ADM809-5SL Просмотр технического описания (PDF) - Analog Devices
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ADM809-5SL Datasheet PDF : 6 Pages
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INTERFACING TO OTHER DEVICES OUTPUT
The ADM809-5S/L is designed to integrate with as many devices
as possible and therefore has an output dependant on VCC.
Because of this design approach, interfacing this device to other
devices is simplified.
ENSURING A VALID RESET OUTPUT DOWN TO VCC = 0 V
When VCC falls below 0.8 V, ADM809-5S/L’s RESET no longer
sinks current. A high impedance CMOS logic input connected
to RESET may, therefore, drift to undetermined logic levels. To
eliminate this problem a 100 kΩ resistor should be connected
from RESET to ground.
VCC
VCC
ADM809-5S/L
RESET
100k⍀
GND
Figure 3. Ensuring a Valid RESET Output Down to
VCC = 0 V
THE BENEFITS OF A VERY ACCURATE RESET
THRESHOLD
In other microprocessor supervisory circuits, tolerances in supply
voltages lead to an overall increase in RESET tolerance levels
due to the deterioration of the microprocessor RESET circuit’s
power supply. The possibility of a malfunction during a power
failure is greatly reduced because the ADM809-5S/L series can
operate effectively even when there are large degradations of the
supply voltages. Another advantage of the ADM809-5S/L series
is its very accurate internal voltage reference circuit. These
benefits combine to produce an exceptionally reliable Voltage
Monitor Circuit.
INTERFACING TO MICROPROCESSORS WITH
MULTIPLE INTERRUPTS
In a number of cases it is necessary to interface many interrupts
from different devices (i.e., thermal, attitude, and velocity sen-
sors). The ADM809-5S/L can easily be integrated into existing
interrupt-handling circuits (Figure 6) or used as a stand-alone
device.
ADM809-5S/L
PRIORITY ENCODER
74LS147
VCC
4 LINE BCD
TO µP
VCC
ADM809
RESET
OTHER SENSING
DEVICES
GND
Figure 4. Interfacing to µPs with Multiple Interrupts
3.3V
100nF
GND
VCC
RESET
ADM809-5S/L
47k⍀
47k⍀
Figure 5. Alternative Application Circuit with Extra
Decoupling
3.3V
100nF
VCC
GND
RESET
ADM809-5S/L
22k⍀
Figure 6. Additional Decoupling Can Be Achieved
Using a 100 nF Capacitor Between VCC and Ground
REV. 0
–5–
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