ASM162MCUS/T - ON Semiconductor L.L.C.

August, 2011 − Rev. 3

1Publication Order Number:

ASM161/D

ASM161, ASM162

mP Supervisory Circuit

Description

The ASM161 and ASM162 are cost effective, low power

supervisory circuits that monitor power supplies in microprocessor,

microcontroller and digital systems. If the power supply drops below

the reset threshold level, a reset is asserted and remains asserted for at

least 800 ms after VCC has risen above the reset threshold. An

improved manual reset architecture gives the system designer

additional flexibility.

The debounced manual reset input is negative edge triggered. The

reset pulse period generated by a MR transition is a minimum of

800 ms and a maximum of 2 sec duration. In addition, The MR input

signal is blocked for an additional 49 mS minimum after the reset pulse

ends. During the MR disable period, the microcontroller is guaranteed

a time period free of additional manual reset signals. During this

period DRAM contents can be refreshed or other critical system tasks

undertaken. Low power consumption makes the ASM161/162 ideal

for use in portable and battery operated equipments. With 3 V

supplies, power consumption is 8 mW typically and 30 mW maximum.

The ASM161 has an open−drain, active−LOW RESET output and

requires an external pull−up resistor. The ASM162 has an active

HIGH RESET output.

The ASM161/162 are offered in compact 4−pin SOT−143 packages.

No external components are required to trim threshold voltage for

monitoring different supply voltages. With six different factory set,

reset, threshold ranges from 2.63 V to 4.63 V, the ASM161/162 are

suitable for monitoring 5 V, 3.6 V and 3.0 V supplies. The

ASM161/162 are available in temperature ranges 0°C to 70°C and

−40°C to +85°C.

Features

•Edge Triggered Manual Reset Input

•Single Pulse Output

•49 mS Minimum MR Disable Period After Reset

•CMOS/TTL Logic or Switch Interface

•Debounced Input

•Low Supply Current Extends Battery Life

6 mA / 15 mA typ/max at 5.5 V

4.5 mA / 10 mA typ/max at 3.6 V

•Long Reset Period

•0.8 Sec Minimum, 2 Sec Maximum

•Two Reset Polarity Options

ASM161: Active LOW, Open−drain

ASM162: Active HIGH

•Pinout Matches the ASM811/812

•Small 4−Pin SOT−143 Package

•Two Temperature Ranges: 0°C to 70°C

and −40°C to +85°C

Applications

•PDAs

•Appliances

•Computers and Embedded Controllers

•Wireless Communication Systems

•Battery Operated and Intelligent Instruments

•Automotive Systems

•Safety Systems

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PIN CONFIGURATIONS

See detailed ordering and shipping information in the package

dimensions section on page 6 of this data sheet.

ORDERING INFORMATION

4.63L

4.38

4.00J

3.08

2.93S

Voltage (V)

RESET THRESHOLD

SOT−143

4 LEAD

CASE 527AF

ASM161

(Top View)

Part Suffix

RESET RESET

GNDGND VCC

VCC

ASM162

(Top View)

RESET is open drain

2.63R

ASM161, ASM162

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Figure 1. Typical Operating Circuit

Figure 2. Block Diagram

Table 1. PIN DESCRIPTION

Pin #

Pin Name Function

ASM161 ASM162

1 1 GND Ground.

2−RESET Active−LOW, open−drain reset output. RESET remains LOW while VCC is below the

reset threshold and for 800 ms minimum after VCC rises above the reset threshold.

An external pull−up resistor is needed.

−2 RESET Active HIGH reset output. RESET remains HIGH while VCC is below the reset

threshold and for 800 ms after VCC rises above the reset threshold.

3 3 MR Manual reset input. A negative going edge transition on MR asserts reset. Reset

remains asserted for one reset time−out period (800 ms min). This active−LOW input

has an internal pull−up resistor. It can be driven from a TTL or CMOS logic line or

shorted to ground with a switch. Leave open if unused.

