LM3722 Datasheet, PDF (1/12 Pages) National Semiconductor (TI) – 5-Pin Microprocessor Reset Circuits

June 2001
LM3722/LM3723/LM3724
5-Pin Microprocessor Reset Circuits
General Description
The LM3722/LM3723/LM3724 microprocessor supervisory
circuits monitor the power supplies in microprocessor and
digital systems. They provide a reset to the microprocessor
during power-up, power-down, brown-out conditions, and
manual reset.
The LM3722/LM3723/LM3724 asserts a reset signal when-
ever the supply decreases below the factory-programmed
reset threshold for at least 100 ms. The reset signal remains
asserted for 190 ms after V_CC rises above the threshold.
The LM3722 has an active-low RESET push-pull output. The
LM3723 has an active-high RESET push-pull output. The
LM3724 has an active-low open-drain RESET output.
Three standard reset voltage options are available, suitable
for monitoring 5V, 3.3V, and 2.5V supply voltages. Additional
reset voltages are also available; contact National Semicon-
ductor for details.
With a low supply current of only 6µA, the
LM3722/LM3723/LM3724 are ideal for use in portable equip-
ment. The LM3722/LM3723/LM3724 are available in the
5-pin SOT23 package.
Features
n Precise monitoring of 2.5V, 3.3V, and 5V supply
voltages
n Fully specified over temperature
Industrial: −40˚C to +85˚C
Extended: −40˚C to +125˚C
n 100 ms minimum Power-On Reset pulse width, 190 ms
typical:
Active-Low RESET Output (LM3722)
Active-High RESET Output (LM3723)
Active-Low RESET Open Drain Output (LM3724)
n Guaranteed RESET Output valid for V_CC ≥ 1V
n Low Supply Current, 6µA typical
n Power supply transient immunity
n Compatible with MAX811/812 applications
Applications
n Microprocessor Systems
n Computers
n Controllers
n Intelligent Instruments
n Portable/Battery-Powered Equipment
Typical Application Circuit
Connection Diagram
20014401
SOT23-5
*( ) are for LM3723
© 2001 National Semiconductor Corporation DS200144
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