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PDF ASM692A Data sheet ( Hoja de datos )
| Número de pieza | ASM692A | |
| Descripción | uP Power Supply Supervisor | |
| Fabricantes | ON Semiconductor | |
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ASM690A/692A,
ASM802L/802M, ASM805L
mP Power Supply Supervisor
with Battery Backup Switch
Description
The ASM690A / ASM692A / ASM802L / ASM802M / ASM805L
offers complete single chip solutions for power supply monitoring and
control battery functions in microprocessor systems. Each device
implements four functions: Reset control, watchdog monitoring,
battery−backup switching and power failure monitoring. In addition to
microprocessor reset under power−up and power−down conditions,
these devices provide battery−backup switching to maintain control in
power loss and brown−out situations. Additional monitoring
capabilities can provide an early warning of unregulated power supply
loss before the voltage regulator drops out. The important features of
these four functions are:
• 1.6 second watchdog timer to keep microprocessor responsive
• 4.40 V or 4.65 V VCC threshold for microprocessor reset at
power−up and power−down
• SPDT (Single−pole, Double−throw) PMOS switch connects backup
power to RAM if VCC fails
• 1.25 V threshold detector for power loss or general purpose voltage
monitoring
These features are pin−compatible with the industry standard
power−supply supervisors. Short−circuit and thermal protection have
also been added. The ASM690A / ASM802L / ASM805L generate a
reset pulse when the supply voltage drops below 4.65 V and the
ASM692A / ASM802M generate a reset below 4.40 V. The ASM802L
/ ASM802M have power−fail accuracy to ±2%. The ASM805L is the
same as the ASM690A except that RESET is provided instead of
RESET.
http://onsemi.com
PDIP−8
P SUFFIX
CASE 646AA
SOIC−8
S SUFFIX
CASE 751BD
PIN CONFIGURATIONS
VOUT
VCC
GND
PFI
1
ASM690A,
ASM692A,
ASM802L,
ASM802M
VBATT
RESET
WDI
PFO
VOUT
VCC
GND
PFI
1
ASM805L
(Top Views)
VBATT
RESET
WDI
PFO
Features
• Two Precision Supply−voltage Monitor Options
4.65 V (ASM690A / ASM802L / ASM805L)
4.40 V (ASM692A / ASM802M)
• Battery−backup Power Switch On−chip
• Watchdog Timer: 1.6 Second Timeout
• Power Failure / Low Battery Detection
• Short Circuit Protection and Thermal Limiting
• Small 8−pin SO and 8−pin PDIP Packages
• No External Components
• Specified Over Full Temperature Range
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 11 of this data sheet.
Applications
• Embedded Control Systems
• Portable/Battery Operated Systems
• Intelligent Instruments
• Wireless Instruments
• Wireless Communication Systems
• PDAs and Hand−held Equipments
• mP / mC Power Supply Monitoring
• Safety System
© Semiconductor Components Industries, LLC, 2011
August, 2011 − Rev. 3
1
Publication Order Number:
ASM690A/D
1 page  
ASM690A/692A, ASM802L/802M, ASM805L
Detailed Description
It is important to initialize a microprocessor to a known
state in response to specific events that could create code
execution errors and “lock−up”. The reset output of these
supervisory circuits send a reset pulse to the microprocessor
in response to power−up, power−down/power−loss or a
watchdog time−out.
RESET/RESET Timing
Power−up reset occurs when a rising VCC reaches the
reset threshold, VRT, forcing a reset condition in which the
reset output is asserted in the appropriate logic state for the
duration of tRS. The reset pulse width, tRS, is typically
around 200 ms and is LOW for the ASM690A, ASM692A,
ASM802 and HIGH for the ASM805L. Figure 3 shows the
reset pin timing.
Power−loss or “brown−out” reset occurs when VCC dips
below the reset threshold resulting in a reset assertion for the
duration of tRS. The reset signal remains asserted as long as
VCC is between VRT and 1.1 V, the lowest VCC for which
these devices can provide a guaranteed logic−low output. To
ensure logic inputs connected to the ASM690A /
ASM692A/ASM802 RESET pin are in a known state when
VCC is under 1.1 V, a 100 kW pull−down resistor at RESET
is needed: the logic−high ASM805L will need a pull−up
resistor to VCC.