4 4 VCC Power supply input voltage.

Detailed Description

The reset function ensures the microprocessor is properly

reset and powers up into a known condition after a power

failure.

Reset Timing

A reset is generated whenever the supply voltage is below

the threshold level (VCC < VTH). The reset duration is at

least 800 ms after VCC has risen above the reset threshold

and is guaranteed to be no more than 2 seconds. The rest

signal remains active as long as the monitored supply

voltage is below the internal threshold voltage.

The ASM161 has an open−drain, active LOW RESET

output (which is guaranteed to be in the correct state for VCC

down to 1.1 V). The ASM161 uses an external pull−up

resistor. Output leakage current is under 1 mA. A high

resistance value can be used to minimize current drain.

The ASM162 generates an active−HIGH RESET output.

ASM161, ASM162

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Part Number Reset Polarity

ASM161 LOW (use external pull−up resistor)

ASM162 HIGH

Manual Reset

The ASM161/162 have a unique manual reset circuit. A

negative going edge transition on MR initiates the reset. A

manual reset generates a single reset pulse of fixed length.

The output−reset pulse remains asserted for the Reset Active

Time−Out Period tRP and then clears. Once the reset pulse

is completed, the MR input remains disabled for at least

49 mS but not more than 122 mS. This period is specified as

tMRD.

During the MR disabled period, the microcontroller is

guaranteed a time period free of new manual reset signals.

This period can be used to refresh critical DRAM contents

or other system tasks.

The MR pin must be taken HIGH and LOW again after the

tMRD period has been completed to initiate another reset

pulse.

The manual reset input has an internal 20 kW pull−up

resistor. MR can be left open if not used.

Figure 3. Manual Reset Timing Figure 4. RESET Valid with VCC under 1.1 V

Application Information

Glitch Resistance

The ASM161/162 are relatively immune to short duration

negative−going VCC transients/glitches. A VCC transient

that goes 100 mV below the reset threshold and lasts 20s or

less will not typically cause a reset pulse.

Valid Reset with VCC under 1.1 V

To ensure that logic inputs connected to the ASM162

RESET pin are in a known state when VCC is under 1.1 V,

a 100 kW pull−down resistor at RESET is needed. The value

is not critical.

This scheme does not work with the open−drain outputs

of ASM161.

Table 2. ABSOLUTE MAXIMUM RATINGS

Parameter Min Max Unit

Pin Terminal Voltage with Respect to Ground

VCC

RESET, RESET and MR

Input Current at VCC and MR

−0.3

6.0

VCC + 0.3

Rate of Rise at VCC 100 V/ms

Power Dissipation (TA = 70°C) 320 mW

Operating Temperature Range −40 85 °C

Storage Temperature Range −65 160 °C

Lead Temperature (soldering, 10 sec) 300 °C

ESD rating

HBM

200

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

ASM161, ASM162

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Table 3. ELECTRICAL CHARACTERISTICS

(Unless otherwise noted, VCC is over the full range and TA = 0°C to 70°C for ASM161/162 X C and TA = −40°C to +85°C for ASM161/162

X E devices. Typical values at TA = 25°C, VCC = 5 V for L/M/J devices, VCC = 3.3 V for T/S devices and VCC = 3 V for R devices.)

Parameter Symbol Conditions Min Typ Max Unit

Input Voltage (VCC)

Range

VCC TA = 0°C to 70°C 1.1 5.5 V

Supply Current

(Unloaded)

ICC TA = 0°C to 70°C,

TA = −40°C to +85°C

VCC < 5.5 V L/M/J 6 15 mA

TA = 0°C to 70°C,

TA = −40°C to +85°C

VCC < 3.6 V R/S/T 4.5 10

Reset Threshold VTH L Devices TA = 25°C

(Note 1)

4.56

4.50

4.63 4.70

4.75

M devices TA = 25°C

(Note 1)

4.31

4.25

4.38 4.45

4.50

J devices TA = 25°C

(Note 1)

