MAX809 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX809 Datasheet PDF : 10 Pages
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3-Pin Microprocessor Reset Circuits
Selector Guide
PART/SUFFIX
MAX803L
MAX803M
MAX803T
MAX803S
MAX803R
MAX803Z
MAX809L
MAX809M
MAX809J
MAX809T
MAX809S
MAX809R
MAX809Z
MAX810L
MAX810M
MAX810T
MAX810S
MAX810R
MAX810Z
RESET THRESHOLD (V)
4.63
4.38
3.08
2.93
2.63
2.32
4.63
4.38
4.00
3.08
2.93
2.63
2.32
4.63
4.38
3.08
2.93
2.63
2.32
OUTPUT TYPE
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
OPEN-DRAIN RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
PUSH-PULL RESET
TOP MARK
SOT
AAAA
ABAA
CWAA
ACAA
ADAA
AFAA
AGAA
AHAA
AJAA
AKAA
ALAA
SC70
AAZ
ABA
ABB
ABC
ABD
ABE
AAN
AAO
AAP
AAQ
AAR
AAS
AAT
AAU
AAV
AAX
AAW
AAY
Detailed Description
Applications Information
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX803/MAX809/MAX810 assert
reset to prevent code-execution errors during power-
up, power-down, or brownout conditions. They assert a
reset signal whenever the VCC supply voltage declines
below a preset threshold, keeping it asserted for at
least 140ms after VCC has risen above the reset thresh-
old. The MAX803 uses an open-drain output, and the
MAX809/MAX810 have a push-pull output stage.
Connect a pull-up resistor on the MAX803’s RESET out-
put to any supply between 0 and 6V.
Pin Description
PIN NAME
1
GND
RESET
(MAX803/
MAX809)
2
RESET
(MAX810)
3
VCC
FUNCTION
Ground
RESET Output remains low while VCC
is below the reset threshold, and for at
least 140ms after VCC rises above the
reset threshold.
RESET Output remains high while VCC
is below the reset threshold, and for at
least 140ms after VCC rises above the
reset threshold.
Supply Voltage (+5V, +3.3V, +3.0V, or
+2.5V)
Negative-Going VCC Transients
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the MAX803/
MAX809/MAX810 are relatively immune to short-duration
negative-going VCC transients (glitches).
Figure 1 shows typical transient duration vs. reset com-
parator overdrive, for which the MAX803/MAX809/
MAX810 do not generate a reset pulse. The graph was
generated using a negative-going pulse applied to VCC,
starting 0.5V above the actual reset threshold and end-
ing below it by the magnitude indicated (reset compara-
tor overdrive). The graph indicates the maximum pulse
width a negative-going VCC transient can have without
causing a reset pulse. As the magnitude of the transient
increases (goes farther below the reset threshold), the
maximum allowable pulse width decreases. Typically, for
the MAX8__L and MAX8__M, a VCC transient that goes
100mV below the reset threshold and lasts 20µs or less
will not cause a reset pulse. A 0.1µF bypass capacitor
mounted as close as possible to the VCC pin provides
additional transient immunity.
Ensuring a Valid Reset Output
Down to VCC = 0
When VCC falls below 1V, the MAX809 RESET output
no longer sinks current—it becomes an open circuit.
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