Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsPMICsPMIC - temperature management Internal, External SMBus uMAX 10

General Description

The MAX6641 temperature sensor and fan controller

accurately measures the temperature of its own die and

the temperature of a remote pn junction. The device

reports temperature values in digital form using a 2-wire

serial interface. The remote pn junction is typically the

emitter-base junction of a common-collector pnp on a

CPU, FPGA, or ASIC.

The 2-wire serial interface accepts standard System

Management Bus (SMBus)

write byte, read byte,

send byte, and receive byte commands to read the

temperature data and program the alarm thresholds.

The temperature data controls a PWM output signal to

adjust the speed of a cooling fan, thereby minimizing

noise when the system is running cool, but providing

maximum cooling when power dissipation increases.

The device also features an over-temperature alarm

output to generate interrupts, throttle signals, or shut

down signals. The MAX6641 operates from supply volt-

ages in the 3.0V to 5.5V range and typically consumes

500µA of supply current.

The MAX6641 is available in a slim 10-pin µMAX

pack-

age and is available over the -40°C to +125°C automo-

tive temperature range.

Applications

Desktop Computers

Notebook Computers

Workstations

Servers

Networking Equipment

Industrial

Features

♦ Tiny 3mm x 5mm µMAX Package

♦ Thermal Diode Input

♦ Local Temperature Sensor

♦ Open-Drain PWM Output for Fan Drive

♦ Programmable Fan Control Characteristics

♦ Automatic Fan Spin-Up Ensures Fan Start

♦ ±1°C Remote Temperature Accuracy (+60°C to

+145°C)

♦ Controlled Rate of Change Ensures Unobtrusive

Fan-Speed Adjustments

♦ Temperature Monitoring Begins at Power-On for

Fail-Safe System Protection

♦ OT Output for Throttling or Shutdown

MAX6641

SMBus-Compatible Temperature Monitor with

Automatic PWM Fan-Speed Controller

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3304; Rev 1; 4/06

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.

PART

PIN-

PACKAGE

SMBus

ADDRESS

PKG

CODE

MAX6641AUB90

10 µMAX

1001 000x

U10-2

MAX6641AUB92

10 µMAX

1001 001x

U10-2

MAX6641AUB94

10 µMAX

1001 010x

U10-2

MAX6641AUB96

10 µMAX

1001 011x

U10-2

PWMOUT

SMBDATA

SMBCLKGND

DXP

DXN

I.C.

MAX6641

µMAX

TOP VIEW

I.C.OT

Pin Configuration

µMAX is a registered trademark of Maxim Integrated Products, Inc.

SMBus is a trademark of Intel Corp.

Typical Application Circuit appears at end of data sheet.

Note: All devices are specified over the -40°C to +125°C tem-

perature range.

Summary of content (17 pages)

