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General Description

The MAX6660 is a remote temperature sensor and fan-

speed regulator that provides a complete fan-control

solution. The remote temperature sensor is typically a

common-collector PNP, such as a substrate PNP of a

microprocessor, or a diode-connected transistor, typi-

cally a low-cost, easily mounted 2N3904 NPN type or

2N3906 PNP type.

The device also incorporates a closed-loop fan con-

troller that regulates fan speed with tachometer feed-

back. The MAX6660 compares temperature data to a

fan threshold temperature and gain setting, both pro-

grammed over the SMBus™ by the user. The result is

automatic fan control that is proportional to the remote-

junction temperature. The temperature feedback loop

can be broken at any time for system control over the

speed of the fan.

Fan speed is voltage controlled as opposed to PWM

controlled, greatly reducing acoustic noise and maxi-

mizing fan reliability. An on-chip power device drives

fans rated up to 250mA.

Temperature data is updated every 0.25s and is read-

able at any time over the SMBus interface. The

MAX6660 is accurate to 1°C (max) when the remote

junction is between +60°C to +100°C. Data is formatted

as a 10-bit + sign word with 0.125°C resolution.

The MAX6660 is specified for -40°C to +125°C and is

available in a 16-pin QSOP package.

Applications

Notebooks

Telecom Systems

Industrial Control Systems

Servers

Workstations

Features

♦ Integrated Thermal Sensing and Fan-Regulation

Solution

♦ Programmable Fan Threshold Temperature

♦ Programmable Temperature Range for Full-Scale

Fan Speed

♦ Accurate Closed-Loop Fan-Speed Regulation

♦ On-Chip Power Device Drives Fans Rated

Up to 250mA

♦ Programmable Under/Overtemperature Alarms

♦ SMBus 2-Wire Serial Interface with Timeout

(Cannot “Lock Up” the SMBus)

♦ Supports SMBus Alert Response

♦ ACPI Compatible, Including OVERT System

Shutdown Function

♦ ±1°C (+60°C to +100°C) Thermal-Sensing Accuracy

♦ MAX6660EVKIT Available

MAX6660

Remote-Junction Temperature-Controlled

Fan-Speed Regulator with SMBus Interface

________________________________________________________________ Maxim Integrated Products 1

19-2225; Rev 1; 5/06

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.

Pin Configuration appears at end of data sheet.

SMBus is a trademark of Intel Corp.

1µF

5kΩ

FAN

+12V

2200pF

PENTIUM

SMBCLK

SMBDATA

ALERT

OVERT

CLOCK

DATA

INTERUPT

TO µP

TO SYSTEM

SHUTDOWN

VFAN

ADD1ADD0

PGND

0.1µF

+3V TO +5.5V

50Ω

STBY

TACH IN

FAN

DXP

DXN

AGND

10kΩ

EACH

MAX6660

Typical Operating Circuit

PART TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX6660AEE

-40°C to +125°C

16 QSOP

E16-5

Ordering Information

Summary of content (21 pages)

