MAX6335/36/37 DS

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General Description

The MAX6335/MAX6336/MAX6337 microprocessor (µP)

supervisory circuits monitor the power supplies in 1.8V

to 3.3V µP and digital systems. They increase circuit reli-

ability and reduce cost by eliminating external compo-

nents and adjustments. They also feature a debounced

manual-reset input.

These devices perform a single function: they assert a

reset signal whenever the V

supply voltage declines

below a preset threshold or whenever manual reset is

asserted. Reset remains asserted for a preset timeout

period after V

has risen above the reset threshold or

after manual reset is deasserted. The only difference

among the three devices is their output. The MAX6336

(push/pull) and MAX6337 (open-drain) have an active-

low RESET output, while the MAX6335 (push/pull) has

an active-high RESET output. The MAX6335/MAX6336

are guaranteed to be in the correct state for V

down

to 0.7V. The MAX6337 is guaranteed to be in the cor-

rect state for V

down to 1.0V.

The reset comparator in these ICs is designed to ignore

fast transients on V

. Reset thresholds are factory-

trimmable between 1.6V and 2.5V, in approximately

100mV increments. There are 15 standard versions

available (2500 piece minimum-order quantity); contact

the factory for availability of nonstandard versions

(10,000 piece minimum-order quantity). For space-criti-

cal applications, the MAX6335/MAX6336/MAX6337

come packaged in a 4-pin SOT143.

Applications

Pentium II™ Computers

Computers

Controllers

Intelligent Instruments

Critical µP/µC Power Monitoring

Portable/Battery-Powered Equipment

Automotive

Features

Ultra-Low 0.7V Operating Supply Voltage

Low 3.3µA Supply Current

Precision Monitoring of 1.8V and 2.5V Power-

Supply Voltages

Reset Thresholds Available from 1.6V to 2.5V,

in Approximately 100mV Increments

Debounced Manual Reset

Fully Specified over Temperature

Three Power-On Reset Pulse Widths Available

(1ms min, 20ms min, 100ms min)

Low Cost

Three Available Output Structures: Push/Pull

RESET

, Push/Pull RESET, Open-Drain

RESET

Guaranteed RESET/

RESET

Valid to V

= 0.7V

(MAX6335/MAX6336)

Power-Supply Transient Immunity

No External Components

4-Pin SOT143 Package

Pin-Compatible with MAX811/MAX812 and

MAX6314/MAX6315

MAX6335/MAX6336/MAX6337

4-Pin, Ultra-Low-Voltage, Low-Power

µP Reset Circuits with Manual Reset

________________________________________________________________

Maxim Integrated Products

19-1412; Rev 0; 12/98

PART*

MAX6335

US__D_-T

MAX6336

US__D_-T

MAX6337

US__D_-T

-40°C to +85°C

TEMP. RANGE

PIN-PACKAGE

4 SOT143

Ordering Information

These devices are available in factory-set V

reset thresh-

olds from 1.6V to 2.5V, in approximately 0.1V increments.

Choose the desired reset threshold suffix from Table 1 and

insert it in the blanks following “US” in the part number.

Factory-programmed reset timeout periods are also available.

Insert the number corresponding to the desired nominal reset

timeout period (1 = 1ms min, 2 = 20ms min, 3 = 100ms min) in

the blank following “D” in the part number. There are 15 stan-

dard versions with a required order increment of 2500 pieces.

Sample stock is generally held on the standard versions only

(see Selector Guide). Contact the factory for availability of non-

standard versions (required order increment is 10,000 pieces).

All devices available in tape-and-reel only.

Typical Operating Circuit and Pin Configuration appear

at end of data sheet.

Selector Guide appears at end of data sheet.

Pentium II is a trademark of Intel Corp.

