LM8364BALMF20 National Semiconductor, LM8364BALMF20 Datasheet - Page 5

• Manufacturer Part Number: LM8364BALMF20
• Description: Micropower Undervoltage Sensing Circuits
• Manufacturer: National Semiconductor

Application Notes
The propagation delay time for the LM8364 is measured
using a 470kΩ pull-up resistor connected to from the RESET
output pin to 5V in addition to a 10pF capacitive load con-
The LM8364 ultra-low current voltage detector was designed
to monitor voltages and to provide an indication when the
monitored voltage, V
threshold voltage. This characteristic is displayed in the typi-
cal operating timing diagram below. V
being monitored and a pull up resistor is connected from the
RESET output pin to V
and then begins to decrease. Since this is an Active Low
device the RESET output is pulled High through the pull-up
resistor and tracks V
old V
now in a fault condition and the output immediately changes
to the Logic Low State. The RESET output will remain in this
low state until V
DET−
. At this point the LM8364 recognizes that V
IN
increases above the threshold V
IN
IN
, dropped below a precisely trimmed
IN
until V
. V
IN
IN
is at some value above V
crosses the trimmed thresh-
IN
FIGURE 1. Propagation Delay Timing Diagrams
is the voltage that is
FIGURE 2. Timing Waveforms
DET−
DET+
IN
is
+
5
nected from the same pin to GND. Figure 1 shows the timing
diagram for the measurement for the propagation delay.
V
and the built in hysteresis, V
V
This built-in hysteresis has been added to the design to help
prevent erratic reset operation when the input voltage
crosses the threshold.
The LM8364 has a wide variety of applications that can take
advantage of its precision and low current consumption to
monitor Input voltages even though it was designed as a
reset controller in portable microprocessor based systems. It
is a very cost effective and space saving device that will
protect your more expensive investments of microproces-
sors and other devices that need a guaranteed supply volt-
age for proper operation.
DET+
HYS
. This point is also known as V
is equal to the sum of the detector threshold, V
HYS
.
DET+
as indicated earlier.
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DET−
,