LM3702,LM3703
LM3702/LM3703 Microprocessor Supervisory Circuits with Low Line Output and
Manual Reset
Literature Number: SNVS147C
LM3702/LM3703
Microprocessor Supervisory Circuits with Low Line
Output and Manual Reset
General Description
The LM3702/LM3703 series of microprocessor supervisory
circuits provide the maximum flexibility for monitoring power
supplies and battery controlled functions in systems without
backup batteries. The LM3702/LM3703 series are available
in a 9-bump micro SMD package.
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.
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
nStandard Reset Threshold voltage: 3.08V
nCustom Reset Threshold voltages: For other voltages
between 2.2V and 5.0V in 10mV increments, contact
National Semiconductor Corp.
nNo external components required
nManual-Reset input
nRESET (LM3702) or RESET (LM3703) outputs
nPrecision supply voltage monitor
nFactory programmable Reset Timeout Delay
nAvailable in micro SMD package for minimum footprint
n±0.5% Reset threshold accuracy at room temperature
n±2% Reset threshold accuracy over temperature
extremes
nReset assertion down to 1V V
CC
(RESET option only)
n28 µA V
CC
supply current
Applications
nEmbedded Controllers and Processors
nIntelligent Instruments
nAutomotive Systems
nCritical µP Power Monitoring
Typical Application
20011503
September 2003
LM3702/LM3703 Microprocessor Supervisory Circuits with Low Line Output and Manual Reset
© 2003 National Semiconductor Corporation DS200115 www.national.com
Connection Diagram
Top View
(looking from the coating side)
micro SMD 9 Bump Package
BPA09
20011501
Pin Descriptions
Bump No. Name Function
A1 MR Manual-Reset input. When MR is less than V
MRT
(Manual Reset Threshold)
RESET/RESET is engaged.
B1 V
CC
Power Supply input.
C1 RESET 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
(LM3702 only).
RESET Reset Logic Output. RESET is the inverse of RESET (LM3703 only).
C3 LLO 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.
B3 GND Ground reference for all signals.
A2, A3, C2 NC No Connect.
B2 NC No Connect. Test input used at factory only. Leave floating.
LM3702/LM3703
www.national.com 2
Block Diagram
20011505
LM3702/LM3703
www.national.com3
Ordering Information
20011504
*For other voltages between 2.2V and 5.0V, please contact National Semiconductor sales office.
LM3702/LM3703
Part Number Output
Reset
Timeout
Period
Package
Marking
LM3702XCBP-308 totem-pole 200ms %%I2
LM3702XCBPX-308 totem-pole 200ms %%I2
LM3703XCBP-308 totem-pole 200ms %%I3
LM3703XCBPX-308 totem-pole 200ms %%I3
LM3703XDBP-308 totem-pole 1600ms %%124
LM3703XDBPX-308 totem-pole 1600ms %%124
LM3702YABP-308 open-drain 1.4ms %%131
LM3702ABPX-308 open-drain 1.4ms %%131
LM3702YDBP-220 open-drain 1600ms %%125
LM3702YDBPX-220 open-drain 1600ms %%125
%% is the datecode and will vary with time.
Table Of Functions
Part
Number
Active
Low
Reset
Active
High
Reset
Output
(X = totem-pole)
(Y = open-drain)
Reset
Timeout
Period
Manual
Reset
Low
Line
Output
LM3702 x X, Y* Customized x x
LM3703 x X Customized x x
* = available upon request. Contact National
LM3702/LM3703
www.national.com 4
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage (V
CC
) −0.3V to 6.0V
All Other Inputs −0.3V to V
CC
+ 0.3V
ESD Ratings (Note 2)
Human Body Model
Machine Model
1.5kV
150V
Power Dissipation (Note 3)
Operating Ratings (Note 1)
Temperature Range −40˚C ≤T
J
≤85˚C
LM3702/LM3703 Series Electrical Characteristics
Limits in the standard typeface are for T
J
= 25˚C and limits in boldface type apply over full operating range. Unless otherwise
specified: V
CC
= +2.2V to 5.5V.
