19-3304; 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. Tiny 3mm x 5mm MAX Package The 2-wire serial interface accepts standard System Management Bus (SMBus) TM 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 voltages in the 3.0V to 5.5V range and typically consumes 500A of supply current. The MAX6641 is available in a slim 10-pin MAX(R) package and is available over the -40C to +125C automotive temperature range. Automatic Fan Spin-Up Ensures Fan Start Thermal Diode Input Local Temperature Sensor Open-Drain PWM Output for Fan Drive Programmable Fan Control Characteristics 1C Remote Temperature Accuracy (+60C to +145C) 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 Ordering Information PINPACKAGE SMBus ADDRESS PKG CODE MAX6641AUB90 10 MAX 1001 000x U10-2 MAX6641AUB92 10 MAX 1001 001x U10-2 MAX6641AUB94 10 MAX 1001 010x U10-2 MAX6641AUB96 10 MAX 1001 011x U10-2 PART Applications Desktop Computers Notebook Computers Workstations Servers Networking Equipment Industrial Note: All devices are specified over the -40C to +125C temperature range. Pin Configuration TOP VIEW Typical Application Circuit appears at end of data sheet. I.C. 1 DXN MAX is a registered trademark of Maxim Integrated Products, Inc. 10 PWMOUT 2 MAX6641 9 VCC DXP 3 8 SMBDATA GND 4 7 SMBCLK OT 5 6 I.C. MAX SMBus is a trademark of Intel Corp. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX6641 General Description 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 = +70C) 10-Pin MAX (derate 5.6mW/C above +70C) .......... 444mW Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range ............................-65C to +150C Lead Temperature (soldering, 10s) ............................... +300C 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. ELECTRICAL CHARACTERISTICS (VCC = +3.0V to +5.5V, TA = 0C to +125C, unless otherwise noted. Typical values are at VCC = 3.3V, TA = +25C.) PARAMETER SYMBOL Operating Supply Voltage Range VCC Operating Current CONDITIONS MIN SMBDATA, SMBCLK not switching External Temperature Error VCC = 3.3V Internal Temperature Error VCC = 3.3V 0.5 MAX UNITS 5.5 V 1 mA +25C TR +125C, TA = +60C 1 0C TR +145C, +25C TA = +100C 3 0C TR +145C, 0C TA +125C 4 +25C TA +100C -3 +3 0C TA +125C -4 +4 Temperature Resolution C C 1 C 8 Bits Conversion Time 200 PWM Frequency Tolerance -20 Remote-Diode Sourcing Current TYP 3.0 250 300 ms +20 % High level 80 100 120 Low level 8 10 12 DXN Source Voltage 0.7 A V I/O OT, SMBDATA, PWMOUT Output Low Voltage VOL IOUT = 6mA 0.4 V OT, SMBDATA, PWMOUT Output-High Leakage Current IOH VCC = 5.5V 1 A SMBDATA, SMBCLK Logic-Low Input Voltage VIL VCC = 3V to 5.5V 0.8 V SMBDATA, SMBCLK Logic-High Input Voltage VIH VCC = 3V to 5.5V 2.1 V SMBDATA, SMBCLK Leakage Current SMBDATA, SMBCLK Input Capacitance 2 1 CIN 5 _______________________________________________________________________________________ A pF SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller MAX6641 ELECTRICAL CHARACTERISTICS (continued) (VCC = +3.0V to +5.5V, TA = 0C to +125C, unless otherwise noted. Typical values are at VCC = 3.3V, TA = +25C.) 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 s Clock High Period tHIGH 90% to 90% 4.7 s Bus Free Time Between Stop and Start Condition tBUF 4.7 s Hold Time After (Repeated) Start Condition tHD:STA 4 s SMBus Start Condition Setup Time tSU:STA 90% of SMBCLK to 90% of SMBDATA 4.7 s Start Condition Hold Time tHD:STO 10% of SMBDATA to 10% of SMBCLK 4 s Stop Condition Setup Time tSU:STO 90% of SMBCLK to 10% of SMBDATA 4 s Data Setup Time tSU:DAT 10% of SMBDATA to 10% of SMBCLK 250 ns tHD:DAT 10% of SMBCLK to 10% of SMBDATA (Note 3) 300 ns Data Hold Time SMBus Fall Time tF 300 ns SMBus Rise Time tR 1000 ns 55 ms 500 ms SMBus Timeout tTIMEOUT Startup Time After POR 29 37 tPOR Note 1: Timing specifications guaranteed by design. Note 2: The serial interface resets when SMBCLK is low for more than tTIMEOUT. Note 3: A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SMBCLK's falling edge. Typical Operating Characteristics (VCC = 3.3V, TA = +25C, unless otherwise noted.) OPERATING SUPPLY CURRENT vs. SUPPLY VOLTAGE 500 450 400 350 1.0 0.5 0 -0.5 -1.0 MAX6641 toc03 2 TEMPERATURE ERROR (C) 1.5 TEMPERATURE ERROR (C) 550 MAX6641 toc02 NO SMBus ACTIVITY OPERATING SUPPLY CURRENT (A) 2.0 MAX6641 toc01 600 LOCAL TEMPERATURE ERROR vs. DIE TEMPERATURE REMOTE TEMPERATURE ERROR vs. REMOTE-DIODE TEMPERATURE 1 0 -1 -1.5 300 -2 -2.0 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 5.0 5.5 0 25 50 75 TEMPERATURE (C) 100 125 0 25 50 75 100 125 TEMPERATURE (C) _______________________________________________________________________________________ 3 Typical Operating Characteristics (continued) (VCC = 3.3V, TA = +25C, unless otherwise noted.) LOCAL TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY -0.50 -0.75 -1.00 0 -0.5 -1.0 TA = +80C, 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 = +80C 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. DIE TEMPERATURE PWM FREQUENCY ERROR vs. SUPPLY VOLTAGE 0 -1 -2 MAX6641 toc10 1 2.0 PWM FREQUENCY ERROR (Hz) MAX6641 toc09 2 PWM FREQUENCY ERROR (Hz) 1 REMOTE TEMPERATURE ERROR vs. DXP - DXN CAPACITANCE NORMALIZED TEMPERATURE ERROR (C) TEMPERATURE ERROR (C) TA = +80C, VIN = 10mVP-P SQUARE WAVE APPLIED TO DXP - DXN 0.1 0.1 FREQUENCY (kHz) REMOTE TEMPERATURE ERROR vs. DIFFERENTIAL-MODE NOISE FREQUENCY 1.0 -0.5 FREQUENCY (kHz) FREQUENCY (kHz) 1.5 0 -1.5 0.1 1000 100 0.5 -1.0 -1.5 -1.25 1.5 1.0 0.5 0 -0.5 TA = +25C -3 -1.0 -50 -25 0 25 50 75 TEMPERATURE (C) 4 1.0 100 MAX6641 toc06 0.5 TA = +25C, 250mV SQUARE WAVE APPLIED AT VCC, NO BYPASS CAPACITOR TEMPERATURE ERROR (C) TA = +80C, 250mV SQUARE WAVE APPLIED AT VCC, NO BYPASS CAPACITOR TEMPERATURE ERROR (C) -0.25 1.0 MAX6641 toc04 0 REMOTE TEMPERATURE ERROR vs. COMMON-MODE NOISE FREQUENCY MAX6641 toc05 REMOTE TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY TEMPERATURE ERROR (C) MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller 125 3.0 3.5 4.0 4.5 5.0 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ 5.5 1000 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. DO NOT LEAVE DXP FLOATING; connect to DXN if no remote diode is used. Place a 2200pF capacitor between DXP and DXN for noise filtering. 4 GND Ground 5 OT 7 SMBCLK 8 SMBDATA 9 VCC 10 FUNCTION Active-Low, Open-Drain, Over-Temperature Output. Use OT as an interrupt, a system shutdown signal, or to control clock throttling. OT can be pulled up to 5.5V, regardless of the voltage on VCC. OT is high impedance when VCC = 0. SMBus Serial-Clock Input. SMBCLK can be pulled up to 5.5V, regardless of VCC. Open drain. SMBCLK is high impedance when VCC = 0. SMBus Serial-Data Input/Output. SMBDATA can be pulled up to 5.5V, regardless of VCC. Open drain. SMBDATA is high impedance when VCC = 0. Positive Supply. Bypass with a 0.1F capacitor to GND. PWMOUT PWM Output to Fan Power Transistor. Connect PWMOUT to the gate of a MOSFET or the base of a bipolar transistor to drive the fan's power supply with a PWM waveform. Alternatively, the PWM output can be connected to the PWM input of a fan with direct speed-control capability, or it can be converted to a DC voltage for driving the fan's power supply. PWMOUT requires a pullup resistor. The pullup resistor can be connected to a voltage supply up to 5.5V, regardless of VCC. Detailed 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 MAX6641 operates from supply voltages of 3.0V to 5.5V and consumes 500A of supply current. The temperature data controls a PWM output signal to adjust the speed of a cooling fan. The device also features an over-temperature alarm output to generate interrupts, throttle signals, or shut down signals. SMBus Digital Interface From a software perspective, the MAX6641 appears as a set of byte-wide registers that contain temperature data, alarm threshold values, and control bits. A standard SMBus-compatible 2-wire serial interface is used to read temperature data and write control bits and alarm threshold data. These devices respond to the same SMBus slave address for access to all functions. The MAX6641 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 when using the shorter protocols in multimaster systems, as a second master could overwrite the command byte without informing the first master. The MAX6641 has four different slave addresses available; therefore, a maximum of four MAX6641 devices can share the same bus. Temperature data within the 0C to +255C range can be read from the read external temperature register (00h). Temperature data within the 0C to +125C range can be read from the read internal temperature register (01h). The temperature data format for these registers is 8 bits, with the LSB representing +1C (Table 1) and the MSB representing +128C. The MSB is transmitted first. All values below 0C are clipped to 00h. Table 1 details the register address and function, whether they can be read or written to, and the power-on reset (POR) state. See Tables 1-5 for all other register functions and the Register Descriptions section. Figure 4 is the MAX6641 block diagram. _______________________________________________________________________________________ 5 MAX6641 Pin Description MAX6641 SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller Table 1. Register Functions READ/ REGISTER WRITE ADDRESS 6 POR STATE FUNCTION/ NAME D7 D6 D5 D4 D3 D2 D1 D0 R 00h 0000 0000 Read remote (external) temperature MSB (+128C) (+64C) (+32C) (+16C) (+8C) (+4C) (+2C) LSB (+1C) R 01h 0000 0000 Read local (internal) temperature MSB (+128C) (+64C) (+32C) (+16C) (+8C) (+4C) (+2C) LSB (+1C) X X R/W 02h 0000 00xx Timeout: 0 = Configuration Reserved