MAXIM MAX703, MAX704 User Manual

MAX703/MAX704

Low-Cost Microprocessor Supervisory

Circuits with Battery Backup

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-0130; Rev 2; 11/05

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.

♦

♦

♦

♦

♦

♦

♦

♦

♦

General Description

The MAX703/MAX704 microprocessor (µP) supervisory
circuits reduce the complexity and number of compo­nents required for power-supply monitoring and battery
control functions in µP systems. These devices signifi­cantly improve system reliability and accuracy com­pared to that obtained with separate ICs or discrete
components.

The MAX703/MAX704 are available in 8-pin DIP and SO
packages and provide four functions:

1) An active-low reset during power-up, power-down,
and brownout conditions.

2) Battery-backup switching for CMOS RAM, CMOS
µPs, or other low-power logic circuitry.

3) A 1.25V threshold detector for power-fail warning,
low-battery detection, or for monitoring a power
supply other than +5V.

4) An active-low manual reset input.

The MAX703 and MAX704 differ only in their supply­voltage monitor levels. The MAX703 generates a reset
when the supply drops below 4.65V, while the MAX704
generates a reset below 4.40V.

Features

Applications

*

Dice are tested at TA= +25°C only.

**

Contact factory for availability and processing to MIL-STD-883.

Devices in PDIP and SO packages are available in both leaded
and lead-free packaging. Specify lead free by adding the +
symbol at the end of the part number when ordering. Lead free
not available for CERDIP package.

Battery-Backup Power Switching
Precision Supply-Voltage Monitor

4.65V (MAX703)

4.40V (MAX704)
200ms Reset Pulse Width
Debounced TTL/CMOS-Compatible Manual Reset

Input
200µA Quiescent Current
50nA Quiescent Current in Battery-Backup Mode
Voltage Monitor for Power-Fail or Low-Battery

Warning
8-Pin DIP and SO Packages
Guaranteed RESET Assertion to V

CC

= 1V

Computers

Controllers

Intelligent Instruments

Automotive Systems

Critical µP Power Monitoring

MR

PFOPFI

1

2

87V

BATT

RESETV

CC

GND

V

OUT

DIP/SO

TOP VIEW

3

4

6

5

MAX703
MAX704

Pin Configuration

MAX703
MAX704

UNREGULATED DC REGULATED +5V

CMOS RAM

MICROPROCESSOR

3.6V
LITHIUM
BATTERY

R1

R2

PFI

PUSHBUTTON
SWITCH

0.1µF

V

OUT

V

BATT

V

CC

NMI

V

CC

GND

GND

GND

BUS

MR

RESET

RESET

PFO

V

CC

Typical Operating Circuit

PART TEMP RANGE PIN-PACKAGE

MAX703C/D 0°C to +70°C Dice*

MAX703CPA 0°C to +70°C 8 PDIP

MAX703CSA 0°C to +70°C 8 SO

MAX703EPA -40°C to +85°C 8 PDIP

MAX703ESA -40°C to +85°C 8 SO

MAX703MJA -55°C to +125°C 8 CERDIP**

MAX704C/D 0°C to +70°C Dice*

MAX704CPA 0°C to +70°C 8 PDIP

MAX704CSA 0°C to +70°C 8 SO

MAX704EPA -40°C to +85°C 8 PDIP

MAX704ESA -40°C to +85°C 8 SO

MAX704MJA -55°C to +125°C 8 CERDIP**

MAX703/MAX704

Low-Cost Microprocessor Supervisory
Circuits with Battery Backup

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +4.75V to +5.5V for MAX703, VCC= +4.5V to +5.5V for MAX704, V

BATT

= 2.8V, TA= T

MIN

to T

MAX

, unless otherwise noted.)

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

V

BATT

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

All Other Inputs (Note 1).........................-0.3V to (V

CB

+ 0.3V)

Input Current

V

CC

...............................................................................200mA

V

BATT

..............................................................................50mA

GND ................................................................................20mA

Output Current

V

OUT

...............................Short-Circuit Protected for Up to 10s

All Other Outputs ............................................................20mA

Rate-of-Rise V

BATT

, VCC.................................................100V/µs

Operating Temperature Range

C Suffix................................................................0°C to +70°C

E Suffix.............................................................-40°C to +85°C

M Suffix ..........................................................-55°C to +125°C

Continuous Power Dissipation (T

A

= +70°C)

8-Pin PDIP (derated 9.09mW/°C above +70°C) ..........727mW

8-Pin SO (derated 5.88mW/°C above +70°C) .............471mW

8-Pin CERDIP (derated 8.00mW/°C above +85°C) .....640mW

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

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

Note 1: V

CB

is the greater of VCCand V

BATT

. The input voltage limits on PFI and MR may be exceeded if the current into these pins

is limited to less than 10mA.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating Voltage Range

