MIC1810-5UYTR - Micrel, Inc. - Datasheet.Directory

July 2005 1 MIC1810

MIC1810 Micrel

MIC1810

Microprocessor Reset Circuit

General Description

The MIC1810 is an inexpensive microprocessor supervisory

circuit that monitors power supplies in microprocessor based

systems.

The function of these devices is to assert a reset if the power

supply drops below a designated reset threshold level. Several

different reset threshold levels are available to accommodate

5%, 10%, or 15% drop in 5V powered systems.

The MIC1810 has an active low /RESET output. The reset

output is guaranteed to remain asserted for a minimum of

100ms after VCChas risen above the designated reset thresh-

old level. The MIC1810 comes in a 3-pin SOT-23 package.

Typical Application

VCC

RESET

µP

RESET

VCC

MIC1810

VCC

Features

• Precision voltage monitor for 5%, 10%, or 15% drop in

5V power supplies

• /RESET remains valid with VCC as low as 1V

• 5µA supply current (typical)

• 100ms minimum reset pulse width

• No external components required

• Available in 3-pin SOT-23 package

Applications

• Portable equipment

• Intelligent instruments

• Critical microprocessor power monitoring

• Printers/computers

• Embedded controllers

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

Ordering Information

Threshold

Part Number Marking* Voltage Operating Temp. Range Package Pb-Free

MIC1810-5U NA 4.62V –40°C to +85°C SOT-23 No

MIC1810-10U NB 4.37V –40°C to +85°C SOT-23 No

MIC1810-15U NC 4.12V –40°C to +85°C SOT-23 No

MIC1810-5UY NA 4.62V –40°C to +85°C SOT-23 Yes

MIC1810-10UY NB 4.37V –40°C to +85°C SOT-23 Yes

MIC1810-15UY NC 4.12V –40°C to +85°C SOT-23 Yes

* Underbar symbol may not be to scale

MIC1810 Micrel

MIC1810 2 July 2005

Pin Description

Pin Number Pin Name Pin Function

1 /RESET /RESET goes low if VCC falls below the reset threshold and remains as-

serted for one reset timeout period (100ms min) after VCC exceeds the reset

threshold.

2 VCC Power supply input.

3 GND IC ground pin

Pin Conﬁguration

GND

MIC1810

RESET

3-Lead SOT-23

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MIC1810 Micrel

Absolute Maximum Ratings(Note 1)

Terminal Voltage (VCC) ....................................–0.3V to +6V

Input Current (VCC) ..................................................... 20mA

Output Current, /RESET ............................................. 20mA

Rate of Rise (VCC) .................................................. 100V/µs

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

Storage Temperature (TS) .......................... –65°C to 150°C

ESD Rating, Note 3 ....................................................... 3kV

Operating Ratings(Note 2)

Operating Temperature Range

MIC1810-5U ........................................... –40°C to +85°C

MIC1810-10U ......................................... –40°C to +85°C

MIC1810-15U ......................................... –40°C to +85°C

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

Electrical Characteristics

For typical values VCC = 5V, TA = 25°C; bold values indicate –40°C ≤ TA ≤ +85°C; unless noted

Symbol Parameter Condition Min Typ Max Units

Operating Voltage Range TA = –40°C to +85°C 1 5.5 V

ICC Supply Current 5 20 µA

VTH Reset Voltage Threshold MIC1810-5 4.50 4.62 4.75 V

MIC1810-10 4.25 4.37 4.50 V

MIC1810-15 4.00 4.12 4.24 V

tRST Reset Timeout Period 100 150 250 ms

VOH /RESET Output Voltage, High ISOURCE = 800µA VCC–1.5 V

VOL /RESET Output Voltage, Low VCC = VTH min., ISINK = 10mA 0.4 V

VCC ≥ 1V, ISINK = 50µA 0.3 V

Note 1. Exceeding the absolute maximum rating may damage the device.

Note 2. The device is not guaranteed to function outside its operating rating.

Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

Timing Diagram

/RESET

VCC

tRST tRST

VTH VTH

Reset Timing Diagram

MIC1810 Micrel

MIC1810 4 July 2005

Functional Diagram

Reset

Threshold (VTH)

VCC (2)

RESET (1)

GND (3)

RESET

GENERATOR

July 2005 5 MIC1810

MIC1810 Micrel

Applications Information

Microprocessor Reset

The /RESET pin is asserted whenever VCC falls below the

reset threshold voltage. The reset pin remains asserted for a

period of tRST after VCC has risen above the reset threshold

voltage. The reset function ensures the microprocessor is

properly reset and powers up into a known condition after

a power failure. /RESET will remain valid with VCC as low

as 1V.

VCC Transients

The MIC1810 is relatively immune to negative-going VCC

glitches below the reset threshold. Typically, a negative-going

transient 125mV below the reset threshold with a duration of

20µs or less will not cause an unwanted reset.

/RESET Valid at Low Voltage

A resistor can be added from the /RESET pin-to-ground to

ensure the /RESET output remains low with VCC down to

0V. A 100kΩ resistor connected from /RESET-to-ground is

recommended. The resistor should be large enough not to

load the /RESET output and small enough to pull-down any

stray leakage currents. See Figure below.

VCC

RESET

µP

RESET

VCC

MIC1810

VCC

100K

/RESET Valid to VCC = 0V

MIC1810 Micrel

MIC1810 6 July 2005

Package Information

0.15 (0.006)

0.076 (0.0030)

0.41 (0.016)

0.13 (0.005)

3.05 (0.120)

2.67 (0.105) 8

0

0.445 (0.0175) TYP 3 PLACES

2.50 (0.098)

2.10 (0.083)

1.40 (0.055)

1.19 (0.047)

0.10 (0.004)

0.013 (0.0005)

1.15 (0.045)

0.76 (0.030)

DIMENSIONS:

MM (INCH)

2.36 (0.093)

2.28 (0.090)

3-Pin SOT-23 Small Outline Transistor

MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com

The information furnished by Micrel in this datasheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use.

Micrel reserves the right to change circuitry and speciﬁcations at any time without notiﬁcation to the customer.

Micrel Products are not�

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