Reserved enabled, 1 = byte set to 0 set to 0 disabled R/W 03h 0110 1110 Remote-diode MSB temperature (+128C) OT limit R/W 04h 0101 0000 Local-diode temperature OT limit R 05h 00xx xxxx OT status R/W 06h 00xx xxxx OT mask R/W 07h R/W Fan PWM invert Min duty cycle: 0 = 0%, Spin-up 1 = fan- disable start duty cycle (+64C) (+32C) (+16C) (+8C) (+4C) (+2C) LSB (+1C) (+64C) (+32C) (+16C) (+8C) (+4C) (+2C) LSB (+1C) Remote 1 Local 1 = = fault fault X X X X X X Remote 1 Local 1 = = masked masked X X X X X X 0110 000x Fan-start duty MSB (64/240) cycle (96 = 40%) (128/240) (32/240) (16/240) (8/240) (4/240) LSB (2/240) X 08h 1111 000x Fan maximum MSB (64/240) (240 = duty cycle (128/240) 100%) (32/240) (16/240) (8/240) (4/240) LSB (2/240) X R/W 09h 0000 000x MSB Fan target duty (64/240) cycle (128/240) (32/240) (16/240) (8/240) (4/240) LSB (2/240) X R 0Ah Fan MSB (64/240) 0000 000x instantaneous (128/240) duty cycle (32/240) (16/240) (8/240) (4/240) LSB (2/240) X R/W 0Bh 0000 0000 (+32C) (+16C) (+8C) (+4C) (+2C) LSB (+1C) MSB (+128C) Remote-diode MSB fan-start (+128C) temperature (+64C) _______________________________________________________________________________________ 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 (+128C) (+64C) (+32C) (+16C) (+8C) (+4C) (+2C) LSB (+1C) Temp Fan Hysteresis: step: 0 = Fan control: control: 0 = 5C, 1C, 1 = 1 = remote 1 = local 1 = 10C 2C X X X X R/W 0Dh 0000 xxxx Fan configuration R/W 0Eh 101x xxxx Duty-cycle rate of change MSB -- LSB X X X X X R/W 0Fh 0101 xxxx Duty-cycle step size MSB -- -- LSB X X X X R/W 10h 010x xxxx PWM frequency select Select A Select B Select C X X X X X R FDh 0000 0001 Read device revision 0 0 0 0 0 0 0 1 R FEh 1000 0111 Read device ID 1 0 0 0 0 1 1 1 R FFh Read 0100 1101 manufacturer ID 0 1 0 0 1 1 0 1 X = Don't care. See register descriptions for further details. _______________________________________________________________________________________ 7 MAX6641 Table 1. Register Functions (continued) 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 address: equivalent to chip-select line ADDRESS RD ACK DATA 7 bits Command byte: selects from which register you are reading Send Byte Format S ADDRESS P 8 bits Slave address: repeated due to change in dataflow direction Data byte: reads from the register set by the command byte Receive Byte Format WR ACK COMMAND 7 bits ACK S P ADDRESS RD ACK DATA 7 bits 8 bits /// P 8 bits 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 Command byte: sends command with no data, usually used for one-shot command S = Start condition P = Stop condition /// Shaded = Slave transmission /// = Not acknowledged Figure 1. SMBus Protocols A B tLOW C D E F G tHIGH H I J K L M SMBCLK SMBDATA tSU:STA tHD:STA tSU:STO 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 F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE H = LSB OF DATA CLOCKED INTO SLAVE I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION Figure 2. SMBus Write Timing Diagram 8 _______________________________________________________________________________________ tBUF 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 = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION Figure 3. SMBus Read Timing Diagram is +128C and the value of the LSB is +1C. The MSB is transmitted first. The POR state of the temperature registers is 00h. VCC DXP DXN PWM GENERATOR BLOCK TEMPERATURE PROCESSING BLOCK PWMOUT LOGIC SMBDATA OT SMBus INTERFACE AND REGISTERS SMBCLK MAX6641 GND Figure 4. Block Diagram Register Descriptions Temperature Registers (00h, 01h) These registers contain the 8-bit results of the temperature measurements. Register 00h contains the temperature reading of the remote diode. Register 01h contains the ambient temperature reading. The value of the MSB Configuration Byte Register (02h) The configuration byte register controls the timeout conditions and various PWMOUT signals. The POR state of the configuration byte register is 00h. See Table 2 for configuration byte definitions. Remote and Local OT Limits (03h, 04h) Set the remote (03h) and local (04h) temperature thresholds with these two registers. Once the temperature is above the threshold, the OT output is asserted low (for the temperature channels that are not masked). The POR state of the remote OT limit register is 6Eh and the POR state of the LOCAL OT limit register is 50h. OT Status (05h) Read the OT status register to determine which channel recorded an over-temperature condition. Bit D7 is high if the fault reading occurred from the remote diode. Bit D6 is high if the fault reading occurred in the local diode. The OT status register is cleared only by reading its contents. Reading the contents of the register also makes the OT output high impedance. If the fault is still present on the next temperature measurement cycle, the corresponding bits and the OT output are set again. After reading the OT status register, a temperature register read must be done to correctly clear the appropriate status bit. The POR state of the OT status register is 00h. _______________________________________________________________________________________ 9 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%. 