19-2865; Rev 1; 12/03 Temperature Monitors and PWM Fan Controllers Internal watchdog set points are provided for both local and remote temperatures. There are two comparison set points for local temperatures and two for remote temperatures. When a set point is crossed, the MAX6653/MAX6663/MAX6664 assert either the INT or THERM outputs. These outputs can be used as interrupts, clock throttle signals, or overtemperature shutdown signals. Two pins on the MAX6653 control the power-up values of the comparison set points, providing fail-safe protection even when the system is unable to program the trip temperatures. The MAX6653 has two additional shutdown outputs, SDR and SDL, that are triggered when the remote or local temperatures exceed the programmed shutdown set points. The INT output for the MAX6653/MAX6663 and THERM outputs for the MAX6653/MAX6663/MAX6664 can also function as inputs if either is pulled low to force the fan to full speed, unless this function is masked by the user. The MAX6653/MAX6663/MAX6664 are available in 16-pin QSOP packages and operate over the -40°C to +125°C temperature range. Features ♦ Remote-Junction Temperature Sensor Within ±1°C Accuracy (+60°C to +100°C) ♦ ACPI-Compatible Programmable Temperature Alarms ♦ 0.125°C Resolution Local and Remote-Junction Temperature Measurement ♦ Programmable Temperature Offset for System Calibration ♦ SMBus 2-Wire Serial Interface with Timeout ♦ Automatic or Manual Fan-Speed Control ♦ PWM Fan Control Output ♦ Fan-Speed Monitoring and Watchdog ♦ Fan Fault and Failure Indicators ♦ Compatible with 2-Wire or 3-Wire Fans (Tachometer Output) ♦ +3V to +5.5V Supply Range ♦ Additional Shutdown Set Point (MAX6653) ♦ Controlled PWM Rise/Fall Times Ordering Information PART TEMP RANGE MAX6653AEE -40°C to +125°C 16 QSOP MAX6663AEE -40°C to +125°C 16 QSOP MAX6664AEE -40°C to +125°C 16 QSOP Applications Personal Computers Servers Workstations Telecom Equipment Networking Equipment Test Equipment Industrial Controls Pin Configurations TOP VIEW PWM_OUT 1 16 SMBCLK TACH/AIN 2 15 SMBDATA CRT0 3 CRT1 4 14 INT MAX6653 13 ADD GND 5 12 SDR VCC 6 11 SDL THERM 7 10 DXP FAN_FAULT 8 Typical Operating Circuits appear at end of data sheet. Functional Diagram appears at end of data sheet. PIN-PACKAGE 9 DXN QSOP Pin Configurations continued at end of data sheet. ________________________________________________________________ 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 MAX6653/MAX6663/MAX6664 General Description The MAX6653/MAX6663/MAX6664 are ACPI-compliant local and remote-junction temperature sensors and fan controllers. These devices measure their own die temperature, as well as the temperature of a remote-PN junction and control the speed of a DC cooling fan based on the measured temperature. Remote temperature measurement accuracy is ±1°C from +60°C to +100°C. Temperature measurement resolution is 0.125°C for both local and remote temperatures. MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers ABSOLUTE MAXIMUM RATINGS All Voltages Are Referenced to GND TACH/AIN ..............................................................-0.3V to +5.5V VCC ...........................................................................-0.3V to +6V DXP, ADD, CRIT0, CRIT1........................-0.3V to + (VCC + 0.3V) DXN .......................................................................-0.3V to +0.8V SMBDATA, SMBCLK, INT, THERM, FAN_FAULT, SDL, SDR............................................-0.3V to +6V SMBDATA, INT, THERM, FAN_FAULT, PWM_OUT Current..............................................-1mA to +50mA DXN Current .......................................................................±1mA ESD Protection (all pins, Human Body Model) ..................2000V Continuous Power Dissipation (TA = +70°C) 16-Pin QSOP (derate 8.3 mW/°C above +70°C)..........667mW Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +165°C Lead Temperature (soldering, 10s) .................................