3.93

3.89

4.00 4.06

4.10

T devices TA = 25°C

(Note 1)

3.04

3.00

3.08 3.11

3.15

S devices TA = 25°C

(Note 1)

2.89

2.85

2.93 2.96

3.00

R devices TA = 25°C

(Note 1)

2.59

2.55

2.63 2.66

2.70

Reset Threshold

Temp Coefficient

TCVTH 30 ppm/

°C

VCC to reset delay VCC = VTH to (VTH −100 mV) 20 mS

Reset Pulse Width tRPW TA = 0°C to 70°C 800 1400 2000 ms

TA = −40°C to 85°C 600 2240

MR Minimum Pulse

Width

tMR 10 mS

MR Glitch Immunity 100 ns

MR to RESET

Propagation Delay

0.5 mS

MR Input Threshold VIH VCC > VTH(MAX), L/M/J devices 2.3 V

VIL 0.8 V

VIH VCC > VTH(MAX), R/S/T devices 0.7VCC V

VIL 0.25VCC V

MR Delay to MR

Retrigger

tMRD TA = 0°C to 70°C 48 85 122 mS

TA = −40°C to 85°C 85

MR pull−up

resistance

10 20 30 KW

Low RESET output

voltage (ASM161)

VOL VCC = VTH min., ISINK = 1.2 mA, ASM161 R/S/T 0.3 V

VCC = VTH min., ISINK = 3.2 mA, ASM161L/M/J 0.4

VCC > 1.1, ISINK = 50 mA0.3

RESET Output

Voltage (ASM162)

VOL VCC = VTH max., ISINK = 1.2 mA, ASM162 R/S/T 0.3 V

VCC = VTH max., ISINK = 3.2 mA, ASM162 L/M/J 0.4

HIGH RESET Output

Voltage (ASM162)

VOH 1.8 < VCC < VTHmin., ISOURCE = 150 mA0.8VCC V

1. Over operating temperature range.

ASM161, ASM162

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PACKAGE DIMENSIONS

SOT−143, 4 Lead

CASE 527AF−01

ISSUE A

E1 E

e1 b

TOP VIEW

SIDE VIEW END VIEW

Notes:

(1) All dimensions are in millimeters. Angles in degrees.

(2) Complies with JEDEC TO-253.

SYMBOL

MIN NOM MAX

0° 8°

0.05

0.75

0.30

0.76

0.40

0.08

2.80

2.10

1.92 BSC

0.54 REF

1.22

0.15

1.07

0.50

0.89

0.60

0.20

3.04

2.64

0.50

0.90

2.90

e1 0.20 BSC

E1 1.20 1.401.30

L2 0.25

0.80

ASM161, ASM162

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Table 4. ORDERING INFORMATION

Part Number (Note 2) Reset Threshold (V) Temperature (5C) Pins−Package

Package Marking

(LL Lot Code)