3 MIN DUTY CYCLE 0 Set MIN DUTY CYCLE to zero for a 0% duty cycle when the measured temperature is below the fan-temperature threshold in automatic mode. When the temperature equals the fan-temperature threshold, the duty cycle is the value in the fan-start duty-cycle register, which increases with increasing temperature. Set MIN DUTY CYCLE to 1 to force the PWM duty cycle to the value in the fan-start duty-cycle register when the measured temperature is below the fan-temperature threshold. As the temperature increases above the temperature threshold, the duty cycle increases as programmed. 2 SPIN-UP DISABLE 0 Set SPIN-UP DISABLE to 1 to disable spin-up. Set to zero for normal fan spin-up. 1 -- X Don't care. 0 -- X Don't care. OT Mask (06h) Set bit D7 to 1 in the OT mask register to prevent the OT output from asserting on faults in the remote-diode temperature channel. Set bit D6 to 1 to prevent the OT output from asserting on faults in the local-diode temperature channel. The POR state of the OT mask register is 00h. Fan-Start Duty Cycle (07h) The fan-start duty-cycle register determines the PWM duty cycle where the fan starts spinning. Bit D3 in the configuration byte register (MIN DUTY CYCLE) determines the starting duty cycle. If the MIN DUTY CYCLE bit is 1, the duty cycle is the value written to the fanstart duty-cycle register at all temperatures below the fan-start temperature. If the MIN DUTY CYCLE bit is zero, the duty cycle is zero below the fan-start temperature and has this value when the fan-start temperature is reached. A value of 240 represents 100% duty cycle. Writing any value greater than 240 causes the fan speed to be set to 100%. The POR state of the fan-start duty-cycle register is 60h, 40%. 10 FUNCTION Fan Maximum Duty Cycle (08h) The fan maximum duty-cycle register sets the maximum allowable PWMOUT duty cycle between 2/240 (0.83% duty cycle) and 240/240 (100% duty cycle). Any values greater than 240 are recognized as 100% maximum duty cycle. The POR state of the fan maximum duty-cycle register is F0h, 100%. In manual control mode, this register is ignored. Fan-Target Duty Cycle (09h) In automatic fan-control mode, this register contains the present value of the target PWM duty cycle, as determined by the measured temperature and the dutycycle step size. The actual duty cycle needs a settling time before it equals the target duty cycle if the dutycycle rate of change register is set to a value other than zero. The actual duty cycle needs the time to settle as defined by the value of the duty-cycle rate-of-change register; therefore, the target duty cycle and the actual duty cycle are often different. In manual fan-control mode, write the desired value of the PWM duty cycle directly into this register. The POR state of the fan-target duty-cycle register is 00h. ______________________________________________________________________________________ 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. See the Automatic PWM Duty-Cycle Control section for details on setting the fan-start thresholds. The POR state of the remote- and local-diode fan-start temperature registers is 00h. Fan Configuration (0Dh) The fan-configuration register controls the hysteresis level, temperature step size, and whether the remote or local diode controls the PWMOUT signal; see Table 1. Set bit D7 of the fan-configuration register to zero to set the hysteresis value to 5C. Set bit D7 to 1 to set the hysteresis value to 10C. Set bit D6 to zero to set the fan-control temperature step size to 1C. Set bit D6 to 1 to set the fan-control temperature step size to 2C. Set bit D5 to 1 to control the fan with the remote-diode's temperature reading. Set bit D4 to 1 to control the fan with the local-diode's temperature reading. If both bits D5 and D4 are high, the device uses the highest PWM value. If both bits D5 and D4 are zero, the MAX6641 runs in manual fan-control mode where only the value written to the fan-target duty-cycle register (09h) controls the PWMOUT duty cycle. In manual fan-control mode, the value written to the fan-target duty-cycle register is not limited by the value in the maximum dutycycle register. It is, however, clipped to 240 if a value above 240 is written. The POR state of the fan-configuration register is 00h. Duty-Cycle Rate of Change (0Eh) Bits D7, D6, and D5 of the duty-cycle rate-of-change register set the time between increments of the duty cycle. Each increment is 2/240 of