+300°C 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 = 0°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V, TA = +25°C.) (Note1) PARAMETER Operating Supply Voltage Range SYMBOL Standby Current Operating Current Average Operating Current External Temperature Error Internal Temperature Error CONDITIONS VCC SMBDAT = SMBCLK = 1, register 00h = 00h IS TACHOMETER Conversion Cycle Time 2 UNITS 5.5 V 10 µA 0.5 1 mA Conversion rate = 4Hz (default) 150 300 µA VCC = +3.3V, TA = 0°C to +100°C, +60°C ≤ TR ≤ +100°C ±1 VCC = +3.3V, 0°C ≤ TR ≤ +100°C ±3 VCC = +3.3V, -25°C ≤ TR ≤ +125°C ±4 VCC = +3.3V, 0°C ≤ TA ≤ +100°C ±2 VCC = +3.3V, -40°C ≤ TA ≤ +125°C ±4 0.125 °C °C °C 11 Bits (Note 2) 6 % 255 Divisor = 1, fan count = 153 4400 Divisor = 2, fan count = 153 2200 Divisor = 4, fan count = 153 1100 Divisor = 8, fan count = 153 Internal Clock Frequency MAX SMBDAT = SMBCLK = 1 Fan TACHOMETER Full-Scale Count TACHOMETER Nominal Input RPM TYP 3.0 Temperature Resolution (Internal and External) Fan TACHOMETER Accuracy MIN RPM 550 254 270 637 _______________________________________________________________________________________ 286 kHz ms Temperature Monitors and PWM Fan Controllers MAX6653/MAX6663/MAX6664 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.) (Note1) PARAMETER SYMBOL CONDITIONS MIN Temperature Conversion Time TYP MAX 250 Conversion Rate Timing Error Remote-Diode Sourcing Current UNITS ms (Note 2) 25 25 High level 80 100 120 Low level 8 10 12 % µA DXN Source Voltage 0.7 V TACHOMETER Input Hysteresis 100 mV Output Low Voltage (Sink Current) VOL SDL, SDR, THERM, FAN_FAULT, SMBDATA, PWM_OUT, VCC = +3V, IOUT = 6mA, INT, VCC = +3V, IOUT = 4mA Output High Leakage Current IOH INT, SDL, SDR, THERM, FAN_FAULT, SMBDATA, PWM_OUT Logic Low Input Voltage VIL SMBDATA, SMBCLK, INT, THERM, TACH/AIN VIH SMBDATA, SMBCLK, INT, THERM, TACH/AIN Logic High Input Voltage Input Leakage Current Input Capacitance ILEAK 3.0V 2.2 5.5V 2.6 0.4 V 1 µA 0.8 V V SMBDATA, SMBCLK, INT, THERM; VIN = VCC or GND ±1 CIN 5 µA pF SMBus TIMING Serial Clock Frequency fSCLK (Note 2) 10 100 kHz Clock Low Period tLOW 10% to 10% (Note 2) 4 µs Clock High Period tHIGH 90% to 90% (Note 2) 4.7 µs Bus Free Time Between Stop and Start Condition tBUF (Note 2) 4.7 µs SMBus Start Condition Setup Time tSU:STA 90% of SMBCLK to 90% of SMBDATA (Note 2) 4.7 µs Start Condition Hold Time tHD:STO 10% of SMBDATA to 10% of SMBCLK (Note 2) 4 µs Stop Condition Setup Time tSU:STO 90% of SMBCLK to 10% of SMBDATA (Note 2) 4 µs Data Setup Time tSU:DAT 10% of SMBDATA to 10% of SMBCLK (Note 2) 250 ns Data Hold Time tHD:DAT 10% of SMBCLK to 10% of SMBDATA (Note 2) 300 SMBus Fall Time tF (Note 2) 300 ns SMBus Rise Time tR (Note 2) 1000 ns 45 ms SMBus Timeout 29 ns 37 +85oC. Note 1: Tested at Values through the temperature range are guaranteed by design. Note 2: Not production tested, guaranteed by design. _______________________________________________________________________________________ 3 Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) 4.0 3.5 3.0 1.5 TEMPERATURE ERROR (°C) 400 350 300 250 200 150 100 2.5 0 3.5 4.0 4.5 5.0 -0.5 -1.0 1 2 3 4 -40 -25 -10 5 20 35 50 65 80 95 110 125 CONVERSION RATE (Hz) REMOTE-DIODE TEMPERATURE (°C) LOCAL TEMPERATURE ERROR vs. DIE TEMPERATURE REMOTE TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY LOCAL TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY 1.0 0.5 0 -0.5 -1.0 250mVP-P 8 7 6 5 4 3 100mVP-P 2 -1.5 1 -2.0 0 0.01 0.1 1 10 6 20mVP-P 2 0 100mVP-P 5 20mVP-P 3 2 COMMON-MODE NOISE FREQUENCY (MHz) 100 10 100 1 0 -1 -2 -3 -4 0 10 1 MAX6653 toc09 30mVP-P 4 0.1 TEMPERATURE ERROR vs. DXP-DXN CAPACITANCE MAX6653 toc08 7 6 0.01 POWER-SUPPLY NOISE FREQUENCY (MHz) 1 1 1 0 0.001 TEMPERATURE ERROR (°C) 8 0.1 2 100 8 TEMPERATURE ERROR (°C) 40mVP-P 0.01 3 TEMPERATURE ERROR vs. DIFFERENTIAL-MODE NOISE FREQUENCY MAX6653 toc07 12 -2 0.0001 0.001 4 POWER-SUPPLY NOISE FREQUENCY (MHz) TEMPERATURE ERROR vs. COMMON-MODE NOISE FREQUENCY 4 250mVP-P 5 -2 DIE TEMPERATURE (°C) 10 6 -1 0.001 -40 -25 -10 5 20 35 50 65 80 95 110 125 7 MAX6653 toc06 9 REMOTE TEMPERATURE ERROR (°C) 1.5 10 MAX6653 toc05 MAX6653 toc04 LOCAL TEMPERATURE ERROR (°C) 0 SUPPLY VOLTAGE (V) 2.0 4 0.5 -2.0 0 5.5 REMOTE TEMPERATURE ERROR (°C) 3.0 1.0 -1.5 50 2.0 MAX6653 toc03 450 SUPPLY CURRENT (µA) 4.5 2.0 MAX6653 toc02 500 MAX6653 toc01 5.0 STANDBY SUPPLY CURRENT (µA) REMOTE TEMPERATURE ERROR vs. REMOTE-DIODE TEMPERATURE AVERAGE OPERATING SUPPLY CURRENT vs. CONVERSION RATE STANDBY SUPPLY CURRENT vs. SUPPLY VOLTAGE TEMPERATURE ERROR (°C) MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers -5 0.01 0.1 1 10 100 DIFFERENTIAL-MODE NOISE FREQUENCY (MHz) 1 10 DXP-DXN CAPACITANCE (nF) _______________________________________________________________________________________ 100 Temperature Monitors and PWM Fan Controllers PIN MAX6653 QSOP MAX6663/ MAX6664 QSOP NAME 1 1 PWM_OUT Digital Output (Open Drain). Pulse-width modulated output to external power transistor. Requires a pullup resistor (10kΩ typ). 