Datasheet LM3710, LM3711 Datasheet (National Semiconductor)

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LM3710/LM3711 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output, Manual Reset and Watchdog Timer

June 2002

LM3710/LM3711 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output,

Manual Reset and Watchdog Timer

General Description

The LM3710/LM3711 series of microprocessor supervisory circuits provide the maximum flexibility for monitoring power supplies and battery controlled functions in systems without backup batteries. The LM3710/LM3711 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.

Watchdog Timer: The WDI (Watchdog Input) monitors one of the µP’s output lines for activity. If no output transition occurs during the watchdog timeout period, reset is activated.

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 (LM3710) or RESET (LM3711) outputs

n Precision supply voltage monitor n Factory programmable Reset and Watchdog Timeout

Delays

n Separate Power Fail comparator n 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 n 28 µA VCCsupply current

(RESET option only)

Applications

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

Typical Application

20011803

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Connection Diagram

LM3710/LM3711

MSOP-10

Top View

(looking from the coating side)

micro SMD 9 Bump Package

BPA09

20011802

20011801

Pin Descriptions

Pin No.

micro

SMD

MSOP

A1 2 MR

B1 1 V

C1 10 RESET

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

C3 7 LLO

B3 5 GND Ground reference for all signals.

A3 4 WDI Watchdog Input Transition Monitor: If no transition activity occurs for a period exceeding

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

B2 6, 9 NC No Connect. Test input used at factory only. Leave floating.

Name Function

Manual-Reset input. When MR is less than V

(Manual Reset Threshold)

MRT

RESET/RESET is engaged.

Power Supply input.

Reset Logic Output. Pulses low for tRP(Reset Timeout Period) when triggered, and stays low whenever V

is below the reset threshold or when MR is below V

for tRPafter either VCCrises above the reset threshold, or after MR input rises above V

(LM3710 only).

MRT

RESET Reset Logic Output. RESET is the inverse of RESET (LM3711 only).

, PFO goes low; otherwise, PFO

PFT

remains high.

Low-Line Logic Output. Early Power-Fail warning output. Low when VCCfalls below 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.

(Watchdog Timeout Period), reset is engaged.

(Power-Fail Reset Threshold),

PFT

the PFO goes low; otherwise, PFO remains high.

. It remains low

MRT

LLOT

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Block Diagram

LM3710/LM3711

20011805

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Ordering Information

LM3710/LM3711

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

20011804

LM3710/LM3711

Part Number Output

Reset Timeout

Period

Watchdog

Timeout

Period

MSOP

Package

micro

SMD

Package

Marking

LM3710XQBP-308 totem-pole 200ms 1600ms x %%IA

LM3710XQBPX-308 totem-pole 200ms 1600ms x %%IA

LM3710XQMM-308 totem-pole 200ms 1600ms x R37B

LM3710XQMMX-308 totem-pole 200ms 1600ms x R37B

LM3711XQBP-308 totem-pole 200ms 1600ms x %%IB

LM3711XQBPX-308 totem-pole 200ms 1600ms x %%IB

LM3711XQMM-308 totem-pole 200ms 1600ms x R38B

LM3711XQMMX-308 totem-pole 200ms 1600ms x R38B

%% is the datecode and will vary with time.

Table Of Functions

Part

Number

LM3710 x X, Y

LM3711 x X Customized Customized x x x

= available upon request. Contact National

Active

Low

Reset

Active

High

Reset

Output (X = totem-pole) (Y = open-drain)

Reset

Timeout

Period

Watchdog

Timeout

Period

Manual

Reset

Power Fail

Comparator

Low Line

Output

Customized Customized x x x

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LM3710/LM3711

Absolute Maximum Ratings (Note 1)

Power Dissipation (Note 3)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Supply Voltage (V

All Other Inputs −0.3V to V

) −0.3V to 6.0V

+ 0.3V

Operating Ratings (Note 1)

Temperature Range −40˚C ≤ T

≤ 85˚C

ESD Ratings (Note 2)

Human Body Model Machine Model

1.5kV 150V

LM3710/LM3711 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

Symbol Parameter Conditions Min Typ Max Units

POWER SUPPLY

RESET THRESHOLD

RST

RSTH

RESET (LM3711)

LKG

RESET (LM3710)

= +2.2V to 5.5V.