the duty cycle; see Table 3. This allows the time from 33% to 100% duty cycle to be adjusted from 5s to 320s. The rate-ofchange control is always active in manual mode. To make instant changes, set bits D7, D6, D5 = 000. The POR state of the duty-cycle rate-of-change register is A0h (1s time between increments). Duty-Cycle Step Size (0Fh) Bits D7-D4 of the duty-cycle step-size register change the size of the duty-cycle change for each temperature step. The POR state of the duty-cycle step-size register is 50h; see Table 4. Table 4. Duty-Cycle Step-Size Register (0Fh) D7-D4 CHANGE IN DUTY CYCLE PER TEMPERATURE STEP TEMPERATURE RANGE FOR FAN CONTROL (1C STEP, 33% TO 100%) 0000 0/240 N/A 0001 2/240 80.00 0010 4/240 40.00 0011 6/240 26.67 0100 8/240 20.00 0101 10/240 16.00 0110 12/240 13.33 0111 14/240 11.43 1000 16/240 10.00 1001 18/240 8.89 1010 20/240 8.00 1011 22/240 7.27 1100 24/240 6.67 1101 26/240 6.15 1110 28/240 5.71 1111 30/240 5.33 PWM Frequency Select (10h) Set bits D7, D6, and D5 (select A, select B, and select C) in the PWM frequency-select register to control the PWMOUT frequency; see Table 5. The POR state of the PWM frequency select register is 40h, 33Hz. The lower frequencies are usually used when driving the fan's power-supply pin as in the Typical Application Circuit, with 33Hz being the most common choice. The 35kHz ______________________________________________________________________________________ 11 MAX6641 Fan Instantaneous Duty Cycle (0Ah) Read the fan instantaneous duty-cycle register to determine the duty cycle at PWMOUT at any time. The POR state of the fan instantaneous duty-cycle register is 00h. 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. PWM Output The PWMOUT signal is normally used in one of three ways to control the fan's speed: 1) PWMOUT drives the gate of a MOSFET or the base of a bipolar transistor in series with the fan's power supply. The Typical Application Circuit shows the PWMOUT pin driving an n-channel MOSFET. In this case, the PWM invert bit (D4 in register 02h) is set to 1. Figure 5 shows PWMOUT driving a p-channel MOSFET and the PWM invert bit must be set to zero. 2) PWMOUT is converted (using an external circuit) into a DC voltage that is proportional to duty cycle. This duty-cycle-controlled voltage becomes the power supply for the fan. This approach is less efficient than 1), but can result in quieter fan operation. Figure 6 shows an example of a circuit that converts the PWM signal to a DC voltage. Because this circuit produces a full-scale output voltage when PWMOUT = 0V, bit D4 in register 02h should be set to zero. 3) PWMOUT directly drives the logic-level PWM speed-control input on a fan that has this type of input. This approach requires fewer external components and combines the efficiency of 1) with the low noise of 2). An example of PWMOUT driving a fan with a speed-control input is shown in Figure 7. Bit D4 in register 02h should be set to 1 when this configuration is used. Whenever the fan has to start turning from a motionless state, PWMOUT is forced high for 2s. After this spin-up period, the PWMOUT duty cycle settles to the predetermined value. If spin-up is disabled (bit 2 in the configuration byte = 1), the duty cycle changes immediately from zero to the nominal value, ignoring the duty-cycle rate-of-change setting. 12 5V 10k PWMOUT P Figure 5. Driving a P-Channel MOSFET for Top-Side PWM Fan Drive +12V 500k P +3.3V 18k 0.01F 10k 120k PWMOUT 1F VOUT TO FAN 1F 27k +3.3V Figure 6. Driving a Fan with a PWM-to-DC Circuit VCC 5V 4.7k PWMOUT Figure 7. Controlling a PWM Input Fan with the MAX6641's PWM Output (Typically, the 35kHz PWM Frequency is Used) ______________________________________________________________________________________ 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. In manual control mode, the value of the maximum duty-cycle register is ignored and does not affect the duty cycle. Automatic PWM Duty-Cycle Control In the automatic control mode, the duty cycle is controlled by the local or remote temperature, according to the settings in the control registers. Below the value of the fan-start temperature threshold (set by registers 03h and 04h), the duty cycle is equal to the fan-start duty cycle. Above the fan-start temperature, the duty cycle increases by one duty-cycle step each time the temperature increases by one temperature step. Below the fanstart temperature, the duty cycle is either 0% or it is equal to the fan-start duty cycle, depending on the value of bit D3 in the configuration byte register. See Figure 8. The target duty cycle is calculated based on the following formula: For temperature > fan-start temperature: DC = FSDC + (T - FST) x DCSS TS MAX6641 The frequency-select register controls the frequency of the PWM signal. When the PWM signal modulates the power supply of the fan, a low PWM frequency (usually 33Hz) should be used to ensure the circuitry of the brushless DC motor has enough time to operate. When driving a fan with a PWM-to-DC circuit, as in Figure 6, the highest available frequency (35kHz) should be used to minimize the size of the filter capacitors. When using a fan with a PWM control input, the frequency should normally be high as well, although some fans have PWM inputs that accept low-frequency drive. The duty cycle of the PWM can be controlled in two ways: 1) Manual PWM control by setting the duty cycle of the fan directly through the fan-target duty-cycle register (09h). 