2 2 TACH/AIN Digital/Analog Input. Fan tachometer input. May be reprogrammed as an analog input to measure speed of a 2-wire fan. See Figure 5. 3 — CRIT0 Input. Used in conjunction with CRIT1 to set THERM and SHUTDOWN default set points (see Table 1). 4 — CRIT1 Input. Used in conjunction with CRIT0 to set THERM and SHUTDOWN default set points (see Table 1). — 3, 4 N.C. No Connection. Not internally connected. 5 5 GND Ground 6 6 VCC Power Supply. Bypass with a 0.01µF capacitor to GND. FUNCTION Digital I/O (Open Drain). An active-low thermal-overload output to indicate that the overtemperature set point has been exceeded. Also acts as an input to provide external fan control. When this pin is pulled low by an external signal, a status bit is set and the fan speed is forced full-on. Requires a pullup resistor (10kΩ typ). 7 7 THERM 8 8 FAN_FAULT 9 9 DXN Combined Current Sink and A/D Negative Input. DXN is internally biased to a diode voltage above ground. 10 10 DXP Combined Current Source and A/D Positive Input for the Remote-Diode Channel. Do not leave DXP floating; connect DXP to DXN if no remote diode is used. Place a 2200pF capacitor between DXP and DXN for noise filtering. 11 — SDL An Active-Low Open-Drain Output. It indicates that local temperature is above the shutdown set point. Normally used to directly deactivate the CPU power supply. 12 — SDR An Active-Low Open-Drain Output. It indicates that remote temperature is above the shutdown set point. Normally used to directly deactivate the CPU power supply. — 11, 12 N.C. Internal Connection. Leave floating or connect to GND. 13 13 ADD Three-State Logic Input. Sets the 2 lower bits of the device SMBus address (Table 2). ADD is not an ordinary logic input pin; ADD should be connected to VCC, GND, or float. Digital Output (Open Drain). Can be programmed as an interrupt output for temperature/fan speed interrupts. Requires a pullup resistor (10kΩ typ). For the MAX6653/MAX6663, it can be used also as an input. If pulled low, fan speed is forced to maximum unless masked. 14 14 INT 15 15 SMBDATA 16 16 SMBCLK — 12 N.C. Digital Output (Active Low, Open Drain). Signals a fan fault. Requires a pullup resistor (10kΩ typ). SMBus Serial-Data Input/Output (Open Drain). Requires a pullup resistor (10kΩ typ). SMBus Serial-Clock Input. Requires a pullup resistor (10kΩ typ). Internal Connection. Leave floating or connect to GND. _______________________________________________________________________________________ 5 MAX6653/MAX6663/MAX6664 Pin Description MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers Table 1. MAX6653 Power-Up Set-Point Decoding CRIT1 CRIT0 GND GND THERM SET POINT (°C) LOCAL REMOTE LOCAL Open 85 55 110 80 GND 90 60 115 85 GND VCC 95 65 120 90 Open Open 100 70 125 95 Open GND 105 75 125 95 Open VCC 110 80 125 95 VCC Open 115 85 125 95 VCC GND 120 90 125 95 VCC VCC 125 95 125 95 Detailed Description The MAX6653/MAX6663/MAX6664 are local/remote temperature monitors and fan controllers for microprocessor-based systems. These devices communicate with the system through a serial SMBus interface. The serial bus controller features a hard-wired address pin for device selection, an input line for a serial clock, and a serial line for reading and writing addresses and data (see Functional Diagram). The MAX6653/MAX6663/MAX6664 fan control section can operate in three modes. In the automatic fan-control mode, the fan’s power-supply voltage is automatically adjusted based on temperature. The control algorithm parameters are programmable to allow optimization to the characteristics of the fan and