MAX6335/MAX6336/MAX6337

4-Pin, Ultra-Low-Voltage, Low-Power

µP Reset Circuits with Manual Reset

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(

= full range, MR =

or unconnected, T

= -40°C to +85°C, unless otherwise noted. Typical values are at T

= +25°C and

= 3V, reset not asserted.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

Terminal Voltage (with respect to GND)

......................................................................-0.3V to +6V

Push/Pull RESET or RESET, MR ............-0.3V to (V

+ 0.3V)

Open-Drain RESET ..............................................-0.3V to +6V

Input Current (V

) .............................................................20mA

Output Current (RESET, RESET).........................................20mA

Rate of Rise, V

............................................................100V/µs

Continuous Power Dissipation (T

= +70°C)

SOT143 (derate 4mW/°C above +70°C) .....................320mW

Operating Temperature Range ...........................-40°C to +85°C

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

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

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Supply Voltage Range

= 0°C to +85°C

MAX6335/MAX6336

0.7

5.5

MAX6337

1.0

5.5

= -40°C to +85°C

MAX6335/MAX6336

0.78

5.5

MAX6337

1.2

5.5

Supply Current

No load

= 1.8V

3.0

6.0

= 2.5V

3.3

7.0

= +25°C

TH -

TH +

1.8%

= -40°C to +85°C

TH -

TH +

Reset Threshold

MAX633_US_ _D_-T,

Table 1

Falling Reset Delay

falling at 10V/ms

MAX633_US_ _D1-T

1.5

MAX633_US_ _D2-T

Reset Active Timeout Period

MAX633_US_ _D3-T

100

150

200

RESET Output Low Voltage

(MAX6336/MAX6337)

SINK

= 50µA, V

≥

1.0V

0.4

Reset

asserted

RESET Output High Voltage

(MAX6336)

SOURCE

= 200µA, V

≥

1.8V

0.8V

SOURCE

= 500µA, V

≥

2.7V

0.8V

RESET Output Voltage

(MAX6335)

Reset

asserted

SOURCE

= 1µA, V

≥

1.0V

0.8V

SOURCE

= 200µA, V

≥

1.8V

0.8V

Reset not

asserted

SINK

= 500µA, V

≥

1.8V

SINK

= 1.2mA, V

≥

2.7V

0.3

Reset not

asserted

0.3V

0.7V

MR Minimum Pulse Width

= 2.6V

160

µs

= 2.6V

0.42

µs

MR Threshold

MR Reset Delay

MR Glitch Immunity

Ω

MR Pull-Up Resistance

SINK

= 500µA, V

≥

1.8V

0.3

0.5

> V

, RESET deasserted

µA

RESET Output Leakage

Current (MAX6337)

4-Pin, Ultra-Low-Voltage, Low-Power

µP Reset Circuits with Manual Reset

_______________________________________________________________________________________

2.0

2.6

2.2

3.0

3.6

3.8

3.4

3.2

4.0

-60

2.4

-40

-20

2.8

100

SUPPLY CURRENT

vs. TEMPERATURE

MAX6335/36/37 toc-1

TEMPERATURE (°C)

(

RESET NOT ASSERTED

= 2.5V

= 1.8V

0.950

0.990

0.970

1.000

1.030

1.040

1.020

1.010

1.050

-60

-40

0.980

-20

0.960

100

NORMALIZED RESET TIMEOUT PERIOD

vs. TEMPERATURE

MAX6335/36/37-2

TEMPERATURE (°C)

NORMALIZED RESET TIMEOUT PERIOD

= 2.2V

0.50

1.00

1.50

2.00

2.50

3.00

OUTPUT VOLTAGE LOW

vs. SUPPLY VOLTAGE

MAX6335/36/37 toc-3

(V)

OUTPUT VOLTAGE LOW (mV)

= 2.5V

SINK

= 500

RESET ASSERTED

= +25°C

= +85°C

= -40°C

100

120

140

160

0.5

1.0 1.25

0.75

1.5 1.75 2.0 2.25 2.5

OUTPUT VOLTAGE HIGH

vs. SUPPLY VOLTAGE

MAX6335/36/37 toc-4

(V)

OUTPUT VOLTAGE HIGH (V

- V

) (mV)

