MAXIM MAX6640 Technical data

General Description

The MAX6640 monitors its own temperature and one external diode-connected transistor or the temperatures of two external diode-connected transistors, typically available in CPUs, FPGAs, or GPUs. The 2-wire serial interface accepts standard System Management Bus (SMBusTM) write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. Temperature data can be read at any time over the SMBus, and three programmable alarm outputs can be used to generate interrupts, throttle signals, or overtemperature shutdown signals.

The temperature data is also used by the internal dual PWM fan-speed controller to adjust the speed of up to two cooling fans, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. Speed control is accomplished by tachometer feedback from the fan, so that the speed of the fan is controlled, not just the PWM duty cycle. Accuracy of speed measurement is ±4%.

The MAX6640 is available in 16-pin QSOP and 16-pin TQFN 5mm x 5mm packages. It operates from 3.0V to

3.6V and consumes just 500μA of supply current.

Applications

Desktop Computers

Notebook Computers

Workstations

Servers

Networking Equipment

Features

♦ Two Thermal-Diode Inputs ♦ Local Temperature Sensor ♦ 1°C Remote Temperature Accuracy (+60°C to

+100°C)

♦ Two PWM Outputs for Fan Drive (Open Drain; can

be Pulled Up to +13.5V)

♦ Programmable Fan-Control Characteristics ♦ Automatic Fan Spin-Up Ensures Fan Start ♦ Controlled Rate-of-Change Ensures Unobtrusive

Fan-Speed Adjustments

♦ ±4% Fan-Speed Measurement Accuracy ♦ Temperature Monitoring Begins at POR for Fail-

Safe System Protection

♦ OT and THERM Outputs for Throttling or

Shutdown

♦ Measures Temperatures Up to +150°C ♦ Tiny 5mm x 5mm 16-Pin TQFN and QSOP

Packages

MAX6640

2-Channel Temperature Monitor with Dual

Automatic PWM Fan-Speed Controller

________________________________________________________________

Maxim Integrated Products

Ordering Information

19-3344; Rev 2; 10/08

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

EVALUATION KIT

AVAILABLE

Pin Configurations

SMBus is a trademark of Intel Corp.

Typical Operating Circuit appears at end of data sheet.

Denotes a lead-free/RoHS-compliant package.

EP = Exposed pad.

PART

M AX6640AE E +

M AX6640ATE +

O PER A T IN G

R A NG E

-40°C to +125°C

M EA SU R EM EN T

R A N G E

0°C to +150°C 16 QSOP

0°C to +150°C 16 TQFN- EP*

PINPACKAGE

PWM1

SDA

TOP VIEW

PWM1

TACH1

PWM2

TACH2

FANFAIL

THERM

MAX6640

QSOP

SCL

SDA

ALERT

I.C.

DXP2

DXN

GND

DXP1

PWM2 1

TACH2 2

FANFAIL

THERM

TACH1

15 14 13

MAX6640

*CONNECT EXPOSED PAD TO GND

6 7 8

5mm x 5mm THIN QFN

SCL

ALERT

I.C.11

109DXP2

DXN

GND

DXP1

MAX6640

2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +3.0V to +3.6V, TA= 0°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V, TA= +85°C.) (Note 1)

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.

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

PWM1, PWM2, TACH1, and TACH2 to GND......-0.3V to +13.5V

DXP1 and DXP2 to GND ..........................-0.3V to +(V

+ 0.3V)

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

SCL, SDA, THERM, OT, FANFAIL,

and ALERT to GND..............................................-0.3V to +6V

SDA, OT, THERM, ALERT, FANFAIL,

PWM1, and PWM2 Current .............................-1mA to +50mA

DXN Current .......................................................................±1mA

ESD Protection (all pins, Human Body Model)..................2000V

Continuous Power Dissipation (T

= +70°C)

16-Pin QSOP (derated 8.3mW/°C above +70°C)....... 667mW

16-Pin TQFN 5mm x 5mm

(derated at 33.3mW/°C above +70°C)................2666.7mW

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

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

Storage Temperature Range .............................-65°C to +150°C

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Operating Supply Voltage Range V

