SP813LEN-L/TR - Exar - Product.Network

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June 2010 Rev. 2.0.0

Exar Corporation www.exar.com

48720 Kato Road, Fremont CA 94538, USA Tel. +1 510 668-7000 – Fax. +1 510 668-7001

GENERAL DESCRIPTION

The SP705-708/813L series is a family of

microprocessor (µP) supervisory circuits that

integrate myriad components involved in

discrete solutions which monitor power-supply

and battery in mP and digital systems.

The SP705-708/813L series will significantly

improve system reliability and operational

efficiency when compared to solutions

obtained with discrete components. The

features of the SP705-708/813L series include

a watchdog timer, a µP reset, a Power Fail

Comparator, and a manual-reset input.

The SP705-708/813L series is ideal for

applications in automotive systems,

computers, controllers, and intelligent

instruments. The SP705-708/813L series is an

ideal solution for systems in which critical

monitoring of the power supply to the µP and

related digital components is demanded.

APPLICATIONS

• Processors & DSPs Based Systems

• Industrial & Medical Instruments

FEATURES

• Precision Voltage Monitor

− SP705/SP707/SP813L: 4.65V

− SP706/SP708: 4.40V

• 200ms RESET Pulse Width

• Independent Watchdog Timer

− 1.6s Timeout (SP705/SP706/SP813L)

• 60µA Maximum Supply Current

• Debounced TTL/CMOS Manual Reset

Input

• RESET Asserted Down to V

CC

=1.1V

• Voltage Monitor for Power Failure or

Low Battery Warning

• 8-Pin PDIP, NSOIC and MSOP Packages

• Pin Compatible with Industry

Standards 705-708-813L Series

• Functionally Compatible to Industry

Standard 1232 Series

Part Number RESET Threshold RESET Active Manual RESET Watchdog PFI Accuracy

SP705 4.65V Low Yes

Yes 4%

SP706 4.40V Low Yes

Yes 4%

SP707 4.65V Low and High Yes No 4%

SP708 4.40V Low and High Yes No 4%

SP813L 4.65V High Yes

Yes 4%

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ABSOLUTE MAXIMUM RATINGS

These are stress ratings only and functional operation of

the device at these ratings or any other above those

indicated in the operation sections of the specifications

below is not implied. Exposure to absolute maximum

rating conditions for extended periods of time may affect

reliability.

V

CC

.......................................................... -0.3V to 6.0V

All Other Inputs (Note 1) ................... -0.3V to (V

CC

+0.3V)

Input Current

VCC ................................................................. 20mA

GND ................................................................ 20mA

Output Current (All outputs) ............................... 20mA

ESD Rating (HBM - Human Body Model) .................... 4kV

Continuous Power Dissipation

Plastic DIP (derate 9.09mW/°C above +70°C) ....727mW

SO (derate 5.88mW/°C above +70°C) ...............471mW

Mini SO (derate 4.10mW/°C above +70°C) ........330mW

Storage Temperature .............................. -65°C to 160°C

Lead Temperature (Soldering, 10 sec) ....................300°C

ELECTRICAL SPECIFICATIONS

Unless otherwise indicated, V

CC

= 4.75V to 5.5V (SP705-SP707-SP813L), V

CC

= 4.50V to 5.5V (SP706-SP708), T

A

= T

MIN

to

T

MAX

, typical at 25°C.

Parameter Min. Typ. Max. Units Conditions

Operating Voltage Range V

CC

1.1 5.5 V

Supply Current I

SUPPLY

40 60 µA

MR=V

CC

or floating, WDI floating

Reset Threshold 4.50 4.65 4.75 V SP705, SP707, SP813L

4.25 4.40 4.50 SP706, SP708 (Note 2)

