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LM3704/LM3705 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output and
Manual Reset
September 2003
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
CC
of
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
CC
.
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.
n
n
n
n
n
n
n
n
n
No external components required
Manual-Reset input
RESET (LM3704) or RESET (LM3705) outputs
Precision supply voltage monitor
Factory programmable Reset Timeout Delay
Separate Power Fail comparator
Available in micro SMD package for minimum footprint
±
0.5% Reset threshold accuracy at room temperature
±
2% Reset threshold accuracy over temperature
extremes
n
Reset assertion down to 1V V
CC
(RESET option only)
n
28 µA V
CC
supply current
Applications
n
n
n
n
Embedded Controllers and Processors
Intelligent Instruments
Automotive Systems
Critical µP Power Monitoring
Features
n
Standard Reset Threshold voltage: 3.08V
n
Custom Reset Threshold voltages: For other voltages
between 2.2V and 5.0V in 10mV increments, contact
National Semiconductor Corp.
Typical Application
10136903
© 2003 National Semiconductor Corporation
DS101369
www.national.com
LM3704/LM3705
Connection Diagram
Top View
(looking from the coating side)
micro SMD 9 Bump Package
BPA09
MSOP-10
10136902
10136901
Pin Description
Pin No.
micro
SMD
A1
B1
C1
MSOP
2
1
10
Name
MR
V
CC
RESET
Function
Manual-Reset input. When MR is less than V
MRT
(Manual Reset Threshold)
RESET/RESET is engaged.
Power Supply input.
Reset Logic Output. Pulses low for t
RP
(Reset Timeout Period) when triggered, and stays
low whenever V
CC
is below the reset threshold or when MR is below V
MRT
. It remains low
for t
RP
after either V
CC
rises above the reset threshold, or after MR input rises above
V
MRT
(LM3704 only).
Reset Logic Output. RESET is the inverse of RESET (LM3705 only).
Power-Fail Logic Output. When PFI is below V
PFT
, PFO goes low; otherwise, PFO
remains high.
Low-Line Logic Output. Early Power-Fail warning output. Low when V
CC
falls below V
LLOT
(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.
Ground reference for all signals.
No Connect.
Power-Fail Comparator Input. When PFI is less than V
PFT
(Power-Fail Reset Threshold),
the PFO goes low; otherwise, PFO remains high.
No Connect. Test input used at factory only. Leave floating.
RESET
C2
C3
8
7
PFO
LLO
B3
A3
A2
B2
5
4, 6
3
9
GND
NC
PFI
NC
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2
LM3704/LM3705
Block Diagram
10136926
3
www.national.com
LM3704/LM3705
Ordering Information
10136904
*For other voltages between 2.2V and 5.0V, please contact National Semiconductor sales office.
LM3704/LM3705
Part Number
LM3704XBBP-232
LM3704XBBPX-232
LM3704XBBP-463
LM3704XBBPX-463
LM3704XBMM-232
LM3704XBMMX-232
LM3704XBMM-463
LM3704XBMMX-463
LM3704XCBP-308
LM3704XCBPX-308
LM3704XCMM-263
LM3704XCMMX-263
LM3704XCMM-308
LM3704XCMMX-308
LM3704XDBP-232
LM3704XDBPX-232
LM3704XDBP-463
LM3704XDBPX-463
LM3704XDMM-220
LM3704XDMMX-220
LM3704XDMM-232
LM3704XDMMx-232
LM3704XDMM-463
LM3704XDMMX-463
LM3704YAMM-308
LM3704YAMMX-308
Output
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
totem-pole
open-drain
open-drain
Reset
Timeout
Period
28ms
28ms
28ms
28ms
28ms
28ms
28ms
28ms
200ms
200ms
200ms
200ms
200ms
200ms
1600ms
1600ms
1600ms
1600ms
1600ms
1600ms
1600ms
1600ms
1600ms
1600ms
1.4ms
1.4ms
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Package
MSOP
micro
SMD
x
x
x
x
Package
Marking
%%I13
%%I13
%%I27
%%I27
R66B
R66B
R27B
R27B
%%I4
%%I4
R79B
R79B
R35B
R35B
%%I15
%%I15
%%I17
%%I17
R65B
R65B
R67B
R67B
R68B
R68B
R78B
R78B
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4