Standby Current SMB static, sleep mode 3 10 μA

Operating Current Interface inactive, ADC active 0.5 1 mA

External Temperature Error

Internal Temperature Error

Supply Sensitivity of Temperature Measurement

Temperature Resolution

Conversion Time 125 ms

Conversion-Rate Timing Error -10 +10 %

PWM Frequency Error -10 +10 %

Tachometer Accuracy

Remote-Diode Sourcing Current

DXN Source Voltage 0.7 V

VCC = +3.3V, +60°C ≤ TA ≤ +100°C and +60°C ≤ T

VCC = +3.3V, +40°C ≤ TA ≤ +100°C and 0°C ≤ T

0°C ≤ T

VCC = +3.3V, +25°C ≤ T

0°C ≤ T

+60°C ≤ T

High level 70 100 130

Low level 7.0 10 13.0

≤ +145°C

= +3.3V,

≤ +145°C

= +3.3V,

≤ +125°C

= 3.135V to 3.345V,

≤ +100°C

≤ +85°C

+3.0 +3.6 V

±0.2 °C/V

+0.125 °C

11 Bits

±1

±2.5

±3.8

±2

±4

±4 %

°C

μA

MAX6640

2-Channel Temperature Monitor with Dual

Automatic PWM Fan-Speed Controller

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3.0V to +3.6V, TA= 0°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V, TA= +85°C.) (Note 1)

Note 1: All parameters tested at a single temperature. Specifications are guaranteed by design. Note 2: Timing specifications guaranteed by design. Note 3: The serial interface resets when SCL is low for more than t

TIMEOUT

Note 4: A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCL's falling edge.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DIGITAL INPUTS AND OUTPUTS

Output Low Voltage (Sink Current) (OT, ALERT, FANFAIL, THERM, SDA, PWM1, and PWM2)

Output High Leakage Current (OT, ALERT, FANFAIL, THERM, SDA, PWM1, and PWM2)

Logic-Low Input Voltage (SDA, SCL, THERM, TACH1, TACH2)

Logic-High Input Voltage (SDA, SCL, THERM, TACH1, TACH2)

Input Leakage Current (SDA, SCL, THERM, TACH1, TACH2)

Input Capacitance C

SMBus TIMING (Note 2)

Serial Clock Frequency f

Clock Low Period t

Clock High Period t

Bus Free Time Between Stop and Start Condition SMBus Start Condition Setup Time

Start Condition Hold Time t

Stop Condition Setup Time t

Data Setup Time t

Data Hold Time t

SMBus Fall Time t

SMBus Rise Time t

SMBus Timeout t

SU:STA

HD:STO

SU:STO

SU:DAT

HD:DAT

TIMEOUT

SCL

LOW

HIGH

BUF

ALERT, FANFAIL, THERM, OT SDA I

PWM1, PWM2, I

VCC = 3.3V 2.1 V

(Note 3) 10 100 kHz

10% to 10% 4 μs

90% to 90% 4.7 μs

90% of SMBCLK to 90% of SMBDATA 4.7 μs

10% of SDA to 10% of SCL 4 μs

90% of SCL to 10% of SDA 4 μs

10% of SDA to 10% of SCL 250 ns

10% of SCL to 10% of SDA (Note 4) 300 ns

= 6mA

SINK

= 4mA 0.4

SINK

= VCC or GND 1 μA

5pF

4.7 μs

58 74 90 ms

0.4

1μA

0.8 V

300 ns

1000 ns

MAX6640

2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VCC= 3.3V, TA= +25°C.)

STANDBY SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX6640 toc01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