2) Automatic PWM control by setting the duty cycle based on temperature. DUTY CYCLE REGISTER 02H, BIT D3 = 1 DUTY CYCLE STEP SIZE FAN START DUTY CYCLE TEMP STEP REGISTER 02H, BIT D3 = 0 TEMPERATURE FAN START TEMPERATURE Figure 8. Automatic PWM Duty Control FSDC = FanStartDutyCycle T = Temperature FST = FanStartTemperature DCSS = DutyCycleStepSize TS = TempStep Duty cycle is recalculated after each temperature conversion if temperature is increasing. If the temperature begins to decrease, the duty cycle is not recalculated until the temperature drops by 5C from the last peak temperature. The duty cycle remains the same until the temperature drops 5C from the last peak temperature or the temperature rises above the last peak temperature. For example, if temperature goes up to +85C and starts decreasing, duty cycle is not recalculated until the temperature reaches +80C or the temperature rises above +85C. If temperature decreases further, the duty cycle is not updated until it reaches +75C. For temperature < fan-start temperature and bit D3 of the configuration byte register = 0: DutyCycle = 0 For temperature < fan-start temperature and bit D3 of the configuration byte register = 1: Dutycycle = FanStartDutyCycle Once the temperature crosses the fan-start temperature threshold, the temperature has to drop below the fan-start temperature threshold minus the hysteresis before the duty cycle returns to either 0% or fan-start duty cycle. The value of the hysteresis is set by D7 of the fan-configuration register. where: DC = DutyCycle ______________________________________________________________________________________ 13 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. Duty-Cycle Rate-of-Change Control To reduce the audibility of changes in fan speed, the rate of change of the duty cycle is limited by the values set in the duty-cycle rate-of-change register. Whenever the target duty cycle is different from the instantaneous duty cycle, the duty cycle increases or decreases at the rate determined by the duty-cycle rate-of-change byte until it reaches the target duty cycle. By setting the rate of change to the appropriate value, the thermal requirements of the system can be balanced against good acoustic performance. Slower rates of change are less noticeable to the user, while faster rates of change can help minimize temperature variations. Remember that the fan controller is part of a complex control system. Because several of the parameters are generally not known, some experimentation may be necessary to arrive at the best settings. Power-Up Defaults At power-up, the MAX6641 has the default settings indicated in Table 1. Some of these settings are summarized below: * Temperature conversions are active. * Remote OT limit = +110C. * * * * Local OT limit = +80C. Manual fan mode. Fan duty cycle = 0. PWM Invert bit = 0. Effect of Ideality Factor The accuracy of the remote temperature measurements depends on the ideality factor (n) of the remote diode (actually a transistor). The MAX6641 is optimized for n = 1.008, which is the typical value for the Intel Pentium(R) III and the AMD AthlonTM MP model 6. If a sense transistor with a different ideality factor is used, the output data is different. Fortunately, the difference is predictable. Assume a remote-diode sensor designed for a nominal ideality factor nNOMINAL is used to measure the temperature of a diode with a different ideality factor, n1. The measured temperature TM can be corrected using: n1 TM = TACTUAL nNOMINAL where temperature is measured in Kelvin. As mentioned above, the nominal ideality factor of the MAX6641 is 1.008. As an example, assume the MAX6641 is configured with a CPU that has an ideality factor of 1.002. If the diode has no series resistance, the measured data is related to the real temperature as follows: n TACTUAL = TM NOMINAL = TM 1.008 = TM (1.00599) n1 1.002 For a real temperature of +85C (358.15K), the measured temperature is +82.87C (356.02K), which is an error of -2.13C. Effect of Series Resistance Series resistance in a sense diode contributes additional errors. For nominal diode currents of 10A and 100A, change in the measured voltage