6-Pin µP Reset Circuit with

Power-Fail Comparator

_______________________________________________________________________________________

5

MAX6344

MAX6342

—

6

Active-High Push-Pull Reset Output. It remains high for 180ms

to high.

6

—

Active-Low Reset Output. Push-pull for MAX6342/MAX6345.

rises above the reset threshold or MR goes from low to high.

5

5

Manual-Reset Input. Pull low to force a reset. RESET or RESET

remains active as long as MR is low and for the reset timeout

period after MR goes high. Leave unconnected or connect to

Pin Description (continued)

MAX6343

—

6

5

MAX6345

6

5

—

RESET

RESET

MR

FUNCTION

PIN

NAME

_______________Detailed Description

Reset Output

A µP’s reset input starts the µP in a known state. These

µP supervisory circuits assert reset to prevent code-

execution errors during power-up, power-down, or

brownout conditions.

RESET and RESET are guaranteed to be asserted at a

acteristics table). Once RESET asserts, it remains

its threshold value or after MR returns high (Figures 1

and 2).

The MAX6343 has an active-low, open-drain reset out-

put. This output sinks current when RESET is asserted.

Connect a pull-up resistor from RESET to any positive

supply voltage up to +5.5V (Figure 3). Select a resistor

value large enough to register a logic low (see the Elec-

trical Characteristics table), and small enough to regis-

ter a logic high while supplying all input current and

leakage paths connected to the RESET line. A 10k

Ω

pull-up is sufficient in most applications.

Manual Reset

The MAX6342/MAX6343/MAX6344s’ manual-reset input

(MR) allows reset to be triggered by a pushbutton

switch. The switch is effectively debounced by the 1µs

min reset pulse width. MR is CMOS-logic compatible.

RESET

GENERATOR

6

(RESET)

5

RESET

4

PFO

1.25V

GND

100k

Ω

( ) ARE FOR MAX6344 ONLY.

1

MR

2

3

PFI

MAX6342

MAX6343

MAX6344

RESET

GENERATOR

6

RESET

5

RESET

4

PFO

1.25V

GND

1

2

3

PFI

MAX6345

Figure 1. MAX6342/MAX6343/MAX6344 Functional Diagram

Figure 2. MAX6345 Functional Diagram