LM3705 National Semiconductor Corporation, LM3705 Datasheet

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LM3705

Manufacturer Part Number
LM3705
Description
Microprocessor Supervisory Circuits With Power Fail Input, Low Line Output And Manual Reset
Manufacturer
National Semiconductor Corporation
Datasheet

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© 2002 National Semiconductor Corporation
LM3704/LM3705
Microprocessor Supervisory Circuits with Power Fail
Input, Low Line Output and Manual Reset
General Description
The LM3704/LM3705 series of microprocessor supervisory
circuits provide the maximum flexibility for monitoring power
supplies and battery controlled functions in systems without
backup batteries. The LM3704/LM3705 series are available
in MSOP-10 and 9-bump micro SMD packages.
Built-in features include the following:
Reset: Reset is asserted during power-up, power-down, and
brownout conditions. RESET is guaranteed down to V
1.0V.
Manual Reset Input: An input that asserts reset when pulled
low.
Power-Fail Input: A 1.225V threshold detector for power fail
warning, or to monitor a power supply other than V
Low Line Output: This early power failure warning indicator
goes low when the supply voltage drops to a value which is
2% higher than the reset threshold voltage.
Features
n Standard Reset Threshold voltage: 3.08V
n Custom Reset Threshold voltages: For other voltages
Typical Application
between 2.2V and 5.0V in 10mV increments, contact
National Semiconductor Corp.
DS101369
CC
.
CC
of
n No external components required
n Manual-Reset input
n RESET (LM3704) or RESET (LM3705) outputs
n Precision supply voltage monitor
n Factory programmable Reset Timeout Delay
n Separate Power Fail comparator
n Available in micro SMD package for minimum footprint
n
n
n Reset assertion down to 1V V
n 28 µA V
Applications
n Embedded Controllers and Processors
n Intelligent Instruments
n Automotive Systems
n Critical µP Power Monitoring
extremes
±
±
0.5% Reset threshold accuracy at room temperature
2% Reset threshold accuracy over temperature
CC
supply current
10136903
CC
(RESET option only)
www.national.com
July 2002

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LM3705 Summary of contents

Page 1

... National Semiconductor Corp. Typical Application © 2002 National Semiconductor Corporation n No external components required n Manual-Reset input n RESET (LM3704) or RESET (LM3705) outputs n Precision supply voltage monitor n Factory programmable Reset Timeout Delay n Separate Power Fail comparator n Available in micro SMD package for minimum footprint ± ...

Page 2

... (LM3704 only). MRT Reset Logic Output. RESET is the inverse of RESET (LM3705 only). Power-Fail Logic Output. When PFI is below V remains high. Low-Line Logic Output. Early Power-Fail warning output. Low when V (Low-Line Output Threshold). This output can be used to generate an NMI (Non-Maskable Interrupt) to provide an early warning of imminent power-failure. ...

Page 3

Block Diagram 3 10136926 www.national.com ...

Page 4

... LM3705XCMM-308 totem-pole LM3705XCMMX-308 totem-pole %% is the datecode and will vary with time. Table Of Functions Part Active Active Number Low High Reset Reset LM3704 x LM3705 available upon request. Contact National www.national.com LM3704/LM3705 Reset Timeout Period 200ms 200ms 200ms 200ms 200ms 200ms 200ms 200ms ...

Page 5

... National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage ( All Other Inputs ESD Ratings (Note 2) Human Body Model Machine Model LM3704/LM3705 Series Electrical Characteristics Limits in the standard typeface are for T specified +2.2V to 5.5V. CC Symbol Parameter POWER SUPPLY V ...

Page 6

... LM3704/LM3705 Series Electrical Characteristics Limits in the standard typeface are for T specified +2.2V to 5.5V. CC Symbol Parameter PFI/MR V PFI Input PFT Threshold V MR Input MR, Low MRT Threshold MR, High V / PFI/MR Threshold PFI/MR falling: V PFTH V Hysteresis MRTH I Input Current (PFI PFI only Pull-up MR Resistance Reset ...

Page 7

Typical Performance Characteristics Supply Current vs Supply Voltage Normalized Reset Threshold Voltage vs Temperature Reset Timeout Period vs Temperature 3.3V Supply Current vs Temperature 10136915 Reset Timeout Period vs V 10136912 Max. Transient Duration vs Reset Comparator Overdrive 10136910 7 ...

Page 8

Typical Performance Characteristics Low-Line Comparator Propagation Delay vs Temperature www.national.com (Continued) 10136914 8 ...

Page 9

... CC (typically 1.02 • V Special Precautions for the micro SMD Package As with most integrated circuits, the LM3704 and LM3705 are sensitive to exposure from visible and infrared (IR) light radiation. Unlike a plastic encapsulated IC, the micro SMD package has very limited shielding from light, and some ...

Page 10

Timing Diagrams www.national.com FIGURE 1. LM3704 Reset Time with MR FIGURE 2. LLO Output FIGURE 3. PFI Comparator Timing Diagram 10 10136928 10136929 10136930 ...

Page 11

Typical Application Circuits FIGURE 5. Monitoring Two Supplies plus Manual Reset FIGURE 4. Monitoring Two Critical Supplies 11 10136918 10136919 www.national.com ...

Page 12

Typical Application Circuits FIGURE 6. Monitoring Dual Supplies plus External Fault Input Note: MR input with its 1.225V nominal threshold, may monitor an additional supply voltage. An internal 56 kΩ pull-up resistor is included on this input. FIGURE 7. Microprocessor ...

Page 13

... Typical Application Circuits (Continued) FIGURE 8. LM3705 Power-On Delay 13 10136924 www.national.com ...

Page 14

... Typical Application Circuits FIGURE 9. LM3705 Power-On Delay with Overvoltage Protection www.national.com (Continued) 14 10136923 ...

Page 15

Typical Application Circuits FIGURE 10. Regulator/Switch with Long-Term Overvoltage Lockout Prevents Overdissipation in Linear Regulator (Continued) FIGURE 11. Switch Debouncer 15 10136922 10136931 www.national.com ...

Page 16

Physical Dimensions unless otherwise noted www.national.com inches (millimeters) 10 Lead MSOP Package NS Package Number MUB10A 16 ...

Page 17

... NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant ...

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