the system. RPM select mode forces the fan speed to a programmed tachometer value. PWM duty cycle select mode allows user selection of the PWM duty cycle. PWM rise and fall times are limited to maximize fan reliability. To ensure overall system reliability, the MAX6653/ MAX6663/MAX6664 feature an SMBus timeout so that the MAX6653/MAX6663/MAX6664 can never “lock” the SMBus. Furthermore, the availability of hard-wired default values for critical temperature set points ensures the MAX6653 controls critical temperature events properly even if the SMBus is “locked” by some other device on the bus. SMBus Digital Interface From a software perspective, the MAX6653/MAX6663/ MAX6664 appear as a set of byte-wide registers. These devices use a standard SMBus 2-wire/I2C-compatible serial interface to access the internal registers. The MAX6653/MAX6663/MAX6664 slave address can be set to three different values by the input pin ADD 6 SHUTDOWN SET POINT (°C) REMOTE (Table 2) and, therefore, a maximum of three MAX6653/ MAX6663/MAX6664 devices can share the same bus. The MAX6653/MAX6663/MAX6664 employ 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. Alert Response Address The MAX6653/MAX6663/MAX6664 respond to the SMBus alert response address, an event which typically occurs after an SMBus host master detects an INT interrupt signal going active (referred to as ALERT in SMBus nomenclature). When the host master puts the alert response address (0001 1001) on the bus, all devices with an active INT output respond by putting their own address onto the bus. The alert response can activate several different slave devices simultaneously, similar to the I2C general call. If more than one slave attempts to respond, bus arbitration rules apply, and the device with the lowest address code wins. The master then services the devices from the lowest address up. Table 2. MAX6653/MAX6663/MAX6664 Slave Address Decoding ADD PIN ADDRESS GND 0101 100 No connect 0101 110 VCC 0101 101 _______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers MAX6653/MAX6663/MAX6664 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 which register you are writing to Data Byte: data goes into the register set by the co mma nd byte ( to se t thresholds, configuration masks, and sampling rate) Read Byte Format S WR ADDRESS ACK COMMAND 7 bits ACK S Slave Address: equivalent to chip-select line ADDRESS RD ACK DATA 7 bits Command Byte: selects which register you are reading from P Data Byte: reads from the register set by the command byte Receive Byte Format WR ACK COMMAND 7 bits ACK P S ADDRESS 8 bits RD ACK DATA 7 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 Data Byte: writes data to the register commanded by the last read byte or write byte transmission S = Start condition P = Stop condition /// 8 bits Slave Address: repeated due to change in dataflow direction Send Byte Format S ADDRESS 8 bits Shaded = Slave transmission / / / = Not acknowledged Figure 1. SMBus Protocols A tLOW B tHIGH C D E F G H I J K L M SMBCLK SMBDATA tSU:STA tHD: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 tSU:DAT tHD:DAT 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 tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION, DATA EXECUTED BY SLAVE M = NEW START CONDITION Figure 2. SMBus Write Timing Diagram _______________________________________________________________________________________ 7 MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers A tLOW B tHIGH C D E F G H I J K L M SMBCLK SMBDATA tSU:STA tHD: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 tSU:DAT tHD:DAT tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLEAR PULSE L = STOP CONDITION, EXECUTED BY SLAVE M = NEW START CONDITION 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 Figure 3. SMBus Read Timing Diagram The MAX6663 resets its INT output and some of the status bits in the status register after responding to an alert response address; however, if the error condition that caused the interrupt is still present, INT is reasserted on the next monitoring cycle. INT is maskable to allow full control of ALERT conditions. Temperature Measurement The MAX6653/MAX6663/MAX6664 contain on-chip