset supply and is adjustable with an external resistive-divider network. Active-low RESET2 is asserted whenever either V_CC or RESET IN2 is below the selected thresholds. Active-low RESET2 remains asserted 140ms (min) or a capacitor-adjustable time period after V_CC and RESET IN2 exceed their thresholds. RESET2 is always deasserted after active-low RESET1 during system power-up and is always asserted before active-low RESET1 during power-down.

The MAX6391 includes two internal pullup resistors for active-low RESET1 and active-low RESET2 (the open-drain outputs can be externally connected to the desired pullup voltages). The MAX6392 includes an active-low manual reset input (MR) that asserts both active-low RESET1 (push-pull) and RESET2 (open drain).

The MAX6391/MAX6392 are available in small 8-pin SOT23 packages and are specified over the -40°C to +85°C extended temperature range.

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