MAX9051 Maxim, MAX9051 Datasheet - Page 9

• Manufacturer Part Number: MAX9051
• Description: The MAX9039–MAX9043 and MAX9050–MAX9053 feature combinations of low-power comparators and precision voltage references
• Manufacturer: Maxim

The MAX9039–MAX9043 and MAX9050–MAX9053 fea-
ture single/dual, low-power, low-voltage comparators
and a precision voltage reference. They operate from a
single 2.5V to 5.5V (MAX9039/MAX904_) or 2.7V to
5.5V (MAX905_) supply. The single comparators with
reference, (MAX9039/MAX9040/MAX9041/MAX9050/
MAX9051 consume only 40µA of supply current, while
the dual comparators with reference (MAX9042/
MAX9043/MAX9052/MAX9053) consume only 55µA of
supply current. Their common-mode input range
extends 0.25V beyond each rail. Internal hysteresis
ensures clean output switching, even with slow-moving
input signals.
The output stage employs a unique design that mini-
mizes supply current surges while switching, virtually
eliminating the supply glitches typical of many other
comparators. Large internal output drivers allow rail-to-
rail output swing that can sink and source up to 8mA of
current.
The precision reference uses a proprietary curvature-
correction circuit and laser-trimmed thin-film resistors,
resulting in a temperature coefficient of less than 30ppm/°C
over the extended temperature range and initial accuracy
of 0.4% (A grade). The reference output voltage is set to
1.23V in the MAX9039, 2.048V in the MAX9040–MAX9043,
and to 2.500V in the MAX9050–MAX9053.
The devices’ input common-mode range extends from
(V
operate at any differential input voltage within these lim-
its. Input bias current is typically 1.0pA if the input volt-
Figure 1. Additional Hysteresis
EE
V
V
REF
IN
- 0.25V) to (V
R2
Comparator Input Stage Circuitry
CC
_______________________________________________________________________________________
Micropower, Single-Supply, UCSP/SOT23
R1
IN+
IN-
+ 0.25V). These comparators may
Detailed Description
Comparator + Precision Reference ICs
MAX9039–MAX9043
MAX9050–MAX9053
V
V
V
CC
CC
EE
OUT
age is between the supply rails. Comparator inputs are
protected from overvoltage by internal body diodes
connected to the supply rails. As the input voltage
exceeds the supply rails, these body diodes become
forward biased and begin to conduct. Consequently,
bias currents increase exponentially as the input volt-
age exceeds the supply rails.
The comparators in these devices contain a unique
output stage capable of rail-to-rail operation with loads
up to 8mA. Many comparators consume orders-of-mag-
nitude more current during switching than during
steady-state operation. However, with this family of com-
parators, the supply current change during an output
transition is extremely small. The Typical Operating
Characteristics graph Supply Current vs. Switching
Frequency shows the minimal supply current increase
as the output switching frequency approaches 1MHz.
This characteristic reduces the need for power-supply
filter capacitors to reduce glitches created by compara-
tor switching currents. Another advantage realized in
high-speed, battery-powered applications is a substan-
tial increase in battery life.
These comparators have ±3mV internal hysteresis.
Additional hysteresis can be generated with two resis-
tors using positive feedback (Figure 1). Use the follow-
ing procedure to calculate resistor values:
1) Calculate the trip points of the comparator using
2) The hysteresis band will be:
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
these formulas:
and
TH
is the threshold voltage at which the comparator
V
HYS
Comparator Output Stage Circuitry
V
TH
IN
drops below the trip point.
=
=
V
Applications Information
TL
V
V
REF
TH
=
V
−
+
REF
V
⎛
⎜
⎜ ⎜
⎝
TL
(
V
⎛
⎜
⎝
TL
1
=
CC
Additional Hysteresis
−
V
R
is the threshold voltage at
CC
R
−
1
1
+
V
R
+
⎛
⎜
⎝
REF
2
R
R
R
2
1
2
R
+
)
⎞
⎟
⎠
R
2
R
2
2
⎞
⎟
⎟ ⎟
⎠
⎞
⎟
⎠
IN
rises
9