is: VM = RS(100A - 10A) = 90A x RS Since 1C corresponds to 198.6V, series resistance contributes a temperature offset of: * PWMOUT is high. When using an nMOS or npn transistor, the fan starts at full speed on power-up. V = 0.453 C V 198.6 C 90 Applications Information Remote-Diode Selection The MAX6641 can directly measure the die temperature of CPUs and other ICs that have on-board temperature-sensing diodes (see the Typical Application Circuit), or they can measure the temperature of a discrete diode-connected transistor. Assume that the diode being measured has a series resistance of 3. The series resistance contributes an offset of: : 3 x 0.453 C = + 1.36C Pentium is a registered trademark of Intel Corp. Athlon is a trademark of AMD. 14 ______________________________________________________________________________________ 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 10A, and at the lowest expected temperature, the forward voltage must be less than 0.95V at 100A. Large power transistors must not be used. Also, ensure that the base resistance is less than 100. Tight specifications for forward-current gain (50 < <150, for example) indicate that the manufacturer has good process controls and that the devices have consistent VBE characteristics. ADC Noise Filtering The integrating ADC used has good noise rejection for low-frequency signals such as 60Hz/120Hz power-supply hum. In noisy environments, high-frequency noise reduction is needed for high-accuracy remote measurements. The noise can be reduced with careful PC board layout and proper external noise filtering. High-frequency EMI is best filtered at DXP and DXN with an external 2200pF capacitor. Larger capacitor values can be used for added filtering, but do not exceed 3300pF because larger values can introduce errors due to the rise time of the switched current source. PC Board Layout Follow these guidelines to reduce the measurement error of the temperature sensors: 1) Place the MAX6641 as close as is practical to the remote diode. In noisy environments, such as a computer motherboard, this distance can be 4in to 8in typically. This length can be increased if the worst noise sources are avoided. Noise sources include CRTs, clock generators, memory buses, and ISA/PCI buses. MAX6641 The effects of the ideality factor and series resistance are additive. If the diode has an ideality factor of 1.002 and series resistance of 3, the total offset can be calculated by adding error due to series resistance with error due to ideality factor: 1.36C - 2.13C = -0.1477C for a diode temperature of +85C. In this example, the effect of the series resistance and the ideality factor partially cancel each other. For best accuracy, the discrete transistor should be a small-signal device with its collector connected to GND and base connected to DXN. Table 6 lists examples of discrete transistors that are appropriate for use with the MAX6641. Table 6. Remote-Sensor Transistor Manufacturers MANUFACTURER Central Semiconductor (USA) Rohm Semiconductor (USA) MODEL NO. CMPT3906 SST3906 Samsung (Korea) KST3906-TF Siemens (Germany) SMBT3906 2) Do not route the DXP-DXN lines next to the deflection coils of a CRT. Also, do not route the traces across fast digital signals, which can easily introduce 30C error, even with good filtering. 3) Route the DXP and DXN traces in parallel and in close proximity to each other, away from any higher voltage traces, such as 12VDC. Leakage currents from PC board contamination must be dealt with carefully since a 20M leakage path from DXP to ground causes about 1C error. If high-voltage traces are unavoidable, connect guard traces to GND on either side of the DXP-DXN traces (Figure 9). 4) Route through as few vias and crossunders as possible to minimize copper/solder thermocouple effects. 5) When introducing a thermocouple, make sure that both the DXP and the DXN paths have matching thermocouples. A copper-solder thermocouple exhibits 3V/C, and takes about 200V of voltage error at DXP-DXN to cause a 1C measurement error. Adding a few thermocouples causes a negligible error. 6) Use wide traces. Narrow traces are more inductive and tend to pick up radiated noise. The 10-mil widths and spacing recommended in Figure 9 are not absolutely necessary, as they offer only a minor improvement in leakage and noise over narrow traces. Use wider traces when practical. 7) Add a 200 resistor in series with V CC for best noise filtering (see the Typical Application Circuit). 