Reset Threshold Hysteresis 40 mV

Note 2

Reset Pulse Width t

RS

140 200 280 ms

Note 2

RESET Output Voltage

V

CC

-1.5

V

I

SOURCE

=800µA, Note 2

0.8 I

SOURCE

=4µA, V

CC

=1.1V, Note 2

0.4 I

SINK

=3.2mA, Note 2

0.3 I

SINK

=100µA, V

CC

=1.2V, Note 2

Watchdog Timeout Period t

WD

1.00 1.60 2.25 s SP705, SP707, SP813L

WDI Pulse Width t

WP

1 µs

V

IL

=0.4V, V

IH

=0.8xV

CC

WDI Input Threshold Low 0.8 V

SP705, SP707, SP813L

V

CC

=5V

WDI Input Threshold High 3.5 V

WDI Input Current 30 75 µA

SP705, SP707, SP813L, WDI=V

CC

-75 -20 µA

SP705, SP707, SP813L, WDI=0V

WDO Output Voltage V

CC

-1.5

V I

SOURCE

=800µA

0.4 I

SINK

=3.2mA

MR Pull-up Current 100 250 600 µA MR = 0V

MR Pulse Width t

MR

150 ns

MR Input Threshold Low 0.8

V

MR Input Threshold High 2.0

MR to Reset Out Delay t

MD

250 ns

Note 2

PFI Input Threshold 1.20 1.25 1.30 V V

CC

=5V

PFI Input Current -25.00 0.01 25.00 nA

PFO Output Voltage V

CC

-1.5

V I

SOURCE

=800µA

0.4 I

SINK

=3.2mA

Note 1: The input voltage limits on PFI and MR can be exceeded if the input current is less than 10mA.

Note 2: Applies to both RESET in the SP705-SP708 and RESET in the SP707/708/813L/813M.

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BLOCK DIAGRAM

Fig. 1: SP705-SP706-SP813L Block Diagram

Fig. 2: SP707-SP708 Block Diagram

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PIN ASSIGNMENT

Fig. 3: Pin Assignment

PIN DESCRIPTION

Name

Pin Number

Description

SP705-SP706 SP707-SP708 SP813L

SOIC MSOP SOIC MSOP DIP

SOIC

MR 1 3 1 3 1

Manual Reset

T

his input triggers a reset pulse when pulled below 0.8V. This

active LOW input has an internal 250µA pull-up current. It

can be driven from a TTL or CMOS logic line or shorted to

ground with a switch.

V

CC

2 4 2 4 2

+5V power supply

GND 3 5 3 5 3

Ground reference for all signals

PFI 4 6 4 6 4

Power-Fail Input

When this voltage monitor input is less than 1.25V, PFO goes

LOW. Connect PFI to ground or V

CC

when not in use.

PFO 5 - 5 7 5

Power-Fail Output

This output is LOW until PFI is less then 1.25V

WDI 6 8 - - 6

Watchdog Input

If this input remains HIGH or LOW for 1.6s, the internal

watchdog timer times out and WDO goes LOW. Floating WDI

or connecting WDI to a high-impedance tri-state buffer

disables the watchdog feature. The internal watchdog timer

clears whenever RESET is asserted, WDI is tri-stated, or

whenever WDI sees a rising or falling edge.

N.C. - - 6 8 -

No Connect

RESET 7 1 7 1 -

Active-LOW RESET Output

This output pulses LOW for 200ms when triggered and stays

LOW whenever V

CC

is below the reset threshold (4.65V for the

SP705/707/813L and 4.40V for the SP706/708). It remains

LOW for 200ms after V

cc

rises above the reset threshold or

MR goes from LOW to HIGH. A watchdog timeout will not

trigger RESET unless WDO is connected to MR.

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Name

Pin Number

Description

SP705-SP706 SP707-SP708 SP813L

SOIC MSOP SOIC MSOP DIP

SOIC

WDO 8 2 - - 8

Watchdog Output

This output pulls LOW when the internal watchdog timer

finishes its 1.6s count and does not go HIGH again until the

watchdog is cleared. WDO also goes LOW during low-line

conditions. Whenever V

CC

is below the reset threshold, WDO

stays LOW. However, unlike RESET, WDO does not have a

minimum pulse width. As soon as V

CC

is above the reset

threshold, WDO goes HIGH with no delay.

RESET - - 8 2 7

Active-HIGH RESET Output

This output is the complement of RESET. Whenever RESET is

HIGH, RESET is LOW and vice-versa. Note that the SP813L

has a reset output only.

