MIC8115 [MICREL]

Microprocessor Reset Circuit; 微处理器复位电路


型号：	MIC8115
厂家：	MICREL SEMICONDUCTOR
描述：	Microprocessor Reset Circuit 微处理器复位电路微处理器复位电路
文件：	总8页 (文件大小：174K)
中文：	中文翻译
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MIC8115 Microprocessor Reset Circuit

MIC8115

Microprocessor Reset Circuit

Description

Pin Configuration

The MIC8115 is an inexpensive microprocessor reset

circuit that monitor power supplies in microprocessor

based systems.

Top View

The function of this device is to assert a reset if either

the power supply drops below a designated reset

threshold level or MR is forced low.

The MIC8115 has an active low RESET output. The

reset output is guaranteed to remain asserted for a

minimum of 1100ms after VCC has risen above the

designated reset threshold level. The MIC8115 comes

in a 4-pin SOT-143 package.

Features

RESET Remains Valid with V

as 1.4V

as Low

Typical Applications

Precision Voltage Monitor for 3.3V

Power Supplies

Portable Equipment

Intelligent Instruments

Available in 4-Pin SOT-143 Package

<15µA Supply Current

Critical Microprocessor Power Monitoring

Printers/Computers

Controllers

1100ms Minimum Reset Pulse Width

Manual Reset Input

Specifically tailored to the reset

requirements of the

AMD Elan SC500 Series

Typical Operating Circuit

Ordering Information

Package

Part

Temp. Range

MIC8115TU

4-Lead SOT-143

-40°C to +85°C

Place the device suffix of desired reset threshold voltage from table above in

blank to complete the part number.

MIC8115 Microprocessor Reset Circuit

Absolute Maximum Ratings

Terminal Voltage

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

Operating Temperature Range

MIC8115TU . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 85°C

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

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

MR . . . . . . . . . . . . . . . . . . . . . -0.3V to (V

+ 0.3V)

Input Current, V , MR . . . . . . . . . . . . . . . . . . . . 20mA

Output Current, RESET . . . . . . . . . . . . . .

Rate of Rise, V . . . . . . . . . . . . . . . . . . . . . . 100V/µs

20mA

Power Dissipation (T = +70°C) . . . . . . . . . . . . . . . . 320mW

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

= 3.3V for MIC8115T, T = Operating Temperature Range, unless otherwise noted.

Parameter

Conditions

Min

Typ

Max

Units

Operating Voltage Range, V

= 0°C to 70°C

= -40°C to 85°C

1.4

1.6

5.5

Supply Current, I

µA

Reset Voltage Threshold, V

Reset Timeout Period

3.00

3.08

1700

3.15

2500

1100

RESET Output Voltage, V

= 500µA

0.8 X V

Source

>1.4V, I

>1.6V, I

Min., I

Sink

=1.2mA

0.3

Sink

=50µA,

= 0°C to 70°C

= -40°C to 85°C

MR Minimum Pulse Width

MR to Reset Delay

µs

0.5

MR Input Threshold, V

0.7 X V

0.25 X

MR Pull-Up Resistance

MR Glitch Immunity

kΩ

100

MIC8115 Microprocessor Reset Circuit

Pin Functions

Pin Name

Pin No.

Description

GND

IC Ground Pin.

RESET

RESET goes low if either V

falls below the supply reset threshold or if MR is

asserted. RESET remains asserted for one reset timeout period 1100ms min.) after

both V exceeds the supply reset threshold and MR is deasserted.

Manual reset input. A logic low on MR forces a reset. The reset will remain asserted

as long as MR is held low and for one reset timeout period (1100ms) min.) after MR

goes high. This input can be shorted to ground via a switch or driven from CMOS or

TTl logic. Pulled high internally through a 20k

Ω resistor. Float if unused.

Power supply input.

MIC8115 Microprocessor Reset Circuit

Block Diagram

Figure 1. MIC8115 Block Diagram

MIC8115 Microprocessor Reset Circuit

Circuit Description

Microprocessor Reset

The RESET pin is asserted whenever V

falls below

the reset threshold voltage or if MR (manual reset) is

forced low. The reset pin remains asserted for a period

of at least 1100ms after V

has risen above the reset

threshold voltage or MR has returned high. The reset

function ensures the microprocessor is properly reset

and powers up into a known condition after a power fail-

ure. RESET will remain valid with V

as low as 1.4V.

Figure 2. Reset Timing Diagram

Transients

The MIC8115 is relatively immune to negative-going

glitches below the reset threshold. Typically, a

negative-going transient 125mV below the reset

threshold with a duration of 25µs or less will not cause

an unwanted reset.

RESET Valid to 0V

A resistor can be added from the RESET pin to ground

to ensure the RESET output remains low with V

down to 0V. A 100KΩ resistor connected from RESET

to ground is recommended. The size of the resistor

should be large enough to not load the RESET output

and small enough to pull-down any stray leakage

currents.

Figure 3. RESET Valid to V

= 0V.

MIC8115 Microprocessor Reset Circuit

Packaging Information

U Package, 4-Pin SOT-143 Small-Outline Transistor Package

Dimensions are in inches.

Device Marking Information

Lot Code

NTXX = MIC8115TU

MIC8115 Microprocessor Reset Circuit

Packaging Information

Tape and Reel Information

4.0–0.1

ﬂ1.5–0.1

1.75–0.1

3.5–0.05

2.0–0.05

8.0–0.3

ﬂ1.1–0.1

4.0–0.1

2.7–0.1

1.2–0.1

3.1–0.1

Dimensions are in millimeters.

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