Maxim MAX822SUS-T, MAX822TUS-T, MAX821LUS-T, MAX821MUS-T, MAX822LUS-T Datasheet

General Description

The MAX821/MAX822 microprocessor (µP) supervisory
circuits monitor power supplies in µP and digital sys­tems. They provide excellent circuit reliability and low
cost by eliminating external components and adjust­ments when used with 5V-powered or 3V-powered cir­cuits. The MAX821/MAX822 also provide a power-on
reset timeout delay that is pin selectable to 1ms (max),
20ms (min), or 100ms (min).

These devices perform a single function: they assert a
reset signal whenever the VCCsupply voltage falls
below a preset threshold, and they keep reset asserted
for the pin-selected reset timeout delay after VCChas
risen above the reset threshold. The only difference
between the two devices is that the MAX821 has an
active-low RESET output (which is guaranteed to be in
the correct state for VCCdown to 1V), while the
MAX822 has an active-high RESET output. The reset
comparator is designed to ignore fast transients on
VCC. Reset thresholds suitable for operation with a vari­ety of supply voltages are available.

Low supply current makes the MAX821/MAX822 ideal
for use in portable equipment. These devices come in a
4-pin SOT143 package.

________________________Applications

Bar-Code Scanners
Computers
Controllers
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Battery-Powered Equipment

Features

♦ Pin-Selectable, Precision Power-On Reset Delay:

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

♦ Precision Monitoring of +3V to +5V Power-Supply

Voltages

♦ 2.5µA Supply Current
♦ Guaranteed Over Temperature (-40°C to +125°C)
♦ Guaranteed RESET Valid to VCC= 1V (MAX821)
♦ Power-Supply Transient Immunity
♦ No External Components
♦ SOT143 Package

MAX821/MAX822

4-Pin µP Voltage Monitors with Pin-Selectable

Power-On Reset Timeout Delay

________________________________________________________________ Maxim Integrated Products 1

1

2

4

3

V

CC

SRT

(RESET) RESET

GND

MAX821
MAX822

SOT143

TOP VIEW

( ) ARE FOR MAX822

Pin Configuration

MAX821
MAX822

V

CC

RESET

(RESET)

RESET
INPUT

GND

V

CC

GND

µP

( ) ARE FOR MAX822

SRT

20ms

100ms

1ms

__________Typical Operating Circuit

19-1122; Rev 1; 12/99

PART

MAX821LUS-T

MAX821MUS-T 4.38

4.63

NOMINAL VTH(V) TOP MARK*

AZ_ _

BA_ _

Ordering Information

* The first two letters in the package top mark identify the part,

while the remaining two letters are the lot-tracking code.

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone].
For small orders, phone [phone].

MAX821PUS-T 4.00 BM_ _
MAX821TUS-T 3.08 BB_ _
MAX821SUS-T 2.93 BC_ _
MAX821UUS-T 2.78 BL_ _
MAX821RUS-T 2.63 BD_ _
MAX822LUS-T

4.63 BF_ _
MAX822MUS-T 4.38 BG_ _
MAX822TUS-T 3.08 BH_ _
MAX822SUS-T 2.93 BJ_ _
MAX822RUS-T 2.63 BK_ _

Note: These parts are offered in the SOT143-4 package, in the

extended temperature range (-40°C to +85°C).

MAX821/MAX822

4-Pin µP Voltage Monitors with Pin-Selectable
Power-On Reset Timeout Delay

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= full range, TA= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.)

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)

V

CC

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

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

CC

+ 0.3V)

Input Current, V

CC

, SRT......................................................20mA

Output Current, RESET or RESET .......................................20mA

Continuous Power Dissipation (T

A

= +70°C)

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

Operating Temperature Range .........................-40°C to +125°C

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

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

SRT = unconnected

V

0.5V

CC

V

OPEN

SRT Input Threshold

0.9V

CC

V

IH

0.07V

CC

V

IL

ms

100 160 200

t

RP

Reset Active Timeout Period 20 32 40

2.5 7.0

V

1.2 5.5

1.0 5.5

VCCRange

0.5 0.8 1

µs50VCCto Reset Delay (Note 1)

ppm/°C30Reset Threshold Tempco

V

2.55 2.70

V

TH

Reset Threshold (Note 1)

