Rainbow Electronics MAX6670 User Manual

General Description

The MAX6668/MAX6670 remote-junction thermal
switches with an internal power transistor drive a cool­ing fan rated for supply voltages up to +12V and
250mA. These devices measure the temperature of an
external P-N junction (typically a diode-connected tran­sistor) and turn on the fan power switch when the
remote temperature rises above a factory-programmed
threshold. Self-contained and requiring no software
development, the MAX6668/MAX6670 are simple
“drop-in” fan-control solutions for a variety of systems.

The MAX6670 features an open-drain WARN output
that goes active when the remote temperature exceeds
the factory-programmed fan activation threshold by
+15°C. The MAX6670 features an open-drain OT output
that goes active when the remote temperature exceeds
the factory-programmed threshold by +30°C. The
MAX6668/MAX6670 provide a fan-control input,
FORCEON, that allows the fan to be driven externally,
regardless of temperature.

Available temperature thresholds range from +40°C to
+75°C in 5°C increments. Hysteresis is preset to 8°C on
the MAX6668 or pin selectable to 4°C, 8°C, or 12°C
using a three-level logic input on the MAX6670.
Temperature threshold accuracy is ±1°C (typ) and
±2.2°C (max) for remote-junction temperatures from
+40°C to +75°C.

The MAX6668/MAX6670 operate from a +3V to +3.6V
power supply, and are specified over the automotive
temperature range (-40°C to +125°C). The MAX6668 is
offered in an 8-pin µMAX package and the MAX6670 is
available in a space-saving 10-pin µMAX package.

Applications

Notebook and Desktop Computers

Network Switches

PC Power Supplies

Laboratory Instruments

Card Racks

Temperature Alarms

Fan Controls

Features

♦ +12V, 250mA Integrated Fan Driver

♦ No Calibration Required

♦ Pin-Selectable 4°C, 8°C, or 12°C Hysteresis

(MAX6670)

♦ Factory-Programmed Temperature Thresholds

from +40°C to +75°C

♦ Overtemperature Warning Signals

♦ 110µA (typ) Supply Current

♦ Space-Saving 8-Pin and 10-Pin µMAX Packages

MAX6668/MAX6670

Remote Temperature Switches with Integrated

Fan Controller/Driver

________________________________________________________________ Maxim Integrated Products 1

Typical Applications Circuit

Ordering Information

19-2133; Rev 0; 8/01

Pin Configuration appears at end of data sheet.

Typical Operating Circuit appears at end of data sheet.

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

*These parts are offered in eight standard temperature ver­sions from +40°C through +75°C in 5°C increments. To com­plete the suffix information, select an available temperature trip
point in degrees centigrade and fill in the blank. For example,
the MAX6670AUB065 describes a MAX6670 in a 10-pin µMAX
package with +65°C trip point.

PART* TEMP. RANGE PIN-PACKAGE

MAX6668AUA_ _ _ -40°C to +125°C 8 µMAX

MAX6670AUB_ _ _ -40°C to +125°C 10 µMAX

+12V

250mA

FAN

V

DD

10kΩ

V

DD

10kΩ

OT

2N3904

2200pF

+3.3V

V

DXP

C

S

DXN

HYST

DD

MAX6670

FANOUT

WARN

V

GND

PGND

FORCEON

DD

MAX6668/MAX6670

Remote Temperature Switches with Integrated
Fan Controller/Driver

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= +3V to +3.6V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VDD= +3.3V and 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.

