Datasheet

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General Description

The MAX6668/MAX6670 remote-junction thermal

switches with an internal power transistor drive a cool-

ing 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 tran-

sistor) 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

DXP

GND

PGND

HYST

MAX6670

FORCEON

FANOUT

WARN

DXN

2200pF

2N3904

10kΩ

250mA

FAN

+3.3V

+12V

Typical Application Circuit

Ordering Information

19-2133; Rev 2; 11/02

Pin Configuration appears at end of data sheet.

Typical Operating Circuit appears at end of data sheet.

Ordering Information continued 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.

PART

TEMP

RANGE

PI N -

PA C K A G E

T H R ESH -

O L D

( ° C )

MAX6668AUA40 -40°C to +125°C 8 µMAX 40

MAX6668AUA45 -40°C to +125°C 8 µMAX 45

MAX6668AUA50 -40°C to +125°C 8 µMAX 50

MAX6668AUA60 -40°C to +125°C 8 µMAX 60

MAX6668AUA70 -40°C to +125°C 8 µMAX 70

MAX6668AUA75 -40°C to +125°C 8 µMAX 75

Summary of content (8 pages)

PAGE 1
9-2133; Rev 2; 11/02 Remote Temperature Switches with Integrated Fan Controller/Driver 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 Ordering Information TEMP RANGE PART PI NPA CK AG E THRESHOLD ( ° C) MAX6668AUA40 -40°C to +125°C 8 µMAX 40 MAX6668
PAGE 2
MAX6668/MAX6670 Remote Temperature Switches with Integrated Fan Controller/Driver ABSOLUTE MAXIMUM RATINGS VDD to 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 (VDD + 0.
PAGE 3
Remote Temperature Switches with Integrated Fan Controller/Driver (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.) PARAMETER SYMBOL FORCEON Input Low Voltage CONDITIONS MIN TYP VIL FORCEON Input Bias Current MAX UNITS 0.2 x VDD V 1 µA 0.5 V 1 µA V FORCEON = VDD or GND WARN, OT Output Voltage Low VOL ISINK = 6mA WARN, OT Output High Leakage Current IOH V WARN or V OT = +5.
PAGE 4
Remote Temperature Switches with Integrated Fan Controller/Driver MAX6668/MAX6670 Pin Description PIN NAME MAX6668 MAX6670 1 1 FUNCTION PGND Power Ground. PGND is the power ground for the FANOUT power MOSFET switch. Fan-Control Input. Drive FORCEON high for normal operation. Drive FORCEON low to force fan on. 2 5 FORCEON 3 3 DXP Current Source Positive Input. Connect to the anode of the external diodeconnected transistor. Do not leave DXP floating.
PAGE 5
Remote Temperature Switches with Integrated Fan Controller/Driver Applications Information Remote-Diode Selection The MAX6668/MAX6670 directly measure the die temperature of CPUs and other ICs that have on-board temperature-sensing diodes (see Typical Operating Circuit) or they can measure the temperature of a discrete diode-connected transistor. For best accuracy, the discrete transistor should be a small-signal device with its collector and base connected together.
PAGE 6
MAX6668/MAX6670 Remote Temperature Switches with Integrated Fan Controller/Driver Pin Configurations TRIP TEMPERATURE TOP VIEW TRIP TEMPERATURE – HYSTERESIS FANOUT PGND MAX6668 MAX6670 1 8 FANOUT 7 GND 3 6 VDD DXN 4 5 GND FORCEON 2 MAX6668 TIME DXP Figure 1. Temperature Trip Threshold Hysteresis µMAX PGND 1 GND 10MILS DXP 10MILS MINIMUM WARN 2 DXP 3 DXN FORCEON 10 FANOUT 9 HYST 8 VDD 4 7 GND 5 6 OT MAX6670 DXN 10MILS 10MILS GND µMAX Figure 2.
PAGE 7
Remote Temperature Switches with Integrated Fan Controller/Driver VDD DXP FANOUT TEMP SENSOR CS TFAN PGND DXN HYST 4°C, 8°C, 12°C HYSTERESIS WARN FORCEON TFAN +15°C OT MAX6670 TFAN +30°C GND VDD DXP FANOUT TEMP SENSOR CS TFAN PGND DXN 8°C HYSTERESIS MAX6668 FORCEON GND _______________________________________________________________________________________ 7 MAX6668/MAX6670 Functional Diagrams
PAGE 8
Package Information 4X S 8 E ÿ 0.50±0.1 8 H MIN 0.002 0.030 0.6±0.1 L 1 α 0.6±0.1 S BOTTOM VIEW D MAX 0.043 0.006 0.037 0.05 0.75 1.10 0.15 0.95 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0∞ 6∞ 0.5250 BSC 0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 6∞ 0∞ 0.0207 BSC c D e E H 1 MILLIMETERS MAX MIN INCHES DIM A A1 A2 b 8LUMAXD.