Datasheet LM3704XDMMX-232, LM3704XDMMX-220, LM3704XDMM-463, LM3704XDBPX-463, LM3704XDBPX-232 Datasheet (NSC)

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.

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.

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

±

0.5% Reset threshold accuracy at room temperature

n

±

2% Reset threshold accuracy over temperature

extremes

n Reset assertion down to 1V V

CC

(RESET option only)

n 28 µA VCCsupply current

Applications

n Embedded Controllers and Processors
n Intelligent Instruments
n Automotive Systems
n Critical µP Power Monitoring

Typical Application

10136903

July 2002

LM3704/LM3705 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output and

Manual Reset

© 2002 National Semiconductor Corporation DS101369 www.national.com

Connection Diagram

MSOP-10

Top View

(looking from the coating side)

micro SMD 9 Bump Package

BPA09

10136902

10136901

Pin Description

Pin No.

Name Function

micro

SMD

MSOP

A1 2 MR

Manual-Reset input. When MR is less than V

MRT

(Manual Reset Threshold)

RESET/RESET is engaged.

B1 1 V

CC

Power Supply input.

C1 10 RESET

Reset Logic Output. Pulses low for tRP(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 tRPafter either VCCrises above the reset threshold, or after MR input rises above
V

MRT

(LM3704 only).

RESET Reset Logic Output. RESET is the inverse of RESET (LM3705 only).

C2 8 PFO Power-Fail Logic Output. When PFI is below V

PFT

, PFO goes low; otherwise, PFO

remains high.

C3 7 LLO

Low-Line Logic Output. Early Power-Fail warning output. Low when VCCfalls 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 5 GND Ground reference for all signals.

A3 4, 6 NC No Connect.

A2 3 PFI Power-Fail Comparator Input. When PFI is less than V

PFT

(Power-Fail Reset Threshold),

the PFO goes low; otherwise, PFO remains high.

B2 9 NC No Connect. Test input used at factory only. Leave floating.

LM3704/LM3705

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Block Diagram

10136926

LM3704/LM3705

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Ordering Information

10136904

*

For other voltages between 2.2V and 5.0V, please contact National Semiconductor sales office.

LM3704/LM3705

Part Number Output

Reset Timeout

Period

Package

Package

Marking

MSOP

micro

SMD

LM3704XCBP-308 totem-pole 200ms x %%I4

LM3704XCBPX-308 totem-pole 200ms x %%I4

LM3704XCMM-308 totem-pole 200ms x R35B

LM3704XCMMX-308 totem-pole 200ms x R35B

LM3705XCBP-308 totem-pole 200ms x %%I5

LM3705XCBPX-308 totem-pole 200ms x %%I5

LM3705XCMM-308 totem-pole 200ms x R36B

LM3705XCMMX-308 totem-pole 200ms x R36B

%% 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

Power Fail

Comparator

Low
Line

Output

LM3704 x X, Y

*

Customized x x x

LM3705 x X Customized x x x

*

= available upon request. Contact National

LM3704/LM3705

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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

LM3704/LM3705 Series Electrical Characteristics

Limits in the standard typeface are for TJ= 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

LM3704 1.0 5.5

V

LM3705 1.2 5.5

I

CC

VCCSupply
Current

All inputs = VCC; all outputs floating 28 50 µA

RESET THRESHOLD

V

RST

Reset Threshold VCCfalling −0.5

−2

V

RST

+0.5

+2

%

V

CC

falling: TA= 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

VCCto Reset
Delay

VCCfalling at 1mV/µs 20 µs

RESET (LM3705)

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 VCC− 1.5V

I

LKG

Output Leakage
Current

V

RESET

= 5.5V 1.0 µA

RESET (LM3704)

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 VCC− 1.5V

LM3704/LM3705

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LM3704/LM3705 Series Electrical Characteristics (Continued)

Limits in the standard typeface are for TJ= 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

PFI/MR

V

PFT

PFI Input
Threshold

1.200 1.225 1.250 V

V

MRT

MR Input
Threshold

MR, Low

0.8

V

MR, High

2.0

V

PFTH

/

V

MRTH

PFI/MR Threshold
Hysteresis

PFI/MR falling: V

CC=VRST MAX

to 5.5V 0.0032•V

RST

mV

I

PFI

Input Current (PFI
only)