VDDto GND..............................................................-0.3V to +6V

PGND to GND .......................................................-0.3V to +0.3V

FANOUT to GND ....................................................-0.3V to +15V

DXN to GND ..........................................................-0.3V to +0.8V

DXP, WARN, HYST, FORCEON, OT...........-0.3V to (V

DD

+ 0.3V)

Current into V

DD

, GND, DXP, DXN, WARN, HYST,

FORCEON, OT..............................................................±20mA

Current into FANOUT, PGND ........................................ ±300mA

Continuous Power Dissipation (T

A

= +70°C)

8-Pin µMAX (derate 4.1mW/°C above +70°C).............333mW

10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW

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

Storage Temperature Range .............................-60°C to +150°C

Junction Temperature......................................................+150°C

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

POWER SUPPLY

Power-Supply Range V

Average Supply Current I

Operating Current During sampling 400 650 µA

Power-On Reset (POR) Threshold POR VDD falling edge 1 1.5 2.0 V

POR Threshold Hysteresis 50 mV

TEMPERATURE SENSOR

FANOUT Temperature
Threshold Accuracy

FANOUT Temperature
Threshold Hysteresis

WARN Temperature Threshold
(MAX6670 Only)

OT Temperature Threshold
(MAX6670 Only)

Supply Sensitivity of Temperature
Threshold

Temperature Sample Frequency 3.3 4 Hz

FAN DRIVE OUTPUT

FANOUT Output Voltage Low V

Thermal Shutdown 170 °C

Thermal Shutdown Hysteresis 20 °C

LOGIC INPUT/OUTPUT

FORCEON Input High Voltage V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DD

DD

TRJ = +40°C to +75°C (Note 1),
T

= 0°C to +85°C, VDD = +3.3V

∆T

T

HYST

TH

OL

IH

A

TRJ = +40°C to +75°C (Note 1),

= -40°C to +125°C, VDD = +3.3V

T

A

HYST = GND 4

MAX6670

MAX6668 8

Relative to FANOUT temperature threshold +15 °C

Relative to FANOUT temperature threshold +30 °C

I

= 250mA 0.5 1 V

SINK

HYST = float 8

HYST = V

DD

3 3.6 V

110 200 µA

±1 ±2.2

±1 ±4

12

1 1.6 °C/V

0.8 x
V

DD

°C

°C

V

MAX6668/MAX6670

Remote Temperature Switches with Integrated

Fan Controller/Driver

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +3V to +3.6V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VDD= +3.3V and TA= +25°C.)

Note 1: T

RJ

is the temperature of the remote P-N junction.

Typical Operating Characteristics

(TA= +25°C, unless otherwise noted.)

0

0.2

0.1

0.4

0.3

0.6

0.5

0.7

0 100 15050 200 250 300

FANOUT CURRENT

vs. FANOUT VOLTAGE

MAX6668/70 toc01

I

FANOUT

(mA)

V

FANOUT

(V)

TA = +25°C

VDD = +3.3V

0

0.6

0.4

0.2

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.0 2.5

3.0

3.5

FANOUT VOLTAGE

vs. SUPPLY VOLTAGE

MAX6668/70 toc02

VDD (V)

V

FANOUT

(V)

TA = +105°C

TA = +65°C

TA = +25°C

I

FANOUT

= 250mA

0

40

20

80

60

120

100

140

SUPPLY CURRENT

vs. TEMPERATURE

MAX6668/70 toc03

TEMPERATURE (°C)

I

DD

(µA)

0 255075100

VDD = +3.3V, I

FANOUT

= 250mA

0

40

20

80

60

120

100

140

3.0 3.63.3

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX6668/70 toc04

VDD (V)

I

DD

(µA)

FORCEON = V

DD

0

5

20

15

10

25

30

-1.00

-0.25

-0.50 0.50-0.75 0 0.25 0.75

1.00

TEMPERATURE THRESHOLD ERROR

MAX6668/70 toc05

THRESHOLD ERROR (°C)

PERCENTAGE OF SAMPLES (%)

MAX6670AUB040
119 SAMPLES

FORCEON Input Low Voltage V

FORCEON Input Bias Current V
WARN, OT Output Voltage Low V

WARN, OT Output High Leakage

Current

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IL

I

OL

I

OH

SINK

V

FORCEON

= VDD or GND 1 µA

= 6mA 0.5 V

or VOT = +5.5V 1 µA

WARN

0.2 x
V

DD

V