Datasheet
MAX917–MAX920
SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
12 ______________________________________________________________________________________
MAX920
IN-
100kΩ
100kΩ
R
PULLUP
3V (5V)
LOGIC OUT
OUT
V
CC
+5V (+3V)
+3V (+5V)
V
EE
5V (3V) LOGIC IN
IN+
LOGIC-LEVEL
TRANSLATOR
V
EE
V
CC
OUT
R3
R2
R1
R4
V
REF
V
IN
V
CC
MAX918
MAX920
Figure 4. MAX918/MAX920 Additional Hysteresis
MAX919
IN+
OUT
V
CC
100mV
P-P
V
CC
V
EE
IN-
Figure 5. Zero-Crossing Detector
Typical Application Circuit
OUT
N.C.
( ) ARE FOR MAX917/MAX918.
V
EE
1
2
8
7
N.C.
V
CC
IN- (REF)
IN+
N.C.
SO
TOP VIEW
3
4
6
5
MAX917
MAX918
MAX919
MAX920
Pin Configurations (continued)
6) Verify the trip voltages and hysteresis as follows:
Hysteresis = V
THR
- V
THF
Board Layout and Bypassing
Power-supply bypass capacitors are not typically
needed, 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 sur-
face-mount components are recommended.
Zero-Crossing Detector
Figure 5 shows a zero-crossing detector application.
The MAX919’s inverting input is connected to ground,
and its noninverting input is connected to a 100mV
P-P
signal source. As the signal at the noninverting input
crosses 0V, the comparator’s output changes state.
Logic-Level Translator
The Typical Application Circuit shows an application
that converts 5V logic to 3V logic levels. The MAX920 is
powered by the +5V supply voltage, and the pullup
resistor for the MAX920’s open-drain output is connect-
ed to the +3V supply voltage. This configuration allows
the full 5V logic swing without creating overvoltage on
the 3V logic inputs. For 3V to 5V logic-level translations,
simply connect the +3V supply voltage to V
CC
and the
+5V supply voltage to the pullup resistor.
V rising : V V R1
1
R1
1
R2
1
R3
V falling : V
IN THR REF
IN THF
=× ++
⎛
⎝
⎜
⎞
⎠
⎟
=
V R1
1
R1
1
R2
1
R3 R4
R1
R3 R4
V
REF CC
=× ++
+
⎛
⎝
⎜
⎞
⎠
⎟
−
+
×