= 2.2V

SOURCE

= 100

RESET ASSERTED

= +25°C

= +85°C

= -40°C

100

1000

100

200

400

300

500

600

0.1

MAXIMUM TRANSIENT DURATION

vs. RESET COMPARATOR OVERDRIVE

MAX6335/36/37 toc-5

RESET COMPARATOR OVERDRIVE (mV)

MAXIMUM TRANSIENT DURATION (

RESET OCCURS

RESET DOES

NOT OCCUR

-20

-60

-40

100

FALLING PROPAGATION DELAY

vs. TEMPERATURE

MAX6332/33/34 toc-6

TEMPERATURE (°C)

PROPAGATION DELAY (

FALLING AT 10V/ms

FALLING AT 1V/ms

__________________________________________Typical Operating Characteristics

(Reset not asserted, T

= +25°C, unless otherwise noted.)

MAX6335/MAX6336/MAX6337

4-Pin, Ultra-Low-Voltage, Low-Power

µP Reset Circuits with Manual Reset

_______________________________________________________________________________________

Pin Description

GND

Ground

—

RESET

Active-Low Reset Output. RESET remains low while V

is below the reset

threshold, or MR is asserted and for a reset timeout period (t

) after V

rises above the reset threshold, or MR is deasserted. RESET on the

MAX6337 is open-drain.

RESET

Active-High Reset Output. RESET remains high while V

is below the

reset threshold, or MR is asserted and for a reset timeout period (t

) after

rises above the reset threshold, or MR is deasserted. RESET also

asserts when MR is low.

NAME

FUNCTION

MAX6335

MAX6336

MAX6337

—

PIN

Applications Information

Manual-Reset Inputs

Many µP-based products require manual-reset capabil-

ity, allowing the operator, a test technician, or external

logic circuitry to initiate a reset. A logic low on MR

asserts reset. Reset remains asserted while MR is low,

and for the reset active timeout period after MR returns

high. MR has an internal 20k

Ω

pull-up resistor, so it can

be left unconnected if not used. Connect a normally

open momentary switch from MR to GND to create a

manual-reset function; external debounce circuitry is

not required.

Interfacing to µPs with

Bidirectional Reset Pins

Since the RESET output on the MAX6337 is open-drain,

this device interfaces easily with µPs that have bidirec-

tional reset pins, such as the Motorola 68HC11.

Connecting the µP supervisor’s RESET output directly

to the microcontroller’s (µC’s) RESET pin with a single

pull-up resistor allows either device to assert reset

(Figure 1).

Negative-Going V

Transients

In addition to issuing a reset to the µP during power-up,

power-down, and brownout conditions, these devices

are relatively immune to short-duration, negative-going

transients (glitches). The

Typical Operating

Characteristics show the Maximum Transient Duration

vs. Reset Comparator Overdrive graph. The graph

shows the maximum pulse width that a negative-going

transient may typically have without issuing a reset

signal. As the amplitude of the transient increases, the

maximum allowable pulse width decreases.

Ensuring a Valid Reset Output

down to V

= 0

When V

falls below 1V and approaches the minimum

operating voltage of 0.7V, push/pull-structured reset

sinking (or sourcing) capabilities decrease drastically.

High-impedance CMOS-logic inputs connected to the

RESET pin can drift to indeterminate voltages. This

does not present a problem in most cases, since most

µPs and circuitry do not operate at V

below 1V. For

the MAX6336, where RESET must be valid down to 0,

adding a pull-down resistor between RESET and GND

removes stray leakage currents, holding RESET low

GND

MAX6337

RESET

GND

RESET

INPUT

MOTOROLA

68HCXX

Figure 1. Interfacing to µPs with Bidirectional Reset Pins

Manual-Reset Input. A logic low on MR asserts reset. Reset remains

asserted as long as MR is low, and for the reset timeout period (t

) after

MR goes high. Leave unconnected or connect to V

if not used.

