MAX931-MAX934
Ultra Low-Power, Low-Cost
Comparators with 2% Reference
8
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_______________Detailed Description
The MAX931-MAX934 comprise various combinations
of a micropower 1.182V reference and a micropower
comparator. The
Typical Operating Circuit shows the
MAX931 configuration, and Figures 1a-1c show the
MAX932/MAX933/MAX934 configurations.
Each comparator continuously sources up to 40mA, and
the unique output stage eliminates crowbar glitches
during output transitions. This makes them immune to
parasitic feedback (which can cause instability) and
provides excellent performance, even when circuit-
board layout is not optimal.
Internal hysteresis in the MAX931/MAX932/MAX933
provides the easiest method for implementing
hysteresis. It also produces faster hysteresis action
and consumes much less current than circuits using
external positive feedback.
Power-Supply and Input Signal Ranges
This family of devices operates from a single +2.5V to
+11V power supply. The MAX931 and MAX934 have
a separate ground for the output driver, allowing
operation with dual supplies ranging from ±1.25V to
±5.5V. Connect V- to GND when operating the
MAX931 and the MAX934 from a single supply. The
maximum supply voltage in this case is still 11V.
For proper comparator operation, the input signal can
be driven from the negative supply (V-) to within one
volt of the positive supply (V+ - 1V). The guaranteed
common-mode input voltage range extends from
V- to (V+ - 1.3V). The inputs can be taken above and
below the supply rails by up to 300mV without damage.
Operating the MAX931 and MAX934 at ±5V provides
TTL/CMOS compatibility when monitoring bipolar input
signals. TTL compatibility for the MAX932 and MAX933
is achieved by operation from a single +5V supply.
Low-Voltage Operation: V+ = 1V
(MAX934 Only)
The guaranteed minimum operating voltage is 2.5V (or
±1.25V). As the total supply voltage is reduced below
2.5V, the performance degrades and the supply
OUTA
V-
INA+
INB+
OUTB
V+
REF
HYST
MAX932
1
2
3
4
8
7
6
5
V-
Figure 1a. MAX932 Functional Diagram
OUTA
V-
INA+
INB-
OUTB
V+
REF
HYST
MAX933
1
2
3
4
8
7
6
5
V-
Figure 1b. MAX933 Functional Diagram
OUTA
V+
INA-
INA+
OUTD
GND
IND+
IND-
MAX934
2
3
4
5
15
14
13
12
16
11
10
9
1
6
7
8
OUTB
INB-
INB+
REF
OUTC
INC+
INC-
V-
A
D
B
C
Figure 1c. MAX934 Functional Diagram