TIN LEAD DEVICES

ASM161LCUS/T 4.63 0 TO 70 4−SOT−143 TALL

ASM161MCUS/T 4.38 0 TO 70 4−SOT−143 TBLL

ASM161JCUS/T 4.00 0 TO 70 4−SOT−143 TCLL

ASM161TCUS/T 3.08 0 TO 70 4−SOT−143 TDLL

ASM161SCUS/T 2.93 0 TO 70 4−SOT−143 TELL

ASM161RCUS/T 2.63 0 TO 70 4−SOT−143 TFLL

ASM162LCUS/T 4.63 0 TO 70 4−SOT−143 TGLL

ASM162MCUS/T 4.38 0 TO 70 4−SOT−143 THLL

ASM162JCUS/T 4.00 0 TO 70 4−SOT−143 TILL

ASM162TCUS/T 3.08 0 TO 70 4−SOT−143 TJLL

ASM162SCUS/T 2.93 0 TO 70 4−SOT−143 TKLL

ASM162RCUS/T 2.63 0 TO 70 4−SOT−143 TLLL

ASM161LEUS/T 4.63 −40 TO 85 4−SOT−143 TMLL

ASM161MEUS/T 4.38 −40 TO 85 4−SOT−143 TNLL

ASM161JEUS/T 4.00 −40 TO 85 4−SOT−143 TOLL

ASM161TEUS/T 3.08 −40 TO 85 4−SOT−143 TPLL

ASM161SEUS/T 2.93 −40 TO 85 4−SOT−143 TQLL

ASM161REUS/T 2.63 −40 TO 85 4−SOT−143 TRLL

ASM162LEUS/T 4.63 −40 TO 85 4−SOT−143 TSLL

ASM162MEUS/T 4.38 −40 TO 85 4−SOT−143 TTLL

ASM162JEUS/T 4.00 −40 TO 85 4−SOT−143 TULL

ASM162TEUS/T 3.08 −40 TO 85 4−SOT−143 TVLL

ASM162SEUS/T 2.93 −40 TO 85 4−SOT−143 TWLL

ASM162REUS/T 2.63 −40 TO 85 4−SOT−143 TXLL

LEAD FREE DEVICES

ASM161LCUSF/T 4.63 0 TO 70 4−SOT−143 MALL

ASM161MCUSF/T 4.38 0 TO 70 4−SOT−143 MBLL

ASM161JCUSF/T 4.00 0 TO 70 4−SOT−143 MCLL

ASM161TCUSF/T 3.08 0 TO 70 4−SOT−143 MDLL

ASM161SCUSF/T 2.93 0 TO 70 4−SOT−143 MELL

ASM161RCUSF/T 2.63 0 TO 70 4−SOT−143 MFLL

ASM162LCUSF/T 4.63 0 TO 70 4−SOT−143 MGLL

ASM162MCUSF/T 4.38 0 TO 70 4−SOT−143 MHLL

ASM162JCUSF/T 4.00 0 TO 70 4−SOT−143 MILL

ASM162TCUSF/T 3.08 0 TO 70 4−SOT−143 MJLL

ASM162SCUSF/T 2.93 0 TO 70 4−SOT−143 MKLL

ASM162RCUSF/T 2.63 0 TO 70 4−SOT−143 MLLL

ASM161LEUSF/T 4.63 −40 TO 85 4−SOT−143 MMLL

ASM161MEUSF/T 4.38 −40 TO 85 4−SOT−143 MNLL

2. For parts to be packed in Tape and Reel, add “−T” at the end of the part number. ON Semiconductor lead free parts are RoHS compliant.

ASM161, ASM162

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Table 4. ORDERING INFORMATION (continued)

Part Number (Note 2)

Package Marking

(LL Lot Code)

Pins−PackageTemperature (5C)Reset Threshold (V)

LEAD FREE DEVICES

ASM161JEUSF/T 4.00 −40 TO 85 4−SOT−143 MOLL

ASM161TEUSF/T 3.08 −40 TO 85 4−SOT−143 MPLL

ASM161SEUSF/T 2.93 −40 TO 85 4−SOT−143 MQLL

ASM161REUSF/T 2.63 −40 TO 85 4−SOT−143 MRLL

ASM162LEUSF/T 4.63 −40 TO 85 4−SOT−143 MSLL

ASM162MEUSF/T 4.38 −40 TO 85 4−SOT−143 MTLL

ASM162JEUSF/T 4.00 −40 TO 85 4−SOT−143 MULL

ASM162TEUSF/T 3.08 −40 TO 85 4−SOT−143 MVLL

ASM162SEUSF/T 2.93 −40 TO 85 4−SOT−143 MWLL

ASM162REUSF/T 2.63 −40 TO 85 4−SOT−143 MXLL

2. For parts to be packed in Tape and Reel, add “−T” at the end of the part number. ON Semiconductor lead free parts are RoHS compliant.

ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice

to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability

arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.

“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All

operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights

nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications

intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should

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and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death

associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal

Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.

ASM161/D

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