AME, Inc.
AME8500 / 8501
µ
Processor Supervisory
n
General Description
The AME8500 family allows the user to customize the
CPU reset function without any external components.
The user has a large choice of reset voltage thresholds,
reset time intervals, and output driver configurations, all
of which are preset at the factory. Each wafer is trimmed
to the customer's specifications.
These circuits monitor the power supply voltage of
µP
based systems. When the power supply voltage drops
below the voltage threshold a reset is asserted immedi-
ately (within an interval T
D1
). The reset remains asserted
after the supply voltage rises above the voltage threshold
for a time interval, T
D2
. The reset output may be either
active high (RESET) or active low (RESETB). The reset
output may be configured as either push/pull or open
drain. The state of the reset output is guaranteed to be
correct for supply voltages greater than 1V.
The AME8501 includes all the above functionality plus
an overtemperature shutdown function. When the ambi-
ent temperature exceeds 80
o
C a reset is asserted and
remains asserted until the temperature falls below 60
o
C.
Space saving SOT23 packages and micropower qui-
escent current (<3.0µA) make this family a natural for
portable battery powered equipment.
n
Typical Operating Circuit
2
V
CC
*
V
CC
AME8500
RESET / RESET
GND
Processor
RESET
Input
GND
3
Note: * External pull-up resistor is required if open-
drain output is used. 10 kΩ is recommended.
n
Block Diagram
AME8500 with Push-Pull RESET
V
DD
R1
I1
P1
Delay
n
Features
l
Small packages: SOT-23, SOT-89
l
11 voltage threshold options
l
Tight voltage threshold tolerance ---±1.50%
l
5 reset interval options
l
4 output configuration options
l
Wide temperature range -------- -40
o
C to 85
o
C
l
Low temperature coefficient --- 100ppm/
o
C
(max)
l
Low quiescent current < 3.0µA
l
Thermal shutdown option (AME8501)
V
DD
GND
RESET
N1
R2
V
REF
AME8500 with Push-Pull RESET
n
Applications
l
l
l
l
l
l
Portable electronics
Power supplies
Computer peripherals
Data acquisition systems
Applications using CPUs
Consumer electronics
R1
I1
P1
Delay
RESET
N1
R2
GND
V
REF
1
AME, Inc.
AME8500 / 8501
µ
Processor Supervisory
n
Pin Configuration (contd.)
SOT-23-L
Top View
3
SOT-23-L
Top View
AME8500BEET
AME8501BEET
1. Reset/ResetB
2. GND
3. V
DD
3
AME8500CEET
AME8501CEET
1. Reset/ResetB
2. V
DD
3. GND
AME8500
AME8500
1
2
1
2
SOT-89
Top View
AME8500AEFT
AME8501AEFT
1. GND
2. V
DD
3. Reset/ResetB
SOT-89
Top View
AME8500BEFT
AME8501BEFT
1. Reset/ResetB
2. V
DD
3. GND
AME8500
AME8500
1
2
3
1
2
3
SOT-89
Top View
AME8500CEFT
AME8501CEFT
1. V
DD
2. GND
3. Reset/ResetB
5
SOT-25
Top View
4
AME8500
AME8500
AME8500BEEV
AME8501BEEV
1. Reset/ResetB
2. V
DD
3. GND
4. N/C
5. N/C
1
2
3
1
2
3
n
Pin Description
Pin Name
GND
RESETB/RESET
Ground
This pin can be ordered as RESET or RESETB. RESET is active high.
RESETB is active low. It is also available with an open drain or pushpull
output.
Positive power supply. A reset is asserted after this voltage drops below
a predetermined level. After V
DD
rises above that level the reset output
remains asserted until the end of the reset timeout period.
Pin Description
V
DD
3
实时操作系统RTOS
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