5.04.54.03.5

3.0 5.5

OPERATING SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX6640 toc02

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

5.04.54.03.5

300

400

500

600

700

800

200

3.0 5.5

REMOTE TEMPERATURE ERROR

vs. REMOTE-DIODE TEMPERATURE

MAX6640 toc03

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

100755025

-1

-2 0 125

FAIRCHILD 2N3906

LOCAL TEMPERATURE ERROR

vs. DIE TEMPERATURE

MAX6640 toc04

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

100755025

-0.5

-1.0

-1.5

0.5

1.0

-2.0 0 125

LOCAL TEMPERATURE ERROR

vs. POWER-SUPPLY NOISE FREQUENCY

MAX6640 toc06

FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

10k1k100

-1.5

-1.0

-0.5

0.5

1.0

1.5

2.0

-2.0 1 10 100k

VIN = 250mV

P-P

SQUARE WAVE APPLIED TO

WITH NO BYPASS CAPACITOR

REMOTE TEMPERATURE ERROR

vs. COMMON-MODE NOISE FREQUENCY

MAX6640 toc07

FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

10k1k100

-1.5

-1.0

-0.5

0.5

1.0

1.5

2.0

-2.0

0.1 1 10 100k

VIN = AC-COUPLED TO DXP AND DXN V

= 100mV

P-P

SQUARE WAVE

REMOTE TEMPERATURE ERROR

vs. DIFFERENTIAL NOISE FREQUENCY

MAX6640 toc08

FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

10k1k100

-1.5

-1.0

-0.5

0.5

1.0

1.5

2.0

-2.0

10 100k

VIN = AC-COUPLED TO DXP V

= 100mV

P-P

SQUARE WAVE

TEMPERATURE ERROR

vs. DXP-DXN CAPACITANCE

MAX6640 toc09

DXP-GND CAPACITANCE (nF)

TEMPERATURE ERROR (°C)

101

-5.0

-4.0

-3.0

-2.0

-1.0

1.0

2.0

-6.0

0.1 100

REMOTE TEMPERATURE ERROR

vs. POWER-SUPPLY NOISE FREQUENCY

MAX6640 toc05

FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

10k1k100

-1.5

-1.0

-0.5

0.5

1.0

1.5

2.0

-2.0

10 100k

VIN = 250mV

P-P

SQUARE WAVE APPLIED TO

WITH NO BYPASS CAPACITOR

MAX6640

2-Channel Temperature Monitor with Dual

Automatic PWM Fan-Speed Controller

_______________________________________________________________________________________ 5

Pin Description

Typical Operating Characteristics (continued)

(VCC= 3.3V, TA= +25°C.)

PWMOUT FREQUENCY

vs. DIE TEMPERATURE

MAX6640 toc10

TEMPERATURE (°C)

PWMOUT FREQUENCY (Hz)

85603510-15

-40 110

PWMOUT FREQUENCY

vs. SUPPLY VOLTAGE

MAX6640 toc11

SUPPLY VOLTAGE (V)

PWMOUT FREQUENCY (Hz)

5.04.54.03.5

3.0 5.5

TQFN-EP QSOP

1, 15

3, 1

2, 16 4, 2

35FANFAIL Active-Low, Open-Drain, Fan-Failure Output. Open circuit when VCC = 0.

46THERM

57OT

68VCCPower-Supply Input. 3.3V nominal. Bypass VCC to GND with a 0.1μF capacitor.

7 10 GND Ground. Connect to a clean ground reference.

8, 10 9, 12

9 11 DXN

11 13 I.C. Internally Connected. Connect to VCC. 12 14 ALERT Active-Low, Open-Drain SMBus Alert Output

13 16 SCL S M Bus S er i al - C l ock Inp ut. C an b e p ul l ed up to 5.5V r eg ar d l ess of V

14 15 SDA

——EP

NAME FUNCTION

PWM2,

PWM1

TACH2,

TACH1

Open-Drain Output to Power Transistor Driving Fan. Connect to the gate of a MOSFET or base of a bipolar transistor. PWM_ requires a pullup resistor. The pullup resistor can be connected to a supply voltage as high as 13.5V, regardless of the MAX6640’s supply voltage.

Tachometer Inputs. Connect to the tachometer output of the fan. TACH_ requires a pullup resistor. The pullup resistor can be connected to a supply voltage as high as 13.5V, regardless of the MAX6640’s supply voltage.

Active-Low, Open-Drain Thermal Alarm Output. Typically used for clock throttling. Open circuit

= 0.

when V

Active-Low, Open-Drain Overtemperature Output. Typically used for system shutdown or clock

DXP1, DXP2

throttling. Can be pulled up to 5.5V regardless of V

Combined Current Source and A/D Positive Input for Remote Diode. Connect to anode of remotediode-connected temperature-sensing transistor. Do not leave unconnected; connect to DXN if no remote diode is used. Place a 2200pF capacitor between DXP_ and DXN for noise filtering.

Combined Current Sink and A/D Negative Input for Remote Diode. Connect cathode of the remotediode-connected transistor to DXN.

SMBus Serial-Data Input/Output, Open Drain. Can be pulled up to 5.5V regardless of V circuit when V

= 0.

Exposed Pad (TQFN package only). Internally connected to GND. Connect to a large ground plane to maximize thermal performance. Not intended as an electrical connection point.

. Open circuit when VCC = 0.

. O p en ci r cui t w hen V

C C

= 0.

