MIC706 [MICREL]

Supervisory Circuits; 监控电路


型号：	MIC706
厂家：	MICREL SEMICONDUCTOR
描述：	Supervisory Circuits 监控电路监控
文件：	总8页 (文件大小：177K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

MIC705/6/7/8 µP Supervisory Circuits

MIC705/6/7/8

µP Supervisory Circuits

Description

Pin Configuration

Top View

The MIC705/MIC706/MIC707/MIC708 are inexpensive

microprocessor supervisory circuits that monitor power

supplies in microprocessor based systems. The circuit

functions include a watchdog timer, microprocessor

reset, power failure warning and a debounced manual

reset input.

N Package - 8 Lead Plastic DIP Package

M Package - 8 Lead Plastic SOIC Package

The MIC705 and MIC706 offer a watchdog timer

function while the MIC707 and MIC708 have an active

high reset output in addition to the active low reset

output.

Supply voltage monitor levels of 4.65V and 4.4V are

available. The MIC705/MIC707 have a nominal reset

threshold level of 4.65V while the MIC706 and MIC708

have a 4.4V nominal reset threshold level. When the

supply voltage drops below the respective reset

threshold level, RESET is asserted.

Features

Debounced Manual Reset Input is

TTL/CMOS Compatible

Reset Pulse Width, 200ms

Typical Applications

Watchdog Timer, 1.6s (MIC705/MIC706)

Automotive Systems

4.4V or 4.65V Precision Voltage Monitor

Intelligent Instruments

Early Power Fail Warning or Low Battery

Detect

Critical Microprocessor Power Monitoring

Printers

Computers

Controllers

Typical Operating Circuit

Ordering Information

Part

Package

Temp. Range

-40°C to +85°C

MIC70_N

MIC70_M

8-Lead PDIP

8-Lead SOIC

MIC705/6/7/8 µP Supervisory Circuits

Absolute Maximum Ratings

Terminal Voltage

Operating Temperature Range

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

MIC70_N, MIC70_M . . . . . . . . . . . . . . . . . -40°C to 85°C

Storage Temperature Range . . . . . . . . . . . . .-65°C to 150°C

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

Power Dissipation (PDIP) . . . . . . . . . . . . . . . . . . . . 475mW

Power Dissipation (SOIC) . . . . . . . . . . . . . . . . . . . . 400mW

All Other Inputs . . . . . . . . . . . . -0.3V to (V

Input Current

+ 0.3V)

Gnd. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25mA

CC,

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

Stresses above those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent device failure. Functionality at or above these limits is not implied. Exposure to absolute

maximum ratings for extended periods may affect device reliability. Operating ranges define those limits between which the functionality of the device is guaranteed.

Electrical Characteristics

= 4.75V to 5.5V for MIC705/MIC707, V

= 4.5V to 5.5V for MIC706/MIC708, T = -40°C to 85°C unless otherwise noted.

Parameter

Conditions

Min

Typ

Max

Units

Operating Voltage Range, V

MIC70--

1.4

5.5

Supply Current

µA

Reset Voltage Threshold

MIC705, MIC707

MIC706, MIC708

4.50

4.25

4.65

4.4

4.75

4.5

Reset Threshold Hysteresis

Reset Pulse Width, t

140

200

280

RESET Output Voltage

= 800µA

- 1.5V

Source

= 3.2mA

0.4

0.3

Sink

MIC70--C, I

= 50µA, V = 1.4V

Sink

RESET Output Voltage

= 800µA

- 1.5V

Source

= 1.2mA

0.4

Sink

Watchdog Timeout Period, t

1.0

1.6

2.25

sec

WDI Minimum Input Pulse, t

WDI Threshold Voltage

= 0.4V, V = 80% of V

IH CC

= 5V

3.5

IH, CC

0.8

IL, CC

WDI Input Current

WDI = 0V

WDI = V

-150

-50

µA

150

0.4

WDO Output Voltage

= 800µA

- 1.5V

Source

= 1.2mA

Sink

MIC705/6/7/8 µP Supervisory Circuits

Electrical Characteristics

= 4.75V to 5.5V for MIC705/MIC707, V

= 4.5V to 5.5V for MIC706/MIC708, T = -40°C to 85°C unless otherwise noted.

Parameter

Conditions

MR = 0V

Min

Typ

Max

Units

MR Pull-Up Current

100

250

600

µA

MR Pulse Width, t

150

2.0

MR Input Threshold

0.8

MR to Reset Output Delay, t

PFI Input Threshold

250

1.3

= 5V

1.2

-25

1.25

0.01

PFI Input Current

+25

0.4

PFO Output Voltage

= 3.2mA

= 5V, I

Sink

= 800µA

- 1.5V

Source

MIC705/6/7/8 µP Supervisory Circuits

Pin Functions

Pin No.

MIC705

MIC707

Pin Name

MIC706

MIC708

Manual Reset Input forces RESET to assert when pulled below 0.8V.