Operating Voltage Range: V

VCCSupply

LM3710 1.0 5.5

LM3711 1.2 5.5

All inputs = VCC; all outputs floating 28 50 µA

Current

Reset Threshold VCCfalling −0.5

−2

falling: TA= 0˚C to 70˚C −1.5 +1.5

Reset Threshold Hysteresis

Reset Timeout Period

VCCto Reset

Reset Timeout Period = E, J, N, S Reset Timeout Period = F, K, P, T Reset Timeout Period = G, L, Q, U Reset Timeout Period = H, M, R, V

140

1120

VCCfalling at 1mV/µs 20 µs

Delay

2.25V, I

2.7V, I

4.5V, I

1.2V, I

1.8V, I

2.25V, I

2.7V, I

4.5V, I

= 5.5V 1.0 µA

RESET

= 900µA 0.3

SINK

= 1.2mA 0.3

SINK

= 3.2mA 0.4

SINK

SOURCE

= 50µA 0.8 V

= 150µA 0.8 V

SOURCE

= 300µA 0.8 V

= 500µA 0.8 V

= 800µA VCC− 1.5V

RESET V

Output Leakage Current

RESET V

1.0V, I

1.2V, I

2.25V, I

2.7V, I

4.5V, I

2.25V, I

2.7V, I

4.5V, I

= 50µA 0.3

SINK

= 100µA 0.3

SINK

= 900µA 0.3

SINK

= 1.2mA 0.3

SINK

= 3.2mA 0.4

SINK

SOURCE

= 300µA 0.8 V

= 500µA 0.8 V

= 800µA VCC− 1.5V

+0.5

RST

0.0032•V

RST

1.4 28

200

1600

280

2240

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LM3710/LM3711 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

Symbol Parameter Conditions Min Typ Max Units

WDI

LM3710/LM3711

WDI Watchdog Input

WDI

PFI/MR

PFT

MRT

PFTH

MRTH

PFI

PFO, LLO

LLO OUTPUT

LLOT

LLOTH

= +2.2V to 5.5V.

−1 +1 µA

Current

Watchdog Input Threshold

Watchdog Timeout Period

PFI Input

Watchdog Timeout Period = E, F, G, H Watchdog Timeout Period = J, K, L, M Watchdog Timeout Period = N, P, Q, R Watchdog Timeout Period = S, T, U, V

0.2

4.3 71

1120

17900

•

1.225 0.8•V

6.2

102

1600

25600

9.3

153

2400

38400

1.200 1.225 1.250 V

Threshold

MR Input Threshold

PFI/MR Threshold

MR, Low

MR, High

PFI/MR falling: V

CC=VRST MAX

2.0

to 5.5V 0.0032•V

0.8

RST

Hysteresis

Input Current

−75 75 nA

(PFI only)

MR Pull-up

35 56 75 kΩ

Resistance

MR to Reset

12 µS

Delay

MR Pulse Width 25 µS

PFO, LLO Output Voltage

LLO Output

2.25V, I

2.7V, I

4.5V, I

2.25V, I

2.7V, I

4.5V, I

= 900µA 0.3

SINK

= 1.2mA 0.3

SINK

= 3.2mA 0.4

SINK

SOURCE

= 300µA 0.8 V

= 500µA 0.8 V

= 800µA VCC− 1.5V

1.01

•

RST

1.02•V

RST

1.03•V

Threshold (V

LLO−VRST,VCC

falling)