Supply Voltage (0.7V to 5.5V)

4-Pin, Ultra-Low-Voltage, Low-Power

µP Reset Circuits with Manual Reset

_______________________________________________________________________________________

MAX6335/MAX6336/MAX6337

GND

MAX6336

RESET

100k

(a)

GND

MAX6335

RESET

100k*

(b)

*ASSUMES HIGH-Z RESET INPUT TO THE

Factory-trimmed reset thresholds are available in approximately

100mV increments, with a ±1.8% room-temperature variance.

= +25°C

= -40°C to +85°C

MIN

TYP

MAX

MIN

MAX

MAX633_US25D_

2.46 2.50

2.55

2.43

2.58

MAX633_US24D_

2.36 2.40

2.44

2.33

2.47

MAX633_US23D_

2.26 2.30

2.34

2.23

2.37

MAX633_US22D_

2.16 2.20

2.24

2.13

2.27

MAX633_US21D_

2.06 2.10

2.14

2.04

2.16

MAX633_US20D_

1.96 2.00

2.04

1.94

2.06

MAX633_US19D_

1.87 1.90

1.93

1.84

1.96

MAX633_US18D_

1.77 1.80 1.83

1.75

1.85

MAX633_US17D_

1.67 1.70 1.73

1.65

1.75

MAX633_US16D_

1.57 1.60

1.63

1.55

1.65

RESET

THRESHOLD

SUFFIX

Table 1. Factory-Trimmed Reset

Thresholds*

Figure 2. Ensuring Reset Valid down to V

= 0

(Figure 2a). The pull-down resistor value is not critical;

100k

Ω

is large enough not to load RESET, and small

enough to pull it low. For the MAX6335, where RESET

must be valid to V

= 0, a 100k

Ω

pull-up resistor

between RESET and V

will hold RESET high when

falls below 0.7V (Figure 2b).

Since the MAX6337 has an open-drain, active-low out-

put, it typically uses a pull-up resistor. With this device,

RESET will most likely not maintain an active condition,

but will drift to a non-active level due to the pull-up

resistor and the reduced sinking capability of the open-

drain device. Therefore, this device is not recommend-

ed for applications where the RESET pin is required to

be valid down to V

= 0.

MAX6335/MAX6336/MAX6337

4-Pin, Ultra-Low-Voltage, Low-Power

µP Reset Circuits with Manual Reset

_______________________________________________________________________________________

PART

OUTPUT STAGE

NOMINAL V

(V)

MINIMUM RESET

TIMEOUT (ms)

SOT TOP MARK

MAX6335

US23D3-T

Push/Pull RESET

2.30

100

KABQ

MAX6335US22D3-T

Push/Pull RESET

2.20

100

KAAR

MAX6335US20D3-T

Push/Pull RESET

2.00

100

KABP

MAX6335US18D3-T

Push/Pull RESET

1.80

100

KAAQ

MAX6335US16D3-T

Push/Pull RESET

1.60

100

KAAP

MAX6336

US23D3-T

Push/Pull RESET

2.30

100

KAAW

MAX6336US22D3-T

Push/Pull RESET

2.20

100

KAAV

MAX6336US20D3-T

Push/Pull RESET

2.00

100

KAAU

MAX6336US18D3-T

Push/Pull RESET

1.80

100

KAAT

MAX6336US16D3-T

Push/Pull RESET

1.60

100

KAAS

MAX6337

US23D3-T

Open-Drain RESET

2.30

100

KABS

MAX6337US22D3-T

Open-Drain RESET

2.20

100

KAAZ

MAX6337US20D3-T

Open-Drain RESET

2.00

100

KABR

MAX6337US18D3-T

Open-Drain RESET

1.80

100

KAAY

MAX6337US16D3-T

Open-Drain RESET

1.60

100

KAAX

Selector Guide (standard versions*)

(RESET)

GND

MAX6335

MAX6336

MAX6337

SOT143

TOP VIEW

RESET

( ) ARE FOR MAX6335

MAX6335

MAX6336

RESET

GND

PUSHBUTTON

SWITCH

GND

(RESET)

( ) ARE FOR MAX6335

Pin Configuration

Typical Operating Circuit

Sample stock is generally held on all standard versions.