temperature sensors to sense their own die (local) temperatures. These devices can also measure remote temperatures such as the die temperature of CPUs or other ICs having on-chip temperature-sensing diodes, or discrete diode-connected transistors as shown in the Typical Operating Circuits. For best accuracy, the discrete diode-connected transistor should be a small-signal device with its collector and base connected together. The on-chip ADC converts the sensed temperature and outputs the temperature data in the format shown in Tables 3 and 4. The temperature measurement resolution is 0.125°C for both local and remote temperatures. The temperature accuracy is within ±1°C for remote temperature measurements from +60°C to +100°C. The Local Temperature Offset (0Dh) and Remote Temperature Offset (0Eh) registers allow the measured temperature to be increased or decreased by a fixed value to compensate for errors due to variations in diode resistance and ideality factor (see the Remote Diode Considerations section). The reported temperature is the measured temperature plus the correction value. Both the measured temperature and the reported value are limited by the sensor’s temperature range. For example, if a remote thermal diode is being measured and its temperature is 135°C, the measured temperature is the maximum 8 value of 127.875°C. If the remote offset value is set to 10°C, the reported value is 117.875°C, not 125°C. The temperature conversion rate is programmable using bits [4:2] of the fan filter register (23h) as shown in Table 5. The DXN input is biased at 0.65V above ground by an internal diode to set up the analog-to-digital inputs for a differential measurement. The worst-case DXP-DXN differential input voltage range is from 0.25V to 0.95V. Excess resistance in series with the remote diode causes about 0.5°C error per ohm. Likewise, a 200µV offset voltage forced on DXP-DXN causes about 1°C error. High-frequency EMI is best filtered at DXP and DXN with an external 2200pF capacitor. This value can be increased to about 3300pF, including cable capacitance. Capacitance higher than 3300pF introduces errors due to the rise time of the switched current source. Table 3. Temperature Data High Byte Format TEMP (°C) DIGITAL OUTPUT (°C) DIGITAL OUTPUT (BINARY) 130.00 +127 0111 1111 127.00 +127 0111 1111 126.00 +126 0111 1110 25.25 +25 0001 1001 0.50 0 0000 0000 0.00 0 0000 0000 -1 — 1111 1111 -125 — 1000 0011 -128 — 1000 0000 Diode fault (short or open) — 1000 0000 _______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers MAX6653/MAX6663/MAX6664 Table 4. Temperature Data Low Byte Format Structure: LLLXXRRR* FRACTIONAL TEMPERATURE (°C) DIGITAL OUTPUT (LOCAL) DIGITAL OUTPUT (REMOTE) 0.000 000X XXXX XXX XX 000 0.125 001X XXXX XXX XX 001 0.25 010X XXXX XXX XX 010 0.375 011X XXXX XXX XX 011 XXX XX 100 0.5 100X XXXX 0.625 101X XXXX XXX XX 101 0.75 110X XXXX XXX XX 110 0.875 111X XXXX XXX XX 111 *Where: LLL = local fractional temperature bits, XX = don’t care, RRR = remote fractional temperature bits. Table 5. Temperature Conversion Rate Setting (Fan Filter Register (23h)—POR = 111) BIT 4 BIT 3 BIT2 CONVERSION RATE (Hz) CONVERSION TIME (s) 0 0 0 0.0625 16 0 0 1 0.125 8 4 0 1 0 0.25 0 1 1 0.5 2 1 0 0 1 1 1 0 1 2 0.5 1 1 0 4 0.25 1 1 1 4 0.25 Table 6. Threshold Limit Registers NAME ADDRESS R/W MAX6653 POR VALUE MAX6663/MAX6664 POR STATE DESCRIPTION Local temp high limit LTH 14h R/W Set by CRIT0 and CRIT1 0011 1100 LTL 15h R/W Set by CRIT0 and CRIT1 0000 0000 Local temp low limit LTHER 16h R/W Set by CRIT0 and CRIT1 0100 0110 Local temp THERM limit RTH 18h R/W Set by CRIT0 and CRIT1 0101 0000 Remote temp high limit RTL 19h R/W Set by CRIT0 and CRIT1 0000 0000 Remote temp low limit RTHER 1Ah R/W Set by CRIT0 and CRIT1 0110 0100 Remote temp THERM limit LTSD 1Bh R/W Set by CRIT0 and CRIT1 N/A Local temp shutdown limit (MAX6653 only) RTSD 1Ch R/W Set by CRIT0 and CRIT1 N/A Remote temp shutdown limit (MAX6653 only) Temperature Comparison and Interrupt System At the end of each conversion cycle, the converted temperature data are compared to various set-point thresholds to control the INT, THERM, SDL, and SDR outputs. All temperature threshold limits