PAGE 1
9-3304; Rev 1; 4/06 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Features The MAX6641 temperature sensor and fan controller accurately measures the temperature of its own die and the temperature of a remote pn junction. The device reports temperature values in digital form using a 2-wire serial interface. The remote pn junction is typically the emitter-base junction of a common-collector pnp on a CPU, FPGA, or ASIC.
PAGE 2
MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND.) VCC, OT, SMBDATA, SMBCLK, PWMOUT...............-0.3V to +6V DXP .........................................................…-0.3V to (VCC + 0.3V) DXN ......................................................................-0.3V to +0.8V ESD Protection (all pins, Human Body Model) ......…………………….±2000V Continuous Power Dissipation (TA = +70°C) 10-Pin µMAX (derate 5.
PAGE 3
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller MAX6641 ELECTRICAL CHARACTERISTICS (continued) (VCC = +3.0V to +5.5V, TA = 0°C to +125°C, unless otherwise noted. Typical values are at VCC = 3.3V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 100 kHz SMBus-COMPATIBLE TIMING (Note 1) (See Figures 2, 3) Serial-Clock Frequency fSCLK (Note 2) Clock Low Period tLOW 10% to 10% 4 µs Clock High Period tHIGH 90% to 90% 4.
PAGE 4
Typical Operating Characteristics (continued) (VCC = 3.3V, TA = +25°C, unless otherwise noted.) LOCAL TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY -0.50 -0.75 -1.00 0 -0.5 -1.0 TA = +80°C, VIN = 100mVP-P SQUARE WAVE APPLIED TO DXP -2.0 -1.50 0.1 1 10 1 10 1000 100 0 3 2 10 0 -1 -2 -3 -4 TA = +80°C 0.1 1000 100 100 1 -5 -1.0 1 10 MAX6641 toc08 MAX6641 toc07 0.5 -0.5 1 100 10 DXP - DXN CAPACITANCE (nF) FREQUENCY (kHz) PWM FREQUENCY ERROR vs.
PAGE 5
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller PIN NAME 1, 6 I.C. Internally Connected. Must be connected to GND. 2 DXN Combined Remote-Diode Cathode Connection and A/D Negative Input. Connect the cathode of the remote-diode-connected transistor to DXN. 3 DXP Combined Remote-Diode Current Source and A/D Positive Input for Remote-Diode Channel. Connect DXP to the anode of a remote-diode-connected temperature-sensing transistor.
PAGE 6
MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Table 1.
PAGE 7
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller READ/ REGISTER WRITE ADDRESS R/W 0Ch POR STATE FUNCTION/ NAME D7 D6 D5 D4 D3 D2 D1 D0 0000 0000 Local-diode fan-start temperature MSB (+128°C) (+64°C) (+32°C) (+16°C) (+8°C) (+4°C) (+2°C) LSB (+1°C) Temp Fan Hysteresis: step: 0 = Fan control: control: 0 = 5°C, 1°C, 1 = 1 = remote 1 = local 1 = 10°C 2°C X X X X R/W 0Dh 0000 xxxx Fan configuration R/W 0Eh 101x xxxx Duty-cycle rate of change MSB —
PAGE 8
MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Write Byte Format 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 to which register you are writing 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 addre
PAGE 9
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller tLOW B C tHIGH D E F G H I J K L MAX6641 A M SMBCLK SMBDATA tSU:STA tHD:STA tSU:DAT A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW tHD:DAT F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO MASTER H = LSB OF DATA CLOCKED INTO MASTER I = MASTER PULLS DATA LINE LOW tSU:STO tBUF J =
PAGE 10
MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Table 2. Configuration Byte Definition (02h) BIT NAME POR STATE 7 — 0 Reserved. Set to zero. 6 — 0 Reserved. Set to zero. 5 TIMEOUT 0 Set TIMEOUT to zero to enable SMBus timeout for prevention of bus lockup. Set to 1 to disable this function. 4 FAN PWM INVERT 0 Set FAN PWM INVERT to zero to force PWMOUT low when the duty cycle is 100%. Set to 1 to force PWMOUT high when the duty cycle is 100%.
PAGE 11
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Table 3. Duty-Cycle Rate-of-Change Register (0Eh) D7, D6, D5 TIME BETWEEN INCREMENTS (s) TIME FROM 33% TO 100% (s) 000 0 0 001 0.0625 5 010 0.1250 10 011 0.2500 20 100 0.5000 40 101 1.0000 80 110 2.0000 160 111 4.0000 320 Remote- and Local-Diode Fan-Start Temperature (0Bh, 0Ch) These registers contain the temperature threshold values at which fan control begins in automatic mode.
PAGE 12
MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Table 5. PWM Frequency Select (10h) VCC PWM FREQUENCY (Hz) SELECT A SELECT B SELECT C 20 0 0 0 33 0 1 0 50 1 0 0 100 1 1 0 35k X X 1 frequency setting is used for controlling fans that have logic-level PWM input pins for speed control. Dutycycle resolution is decreased from 2/240 to 4/240 at the 35kHz frequency setting.
PAGE 13
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Manual PWM Duty-Cycle Control Setting bits D5 and D4 to zero in the fan-configuration register (0Dh) enables manual PWMOUT control. In this mode, the duty cycle written to the fan-target dutycycle register controls the PWMOUT duty cycle. The value is clipped to a maximum of 240, which corresponds to a 100% duty cycle. Any value above that is limited to the maximum duty cycle.
PAGE 14
MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller The duty cycle is limited to the value in the fan maximum duty-cycle register. If the duty-cycle value is larger than the maximum fan duty cycle, it can be set to the maximum fan duty cycle as in the fan maximum dutycycle register. The temp step is bit D6 of the fan-configuration register (0Dh). If duty cycle is an odd number, the MAX6641 automatically rounds down to the nearest even number.
PAGE 15
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller The transistor must be a small-signal type with a relatively high forward voltage; otherwise, the A/D input voltage range can be violated. The forward voltage at the highest expected temperature must be greater than 0.25V at 10µA, and at the lowest expected temperature, the forward voltage must be less than 0.95V at 100µA. Large power transistors must not be used. Also, ensure that the base resistance is less than 100Ω.
PAGE 16
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller MAX6641 Thermal Mass and Self-Heating GND 10 mils 10 mils DXP MINIMUM 10 mils DXN 10 mils GND Figure 9. Recommended DXP-DXN PC Traces Twisted-Pair and Shielded Cables Use a twisted-pair cable to connect the remote sensor for remote-sensor distance longer than 8in or in very noisy environments. Twisted-pair cable lengths can be between 6ft and 12ft before noise introduces excessive errors.
PAGE 17
SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller 10LUMAX.EPS e 4X S 10 10 INCHES H Ø0.50±0.1 0.6±0.1 1 1 0.6±0.1 BOTTOM VIEW TOP VIEW D2 MILLIMETERS MAX DIM MIN 0.043 A 0.006 A1 0.002 A2 0.030 0.037 0.120 D1 0.116 0.118 D2 0.114 E1 0.116 0.120 0.118 E2 0.114 0.199 H 0.187 L 0.0157 0.0275 L1 0.037 REF b 0.007 0.0106 e 0.0197 BSC c 0.0035 0.0078 0.0196 REF S α 0° 6° MAX MIN 1.10 0.05 0.15 0.75 0.95 2.95 3.05 2.89 3.00 2.95 3.05 2.89 3.00 4.75 5.05 0.40 0.70 0.