LMV7239M5 National Semiconductor, LMV7239M5 Datasheet - Page 9

• Manufacturer Part Number: LMV7239M5
• Manufacturer: National Semiconductor

Specifications of LMV7239M5

• Number Of Elements: 1
• Output Type: Push-Pull
• Technology: BiCMOS
• Input Offset Voltage: 6@5VmV
• Input Bias Current (typ): 40nA
• Single Supply Voltage (typ): 3/5V
• Dual Supply Voltage (typ): Not RequiredV
• Supply Current (max): 0.095@5VmA
• Common Mode Rejection Ratio: 67dB
• Power Supply Rejection Ratio: 85dB
• Power Supply Requirement: Single
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 5
• Package Type: SOT-23
• Dc: 2002+
• Lead Free Status / Rohs Status: Not Compliant

Application Information
The LMV7235/LMV7239 are single supply comparators with
45ns of propagation delay and only 65µA of supply current.
The LMV7235/LMV7239 are rail-to-rail input and output. The
typical input common mode voltage range of −0.2V below the
ground to 0.2V above the supply. The LMV7235/LMV7239
use a complimentary PNP and NPN input stage in which the
PNP stage senses common mode voltage near V
NPN stage senses common mode voltage near V
of the input signals falls below the negative common mode
limit, the parasitic PN junction formed by the substrate and
the base of the PNP will turn on resulting in an increase of
input bias current.
If one of the input goes above the positive common mode limit,
the output will still maintain the correct logic level as long as
the other input stays within the common mode range. How-
ever, the propagation delay will increase. When both inputs
are outside the common mode voltage range, current satu-
ration occurs in the input stage, and the output becomes
unpredictable.
The propagation delay does not increase significantly with
large differential input voltages. However, large differential
voltages greater than the supply voltage should be avoided
to prevent damage to the input stage.
The LMV7239 has a push-pull output. When the output
switches, there is a direct path between V
causing high output sinking or sourcing current during the
transition. After the transition, the output current decreases
and the supply current settles back to about 65µA at 5V, thus
conserving power consumption.
The LMV7235 has an open drain that requires a pull-up re-
sistor to a positive supply voltage for the output to switch
properly. When the internal output transistor is off, the output
voltage will be pulled up to the external positive voltage.
FIGURE 1. Inverting Comparator with Hysteresis
CC
and ground,
+
−
. If either
and the
9
COMPARATOR WITH HYSTERESIS
The basic comparator configuration may oscillate or produce
a noisy output if the applied differential input voltage is near
the comparator's offset voltage. This usually happens when
the input signal is moving very slowly across the comparator's
switching threshold. This problem can be prevented by the
addition of hysteresis or positive feedback.
INVERTING COMPARATOR WITH HYSTERESIS
The inverting comparator with hysteresis requires a three re-
sistor network that is referenced to the supply voltage V
the comparator, as shown in Figure 1. When V
verting input is less than V
node of the comparator (V
(for simplicity assume V
network resistors can be represented as R1||R3 in series with
R2. The lower input trip voltage V
When V
low, very close to ground. In this case the three network re-
sistors can be presented as R2||R3 in series with R1. The
upper trip voltage V
The total hysteresis provided by the network is defined as
To assure that the comparator will always switch fully to V
and not be pulled down by the load the resistors, values
should be chosen as follow:
V
IN
A1
is greater than V
= V
V
A2
CC
= V
R2 / ((R1||R3) + R2)
A2
CC
Delta V
R
is defined as
PULL-UP
(R2||R3) / ((R1+ (R2||R3)
10135919
O
switches as high as V
IN
A
A
, the voltage at the non-inverting
A
< V
(V
= V
<< R
IN
A
A1
), the output voltage is high
> V
A1
LOAD
- V
is defined as
A
), the output voltage is
A2
CC
www.national.com
IN
). The three
at the in-
CC
CC
of