8) Copper cannot be used as an EMI shield; only ferrous materials such as steel work well. Placing a copper ground plane between the DXP-DXN traces and traces carrying high-frequency noise signals does not help reduce EMI. ______________________________________________________________________________________ 15 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. For longer distances, the best solution is a shielded twisted pair like that used for audio microphones. For example, Belden 8451 works well for distances up to 100ft in a noisy environment. At the device, connect the twisted pair to DXP and DXN and the shield to GND. Leave the shield unconnected at the remote sensor. For very long cable runs, the cable's parasitic capacitance often provides noise filtering, so the 2200pF capacitor can often be removed or reduced in value. Cable resistance also affects remote-sensor accuracy. For every 1 of series resistance, the error is approximately 0.5C. Typical Application Circuit VCC (3.0V TO 5.5V) VFAN (5V OR 12V) When sensing local temperature, these devices are intended to measure the temperature of the PC board to which they are soldered. The leads provide a good thermal path between the PC board traces and the die. Thermal conductivity between the die and the ambient air is poor by comparison, making air temperature measurements impractical. Because the thermal mass of the PC board is far greater than that of the MAX6641, the devices follow temperature changes on the PC board with little or no perceivable delay. When measuring the temperature of a CPU or other IC with an onchip sense junction, thermal mass has virtually no effect. The measured temperature of the junction tracks the actual temperature within a conversion cycle. When measuring temperature with discrete remote sensors, smaller packages, such as MAXes, yield the best thermal response times. Take care to account for thermal gradients between the heat source and the sensor, and ensure stray air currents across the sensor package do not interfere with measurement accuracy. Self-heating does not significantly affect measurement accuracy. Remote-sensor self-heating due to the diode current source is negligible. Chip Information TRANSISTOR COUNT: 18,769 PROCESS: BiCMOS 5V 0.1F 10k PWMOUT DXP 2200pF DXN MAX6641 5V 10k EACH SMBCLK P SMBDATA OT GND 16 TO CLOCK THROTTLE OR SYSTEM SHUTDOWN ______________________________________________________________________________________ SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller 10LUMAX.EPS e 4X S 10 10 INCHES H O0.500.1 0.60.1 1 1 0.60.1 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 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 0.940 REF 0.177 0.270 0.500 BSC 0.090 0.200 0.498 REF 0 6 E2 GAGE PLANE A2 c A b A1 E1 L D1 L1 FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 10L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0061 REV. 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 17 (c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX6641 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) ENGLISH * ???? * ??? * ??? WHAT'S NEW PRODUCTS SOLUTIONS DESIGN APPNOTES SUPPORT BUY COMPANY MEMBERS MAX6641 Part Number Table Notes: 1. See the MAX6641 QuickView Data Sheet for further information on this product family or download the MAX6641 full data sheet (PDF, 476kB). 2. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales. 3. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day. 4. Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt. More: See full data sheet or Part Naming C onventions. 5. * Some packages have variations, listed on the drawing. "PkgC ode/Variation" tells which variation the product uses. Part Number Free Sample Buy Direct Package: TYPE PINS SIZE DRAWING CODE/VAR * Temp RoHS/Lead-Free? Materials Analysis MAX6641AUB90 uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB96+ uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis MAX6641AUB94+T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis MAX6641AUB94+ uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis MAX6641AUB92+T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis MAX6641AUB92+ uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis MAX6641AUB90+T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis MAX6641AUB90+ uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis MAX6641AUB96-T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB96 uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB94-T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB94 uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB92-T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB92 uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB90-T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10-2* -40C to +125C RoHS/Lead-Free: No Materials Analysis MAX6641AUB96+T uMAX;10 pin;3 x 3mm Dwg: 21-0061I (PDF) Use pkgcode/variation: U10+2* -40C to +125C RoHS/Lead-Free: Yes Materials Analysis Didn't Find What You Need? C ONTAC T US: SEND US AN EMAIL C opyright 2 0 0 7 by M axim I ntegrated P roduc ts , Dallas Semic onduc tor * Legal N otic es * P rivac y P olic y