Low-Cost, Power-On Reset

and Watchdog Controllers

Pin Description

PIN

SO

PDIP

NAME

FUNCTION

1, 4, 9

3, 4, 8

GND

Chip Power Ground

2, 3

1, 2

+5V Sense Input and MAX698/MAX699 Chip Power

5–8, 10–14

5, 6

N.C.

No Connection

10

6

WDI (MAX699 Only)

(MAX699 Only.) A three-level input. If WDI remains high or low for

more than the watchdog timeout period, RESET pulses low (WDO

also goes low on the MAX699 SO package). If WDI is unconnected,

the watchdog circuit is disabled.

14

—

WDO (MAX699 Only)

(MAX699 Only.) Goes low when WDI remains high or low for more

than the watchdog timeout period. WDO is set high at the next WDI

transition. If WDI is unconnected or at midsupply, WDO remains high.

15

7

RESET

Electrical Characteristics table).

16

—

RESET

WDI*

WATCHDOG

TIMER

RESET

TIMER

GND

WDO*

RESET

RESET*

POWER-ON

RESET

4.65V

MAX698

MAX699

*WDI ON MAX699 ONLY

RESET ON SO PACKAGE ONLY

WDO ON SO MAX699 ONLY

Figure 1. Block Diagram

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