ORDERING INFORMATION

Part Number Temperature

Range Marking Package Packing

Quantity Note 1 Note 2

SP705CN-L 0°C≤T

A

≤+70°C

SP705C

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP705CN-L/TR 0°C≤T

A

≤+70°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP705EN-L -40°C≤T

A

≤+85°C

SP705E

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP705EN-L/TR -40°C≤T

A

≤+85°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP705CU-L 0°C≤T

A

≤+70°C

705C

#

YWW

8-pin MSOP Bulk Lead Free

SP705CU-L/TR 0°C≤T

A

≤+70°C 8-pin MSOP 2.5K/Tape & Reel Lead Free

SP706CN-L 0°C≤T

A

≤+70°C

SP706C

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP706CN-L/TR 0°C≤T

A

≤+70°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP706EN-L -40°C≤T

A

≤+85°C

SP706E

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP706EN-L/TR -40°C≤T

A

≤+85°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP706CU-L 0°C≤T

A

≤+70°C

706C

#

YWW

8-pin MSOP Bulk Lead Free

SP706CU-L/TR 0°C≤T

A

≤+70°C 8-pin MSOP 2.5K/Tape & Reel Lead Free

SP707CN-L 0°C≤T

A

≤+70°C

SP707C

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP707CN-L/TR 0°C≤T

A

≤+70°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP707EN-L -40°C≤T

A

≤+85°C

SP707E

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP707EN-L/TR -40°C≤T

A

≤+85°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP707CU-L 0°C≤T

A

≤+70°C

707C

#

YWW

8-pin MSOP Bulk Lead Free

SP707CU-L/TR 0°C≤T

A

≤+70°C 8-pin MSOP 2.5K/Tape & Reel Lead Free

SP708CN-L 0°C≤T

A

≤+70°C

SP708C

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP708CN-L/TR 0°C≤T

A

≤+70°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP708EN-L -40°C≤T

A

≤+85°C

SP708E

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP708EN-L/TR -40°C≤T

A

≤+85°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP813LCN-L 0°C≤T

A

≤+70°C

SP813LC

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP813LCN-L/TR 0°C≤T

A

≤+70°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP813LEN-L -40°C≤T

A

≤+85°C

SP813LE

YYWWL

#

8-pin NSOIC Bulk Lead Free

SP813LEN-L/TR -40°C≤T

A

≤+85°C 8-pin NSOIC 2.5K/Tape & Reel Lead Free

SP813LCP-L 0°C≤T

A

≤+70°C

SP813LC

YWWL#

8-pin PDIP Bulk Lead Free

SP813LEP-L -40°C≤T

A

≤+85°C

SP813LE

YWWL#

8-pin PDIP Bulk Lead Free

“YY” = Year – “WW” = Work Week – “#” = Lot Number

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TYPICAL PERFORMANCE CHARACTERISTICS

All data taken at V

IN

= 2.7V to 5.5V, T

J

= T

A

= 25°C, unless otherwise specified - Schematic and BOM from Application

Information section of this datasheet.

Fig. 4: Power-Fail Comparator

De-Assertion Response Time

Fig. 5: Power-Fail Comparator

De-Assertion Response Time Circuit

Fig. 6: Power-Fail Comparator

Assertion Response Time

Fig. 7: Power-Fail Comparator

Assertion Response Time Circuit

Fig. 8: SP705/707 RESET Output Voltage

vs. Supply Voltage

Fig. 9: SP705/707 RESET Output Voltage

vs. Supply Voltage Circuit

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Fig. 10: SP705/707 RESET Response Time

Fig. 11: SP705/707 RESET Response Time Circuit

Fig. 12: SP707 RESET and RESET Assertion

Fig. 13: SP707 RESET and RESET De-Assertion

Fig. 14: SP707 RESET and RESET Assertion and De-Assertion Circuit

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Fig. 15: SP707/708/813L RESET Output Voltage

vs. Supply Voltage

Fig. 16: SP813L RESET Response Time

Fig. 17: SP707/708/813L RESET Output Voltage vs. Supply Voltage

and SP813L RESET Response Time Circuit

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FEATURES

The SP705-708/813L series provides four

key

functions:

1. A reset output during power-up, power-

down

and brownout conditions.

2. An independent watchdog output that goes

LOW if the watchdog input has not been

toggled

within 1.6 seconds.

3. A 1.25V threshold detector for power-fail

warning, low battery detection, or monitoring

a

power supply other than +5V.

4. An active-LOW manual-reset that allows

RESET to be triggered by a pushbutton switch.

