AME8570 Datasheet, PDF (9/17 Pages) Analog Microelectronics – mProcessor Supervisory

AME, Inc.
AME8570
n Detailed Description
The AME8570 are designed to interface with the reset
input of a microprocessor and to prevent code-execution
errors due to power up, power down, and other power
supply errors.
Reset Output
Each output pin in the family can be configured to be
either push-pull or open-drain. In addition each output may
be either active high or active low. Active high reset out-
puts are denoted as RESET. Active low reset outputs
are denoted as RESETB. The selection guide on this
data sheet shows all possible combinations of output
driver configuration.
A reset will be asserted if any of two things happen:
1) V drops below the threshold (V )
IN
TH
2) The MRB pin is pulled low.
The reset will remain asserted for the prescribed reset
interval after:
1) V_IN rises above the threshold (V_TH)
2) MRB goes high
µProcessor Supervisory
Manual Reset Input
The AME8570 feature a manual reset feature (MRB).
A logic low on the MRB pin asserts a reset. The reset
remains asserted as long as the MRB pin remains low.
After the MRB pin transitions to a high state the reset
remains asserted for the prescribed reset interval (T ).
D2
The MRB pin is internally pulled up to V_IN by a 100K
resistor. It is internally debounced to reject switching
transients.
The MRB pin is ESD protected by diodes connected
to V_IN and GND. So the MRB pin should never be driven
higher than V or lower than GND.
IN
Glitch Rejection
The AME8570 family will reject negative going transients
on the V_IN line to some extent. The smaller the duration
of the transient the larger its amplitude may be without
triggering a reset. The "Glitch Rejection" chart in the
graphs section of this datasheet shows the relation be-
tween glitch amplitude and allowable glitch duration to
avoid unintended resets.
Accurate Output State at Low V_IN
With V_IN voltage on the order of the MOS transistor
threshold (<1.0V) the outputs of the AME8570 may be-
come undefined. For parts with active low output
(RESETB) a resistor placed between RESETB and GND
on the order of 100K will ensure that the RESETB output
stays low when V is lower than the threshold voltage of
IN
the part. In a like manner a resistor on the order of 100K
when placed between RESET and V_IN will ensure parts
with active high output (RESET) will remain high when
V_IN is lower than the threshold voltage of the part.
9
Rev. A.01