User guide

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General Description

The MAX6665 is a fully integrated thermal switch with

an internal power transistor for driving a cooling fan

rated up to 24V and 250mA. When the MAX6665’s tem-

perature rises above a factory-programmed threshold,

the FANOUT pin becomes active and powers the fan.

The MAX6665 is available with factory-programmed fan

activation threshold temperatures from +40°C to +70°C

in 5°C increments. Accuracy of the fan activation trip

point is ±1°C (typ) and ±3°C (max). The trip point’s hys-

teresis is pin selectable to 1°C, 4°C, or 8°C. Two open-

drain logic outputs indicate overtemperature con-

ditions: WARN is activated when the temperature is

15°C above the fan activation threshold, and OT is acti-

vated when the temperature is 30°C above the thresh-

old. These features can be used to safely power down

systems that are overheated.

The MAX6665 operates from a +2.7V to +5.5V power

supply, and the associated fan can be powered from

4.5V to 24V. It is available in an 8-pin SO package and

operates from -40°C to +125°C.

Applications

Notebook and Desktop Computers

Servers

PC Power Supplies

Laboratory Instruments

Card Racks

Features

♦ On-Chip 250mA Fan Switch

♦ No External Components Required

♦ Factory-Programmed Thresholds

♦ Two Overtemperature Warning Signals

♦ Pin-Selectable 1°C, 4°C, and 8°C Hysteresis

♦ Low 65µA Supply Current

MAX6665

Fan Controller/Driver with Factory-

Programmed Temperature Thresholds

________________________________________________________________ Maxim Integrated Products 1

FANON

7 V

HYST

GND

TOP VIEW

MAX6665

FORCEON

FANOUT

WARN

Pin Configuration

FANON

GND

HYST

+3.3V

+4.5V TO +24V

100mA TO 250mA

COOLING FAN

100kΩ

1µF

MAX6665

FORCEON

FANOUT

WARN

100kΩ

Typical Operating Circuit

19-2056; Rev 0; 5/01

Ordering Information

PART

TEMP.

RANGE

PIN-

PACKAGE

THRESHOLD

MAX6665ASA40

-40°C to

+125°C

8 SO-EP* 40°C

MAX6665ASA45

-40°C to

+125°C

8 SO-EP* 45°C

MAX6665ASA50

-40°C to

+125°C

8 SO-EP* 50°C

MAX6665ASA55

-40°C to

+125°C

8 SO-EP* 55°C

MAX6665ASA60

-40°C to

+125°C

8 SO-EP* 60°C

MAX6665ASA65

-40°C to

+125°C

8 SO-EP* 65°C

MAX6665ASA70

-40°C to

+125°C

8 SO-EP* 70°C

*Exposed paddle

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.

Summary of content (6 pages)

PAGE 1
9-2056; Rev 0; 5/01 Fan Controller/Driver with FactoryProgrammed Temperature Thresholds Applications Notebook and Desktop Computers Features ♦ On-Chip 250mA Fan Switch ♦ No External Components Required ♦ Factory-Programmed Thresholds ♦ Two Overtemperature Warning Signals ♦ Pin-Selectable 1°C, 4°C, and 8°C Hysteresis ♦ Low 65µA Supply Current Ordering Information PART TEMP.
PAGE 2
MAX6665 Fan Controller/Driver with FactoryProgrammed Temperature Thresholds ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V FANOUT to GND ....................................................-0.3V to +28V FORCEON, HYST, FANON to GND............-0.3V to (VDD + 0.3V) WARN, OT to GND ...................................................-0.3V to +6V FANOUT Continuous Current............................................400mA All Other Pins .............
PAGE 3
Fan Controller/Driver with FactoryProgrammed Temperature Thresholds FANOUT VOLTAGE vs. CURRENT TA = +75°C 800 VDD = +2.7V FANOUT VOLTAGE (mV) 600 VDD = +3.3V 500 400 300 TA = +75°C 450 TA = +50°C 400 350 200 300 VDD = +5.0V 100 0 250 2.7 1000 3.1 3.5 3.9 4.3 4.7 5.1 FANOUT CURRENT (mA) SUPPLY VOLTAGE (V) NO-LOAD SUPPLY CURRENT vs. TEMPERATURE TEMPERATURE THRESHOLD DISTRIBUTION FORCEON = VDD 80 MAX6665 toc03 90 100 VDD = +5V VDD = +3.3V 70 60 VDD = +2.7V 50 40 50 45 5.
PAGE 4
Fan Controller/Driver with FactoryProgrammed Temperature Thresholds MAX6665 Pin Description PIN NAME FUNCTION 1 GND 2 FORCEON 3 HYST 4 FANON Fan-On Indicator Output. Push-pull output. FANON is high when the fan switch is on. FANON is low when the fan switch is off. 5 OT Overtemperature Output. Active-low when the temperature is 30°C above the fan threshold. Opendrain output, requires resistive pullup. 6 WARN 7 VDD 8 FANOUT Exposed Paddle GND Ground Force Fan On Input.
PAGE 5
Fan Controller/Driver with FactoryProgrammed Temperature Thresholds MAX6665 +4.5V TO +24V 100mA TO 250mA COOLING FAN VDD +3.3V FANOUT VDD 1µF MAX6665 100kΩ HYST WARN FORCEON FANON I/O µP I/O VDD 100kΩ SYSTEM POWER SHUTDOWN OT GND Figure 1. High-Reliability, Fail-Safe Fan Controller and Temperature Monitor increases by a maximum of: 51°C/W x 0.03125W = 1.59°C Therefore, the effective hysteresis is about 1.59°C higher than the hysteresis selected by the HYST pin.
PAGE 6
Chip Information TRANSISTOR COUNT: 1543 MOS 119 BIPOLAR PROCESS: BiCMOS Package Information 8L, SOIC EXP. PAD.EPS MAX6665 Fan Controller/Driver with FactoryProgrammed Temperature Thresholds Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.