_______________Detailed Description

The MAX6338 is a low-power (25µA), quad voltage

monitor designed for multivoltage systems. Preset volt-

age options for +5.0V, +3.3V, +3.0V, +2.5V, +1.8V, and

-5.0V make these quad monitors ideal for applications

such as telecommunications, desktop and notebook

computers, high-end printers, data storage equipment,

and networking equipment.

The MAX6338 has an internally trimmed threshold that

minimizes or eliminates the need for external compo-

nents. The four open-drain outputs have weak (10µA)

with other logic devices. The MAX6338 can monitor

power supplies with either 5% or 10% tolerance specifi-

cations, depending on the selected version. An addi-

tional high-input-impedance comparator option can be

used as an adjustable voltage monitor, general-pur-

pose comparator, or digital level translator.

The weak internal pullups can be overdriven by external

pullups to any voltage from 0 to +5.5V. Internal circuitry

prevents current flow from the external pullup voltage to

good” signal.

The MAX6338 has either one or two auxiliary inputs and

two or three factory-programmed threshold voltages, or

four fixed voltages. The inverting input of all compara-

tors is connected to a 1.23V bandgap reference for all

positive voltages. The noninverting terminals are acces-

sible through internal resistive voltage-dividers with

preset factory threshold voltages. In the case of auxil-

iary (AUX) input, the positive terminal of the comparator

is accessible directly for setting the threshold for the

monitored voltage.

When any of the inputs (IN1–IN4) are higher than the

threshold level, the output is high. The output goes low

as the input drops below the threshold voltage monitor.

The undervoltage lockout circuitry remains active and

Applications Information

Hysteresis

When the voltage on one comparator input is at or near

the voltage on the other input, ambient noise generally

causes the comparator output to oscillate. The most

common way to eliminate this problem is through hys-

teresis. When the two comparator input voltages are

equal, hysteresis causes one comparator input voltage

to move quickly past the other, thus taking the input out

of the region where oscillation occurs. Standard com-

parators require hysteresis to be added through the

use of external resistors. The external resistive network

usually provides a positive feedback to the input in

order to cause a jump in the threshold voltage when

Quad Voltage Monitor in µMAX Package

4

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Pin Description

PIN

NAME

FUNCTION

1

IN1

Input Voltage 1. See Selector Guide for monitored voltages.

2

IN2

Input Voltage 2. See Selector Guide for monitored voltages.

3

IN3

Input Voltage 3. See Selector Guide for monitored voltages.

4

IN4

Input Voltage 4. See Selector Guide for monitored voltages.

5

GND

Ground

6

OUT4

7

OUT3

8

OUT2

µA

9

OUT1

µA

10