Datasheet

Output Stage Circuitry
The MAX9140/MAX9141/MAX9142/MAX9144 contain a
current-driven output stage as shown in Figure 4. During
an output transition, I
SOURCE
or I
SINK
is pushed or
pulled to the output pin. The output source or sink current
is high during the transition, creating a rapid slew rate.
Once the output voltage reaches V
OH
or V
OL
, the source
or sink current decreases to a small value, capable of
maintaining the V
OH
or V
OL
static condition. This signifi-
cant decrease in current conserves power after an output
transition has occurred.
One consequence of a current-driven output stage is a
linear dependence between the slew rate and the load
capacitance. A heavy capacitive load will slow down a volt-
age output transition. This can be useful in noisesensitive
applications where fast edges may cause interference.
Applications Information
Circuit Layout and Bypassing
The high-gain bandwidth of the MAX9140/MAX9141/
MAX9142/MAX9144 requires design precautions to real-
ize the full high-speed capabilities of these comparators.
The recommended precautions are:
1) Use a PCB with a good, unbroken, low-inductance
ground plane.
2) Place a decoupling capacitor (a 0.1μF ceramic capaci-
tor is a good choice) as close to V
CC
as possible.
3) Pay close attention to the decoupling capacitor’s band-
width, keeping leads short.
4) On the inputs and outputs, keep lead lengths short to
avoid unwanted parasitic feedback around the com-
parators.
5) Solder the device directly to the PCB instead of using
a socket.
Figure 2. MAX9141 Timing Diagram with Latch Operator
Figure 3. Input Stage Circuitry
V
OH
t
LPW
OUT
t
LPD
t
PD
V
CC
0
V
CC
2
V
CC
2
V
OL
LE
DIFFERENTIAL
INPUT
VOLTAGE
V
OS
V
OD
t
H
t
S
4.1kΩ
4.1kΩ
TO INTERNAL
CIRCUITRY
TO INTERNAL
CIRCUITRY
IN–
IN+
MAX9140
MAX9141
MAX9142
MAX9144
MAX9140/MAX9141/
MAX9142/MAX9144
40ns, Low-Power, 3V/5V, Rail-to-Rail
Single-Supply Comparators
www.maximintegrated.com
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