Symbol Parameter Conditions Min Typ Max Units
POWER SUPPLY
V
CC
Operating Voltage
Range: V
CC
LM3702 1.0 5.5 V
LM3703 1.2 5.5
I
CC
V
CC
Supply
Current
All inputs = V
CC
; all outputs floating 28 50 µA
RESET THRESHOLD
V
RST
Reset Threshold V
CC
falling −0.5
−2 V
RST
+0.5
+2 %
V
CC
falling: T
A
= 0˚C to 70˚C −1.5 +1.5
V
RSTH
Reset Threshold
Hysteresis
0.0032•V
RST
mV
t
RP
Reset Timeout
Period
Reset Timeout Period = A
Reset Timeout Period = B
Reset Timeout Period = C
Reset Timeout Period = D
1
20
140
1120
1.4
28
200
1600
2
40
280
2240
ms
t
RD
V
CC
to Reset
Delay
V
CC
falling at 1mV/µs 20 µs
RESET (LM3703)
V
OL
RESET V
CC
>2.25V, I
SINK
= 900µA 0.3
VV
CC
>2.7V, I
SINK
= 1.2mA 0.3
V
CC
>4.5V, I
SINK
= 3.2mA 0.4
V
OH
RESET V
CC
>1.2V, I
SOURCE
= 50µA 0.8 V
CC
V
V
CC
>1.8V, I
SOURCE
= 150µA 0.8 V
CC
V
CC
>2.25V, I
SOURCE
= 300µA 0.8 V
CC
V
CC
>2.7V, I
SOURCE
= 500µA 0.8 V
CC
V
CC
>4.5V, I
SOURCE
= 800µA V
CC
− 1.5V
I
LKG
Output Leakage
Current
V
RESET
= 5.5V 1.0 µA
RESET (LM3702)
V
OL
RESET V
CC
>1.0V, I
SINK
= 50µA 0.3
V
V
CC
>1.2V, I
SINK
= 100µA 0.3
V
CC
>2.25V, I
SINK
= 900µA 0.3
V
CC
>2.7V, I
SINK
= 1.2mA 0.3
V
CC
>4.5V, I
SINK
= 3.2mA 0.4
V
OH
RESET V
CC
>2.25V, I
SOURCE
= 300µA 0.8 V
CC
V
CC
>2.7V, I
SOURCE
= 500µA 0.8 V
CC
V
CC
>4.5V, I
SOURCE
= 800µA V
CC
− 1.5V
LM3702/LM3703
www.national.com5
LM3702/LM3703 Series Electrical Characteristics (Continued)
Limits in the standard typeface are for T
J
= 25˚C and limits in boldface type apply over full operating range. Unless otherwise
specified: V
CC
= +2.2V to 5.5V.
Symbol Parameter Conditions Min Typ Max Units
MR
V
MRT
MR Input
Threshold
MR, Low 0.8 V
MR, High 2.0
V
MRTH
MR Threshold
Hysteresis
MR falling: V
CC
=V
RST MAX
to 5.5V 0.0032•V
RST
mV
R
MR
MR Pull-up
Resistance
35 56 75 kΩ
t
MD
MR to Reset
Delay
12 µS
t
MR
MR Pulse Width 25 µS
LLO
V
OL
LLO Output
Voltage
V
CC
>2.25V, I
SINK
= 900µA 0.3
V
V
CC
>2.7V, I
SINK
= 1.2mA 0.3
V
CC
>4.5V, I
SINK
= 3.2mA 0.4
V
OH
V
CC
>2.25V, I
SOURCE
= 300µA 0.8 V
CC
V
CC
>2.7V, I
SOURCE
= 500µA 0.8 V
CC
V
CC
>4.5V, I
SOURCE
= 800µA V
CC
− 1.5V
LLO OUTPUT
V
LLOT
LLO Output
Threshold
(V
LLO
−V
RST
,V
CC
falling)
1.01•V
RST
1.02•V
RST
1.03•V
RST
V
V
LLOTH
Low-Line
Comparator
Hysteresis
0.0032•V
RST
mV
t
CD
Low-Line
Comparator Delay
V
CC
falling at 1mV/µs 20 µs
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device
is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the
listed conditions.
Note 2: The Human Body model is a 100 pF capacitor discharged through a 1.5 kΩresistor into each pin. The machine model is a 200pF capacitor discharged
directly into each pin.
Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, θJ-A,
and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperture is calculated using:
Where the value of θJ-A for the micro SMD package is 220˚C/W.
LM3702/LM3703
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Typical Performance Characteristics
Supply Current vs Supply Voltage 3.3V Supply Current vs Temperature
20011515
20011511
Normalized Reset Threshold Voltage vs Temperature Reset Timeout Period vs V
CC
20011512
20011532
Reset Timeout Period vs Temperature
Max. Transient Duration vs Reset Comparator Overdrive
(V
CC
= 3.3V)
20011510
20011516
LM3702/LM3703
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Typical Performance Characteristics (Continued)
Low-Line Comparator Propagation Delay vs Temperature
20011514
LM3702/LM3703
www.national.com 8
Circuit Information
RESET OUTPUT
The Reset input of a µP initializes the device into a known
state. The LM3702/LM3703 microprocessor supervisory cir-
cuits assert a forced reset output to prevent code execution
errors during power-up, power-down, and brownout condi-
tions.
