MAX9026EBT+T Maxim Integrated Products, MAX9026EBT+T Datasheet - Page 11

• Manufacturer Part Number: MAX9026EBT+T
• Description: IC COMPARATOR BTR 6-UCSP
• Manufacturer: Maxim Integrated Products
• Series: Beyond-the-Rails™r
• Type: with Voltage Referencer

Specifications of MAX9026EBT+T

• Number Of Elements: 1
• Output Type: Open-Drain, Rail-to-Rail
• Voltage - Supply: 1.8 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 6-UCSP®
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: MAX9026EBT+T; MAX9026EBT+TTR

The simplest circuit for adding external hysteresis is
shown in Figure 3. In this example, the hysteresis is
defined by:
where R
back resistance. Because the comparison threshold is
1/2 V
put and lack of reference. This provides symmetrical
hysteresis around the threshold.
In most cases, the push-pull outputs of the
MAX9025/MAX9027 are best for external hysteresis.
The open-drain output of the MAX9026/MAX9028 can
be used, but the effect of the feedback network on the
actual output high voltage must be considered.
Because the MAX9025–MAX9028 are intended for very
low power-supply systems, the highest impedance cir-
cuits should be used wherever possible. The offset
error due to input-bias current is proportional to the
total impedance seen at the input. For example, select-
ing components for Figure 3, with a target of 50mV hys-
teresis, a 5V supply, and choosing an R
gives R
therefore 10MΩ || 100kΩ, or 99kΩ. The maximum I
the MAX9025–MAX9028 is 2nA; therefore, the error due
to source impedance is less than 400µV.
Figure 2. Threshold Hysteresis Band
OUT
IN+
IN-
CC
V
V
THR
THF
S
, the MAX9027 was chosen for its push-pull out-
S
as 100kΩ. The total impedance seen at IN+ is
is the source resistance and R
V
Hysteresis
HB
UCSP, 1.8V, Nanopower, Beyond-the-Rails
______________________________________________________________________________________
THRESHOLDS
HYSTERESIS
=
Comparators With/Without Reference
BAND
R
R
FB
S
Output Considerations
×
Component Selection
V
CC
Simplest Circuit
FB
FB
is the feed-
of 10MΩ
B
of
When the input threshold is not set at 1/2 V
teresis added to the input threshold will not be symmet-
rical. This is typical of the MAX9025/MAX9026 where
the internal reference is usually used as the threshold.
If the asymmetry is unacceptable, it can be corrected
by adding resistors to the circuit.
Power-supply bypass capacitors are not typically need-
ed, but use 100nF bypass capacitors close to the
device’s supply pins when supply impedance is high,
supply leads are long, or excessive noise is expected
on the supply lines. Minimize signal trace lengths to
reduce stray capacitance. A ground plane and surface-
mount components are recommended. If the REF pin is
decoupled, use a new low-leakage capacitor.
Figure 4 shows a zero-crossing detector application.
The MAX9027’s inverting input is connected to ground,
and its noninverting input is connected to a 100mV
signal source. As the signal at the noninverting input
crosses 0V, the comparator’s output changes state.
The Typical Application Circuit shows an application
that converts 5V logic to 3V logic levels. The MAX9028
is powered by the +5V supply voltage, and the pullup
resistor for the MAX9028’s open-drain output is con-
nected to the +3V supply voltage. This configuration
allows the full 5V logic swing without creating overvolt-
age on the 3V logic inputs. For 3V to 5V logic-level
translations, simply connect the +3V supply voltage to
V
Figure 3. MAX9025/MAX9027 External Hysteresis
CC
VIN
and the +5V supply voltage to the pullup resistor.
R
S
V
CC
Board Layout and Bypassing
/2
Zero-Crossing Detector
Logic-Level Translator
Asymmetrical Hysteresis
MAX9027
V
CC
R
FB
CC
, the hys-
OUT
P-P
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