Low-Line

0.0032

•

RST

Comparator Hysteresis

Low-Line

VCCfalling at 1mV/µs 20 µs

Comparator Delay

RST

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LM3710/LM3711 Series Electrical Characteristics (Continued)

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 and the ambient temperature, T

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

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

J-A

LM3710/LM3711

Where the value of θ

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

J-A

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Typical Performance Characteristics

Supply Current vs Supply Voltage 3.3V Supply Current vs Temperature

LM3710/LM3711

20011815

Normalized Reset Threshold Voltage vs Temperature Reset Timeout Period vs V

20011812

Max. Transient Duration vs Reset Comparator Overdrive

Reset Timeout Period vs Temperature

(VCC= 3.3V)

20011811

20011832

20011810

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20011816

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Typical Performance Characteristics (Continued)

Watchdog Timeout Period vs Temperature

programmed as 6.2ms) Low-Line Comparator Propagation Delay vs Temperature

LM3710/LM3711

20011813

Circuit Information

Reset Output

The Reset input of a µP initializes the device into a known state. The LM3710/LM3711 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 ceeds the reset threshold, an internal timer maintains the output for the reset timeout period. After this interval, reset goes high. The LM3710 offers an active-low RESET; The LM3711 offers an active-high RESET.

Any time V

drops below the reset threshold (such as

during a brownout), the reset activates. When V rises above the reset threshold, the internal timer starts. Reset holds until V

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 LM3710/LM3711 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

(1.225V) for more than 25 µs,

MRT

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 with digital logic to assert or to daisy chain supervisory circuits. It may be used as another low-line comparator by adding a buffer.

1V. Once VCCex-

MRT

again

. Use MR

20011814

Power-Fail Comparator (PFI/PFO)

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

, the Power Fail Output PFO drops low.

PFT

.If

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

several milliseconds

PFT

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

The voltage threshold is set by R

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 monitors VCCand goes low when VCCfalls below V (typically 1.02•V

) with hysteresis of 0.0032•V

RST

begins falling. LLO

RST

LLOT

Watchdog Timer Input (WDI)

The watchdog timer input monitors one of the microprocessor’s output lines for activity. Each time a transition occurs on this monitored line, the watchdog counter is reset. However, if no transition occurs and the timeout period is reached, the LM3710/LM3711 assumes that the microprocessor has locked up and the reset output is activated.

WDI is a high impedance input.

Special Precautions for the micro SMD Package

As with most integrated circuits, the LM3710 and LM3711 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

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Circuit Information (Continued)

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.

LM3710/LM3711

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.

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Timing Diagrams

LM3710/LM3711

20011828

FIGURE 1. LM3710/LM3711 Reset Time with MR and WDI

FIGURE 2. LLO Output

FIGURE 3. PFI Comparator Timing Diagram

20011829

20011830

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Typical Application Circuits

LM3710/LM3711

20011818

FIGURE 4. Monitoring Two Critical Supplies And Dataline

FIGURE 5. Monitoring Two Supplies plus Manual Reset And Dataline

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20011819

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Typical Application Circuits (Continued)

FIGURE 6. Monitoring Dual Supplies plus External Fault Input And Dataline

LM3710/LM3711

20011820

20011821

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

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Typical Application Circuits (Continued)

LM3710/LM3711

FIGURE 8. LM3710 Long Period oscillator

20011840

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Physical Dimensions inches (millimeters)

unless otherwise noted

LM3710/LM3711

10 Lead MSOP Package

NS Package Number MUB10A

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

Manual Reset and Watchdog Timer

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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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 into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the

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 safety or effectiveness.

labeling, can be reasonably expected to result in a significant injury to the user.

National Semiconductor Corporation

Americas Email: support@nsc.com

LM3710/LM3711 Microprocessor Supervisory Circuits with Power Fail Input, Low Line Output,

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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.

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Fax: +49 (0) 180-530 85 86

Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790

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