12

1.8 5.5

µA

9

I

CC

Supply Current

2.59 2.63 2.66

UNITSMIN TYP MAXSYMBOLPARAMETER

TA= -40°C to +85°C

TA= 0°C to +70°C

VCCfalling at 1mV/µs

RESET = low for MAX821,
RESET = high for MAX822

MAX82_R

MAX82_L/M/P,
VCC= 5.5V, I

OUT

= 0

MAX82_R/S/T/U,
V

CC

= 5.5V, I

OUT

= 0

CONDITIONS

4.56 4.63 4.70

4.50 4.75

4.31 4.38 4.45

4.25 4.50

MAX82_L

MAX82_M

3.97 4.00 4.04

3.91 4.09

2.89 2.93 2.96

3.04 3.08 3.11

2.85 3.00

3.00 3.15

MAX82_P

2.74 2.78 2.81

2.70 2.85

MAX82_S

MAX82_U

µA

-1 1

SRT Input Current (Note 2) 100

-100

RESET = low for MAX821,
RESET = high for MAX822

SRT = GND
SRT = V

CC

TA= +25°C

TA= +25°C

TA= +25°C

TA= +25°C

TA= +25°C

MAX82_T

TA= +25°C

TA= +25°C

TA= +25°C

TA= +25°C

SRT = GND

SRT = unconnected

SRT = V

CC

TA= -40°C to +125°C

TA= -40°C to +125°C

TA= -40°C to +125°C

TA= -40°C to +125°C

TA= -40°C to +125°C

TA= -40°C to +125°C

TA= -40°C to +125°C

TA= T

MIN

to T

MAX

TA= T

MIN

to T

MAX

MAX821/MAX822

4-Pin µP Voltage Monitors with Pin-Selectable

Power-On Reset Timeout Delay

_______________________________________________________________________________________ 3

Note 1: RESET output for MAX821; RESET output for MAX822.
Note 2: During reset active timeout period only.
Note 3: Guaranteed by design.

ELECTRICAL CHARACTERISTICS (continued)

(VCC= full range, TA= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.)

0.3

0.4

pF20

SRT Input Capacitance
(Note 3) (see Setting

the Reset Timeout Delay

section)

UNITSMIN TYP MAXSYMBOLPARAMETER

MAX821R/S/T/U only, I

SINK

= 1.2mA,

VCC= V

TH(MIN)

MAX821L/M/P only, I

SINK

= 3.2mA,

VCC= V

TH(MIN)

Internal

CONDITIONS

0.3

V

OL

0.3

I

SINK

= 50µA

0.3

0.4

MAX822R/S/T only, I

SINK

= 1.2mA,

V

CC

= V

TH(MAX)

MAX822L/M only, I

SINK

= 3.2mA,

V

CC

= VTH(MAX)

V

0.8V

CC

V

OH

RESET Output Voltage
(MAX821)

VCC-1.5

MAX821R/S/T/U only, I

SOURCE

= 500µA,

VCC≥ V

TH(MAX)

MAX821L/M/P only, I

SOURCE

= 800µA,

VCC≥ V

TH(MAX)

0.6

-40

RESET TIMEOUT PERIOD

vs. TEMPERATURE

0.7

MAX 821/822 TOC-04

TEMPERATURE (°C)

RESET TIMEOUT PERIOD (ms)

40 60 80

0.9

0.8

-20 20 100

1.0

0

SRT = GND

30

-40

RESET TIMEOUT PERIOD

vs. TEMPERATURE

32

31

MAX 821/822 TOC-05

TEMPERATURE (°C)

RESET TIMEOUT PERIOD (ms)

40 60 80

35

34

33

-20 20 100

36

0

SRT = V

CC

150

-40

RESET TIMEOUT PERIOD

vs. TEMPERATURE

160

155

MAX 821/822 TOC-06

TEMPERATURE (°C)

RESET TIMEOUT PERIOD (ms)

40 60 80

175

170

165

-20 20 100

180

0

SRT = UNCONNECTED

V

OL

V

V

OH

RESET Output Voltage
(MAX822)

0.8V

CC

I

SOURCE

= 150µA, 1.4V ≤ VCC≤ V

TH(MIN)

__________________________________________Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

TA= 0°C to +70°C,
VCC≥ 1V

TA = -40°C to +85°C,
VCC≥ 1.2V