RESET is guaranteed valid for V
CC
>1V. Once V
CC
ex-
ceeds the reset threshold, an internal timer maintains the
output for the reset timeout period. After this interval, reset
goes high. The LM3702 offers an active-low RESET; The
LM3703 offers an active-high RESET.
Any time V
CC
drops below the reset threshold (such as
during a brownout), the reset activates. When V
CC
again
rises above the reset threshold, the internal timer starts.
Reset holds until V
CC
exceeds the reset threshold for longer
than the reset timeout period. After this time, reset releases.
The Manual Reset input (MR) will initiate a forced reset also.
See the Manual Reset Input section.
RESET THRESHOLD
The LM3702/LM3703 family is available with a reset voltage
of 3.08V. Other reset thresholds in the 2.20V to 5.0V range,
in steps of 10 mV, are available; contact National Semicon-
ductor for details.
MANUAL RESET INPUT (MR)
Many µP-based products require a manual reset capability,
allowing the operator to initiate a reset. The MR input is fully
debounced and provides an internal 56 kΩpull-up. When the
MR input is pulled below V
MRT
(1.225V) for more than 25 µs,
reset is asserted after a typical delay of 12 µs. Reset remains
active as long as MR is held low, and releases after the reset
timeout period expires after MR rises above V
MRT
. Use MR
with digital logic to assert or to daisy chain supervisory
circuits. It may be used as another low-line comparator by
adding a buffer.
LOW-LINE OUTPUT (LLO)
The low-line output comparator is typically used to provide a
non-maskable interrupt to a µP when V
CC
begins falling. LLO
monitors V
CC
and goes low when V
CC
falls below V
LLOT
(typically 1.02 •V
RST
) with hysteresis of 0.0032 •V
RST
.
SPECIAL PRECAUTIONS FOR THE MICRO SMD
PACKAGE
As with most integrated circuits, the LM3702 and LM3703
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
sensitivity to light reflected from the surface of the PC board
or long wavelength IR entering the die from the side may be
experienced. This light could have an unpredictable affect on
the electrical performance of the IC. Care should be taken to
shield the device from direct exposure to bright visible or IR
light during operation.
MICRO SMD MOUNTING
The micro SMD package requires specific mounting tech-
niques which are detailed in National Semiconductor Appli-
cation Note AN-1112. Referring to the section Surface
Mount Technology (SMT) Assembly Considerations,it
should be noted that the pad style which must be used with
the 9-pin package is the NSMD (non-solder mask defined)
type.
For best results during assembly, alignment ordinals on the
PC board may be used to facilitate placement of the micro
SMD device.
LM3702/LM3703
www.national.com9
Timing Diagrams
20011528
FIGURE 1. LM3702 Reset Time with MR
20011529
FIGURE 2. LLO Output
LM3702/LM3703
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Typical Application Circuits
20011524
FIGURE 3. LM3703 Power-On Delay
LM3702/LM3703
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Typical Application Circuits (Continued)
20011522
FIGURE 4. Regulator/Switch with Long-Term Overvoltage Lockout Prevents Overdissipation in Linear Regulator
20011531
FIGURE 5. Switch Debouncer
LM3702/LM3703
www.national.com 12
Physical Dimensions inches (millimeters)
unless otherwise noted
NOTES: UNLESS OTHERWISE SPECIFIED
1. EPOXY COATING
2. 63Sn/37Pb EUTECTIC BUMP
3. RECOMMEND NON-SOLDER MASK DEFINED LANDING PAD.
4. PIN 1 IS ESTABLISHED BY LOWER LEFT CORNER WITH RESPECT TO TEXT ORIENTATION. REMAINING PINS ARE NUMBERED COUNTER
CLOCKWISE.
5. XXX IN DRAWING NUMBER REPRESENTS PACKAGE SIZE VARIATION WHERE X1 IS PACKAGE WIDTH, X2 IS PACKAGE LENGTH AND X3 IS
PACKAGE HEIGHT.
6.NO JEDEC REGISTRATION AS OF AUG.1999.
9 bump micro SMD Package
NS Package Number BPA09FFB
The dimensions of X1, X2 and X3 are given below
X1 = 1.412mm
X2 = 1.412mm
X3 = 0.850mm
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LM3702/LM3703 Microprocessor Supervisory Circuits with Low Line Output and Manual Reset
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