mxd1818ur31t Maxim Integrated Products, Inc., mxd1818ur31t Datasheet - Page 5

• Manufacturer Part Number: mxd1818ur31t
• Description: Low-power ?p Reset Circuits In 3-pin Sc70/sot23
• Manufacturer: Maxim Integrated Products, Inc.

MXD1812/MXD1817
MXD1813/MXD1818
A microprocessor’s (μP’s) reset input starts the micro-
processor in a known state. The MXD1810–MXD1813/
MXD1815–MXD1818 μP supervisory circuits assert
reset to prevent code-execution errors during power-
up, power-down, and brownout conditions (Figure 4).
Whenever V
output asserts. Once V
an internal timer keeps the reset output asserted for the
specified reset timeout period (t
gered by an externally initiated rising edge on the
RESET pin (MXD1813/MXD1818), following a low signal
of 1.5μs minimum duration.
Many μP-based products require push-button reset
capability (Figure 5), allowing the operator, a test tech-
nician, or external logic circuitry to initiate reset. On the
MXD1813/MXD1818, a logic-low on RESET held for
greater than 1.5μs asserts a reset. RESET deasserts
following a 100ms minimum reset timeout delay
SC70
SC70
Push-Button Reset (MXD1813/MXD1818)
2
1
3
2
1
3
PIN
PIN
CC
SOT23
SOT23
1
2
3
1
2
3
falls below the reset threshold, the reset
_______________________________________________________________________________________
Detailed Description
CC
RESET
NAME
RESET
NAME
GND
V
GND
V
Low-Power μP Reset Circuits in 3-Pin
CC
exceeds the reset threshold,
CC
RESET /RESET Output
RP
Push-Pull, Active-High Reset Output. RESET changes from low to high when V
below the selected reset threshold. RESET remains high for the reset timeout period after
V
Supply Voltage and Input for Reset Threshold Monitor
Ground
). Reset is also trig-
Open-Drain, Active-Low Reset Output with Manual Reset Detect. RESET changes from
high to low when V
pulled low for at least 1.5μs. RESET remains low for the reset timeout period after V
exceeds the device reset threshold or after the external manual reset is released. RESET
has an internal 5.5kΩ pullup resistor.
Supply Voltage and Input for Reset Threshold Monitor
Ground
CC
exceeds the device reset threshold.
CC
drops below the selected reset threshold, or RESET is externally
(t
release RESET without the 100ms minimum reset time-
out delay. To facilitate use with mechanical switches,
the MXD1813/MXD1818 contain internal debouncing
circuitry. A debounced waveform is shown in Figure 6.
Since the RESET output on the MXD1811/MXD1816 is
open drain, these devices interface easily with μPs that
have bidirectional reset pins, such as the Motorola
68HC11. Connecting the μP supervisor’s RESET output
directly to the microcontroller’s (μC’s) RESET pin allows
either device to assert reset (Figure 7). No external
pullup resistor is required, as it is contained within the
MXD1811/MXD1816.
In addition to issuing a reset to the μP during power-up,
power-down, and brownout conditions, these devices
are relatively immune to short-duration, negative-going
V
PBRST
CC
transients (glitches).
). A manual reset input shorter than 1.5μs may
Interfacing to μPs with Bidirectional
FUNCTION
FUNCTION
Pin Descriptions (continued)
Negative-Going V
Applications Information
SC70/SOT23
CC
Reset Pins
Transients
CC
drops
CC
5