PAGE 1
9-2225; Rev 1; 5/06 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Features The MAX6660 is a remote temperature sensor and fanspeed regulator that provides a complete fan-control solution. The remote temperature sensor is typically a common-collector PNP, such as a substrate PNP of a microprocessor, or a diode-connected transistor, typically a low-cost, easily mounted 2N3904 NPN type or 2N3906 PNP type.
PAGE 2
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) VCC, ADD0, ADD1, SMBDATA, SMBCLK, ALERT, OVERT ...................................-0.3V to +6V VFAN, TACH IN, FAN .............................................-0.3V to +16V DXP, GAIN..................................................-0.3V to (VCC + 0.3V) DXN.............................................................................-0.
PAGE 3
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface (VCC = +3V to +5.5V, VVFAN = +12V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Tach Input Transition Level VVFAN = 12V 10.5 V Tach Input Hysteresis VFAN = 12V 190 mV Current-Sense Tach Threshold 20 mA Current-Sense Tach Hysteresis 0.
PAGE 4
Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) TEMPERATURE ERROR vs. REMOTE-DIODE TEMPERATURE PATH = DXP TO GND 5 0 -5 -10 PATH = DXP TO VCC (+5V) -15 3 2 1 0 -1 -2 10 5 -5 -10 -15 -20 -25 -4 -25 -30 -5 100 0 50 100 100 1k 2.5 VIN = 100mVp-p 2.0 1.5 1.0 0.5 VIN = 50mVp-p 0 0 -0.5 -1.0 MAX6660 toc05 1 MAX6660 toc04 VIN = SQUARE WAVE AC-COUPLED TO DXN 10k 100k 1M 10M 100M FREQUENCY (Hz) TEMPERATURE ERROR vs.
PAGE 5
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface PIN NAME 1 VFAN FUNCTION Fan Drive Power-Supply Input. 4.5V to 13.5V. 2 VCC Supply Voltage Input. +3V to +5.5V. Bypass VCC to ground with a 0.1µF capacitor. 3 DXP Input: Remote-Junction Anode. Place a 2200pF capacitor between DXP and DXN for noise filtering. 4 DXN Input: Remote-Junction Cathode. DXN is internally biased to a diode voltage above ground. 5 FAN Open-Drain Output to Fan Low Side.
PAGE 6
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface VFAN TACH IN FAN-SPEED REGULATOR FAN FAN N REGISTERS TMAX DXP MUX ADC THYST COMPARAT0R OVERT DXN REMOTE DATA TEMPERATURE CENTRAL LOGIC ALERT THIGH SMBCLK SMBDATA ADD0 ADD1 SMBus INTERFACE ADDRESS DECODER TLOW CONFIGURATION FAN COUNT DIVISOR (FC) TFAN (FT) THERMAL OPEN/ CLOSED LOOP FAN CONTROL CIRCUIT FAN OPEN/ CLOSED LOOP FAN GAIN (FG) FAN SPEED LIMIT (FS) FAN LIMIT (FL) MODE (M) FAN CONVERSION RATE
PAGE 7
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface The transistor must be a small-signal type with a relatively high forward voltage. Otherwise, the A/D input range could be violated. The forward voltage must be greater than 0.25V at 10µA. Check to ensure this is true at the highest expected temperature. The forward voltage must be less than 0.95V at 100µA. Check to ensure that this is true at the lowest expected temperature.
PAGE 8
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface improvement in leakage and noise over narrow traces. Use wider traces when practical. 7) PC Board Layout Checklist • Place the MAX6660 close to the remote-sense junction. • • • • 10mils 10mils DXP MINIMUM 10mils DXN Keep traces away from high voltages (+12V bus). Keep traces away from fast data buses and CRTs. Use recommended trace widths and spacings. Place a ground plane under the traces.
PAGE 9
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface S ADDRESS WR ACK COMMAND 7 bits ACK DATA 8 bits Slave Address: equivalent to chip-select line of a 3-wire interface ACK P 8 bits Command Byte: selects which register you are writing to MAX6660 Write Byte Format 1 Data Byte: data goes into the register set by the command byte (to set thresholds, configuration masks, and sampling rate) Read Byte Format S ADDRESS WR ACK COMMAND 7 bits ACK S 8 bits Slave A
PAGE 10
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface The SMBus interface includes a Timeout, which resets the interface any time the data or clock line is held low for more than 35ms, ensuring that the MAX6660 can never “lock” the bus. Remote Temperature Data Register Two registers, at addresses 00h and 01h, store the measured temperature data from the remote diode. The data format for the remote-diode temperature is 10 bit + sign, with each bit corresponding to 0.
PAGE 11
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Table 3.
PAGE 12
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Table 4.
PAGE 13
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface MAX6660 Table 5. Configuration-Byte Bit Assignments POR STATE BIT NAME DESCRIPTION 7(MSB) ALERT Mask 0 When set to 1, ALERT is masked from internally generated errors. 6 Run/Stop 0 When set to 1, the MAX6660 enters low-power standby. 5 OVERT Polarity 0 0 provides active low, 1 provides active high. 0 When set to 1, Write Protect is in effect for the following applicable registers: 1.
PAGE 14
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Table 7. POR Slave Address Decoding (ADD0 and ADD1) Power-up defaults include: • Interrupt latch is cleared. • ADC begins autoconverting. ADD0 GND ADD1 GND ADDRESS 0011 000 • GND High-impedance 0011 001 • GND VCC 0011 010 • Command register is set to 00h to facilitate quick internal Receive Byte queries. THIGH and TLOW registers are set to +127°C and -55°C, respectively.
PAGE 15
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Table 8. Fan Conversion Update Rate DATA BINARY FAN UPDATE RATE (Hz) SECONDS BETWEEN UPDATES 00h 01h 02h 03h 04h 05h 00000000 00000001 00000010 00000011 00000100 00000101 0.0625 0.125 0.25 0.5 1 2 16 8 4 (POR) 2 1 0.5 06h 00000110 4 0.25 from fan off to full fan speed. If bits 6 and 5 are set to 01, the thermal control loop has a control range of 16°C with 32 temperature steps from fan off to full fan speed.
PAGE 16
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface should be set such that the full-speed fan frequency divided by the prescalar fall in the 33Hz to 66Hz range. The (UP/DN) counter has six stages that form the input of a 6-bit resistive ladder DAC whose voltage is divided down from VVFAN. This DAC determines the voltage applied to the fan.
PAGE 17
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface REGISTER/ ADDRESS COMMAND FCD (1Dh = READ, 1Eh = WRITE) READ LIMIT/FAILURE REGISTER Bit 7 6 5 4 3 2 1 0 POR State 0 0 0 0 0 0 0 1 Notes: This byte sets the prescalar division ratio for tachometer or current-sense feedback. (This register does not apply to the tach signal used in the Fan-Speed register).
PAGE 18
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Fan Conversion Rate Byte TACH IN The FCR register (Table 8) programs the fan’s update time interval in free-running autonomous mode (RUN/ STOP = 0). The conversion rate byte’s POR state is 02h (0.25Hz). The MAX6660 uses only the 3LSBs of this register. The 4MSBs are “don’t cares.” The update rate tolerance is ±25% (max) at any rate setting. The TACH IN input connects directly to the tachometer output of a fan.
PAGE 19
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Applications Information Mode Register Resistance in series with the remote-sensing junction causes conversion errors on the order of 0.5°C per ohm. The MAX6660 Mode register gives the ability to eliminate the effects of external series resistance of up to several hundred ohms on the remote temperature measurement and to adjust the temperature measuring ADC to suit different types of remote-diode sensor.
PAGE 20
MAX6660 Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface Low-Speed Operation Table 14. Fan Manufacturers MANUFACTURER FAN MODEL OPTION Comair Roton All DC brushless models can be ordered with optional tachometer output. EBM-Papst Tachometer output optional on some models. NMB All DC brushless models can be ordered with optional tachometer output. Panasonic Panaflo and flat unidirectional miniature fans can be ordered with tachometer output.
PAGE 21
Remote-Junction Temperature-Controlled Fan-Speed Regulator with SMBus Interface QSOP.EPS PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 F 1 1 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.