. Open

MAX6640

Detailed Description

The MAX6640 monitors its own temperature and a remote diode-connected transistor or the temperatures of two external diode-connected transistors, which typically reside on the die of a CPU or other integrated circuit. The 2-wire serial interface accepts standard SMBus write byte, read byte, send byte, and receive byte commands to read the temperature data and program the alarm thresholds. Temperature data can be read at any time over the SMBus, and a programmable alarm output can be used to generate interrupts, throttle signals, or overtemperature shutdown signals.

The temperature data is also used by the internal dual PWM fan-speed controller to adjust the speed of up to two cooling fans, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. RPM feedback allows the MAX6640 to control the fan’s actual speed.

2-Channel Temperature Monitor with Dual Automatic PWM Fan-Speed Controller

6 _______________________________________________________________________________________

Block Diagram

Write Byte Format

Read Byte Format

Send Byte Format

Receive Byte Format

Slave Address: equivalent to chip-select line of a 3-wire interface

Command Byte: selects which register you are writing to

Data Byte: data goes into the register set by the command byte (to set thresholds, configuration masks, and sampling rate)

Slave Address: equivalent to chip-select line

Command Byte: selects which register you are reading from

Slave Address: repeated due to change in dataflow direction

Data Byte: reads from the register set by the command byte

Command Byte: sends command with no data, usually used for one-shot command

Data Byte: reads data from the register commanded by the last Read Byte or Write Byte transmission; also used for SMBus Alert Response return address

S = Start condition Shaded = Slave transmission P = Stop condition /// = Not acknowledged

Figure 1. SMBus Protocols

S ADDRESS RD ACK DATA /// P

7 bits 8 bits

WRS ACK COMMAND ACK P

8 bits

ADDRESS

7 bits

ACKDATA

8 bits

ACKCOMMAND

8 bits

ACKWRADDRESS

7 bits

S ADDRESS WR ACK COMMAND ACK S ADDRESS

7 bits8 bits7 bits

RD ACK DATA

8 bits

/// P

DXP1

DXN

DXP2

SDA

SCL

TEMPERATURE

PROCESSING

BLOCK

INTERFACE AND

REGISTERS

SMBus

MAX6640

PWM

GENERATOR

BLOCK

LOGIC

GND

PWM1

PWM2

THERM

FANFAIL

ALERT

TAC H1

TAC H2

SMBus Digital Interface

From a software perspective, the MAX6640 appears as a set of byte-wide registers. This device uses a standard SMBus 2-wire/I2C-compatible serial interface to access the internal registers. The MAX6640 has a fixed slave address of 0101111.

The MAX6640 employs four standard SMBus protocols: write byte, read byte, send byte, and receive byte (Figures 1, 2, and 3). The shorter receive byte protocol allows quicker transfers, provided that the correct data register was previously selected by a read byte instruction. Use caution with the shorter protocols in multimaster systems, since a second master could overwrite the command byte without informing the first master.

Table 3 details the register addresses and functions, whether they can be read or written to, and the poweron reset (POR) state. See Tables 4–8 for all other register functions and the

section.

Temperature Reading

Temperature data can be read from registers 00h and 01h. The temperature data format for these registers is 8 bits, with the LSB representing 1°C (Table 1) and the MSB representing +128°C. The MSB is transmitted first. Three additional temperature bits provide resolution down to 0.125°C and are in the channel 1 extended temperature (05h) and channel 2 extended temperature (06h) registers. All values below 0°C clip to 00h.

The MAX6640 employs a register lock mechanism to avoid getting temperature results from the temperature register and the extended temperature register sampled at two different time points. Reading the extended register stops the MAX6640 from updating the temperature register for at least 0.25s, unless there is a temperature register read before the scheduled update. This allows enough time to read the main register before it is

MAX6640

2-Channel Temperature Monitor with Dual

Automatic PWM Fan-Speed Controller

_______________________________________________________________________________________ 7

Figure 2. SMBus Write Timing Diagram

Figure 3. SMBus Read Timing Diagram

AB CDEFG

HIGH

LOW

SCL

SDA

SU:STAtHD:STA

A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE

SU:DAT

AB CDEFG HIJ

LOWtHIGH

SCL

SDA

HD:STA

SU:STA

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

E = SLAVE PULLS SMBDATA LINE LOW F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE H = LSB OF DATA CLOCKED INTO SLAVE

SU: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

HD:DAT

HIJ

I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION

SU:STO

J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION

LMK

SU:STOtBUF

BUF

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