are stored in the threshold limit registers (Table 6) and can be changed through the SMBus digital interface. THERM is an active-low thermal-overload output indicating that the THERM overtemperature set point is exceeded. With the THERM threshold set to an appropriate value, the THERM output can be used to control clock throttling. When this pin is pulled low by an external signal, a status bit (bit 7, status register 2) is set, and the fan speed is unconditionally forced to full-on speed. The only way to reset the status bit is to read status register 2. Connect a 10kΩ pullup resistor between THERM and VCC. _______________________________________________________________________________________ 9 MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers INT is an open-drain digital output that reports the status of temperature interrupt limits and fan out-of-limit conditions. Set bit 1 of configuration register 1 (00h) to 1 to enable INT output or reset this bit to zero to disable the INT output function. Status register 1 contains status information for the conditions that cause INT to assert. Reading status register 1 resets INT, but INT is reasserted if the fault condition still exists. Connect a 10kΩ pullup resistor between INT and VCC. SDL and SDR are open-drain digital outputs on the MAX6653 that can be used to shut the system down based on the local (die) temperature of the MAX6653 or the temperature of the remote sensor, respectively. The trip thresholds for SDL and SDR are normally set above the THERM and INT limits. Their power-up values are set by the CRIT1 and CRIT0 pins, as shown in Table 1. Fan-Speed Control The MAX6653/MAX6663/MAX6664 fan-control section can operate in one of three modes depending on the setting of bit 7 to bit 5 of configuration register 1 (00h). Regardless of the mode of operation, the PWM output frequency is programmable, and the fan speed is measured with the result stored in the fan-speed register (08h). PWM Output Frequency The PWM output frequency is programmed by bit 5, bit 4, and bit 3 of the fan characteristics register (20h), regardless of the mode of operation. See Table 7. Fan-Control Mode The mode of fan-speed control operation is set by bit 7, bit 6, and bit 5 in configuration register 1 (00h), as shown in Table 8. PWM Duty-Cycle Fan-Control Mode Bits [3:0] of the fan-speed configuration register set the PWM duty cycle. See Table 9 for more details. RPM Select Fan-Control Mode In RPM select mode, the MAX6653/MAX6663/MAX6664 adjust their PWM output duty cycle to match a selected fan speed measured by a tachometer count value. Before selecting this mode by setting bits [7:5] of configuration register 1 (00h) to 0x1, the desired tachometer count value should be written to the fan tachometer high-limit register (10h). In this mode, the MAX6653/MAX6663/ MAX6664 are not able to detect underspeed fan faults because the fan tachometer high-limit register (10h) functions as the target tachometer count. The MAX6653/MAX6663/MAX6664 detect fan stall faults by comparing the fan-speed reading to the fullscale constant of 254 (FEh). Therefore, the MAX6653/MAX6663/MAX6664 signal a fan fault when the fan-speed reading is 255 (FFh). Note that the RPM mode cannot be used for speeds below 10% of the fan’s maximum speed. It is important to verify that a fan works properly at lower RPM values if a low-RPM operation in this mode is desired. Table 7. Setting PWM Output Frequency FAN CHARACTERISTICS REGISTER (20H) POR = 011 BIT 5 BIT 4 BIT 3 PWM FREQUENCY (Hz) 0 0 0 11.7 0 0 1 15.6 0 1 0 23.4 0 1 1 31.25 1 0 0 37.5 1 0 1 46.9 1 1 0 62.5 1 1 1 93.5 Table 8. Setting the Fan-Speed Control Mode (Default = 100) Bits [7:5] MODE OF OPERATION 0x0 PWM duty-cycle mode 10 DESCRIPTION Directly program the PWM duty cycle by writing to bits [3:0] of the fan-speed configuration register (22h). 0x1 RPM select mode Program the desired fan speed by writing to the fan tachometer high-limit register (10h). This value should be written after selecting the RPM mode. The MAX6653/MAX6663/MAX6664 then adjust the PWM duty cycle to cause the fan to spin at the programmed speed. 100 Automatic mode PWM duty cycle is automatically controlled by the remote temperature. 