MAX44268 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX44268

1.3mm x 1.3mm, Low-Power Dual Comparator with Reference

Maxim Integrated 

MAX44268

1.3mm x 1.3mm, Low-Power

Dual Comparator with Reference

Detailed Description

The MAX44268 is a general-purpose dual comparator for

battery-powered devices where area, power, and cost

constraints are crucial. The IC can operate with a low

1.8V supply rail typically consuming 0.7µA quiescent cur-

rent per comparator. This makes it ideal for mobile and

very low-power applications. The IC’s common-mode

input voltage range extends 200mV beyond-the-rails. An

internal 4mV hysteresis ensures clean output switching,

even with slow-moving input signals.

Input Stage Structure

The input common-mode voltage range extends from

(VGND - 0.2V) to (VCC + 0.2V). The comparator operates

at any different input voltage within these limits with low

input bias current. Input bias current is typically 0.15nA if

the input voltage is between the supply rails. The device

also features a 1.236V reference voltage output on the

inverting input of comparator A.

The IC features a unique input ESD structure that can

handle voltages from -0.3V to +6V independent of supply

voltage. This allows for the device to be powered down

with a signal still present on the input without damag-

ing the part. This feature is useful in applications where

one of the inputs has transient spikes that exceed the

supply rails.

No Output Phase Reversal

for Overdriven Inputs

The IC’s design is optimized to prevent output phase

reversal if both the inputs are within the input common-

mode voltage range. If one of the inputs is outside the

input common-mode voltage range, then output phase

reversal does not occur as long as the other input is

kept within the valid input common-mode voltage range.

This behavior is shown in the No Output Phase Reversal

graph in the Typical Operating Characteristics section.

Open-Drain Output

The IC features an open-drain output, enabling greater

control of speed and power consumption in the circuit

design. The output logic level is also independent from

the input, allowing for simple level translation.

RF Immunity

The IC has very high RF immunity due to on-chip filtering

of RF sensitive nodes. This allows the IC to hold its output

state even in the presence of high amounts of RF noise.

This improved RF immunity makes the IC ideal for mobile

wireless devices.

Applications Information

Hysteresis

Many comparators oscillate in the linear region of opera-

tion because of noise or undesired parasitic feedback.

This tends to occur when the voltage on one input is

equal or very close to the voltage on the other input.

The hysteresis in a comparator creates two trip points:

one for the rising input voltage and one for the falling input

voltage (Figure 1). The difference between the trip points

is the hysteresis. When the comparator’s input voltages

are equal and the output trips, the hysteresis effectively

causes one comparator input to move quickly past the

other. This takes the input out of the region where oscil-

lation occurs. This provides clean output transitions for

noisy, slow-moving input signals. The IC has an internal

hysteresis of 4mV. Additional hysteresis can be generat-

ed with three resistors using positive feedback (Figure 2).

IN+

THERSHOLDS

HYSTERESIS BAND

VTH

IN-

VHYST

VTL

OUT

Figure 1. Threshold Hysteresis Band (Not to Scale)

VCC

R3

R2

VIN

MAX44268

R1

OUT

R4

VREF

GND

Figure 2. Adding Hysteresis with External Resistors

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