The SP707/708 devices are the same as the

SP705/706 devices except for the active-HIGH

RESET substitution of the watchdog timer. The

SP813L is the same as the SP705 except an

active-HIGH RESET is provided rather than an

active-LOW RESET. The SP705/707/813L

devices generate a reset when the supply

voltage

drops below 4.65V. The SP706/708

devices generate a reset below 4.40V.

The SP705-708/813L series is ideally suited

for applications in automotive systems,

intelligent instruments, and battery-powered

computers and controllers. The SP705-

708/813L series is ideally applied in

environments where monitoring of power

supply to a µP and its related components is

critical.

THEORY OF OPERATION

The SP705-708/813L series is a

microprocessor (µP) supervisory circuit that

monitors the power supplied to digital circuits

such as microprocessors, microcontrollers, or

memory. The series is an ideal solution for

portable, battery-powered equipment that

requires power supply monitoring.

Implementing this series will reduce the

number of components and overall complexity.

The watchdog functions of this product family

will continuously oversee the operational

status of a system. The operational features

and benefits of the SP705-708/813L series are

described in more detail below.

RESET OUTPUT

A microprocessor's reset input starts the µP in

a known state. The SP705-708/813L series

asserts reset during power-up and prevents

code execution errors during power down or

brownout conditions.

On power-up, once V

CC

reaches 1.1V, RESET is

a guaranteed logic LOW of 0.4V or less. As V

CC

rises, RESET stays LOW. When V

CC

rises above

the reset threshold, an internal timer releases

RESET after 200ms. RESET pulses LOW

whenever V

CC

dips below the reset threshold,

such as in a brownout condition. When a

brownout condition occurs in the middle of a

previously initiated reset pulse, the pulse

continues for at least another 140ms. On

power down, once V

CC

falls below the reset

threshold, RESET stays LOW and is

guaranteed to be 0.4V or less until V

CC

drops

below 1.1V.

The SP707/708/813L active-HIGH RESET

output is simply the complement of the RESET

output and is guaranteed to be valid with V

CC

down to 1.1V. Some µPs, such as Intel's

80C51, require an active-HIGH reset pulse.

WATCHDOG TIMER

The SP705/706/813L watchdog circuit

monitors the µP's activity. If the µP does not

toggle the watchdog input (WDI) within 1.6

seconds and WDI is not tri-stated, WDO goes

LOW. As long as RESET is asserted or the WDI

input is tri-stated, the watchdog timer will stay

cleared and will not count. As soon as RESET

is released and WDI is driven HIGH or LOW,

the timer will start counting. Pulses as short as

50ns can be detected.

Typically, WDO will be connected to the non-

maskable interrupt input (NMI) of a µP. When

V

CC

drops below the reset threshold, WDO will

go LOW whether or not the watchdog timer

had timed out. Normally this would trigger an

NMI but RESET goes LOW simultaneously and

thus overrides the NMI.

If WDI is left unconnected, WDO can be used

as a low-line output. Since floating WDI

disables the internal timer, WDO goes LOW

only when V

CC

falls below the reset threshold,

thus functioning as a low-line output.

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Fig. 18: SP705/706/813L Watchdog Timing Waveforms

Fig. 19: SP705/706 Timing Diagrams with WDI tri-stated.

P

OWER-FAIL COMPARATOR

The power-fail comparator can be used for

various purposes because its output and non

inverting input are not internally connected.

The inverting input is internally connected to a

1.25V reference.

To build an early-warning circuit for power

failure, connect the PFI pin to a voltage divider

as shown in Figure 20. Choose the voltage

divider ratio so that the voltage at PFI falls

below 1.25V just before the +5V regulator

drops out. Use PFO to interrupt the µP so it

can prepare for an orderly power-down.

Fig. 20: Typical Operating Circuit

M

ANUAL RESET

The manual-reset input (MR) allows RESET to

be triggered by a pushbutton switch. The

switch is effectively debounced by the 140ms

minimum RESET pulse width. MR is TTL/CMOS

logic compatible, so it can be driven by an

external logic line. MR can be used to force a

watchdog timeout to generate a RESET pulse

in the SP705/706/813L. Simply connect WDO

to MR.

Ensuring a Valid Reset Output Down to

V

CC

=0V

When V

CC

falls below 1.1V, the

SP705/706/707/708 RESET output no longer

sinks current, it becomes an open circuit.