111 Automatic mode PWM duty cycle is automatically controlled by both the remote and the local temperatures. See the Automatic Fan-Control Mode section. ______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers BITS [3:0] OF FAN-SPEED CONFIGURATION REGISTER (22h) % DUTY CYCLE (%) BIT 3 BIT 2 BIT 1 BIT 0 0 0 0 0 0 0 0 1 7 0 0 1 0 14 0 0 1 1 20 0 1 0 0 27 0 1 0 1 33 0 1 1 0 40 0 1 1 1 47 1 0 0 0 53 1 0 0 1 60 1 0 1 0 67 1 0 1 1 73 1 1 0 0 80 1 1 0 1 87 1 1 1 0 93 1 1 1 1 100 0 Automatic Fan-Control Mode Automatic fan-speed control is selected by setting bits [7:5] of configuration register 1 (00h) to 100 (to control speed based on the remote temperature) or 101 (to control speed based on both remote and local temperature). Program a threshold, or starting temperature TMIN, and the desired temperature range, TRANGE, into the local temp TMIN/TRANGE register (24h) for local temperature and into the remote temp TMIN/TRANGE register (25h) for remote temperature (Tables 10 and 11). If the fan control responds to both local and remote temperatures, the higher PWM duty cycle has priority. Table 10. TRANGE Fan-Control Temperature Range Bits [2:0] TMIN/TRANGE Registers (24h and 25h)—POR = 001 BIT 2 BIT 1 BIT 0 TEMPERATURE RANGE (°C) 0 0 0 5 0 0 1 10 0 1 0 20 0 1 1 40 1 0 0 80 When the temperature exceeds T MIN , the fan is enabled at a minimum duty cycle programmed in bits [3:0] of the fan-speed configuration register (22h). The duty cycle increases in proportion to the temperature difference and reaches 100% at a temperature equal to (TMIN + TRANGE). A hysteresis of 5°C is built into the TMIN set point to prevent the fan from starting and stopping when the temperature is at the set point. Spin-Up To ensure proper fan startup, the MAX6653/MAX6663/ MAX6664 can be set to drive the fan to 100% duty cycle for a short period on startup, and then revert to the correct duty cycle. The spin-up time is programmed by bits [2:0] in the fan characteristics register (20h). The spin-up feature can be disabled by setting bit 7 of the fan-filter register (23h) to 1; POR value is zero. Table 12 shows programming of the spin-up time. Fan-Filter Mode When the MAX6653/MAX6663/MAX6664 are used for automatic fan-speed control, the fan-filter mode helps minimize the audible effects of varying fan speeds. The fan-filter mode limits the rate at which fan speed can change. Each time a new temperature measurement is made, the fan-filter mode allows the PWM duty cycle to increment by a selectable amount. The duty cycle can change by 1/240, 2/240, 4/240, or 8/240 (0.416%, 0.833%, 1.667%, or 3.333%) of the PWM period after each temperature-monitoring cycle. This prevents sudden changes in fan speed, even when temperature changes suddenly. The filter mode is set by bit 0 of the fan-filter register (23h). To enable the fan-filter mode, write a 1 to this bit. Bits [6:5] of the same register control the size of the PWM steps. Note that the rate of change depends on both the value selected by the fan-filter bits and on the temperature Table 11.TMIN Fan-Control Start Temperature; Bits [7:3] TMIN/TRANGE Registers (24h—POR = 01000 and 25h—POR = 01100 BIT 7 BIT 6 BIT5 BIT 4 MSB = +64°C BIT3 LSB = +4°C Min threshold = 0°C Max threshold = +127°C LSB/step size = +4°C POR = +48°C or 01100b ______________________________________________________________________________________ 11 MAX6653/MAX6663/MAX6664 Table 9. Setting PWM Duty Cycle MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers Table 12. Spin-Up Time; Bits [2:0] Fan Characteristics Register (20h)—POR = 101 BIT 2 BIT 1 BIT 0 SPIN-UP TIME (s) 0 0 0 0.2 0 0 1 0.4 0 1 0 0.6 0 1 1 0.8 1 0 0 1 1 0 1 2 1 1 0 4 1 1 1 8 Table 13. Fan Filter Ramp Rate; Bits [6:5] Fan Filter Register (23h)—POR = 10; BIT 6 BIT 5 RAMP RATE (x100% / 240) RAMP RATE (% DUTY CYCLE) 0 0 1 0.416 0 1 2 0.833 1 0 4 1.667 1 1 8 3.333 measurement rate, which is controlled by bits [4:2] of the fan-filter register (23h). Table 5 shows the effect of the temperature measurement rate control bits. As an example, assume that the temperature measurement rate is 2Hz, or 0.5s per monitoring cycle, and the fan-filter rate is 0.416% per