−75 75 nA

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

PFO, LLO

V

OL

PFO, 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 VCC− 1.5V

LLO OUTPUT

V

LLOT

LLO Output
Threshold
(V

LLO−VRST,VCC

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

VCCfalling 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 kΩ resistor 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, T

J

(MAX), the junction-to-ambient thermal resistance, θ

J-A

,

and the ambient temperature, T

A

. The maximum allowable power dissipation at any ambient temperture is calculated using:

Where the value of θ

J-A

for the MSOP-10 package is 195˚C/W in a typical PC board mounting and the micro SMD package is 220˚C/W.

LM3704/LM3705

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Typical Performance Characteristics

Supply Current vs Supply Voltage 3.3V Supply Current vs Temperature

10136915

10136911

Normalized Reset Threshold Voltage vs Temperature Reset Timeout Period vs V

CC

10136912

10136932

Reset Timeout Period vs Temperature

Max. Transient Duration vs Reset Comparator Overdrive

(VCC= 3.3V)

10136910

10136916

LM3704/LM3705

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Typical Performance Characteristics (Continued)

Low-Line Comparator Propagation Delay vs Temperature

10136914

LM3704/LM3705

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Circuit Information

Reset Output

The Reset input of a µP initializes the device into a known
state. The LM3704/LM3705 microprocessor supervisory cir­cuits assert a forced reset output to prevent code execution
errors during power-up, power-down, and brownout condi­tions.

RESET is guaranteed valid for V

CC

>

1V. Once VCCex­ceeds the reset threshold, an internal timer maintains the
output for the reset timeout period. After this interval, reset
goes high. The LM3704 offers an active-low RESET; The
LM3705 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 LM3704/LM3705 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 Semicon­ductor 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 kΩ pull-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.

Power-Fail Comparator (PFI/PFO)

The PFI is compared to a 1.225V internal reference, V

PFT

.If

PFI is less than V

PFT

, the Power Fail Output PFO drops low.
The power-fail comparator signals a falling power supply,
and is driven typically by an external voltage divider that
senses either the unregulated supply or another system

supply voltage. The voltage divider generally is chosen so
the voltage at PFI drops below V

PFT

several milliseconds
before the main supply voltage drops below the reset thresh­old, providing advanced warning of a brownout.

The voltage threshold is set by R

1

and R2and is calculated

as follows:

Note this comparator is completely separate from the rest of
the circuitry, and may be employed for other functions as
needed.

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 VCCand goes low when VCCfalls 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 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
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 tech­niques which are detailed in National Semiconductor Appli­cation 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.

LM3704/LM3705

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Timing Diagrams

10136928

FIGURE 1. LM3704 Reset Time with MR

10136929

FIGURE 2. LLO Output

10136930

FIGURE 3. PFI Comparator Timing Diagram

LM3704/LM3705

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Typical Application Circuits

10136918

FIGURE 4. Monitoring Two Critical Supplies

10136919

FIGURE 5. Monitoring Two Supplies plus Manual Reset

LM3704/LM3705

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Typical Application Circuits (Continued)

10136920

FIGURE 6. Monitoring Dual Supplies plus External Fault Input

10136921

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 Supervisor with Early Warning Detector

LM3704/LM3705

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Typical Application Circuits (Continued)

10136924

FIGURE 8. LM3705 Power-On Delay

LM3704/LM3705

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Typical Application Circuits (Continued)

10136923

FIGURE 9. LM3705 Power-On Delay with Overvoltage Protection

LM3704/LM3705

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Typical Application Circuits (Continued)

10136922

FIGURE 10. Regulator/Switch with Long-Term Overvoltage Lockout Prevents Overdissipation in Linear Regulator

10136931

FIGURE 11. Switch Debouncer

LM3704/LM3705

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Physical Dimensions inches (millimeters)

unless otherwise noted

10 Lead MSOP Package

NS Package Number MUB10A

LM3704/LM3705

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Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

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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COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:

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whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.

2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
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LM3704/LM3705 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output and

Manual Reset

National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.