NSC LM809M3X-4.00, LM809M3X-3.08, LM809M3X-2.93, LM809M3X-2.63, LM809M3-4.38 Datasheet
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September 1999
LM809/LM810
3-Pin Microprocessor Reset Circuits
General Description
The LM809/810 microprocessor supervisory circuits can be used to monitor the power supplies in microprocessor and digital systems. They provide a reset to the microprocessor during power-up, power-down and brown-out conditions.
The function of the LM809/810 is to monitor the VCC supply voltage, and assert a reset signal whenever this voltage declines below the factory-programmed reset threshold. The reset signal remains asserted for 240ms after VCC rises above the threshold. The LM809 has an active-low RESET output, while the LM810 has an active-high RESET output.
Six standard reset voltage options are available, suitable for monitoring 5V, 3.3V, and 3V supply voltages.
With a low supply current of only 15µA, the LM809/810 are ideal for use in portable equipment. The LM809/LM810 are available in the 3-pin SOT23 package.
Features
nPrecise monitoring of 3V, 3.3V, and 5V supply voltages
nSuperior upgrade to MAX809/810
nFully specified over temperature
n140ms min. Power-On Reset pulse width, 240ms typical Active-low RESET Output (LM809)
Active-high RESET Output (LM810)
nGuaranteed RESET Output valid for VCC³1V
nLow Supply Current, 15µA typ.
nPower supply transient immunity
Applications
nMicroprocessor Systems
nComputers
nControllers
nIntelligent Instruments
nPortable/Battery-Powered Equipment
nAutomotive
Typical Application Circuit |
Connection Diagram |
DS101057-2
( ) are for LM810
DS101057-1
Circuits Reset Microprocessor Pin-3 LM809/LM810
© 1999 National Semiconductor Corporation |
DS101057 |
www.national.com |
Ordering Information
Reset Threshold |
LM809 Supplied as |
LM809 Supplied as |
Package |
Package Type |
NSC Package |
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(V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
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4.63 |
LM809M3-4.63 |
LM809M3X-4.63 |
S8B |
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4.38 |
LM809M3-4.38 |
LM809M3X-4.38 |
S7B |
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4.00 |
LM809M3-4.00 |
LM809M3X-4.00 |
S6B |
SOT23-3 |
M03B |
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3.08 |
LM809M3-3.08 |
LM809M3X-3.08 |
S5B |
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2.93 |
LM809M3-2.93 |
LM809M3X-2.93 |
S4B |
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2.63 |
LM809M3-2.63 |
LM809M3X-2.63 |
S3B |
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Reset Threshold |
LM810 Supplied as |
LM810 Supplied as |
Package |
Package Type |
NSC Package |
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(V) |
1000 units, tape & reel |
3000 units, tape & reel |
Top Mark |
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4.63 |
LM810M3-4.63 |
LM810M3X-4.63 |
SEB |
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4.38 |
LM810M3-4.38 |
LM810M3X-4.38 |
SDB |
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4.00 |
LM810M3-4.00 |
LM810M3X-4.00 |
SCB |
SOT23-3 |
M03B |
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3.08 |
LM810M3-3.08 |
LM810M3X-3.08 |
SBB |
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2.93 |
LM810M3-2.93 |
LM810M3X-2.93 |
SAB |
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2.63 |
LM810M3-2.63 |
LM810M3X-2.63 |
S9B |
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Custom voltages and improved accuracies are available, subject to minimum orders. Contact your local National Semiconductor Sales Office for information.
Pin Description
PIN |
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NAME |
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FUNCTION |
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1 |
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GND |
Ground reference |
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Active-low output. |
RESET |
remains low while VCC is below the reset threshold, and |
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RESET (LM809) |
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for 240ms after VCC rises above the reset threshold. |
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2 |
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RESET (LM810) |
Active-high output. RESET remains high while VCC is below the reset threshold, and |
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for 240ms after VCC rises above the reset threshold. |
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3 |
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VCC |
Supply Voltage (+5V, +3.3V, or +3.0V) |
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www.national.com |
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