, V

V

CC

BATT

Supply Current (Excluding

)

I

OUT

I

in Battery-Backup

SUPPLY

Mode (Excluding I

V

Standby Current

BATT

OUT

)

(Note 3)

V

Output

OUT

V

in Battery-Backup

OUT

Mode

Battery Switch Threshold

- V

(V

CC

BATT

)

I

SUPPLY

(Note 2) 0 5.5 V

MAX70_C 200 350

MAX70_E/M 200 500

V

= 0V, V

CC

BATT

2.8V

5.5V > VCC > V
+ 0.2V

I

= 5mA

OUT

= 50mA

I

OUT

I

= 250µA, VCC < V

OUT

V

< V

CC

RST

TA = +25°C 0.05 1.0

=

T

A

TA = +25°C -0.10 +0.02

BATT

T

A

BATT

Power-up 20

Power-down -20

Battery Switchover Hysteresis 40 mV

RESET Threshold V

RST

MAX703 4.50 4.65 4.75

MAX704 4.25 4.40 4.50

RESET Threshold Hysteresis 40 mV
RESET Pulse Width t

RESET Output Voltage

V

V

RST

OH

OL

I

I

= 800µA

SOURCE

= 3.2mA 0.4

SINK

MAX70_C, VCC = 1V, VCC falling,
V

BATT

= 0V, I

SINK

= 50µA

MAX70_E/M, VCC = 1.2V, VCC falling,
V

BATT

= 0V, I

SINK

= 100µA

= T

= T

MIN

MIN

- 0.2V

to T

to T

VCC -

0.025

VCC -

0.25

-

V

-

BATT

0.02

5.0

MAX

MAX

-1.00 +0.02

V

-

CC

0.05

V

-

CC

0.5

V

BATT

0.1

140 200 280 ms

V

-

CC

1.5

0.3

0.3

µA

µA

µA

V

V

mV

V

V

MAX703/MAX704

Low-Cost Microprocessor Supervisory

Circuits with Battery Backup

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +4.75V to +5.5V for MAX703, VCC= +4.5V to +5.5V for MAX704, V

BATT

= 2.8V, TA= T

MIN

to T

MAX

, unless otherwise noted.)

Note 2: Either VCCor V

BATT

can go to 0V if the other is greater than 2.0V.

Note 3: “-“ = battery-charging current, “+” = battery-discharging current.

OUTPUT VOLTAGE vs. LOAD CURRENT

MAX703 toc01

I

OUT

(mA)

V

OUT

(V)

40302010

4.80

4.85

4.90

4.95

5.00

4.75
050

VCC = +5V

V

BATT

= +2.8V

T

A

= +25°C

SLOPE = 5

Ω

OUTPUT VOLTAGE vs. LOAD CURRENT

MAX703 toc02

I

OUT

(mA)

V

OUT

(V)

0.80.60.40.2

2.72

2.74

2.76

2.78

2.80

2.70
0 1.0

VCC = 0V

V

BATT

= +2.8V

T

A

= +25°C

SLOPE = 80

Ω

MAX703 toc03

500ms/div

MAX703 RESET OUTPUT VOLTAGE

vs. SUPPLY VOLTAGE

OV

V

CC

+5V

1V/div

+5V

1V/div

0V

V

BATT

= 0V

T

A

= +25°C

RESET

330pF

2kΩ

RESET

RESET

GND

V

CC

V

CC

MAX703 toc04

2µs/div

MAX703 RESET RESPONSE TIME

+5V

+5V
V

CC

1V/div

+4V

0V

TA = +25°C

RESET

30pF

10kΩ

RESET

RESET

GND

V

CC

V

CC

MAX703 toc05

400ns/div

POWER-FAIL COMPARATOR

RESPONSE TIME

+1.30V

+5V

+1.20V

0V

VCC = +5V

T

A

= +25°C

PFI

PFO

30pF

1kΩ

PFO

PFI

+5V

1.25V

MAX703 toc06

400ns/div

POWER-FAIL COMPARATOR

RESPONSE TIME

+1.20V

+1.30V

+3V

0V

PFI

PFO

30pF

PFO

1kΩ

PFI

+5V

1.25V

VCC = +5V

T

A

= +25°C

Typical Operating Characteristics

(VCC= +5V, V

BATT

= 2.8V, TA= +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

MR Input Threshold

MR Pulse Width t
MR to RESET Delay t

V

V

MR

MD

Low 0.8

IL

High 2.0

IH

MR Pullup Current MR = 0V 100 250 600 µA

PFI Input Threshold VCC = 5V 1.20 1.25 1.30 V

PFI Input Current -25 +0.01 +25 nA

PFO Output Voltage

V

OH

V

OL

I

I

= 800µA

SOURCE

= 3.2mA 0.4

SINK

150 ns

250 ns

-

V

CC

1.5

V

V