Watchdog Timer
A Watchdog time−out reset occurs when a logic “1” or
logic “0” is continuously applied to the WDI pin for more
than 1.6 seconds. After the duration of the reset interval, the
watchdog timer starts a new 1.6 second timing interval; the
microprocessor must service the watchdog input by
changing states or by floating the WDI pin before this
interval is finished. If the WDI pin is held either HIGH or
LOW, a reset pulse will be triggered every 1.8 seconds (the
1.6 second timing interval plus the reset pulse width tRS).
Application Information
Microprocessor Interface
The ASM690 has logic−LOW RESET output while the
ASM805 has an inverted logic−HIGH RESET output.
Microprocessors with bidirectional reset pins can pose a
problem when the supervisory circuit and the
microprocessor output pins attempt to go to opposite logic
states. The problem can be resolved by placing a 4.7 kW
resistor between the RESET output and the microprocessor
reset pin. This is shown in Figure 4. Since the series resistor
limits drive capabilities, the reset signal to other devices
should be buffered.
Figure 3. RESET/RESET Timing
Figure 4. Interfacing with Bi−directional
Microprocessor Reset Inputs
http://onsemi.com
5
5 Page 
ASM690A/692A, ASM802L/802M, ASM805L
Table 7. ORDERING INFORMATION − Tin − Lead Devices
Part Number (Note 5)
Reset Threshold (V) Temperature (5C)
Pins−Package
Package Marking
ASM690A
ASM690ACPA
4.5 to 4.75
0 to +70
8−Plastic DIP
ASM690ACPA
ASM690ACSA
4.5 to 4.75
0 to +70
8−SO
ASM690ACSA
ASM690AEPA
4.5 to 4.75
−40 to +85
8−Plastic DIP
ASM690AEPA
ASM690AESA
4.5 to 4.75
−40 to +85
8−SO
ASM690AESA
ASM692A
ASM692ACPA
4.25 to 4.50
0 to +70
8−Plastic DIP
ASM692ACPA
ASM692ACSA
4.25 to 4.50
0 to +70
8−SO
ASM692ACSA
ASM692AEPA
4.25 to 4.50
−40 to +85
8−Plastic DIP
ASM692AEPA
ASM692AESA
4.25 to 4.50
−40 to +85
8−SO
ASM692AESA
ASM802L
ASM802LCPA
4.5 to 4.75
0 to +70
8−Plastic DIP
ASM802LCPA
ASM802LCSA
4.5 to 4.75
0 to +70
8−SO
ASM802LCSA
ASM802LEPA
4.5 to 4.75
−40 to +85
8−Plastic DIP
ASM802LEPA
ASM802LESA
4.5 to 4.75
−40 to +85
8−SO
ASM802LESA
ASM802M
ASM802MCPA
4.25 to 4.50
0 to +70
8−Plastic DIP
ASM802MCPA
ASM802MCSA
4.25 to 4.50
0 to +70
8−SO
ASM802MCSA
ASM802MEPA
4.25 to 4.50
−40 to +85
8−Plastic DIP
ASM802MEPA
ASM802MESA
4.25 to 4.50
−40 to +85
8−SO
ASM802MESA
ASM805L
ASM805LCPA
4.5 to 4.75
0 to +70
8−Plastic DIP
ASM805LCPA
ASM805LCSA
4.5 to 4.75
0 to +70
8−SO
ASM805LCSA
ASM805LEPA
4.5 to 4.75
−40 to +85
8−Plastic DIP
ASM805LEPA
ASM805LESA
4.5 to 4.75
−40 to +85
8−SO
ASM805LESA
5. For parts to be packed in Tape and Reel, add “−T” at the end of the part number. ON Semiconductor lead free parts are RoHS compliant.
http://onsemi.com
11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet ASM692A.PDF ] | |
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