LMV7231SQX/NOPB National Semiconductor, LMV7231SQX/NOPB Datasheet - Page 13

• Manufacturer Part Number: LMV7231SQX/NOPB
• Description: IC COMP HEX WINDOW W/REF 24-LLP
• Manufacturer: National Semiconductor
• Type: Windowr

Specifications of LMV7231SQX/NOPB

• Number Of Elements: 6
• Output Type: NMOS, Open-Drain
• Voltage - Supply: 2.2 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 24-LLP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Application Information
3 RESISTOR VOLTAGE DIVIDER SELECTION
The LMV7231 trip points can be set by external resistor di-
viders as shown in
Figure 1
30114953
FIGURE 1. External Resistor Dividers
Each trip point, over-voltage, V
, and under-voltage, V
,
OV
UV
can be optimized for a falling supply, V
, or a rising supply,
THF
V
. Therefore there are 2
2
= 4 different optimization cases.
THR
Exiting the voltage detection window
(Figure
2), entering the
window
(Figure
3), rising into and out of the window
(Figure
4), falling into and out of the window
(Figure
5). Note that for
each case each trip point can be optimized for either a rising
or falling signal, not both. The governing equations make it
such that if the same resistor, R3, and over/under-voltage ra-
tio, V
/V
, is used across the channels the same nominal
OV
UV
current will travel through the resistor ladder. As a result R2
will also be the same across channels and only R1 needs to
change to set voltage detection window maximizing reuse of
resistor values and minimizing design complexity. Select the
R3 resistor value to be below 100kΩ so the current through
the divider ladder is much greater than the LMV7231 bias
current. If the current traveling through the resistor divider is
on the same magnitude of the LMV7231 I
, the I
current
BIAS
BIAS
will create error in your circuit and cause trip voltage shifts.
Keep in mind the greatest error due to I
will be caused
BIAS
when that current passes through the greatest equivalent re-
sistance, REQ = R1 (R2+R3), which will be seen by the
positive input of the window comparator, +IN.
13
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