Detailed Description

The MAX40000/MAX40001 feature an on-board

voltage reference with ±1% initial accuracy. This family

of comparators with internal references are available in

multiple voltage reference options. The Ordering

Information table provides exact part numbers associated

with a particular voltage reference option. The common-

mode voltage range of this family extends 200mV beyond

the rails, allowing signals slightly beyond the rails to

trigger the comparator. The 2.5mV internal hysteresis

ensures clean output switching even with slow moving

input signals. Large internal output drivers allow rail-to-rail

output swing with up to ±2mA loads.

The output stage employs a unique design that minimizes

supply current surges while switching, virtually eliminating

supply glitches typical of many other comparators. The

MAX40000 has a push-pull output stage that sinks as

well as sources current. The MAX40001 has an open-

maximum of 5.5V above GND. Multiple comparators with

open-drain outputs (OUT) can be connected together in

parallel and share a single pullup resistor. This enables

user to detect if there is any fault if at least one comparator

trips different to other comparators.

Input Stage Circuitry

The input common-mode voltage range extends from

differential input voltage within these limits. Input bias cur-

rent is typically ±1nA if the input voltage is between the

supply rails.

Output Stage Structure

The devices contain a unique break-before-make output

stage capable of rail-to-rail operation with up to ±2mA

loads. Many comparators consume orders of magnitude

more current during switching than during steady-state

operation. In the Typical Operating Characteristics,

the Supply Current vs. Output Transition Frequency

graphs show the minimal supply-current increase as the

output switching frequency approaches 1kHz. This

characteristic reduces the need for power-supply filter

capacitors to reduce glitches created by comparator

switching currents. In battery-powered applications, this

characteristic results in a substantial increase in battery life.

Voltage Reference

The MAX40000/MAX40001 come with different internal

voltage reference options that has initial accuracy of ±1%.

1.252V, 1.6V, 1.9V, and 2.2V options of internal voltage

references are available. The devices’ internal reference

has a typical temperature coefficient of 15ppm/°C over

the full -40°C to +125°C temperature range. The reference

is a very-low-power bandgap cell, with a maximum 10kΩ

output impedance. REF pin can source and sink up to

100nA to external circuitry. For applications that need

increased drive, buffer REF with a low input-bias current

op amp such as the MAX44265. Most applications require

no bypass capacitor on REF pin.

MAX40000

MAX40001

REF

GND

IM

OUT

IP

REF

MAX40000/MAX40001

1.7V, 0.9µA Comparators with

Built-in Reference

www.maximintegrated.com

Maxim Integrated │ 10

Functional Diagram