High-impedance CMOS logic inputs can drift to

undetermined voltages if left undriven. If a

pull-down resistor is added to the RESET pin,

any stray charge or leakage currents will be

shunted to ground, holding RESET LOW. The

resistor value is not critical. It should be about

100KW, large enough not to load RESET and

small enough to pull RESET to ground.

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MONITORING VOLTAGES OTHER THAN THE

UNREGULATED DC INPUT

Monitor voltages other than the unregulated

DC by connecting a voltage divider to PFI and

adjusting the ratio appropriately. If required,

add hysteresis by connecting a resistor (with a

value approximately 10 times the sum of the

two resistors in the potential divider network)

between PFI and PFO. A capacitor between PFI

and GND will reduce the power-fail circuit's

sensitivity to high-frequency noise on the line

being monitored. RESET can be used to

monitor voltages other than the +5V V

CC

line.

Connect PFO to MR to initiate a RESET pulse

when PFI drops below 1.25V. Figure 21 shows

the SP705/706/707/708 configured to assert

RESET when the +5V supply falls below the

RESET threshold, or when the +12V supply

falls below approximately 11V.

Fig. 21: Monitoring +5V and +12V Power Supplies

M

ONITORING A NEGATIVE VOLTAGE SUPPLY

The power-fail comparator can also monitor a

negative supply rail, shown in Figure 22. When

the negative rail is good (a negative voltage of

large magnitude), PFO is LOW. By adding the

resistors and transistor as shown, a HIGH PFO

triggers RESET. As long as PFO remains HIGH,

the SP705-708/813L will keep RESET asserted

(where RESET = LOW and RESET = HIGH).

Note that this circuit's accuracy depends on

the PFI threshold tolerance, the V

CC

line, and

the resistors.

Fig. 22: Monitoring a Negative Voltage Supply

I

NTERFACING TO µPS WITH BIDIRECTIONAL

RESET PINS

µPs with bidirectional RESET pins, such as the

Motorola 68HC11 series, can contend with the

SP705/706/707/708 RESET output. If, for

example, the RESET output is driven HIGH and

the µP wants to pull it LOW, indeterminate

logic levels may result. To correct this,

connect a 4.7KΩ resistor between the RESET

output and the µP reset I/O, as shown if

Figure 23. Buffer the RESET output to other

system components.

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Fig. 23: Interfacing to Microprocessors

with Bidirectional REST I/O (SP705/706/708)

APPLICATIONS

The SP705-708/813L series offers unmatched

performance and the lowest power

consumption for these industry standard

devices. Refer to Figures 24 and 25 for supply

current performance characteristics rated

against temperature and supply voltages.

Table 2 shows how the SP705-708/813L series

can be used instead of the Dallas

Semiconductor DS1232LP/LPS. Table 2

illustrates to a designer the advantages and

tradeoffs of the SP705-708/813L series

compared to the Dallas Semiconductor device.

While the names of the pin descriptions may

differ, the functions are the same or very

similar. Unlike the DS1232, the SP705-

708/813L series has a separate watchdog

output pin WDO which can be simply

connected to the MR input to generate a Reset

signal. The DS1232 has pin selectable

features, while the SP705-708/813L series has

more fixed functions of reset threshold and

watchdog time-out delay. For most

applications, the fixed functions will be

preferred, with the benefit of reduced cost due

to a less complex part. In addition, the SP705-

708/ 813L series has a power fail input and

output function not available with the DS1232

that is useful for monitoring systems with

unregulated supply voltages. The SP705-

708/813L series is available in one of the

industry's smallest space-saving package

sizes, the MSOP.

Fig. 24: Supply Current vs. Temperature

Fig. 25: Supply Current vs. Supply Voltage

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Fig. 26: Device Overviw on Maxim/Dallas Semiconductor

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PACKAGE SPECIFICATION

8-PIN NSOIC

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8-PIN MSOP

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8-PIN PDIP

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REVISION HISTORY

Revision Date Description

2.0.0 06/03/2010 Reformat of datasheet

FOR FURTHER ASSISTANCE

Email: customersupport@exar.com

Exar Technical Documentation: http://www.exar.com/TechDoc/default.aspx?

E

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