AME, Inc.
AME8510 / 8520 / 8530
Micropower
µ
P Watch Dog Timer
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General Description
The AME8510/8520/8530 family allows the user to cus-
tomize the CPU monitoring function without any external
components. The user has a large choice of reset volt-
age thresholds and output driver configurations, all of
which are preset at the factory. Each wafer is trimmed
to the customer's specifications.
These circuits will ignore fast negative going transients
on V
DD
. The state of the reset output is guaranteed to be
correct down to 1V.
After V
DD
crosses above a factory preset threshold,
the AME8510/8520/8530 assert a reset signal. After a
predetermined time (the “reset” interval) the reset is
deasserted. If V
DD
ever drops below the threshold voltage
a reset is asserted immediately. In addition to a supply
monitoring function the AME8510/8520 also monitor tran-
sitions at the watch dog (WDI) input. If a logic transition
does not occur at the WDI pin within a certain time inter-
val (the “watchdog” interval) then a reset is asserted. The
reset deasserts after the reset interval, as explained ear-
lier.
The AME8510/8530 can both assert a reset manually
by pulling the MRB input to ground.
Space saving SOT-25 packages and micropower qui-
escent current make this family a natural for portable
battery powered equipment.
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Applications
l
l
l
l
Motherboards
Computer peripherals
Portable electronics
Applications using CPUs
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Consumer electronics
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Pin Configuration
SOT-25
Top View
5
4
AME8510
1. Reset/ResetB
2. GND
3. MRB
4. WDI
5. V
DD
AME8510
1
2
3
SOT-25
Top View
5
4
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Features
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Small packages: SOT-25
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7 voltage threshold options
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Tight voltage threshold tolerance ---±1.50%
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12 output driver configuration options
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Wide temperature range -------- -40
o
C to 85
o
C
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Low temperature coefficient --- 100ppm/
o(max)
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Low quiescent current < 3.0µA
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3 bonding options
AME8520
AME8520
1. Reset/ResetB
2. GND
3. ResetB/Reset
4. WDI
5. V
DD
1
2
3
SOT-25
Top View
5
4
AME8530
AME8530
1. Reset/ResetB
2. GND
3. ResetB/Reset
4. MRB
5. V
DD
1
2
3
1
AME, Inc.
AME8510 / 8520 / 8530
Micropower
µ
P Watch Dog Timer
n
Pin Description
Pin #
Pin Name
AME8510 AME8520 AME8530
This pin may be either RESET or RESETB. RESETB is active
low. In the case of the AME8520 and AME8530 this pin will
always be the opposite polarity from pin 3. This pin can be
push/pull or open drain.
Pin Description
1
1
1
RESET/
RESETB
2
2
2
GND
Ground
N/A
3
3
RESET/
RESETB
This pin may be either RESETB or RESET. RESET is active
high. In the case of the AME8520 and AME8530 this pin will
always be the opposite polarity from pin 1. This pin can be
either push/pull or open drain.
Manual Reset. Active low. Pulling this pin low forces a reset.
After a low to high transition reset remains asserted for exactly
one reset timeout period. This pin is internally pulled high. If
this function is unused then float this pin or tie it to V
DD
.
3
N/A
4
MRB
4
4
N/A
WDI
Watch Dog Input. Any transition on this pin will reset the watch
dog timer. If this pin remains high or low for longer than the
watch dog interval then a reset is asserted. Float or tristate this
pin to disable the watch dog feature.
Positive power supply. A reset is asserted after this voltage
drops below a predetermined level. After V
DD
rises above that
level reset remains asserted until the end of the reset timeout
period.
5
5
5
V
DD
2
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