Single-/Dual-/Triple-Voltage µP Supervisory

Circuits with Independent Watchdog Output

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7

Pin Description

PIN

MAX6730

MAX6731

MAX6732

MAX6733

MAX6734

MAX6735

NAME

FUNCTION

11

1

RST

Active-Low Reset Output. The MAX6730/MAX6732/MAX6734 provide an open-drain

output. The MAX6731/MAX6733/MAX6735 provide a push-pull output. RST asserts

preset threshold, RSTIN drops below its reset threshold, or MR is driven low. Open-

drain versions require an external pullup resistor.

2

2

2

GND

Ground

33

4

WDO

Active-Low Watchdog Output. The MAX6730/MAX6732/MAX6734 provide an open-

drain WDO output. The MAX6731/MAX6733/MAX6735 provide a push-pull WDO

output. WDO asserts low when no low-to-high or high-to-low transition occurs on

reset input is asserted. Open-drain versions require an external pullup resistor.

4—

5

MR

Active-Low Manual Reset Input. Drive MR low to force a reset. RST remains

asserted as long as MR is low and for the reset timeout period after MR releases

high. MR has a 50k

unused.

5

5

3

WDI

Watchdog Input. If WDI remains high or low for longer than the watchdog timeout

period, the internal watchdog timer expires and the watchdog output asserts low.

The internal watchdog timer clears whenever RST asserts or a rising or falling edge

on WDI is detected. The watchdog has an initial watchdog timeout period (35s min)

after each reset event and a short timeout period (1.12s min) after the first valid

WDI transition. Leaving WDI unconnected does not disable the watchdog timer

function.

66

8

—4

6

—

—

7

RSTIN

Undervoltage Reset Comparator Input. RSTIN provides a high-impedance

comparator input for the adjustable reset monitor. RST asserts low if the voltage at

RSTIN drops below the 626mV internal reference voltage. Connect a resistive

voltage-divider to RSTIN to monitor voltages higher than 626mV. Connect RSTIN to