max9101eukt Maxim Integrated Products, Inc., max9101eukt Datasheet - Page 7

• Manufacturer Part Number: max9101eukt
• Description: +1.0v Micropower Sot23 Comparators
• Manufacturer: Maxim Integrated Products, Inc.

The MAX9101 has an open-drain output, which can be
pulled up to +6.0V above ground independent of the
supply voltage. This is typically used with an external
pullup resistor, facilitating interface between mixed logic
voltages. Alternatively, multiple open-drain comparator
outputs can be connected in a wired-OR configuration.
The minimum operating voltage is +1.0V. At lower sup-
ply voltages, the input common-mode range remains
rail-to-rail, but the comparator’s output drive capability is
reduced and propagation delay increases (see the
Typical Operating Characteristics).
Hysteresis increases the comparators’ noise margin by
increasing the upper threshold and decreasing the
lower threshold (Figure 1). This hysteresis prevents the
comparator from providing multiple poles when driven
with a very-slow-changing signal.
These comparators have 1.0mV internal hysteresis.
Additional hysteresis can be generated with two resis-
tors using positive feedback (Figure 2). Use the follow-
ing procedure to calculate resistor values:
1) Calculate the trip points of the comparator using
Figure 1. Threshold Hysteresis Band
V
IN
these formulas:
and
V
OUT
- +V
IN+
IN
IN-
- V
HYST/2
HYST
V
TH
Low-Voltage Operation: V
=
V
V
V
TL
HYST
REF
Applications Information
Open-Drain Output (MAX9101)
=
_______________________________________________________________________________________
+
V
REF
⎛
⎜
⎜ ⎜
⎝
+1.0V Micropower SOT23 Comparators
(
V
THRESHOLDS
CC
⎛
⎜
⎝
1
HYSTERESIS
R
−
BAND
−
1
R
+
V
1
R
REF
Internal Hysteresis
R
+
2
2
R
Additional Hysteresis
2
)
R
⎞
⎟
⎠
2
⎞
⎟
⎟ ⎟
⎠
CC
= 1V
2) The hysteresis band will be:
3) In this example, let V
4) Select R2. In this example, we will choose 1kΩ.
5) Select V
6) Solve for R1:
where R1 ≈ 100kΩ, V
A power-supply bypass capacitor is not normally
required, but 100nF bypass capacitors can be used
when the supply impedance is high or when the supply
Figure 2. Additional Hysteresis (MAX9100)
V
switches its output from high to low as V
above the trip point. V
which the comparator switches its output from low to
high as V
and
TH
V
is the threshold voltage at which the comparator
REF
V
HYS
HYS
IN
R2
drops below the trip point.
. In this example, we will choose 50mV.
= V
V
V
TH
V
0 050
TL
Board Layout and Bypassing
HYS
TH
.
=
TH
=
- V
2 5 2 5
V
2 5 1
=
IN
CC
.
.
=
= 2.525V, and V
TL
V
TL
5
⎛
⎜
⎝
+
CC
= +5V and V
⎛
⎜
⎝
R2
= V
−
R
is the threshold voltage at
.
⎛
⎜
⎝
1 1000
R
1000
R
GND
⎛
⎜
⎝
+
V
1
V
CC
1
CC
R
R
CC
R
+
+
1
2
2
R
R
R
+
MAX9100
2
2
⎛
⎜
⎝
2
R
R
⎞
⎟
⎠
⎞
⎟
⎠
⎞
⎟
⎠
2
1
OUT
R
⎞
⎟
⎠
+
REF
2
TL
R
2
= 2.475V.
⎞
⎟
⎠
= +2.5V:
IN
rises
7