An internal pull-up current of 250µA on this input forces it high when left

floating. This input can also be driven from TTL or CMOS logic.

VCC

GND

PFI

Primary supply input, +5V.

IC ground pin, 0V reference.

Power fail input. Internally connected to the power fail comparator

which is referenced to 1.25V. The power fail output (PFO) remains

high if PFI is above 1.25V. PFI should be connected to GND or V

if the power fail comparator is not used.

OUT

PFO

WDI

Power fail output. The power fail comparator is independent of all other

functions on this device.

N/A

Watchdog input. The WDI input monitors microprocessor activity, an

internal watchdog timer resets itself with each transition on the

watchdog input. If the WDI pin is held high or low for longer than the

watchdog timeout period, WDO is forced to active low. The watchdog

function can be disabled by floating the WDI pin.

N/C

N/A

No Connect

RESET

RESET is asserted if either V

goes below the reset threshold or by a

low signal on the manual reset input (MR). RESET remains asserted

for one reset timeout period (200ms) after V exceeds the reset

threshold or after the manual reset pin transitions from low to high. The

watchdog timer will not assert RESET unless WDO is connected to

MR.

WDO

N/A

Output for the watchdog timer. The watchdog timer resets itself with

each transition on the watchdog input. If the WDI pin is held high or

low for longer than the watchdog timeout period, WDO is forced low.

WDO will also be forced low if V

is below the reset threshold and

returns to a valid level.

will remain low until V

RESET

N/A

RESET is the compliment of RESET and is asserted if either V

goes

below the reset threshold or by a low signal on the manual reset input

(MR). RESET is suitable for microprocessors systems that use an

active high reset.

MIC705/6/7/8 µP Supervisory Circuits

Block Diagram

* 4.4V for MIC706

Figure 1. MIC705/MIC706 Block Diagram

* 4.4V for MIC708

Figure 2. MIC707/MIC708 Block Diagram

MIC705/6/7/8 µP Supervisory Circuits

Circuit Description

Power Fail Warning

An additional comparator which is independent of other

functions on the MIC705/706/707/708 is provided for

early warning of power failure. An external voltage

The output of the watchdog timer (WDO) will remain

high if WDI sees a valid transition within the watchdog

timeout period or if WDI is left floating. If V falls

below the reset threshold voltage then WDO goes low

immediately regardless of WDI. Thus, if WDI is left

floating, then WDO can be used as a low line indicator.

Unregulated DC

Microprocessor Reset

The RESET pin is asserted whenever V

the reset threshold voltage or when MR goes low. The

reset pin remains asserted for a period of 200ms after

falls below

PFI

PFO

1.25V

has risen above the reset threshold voltage and

MR goes high. The reset function ensures the

Figure 3. Power Fail Comparator

divider can be used to compare unregulated DC to an

internal 1.25V reference. The voltage divider ratio on

the input of the power fail comparator (PFI) can be

chosen so as to trip the power fail comparator a few

milliseconds before V

CC falls below the maximum reset

threshold voltage. The output of the power fail

comparator (PFO) can be used to interrupt the

microprocessor when used in this mode and execute

shut-down procedures prior to power loss.

Figure 4. Reset Timing Diagram

Watchdog Timer

The microprocessor can be monitored by connecting

the WDI pin (watchdog input) to a bus line or I/O line. If

a transition doesn’t occur on the WDI pin within the

microprocessor is properly reset and powers up into a

known condition after a power failure. RESET will

remain valid with V

as low as 1.4V.

watchdog timeout period, then WDO will go low.

minimum pulse of 50ns or any transition low-to-high or

high-to-low on the WDI pin will reset the watchdog timer.

MIC705/6/7/8 µP Supervisory Circuits

Alternate Source Cross Reference Guide

MIC Direct

Replacement

MIC705N

MIC705M

MIC705N

MIC705M

MIC705N

MIC705M

MIC706N

MIC706M

MIC706N

MIC706M

MIC707N

MIC707M

MIC707N

MIC707M

MIC707N

MIC707M

MIC708N

MIC708M

MIC708N

MIC708M

MIC708N

MIC708M

Industry P/N

MAX705CPA

MAX705CSA

MAX705EPA

MAX705ESA

ADM705AN

DS1705EPA

DS1705ESA

MAX706CPA

MAX706CSA

MAX706EPA

ADM706AN

DS1706EPA

DS1706ESA

MAX707CPA

MAX707CSA

MAX707EPA

MAX707ESA

ADM707AN

DS1707EPA

DS1707ESA

MAX708CPA

MAX708CSA

MAX708EPA

MAX708ESA

ADM708AN

DS1708EPA

DS1708ESA

MIC705/6/7/8 µP Supervisory Circuits

Packaging Information

M Package, 8-Pin Small Outline

N Package, 8-Pin Plastic Dual-In-Line

0.400

0.370

0.260

0.240

0.310

0.290

0.150

0.035

0.120

0.015

0.150

0.125

0.110

0.090

0.370

0.300

0.023

0.015

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