MAX44268 Maxim, MAX44268 Datasheet - Page 9

• Manufacturer Part Number: MAX44268
• Description: The MAX44268 is an ultra-small and low-power dual comparator ideal for battery-powered applications such as cell phones, notebooks, and portable medical devices that have extremely aggressive board space and power constraints
• Manufacturer: Maxim

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.
The input common-mode voltage range extends from
(V
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.
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
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.
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.
GND
- 0.2V) to (V
Typical Operating Characteristics
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CC
+ 0.2V). The comparator operates
No Output Phase Reversal
Detailed Description
Input Stage Structure
for Overdriven Inputs
Open-Drain Output
RF Immunity
Dual Comparator with Reference
section.
1.3mm x 1.3mm, Low-Power
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
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 1. Threshold Hysteresis Band (Not to Scale)
Figure 2. Adding Hysteresis with External Resistors
OUT
IN+
IN-
V
IN
V
(Figure
HYST
R2
R4
1). The difference between the trip points
Applications Information
V
REF
THERSHOLDS
HYSTERESIS BAND
R3
MAX44268
V
MAX44268
CC
GND
OUT
Hysteresis
(Figure
V
V
TH
TL
R1
2).