monitoring cycle. For the fan drive to change from 50% to 100% requires 50% / 0.416% = 120 temperature monitoring cycles. Thus, for a temperature-monitoring cycle of 0.5s, the time required for the drive to change from 50% to 100% is 60s. clock frequency into a fan-speed counter. The measurement is initialized on the starting edge of a PWM output if fan-speed measurement is enabled by setting bit 2 of configuration register 2 (01h) to 1. Counting begins on the leading edge of the second tachometer pulse and lasts for two tachometer periods or until the counter overranges (255). The measurement repeats unless monitoring is disabled by resetting bit 2 in the configuration register 2 (01h). The measured result is stored in the fan-speed reading register (08h). The fan-speed count is given by: The fan-speed count is given675 by:,000 Count = RPM × N where RPM = fan speed in RPM. N determines the speed range and is programmed by bits [7:6] in the fan characteristics register (20h) as shown in Table 14. When the speed falls below the value in the speed range column, a fan failure is detected. The TACH/AIN input can be either a digital signal (from the fan’s tachometer output) or an analog signal, depending on the setting of bit 2 of the configuration register 1 (00h). The default setting is zero, which sets up TACH/AIN as a digital input. For the analog input (Figure 4), the detected voltage threshold is typically at 250mV, which is appropriate for sensing the voltage of a sense resistor connected to the ground lead of a 2wire fan. The AIN input only responds to pulse widths greater than 10µs. TACH INPUT 0.1µF VREF 1 Fan-Speed Measurement The fan speed is measured by using the relatively slow tachometer signal from the fan to gate an 11.25kHz FF 100Ω VREF 2 MAX6653 MAX6663 MAX6664 CLK Figure 4. Simplified Tachometer Analog Input Structure Table 14. N Factor for Speed-Range Adjustment (Assuming Two Tachometer Pulses per Revolution) FAN CHARACTERISTICS REGISTER (20h) POR = 01 12 N SPEED RANGE (FAIL SPEED) (RPM) 0 1 2647 0 1 2 1324 1 0 4 662 1 1 8 331 BIT 7 BIT 6 0 ______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers Fan-Fault Detection The FAN_FAULT output is used to indicate fan slow down or failure. POR disables the FAN_FAULT output on the MAX6653/MAX6663. POR enables FAN_FAULT output on the MAX6664. If FAN_FAULT is not enabled, writing a logic 1 to bit 4 of configuration register 1 (00h) enables the FAN_FAULT output pin. Either underspeed or stalled fans are detected as fan faults. FAN_FAULT is asserted low only when five consecutive interrupts are generated by the MAX6653/MAX6663/ MAX6664s’ INT due to fan faults. The MAX6653/ MAX6664 apply 100% duty cycle for the duration of the spin-up time once an INT is asserted. The MAX6663 goes to 100% duty cycle for the duration of the spin-up time once INT is asserted and status register 1 is read. Fan-fault detection works by comparing the value of the fan tachometer high-limit register (10h) with the value of the fan-speed reading register (08h), which contains the value of the most recent fan-speed measurement. Note that the value of the fan-speed reading register (08h) must exceed the value of the fan tachometer high limit (10h) by 1 in order to qualify as a fault. The fault generates an interrupt signal by asserting the INT output, but does not cause the FAN_FAULT output to assert until five consecutive failures have been detected. The fan runs at 100% duty cycle when five consecutive failures have been detected, whether FAN_FAULT is enabled or not. As an example of the function of the fan-fault detection, assume a fan is stalled or under speed. The MAX6663 initially indicates the failure by generating an interrupt on the INT pin. The fan fault bit (bit 1) of interrupt status register 1 (02h) is also set to 1. Once the processor has acknowledged the INT by reading status register 1, the INT is cleared. PWM_OUT is then brought high for a 2s (fan 5V 3.3V 2-WIRE FAN 100Ω (TYP) PWM_OUT MAX6653 MAX6663 MAX6664 N NDT3055L C1 TACH/AIN 2Ω RSENSE Figure 5. Using the MAX6653/MAX6663/MAX6664 with a 2-Wire Fan spin-up default, Table 12) spin-up period to restart the fan. Subsequent fan failures cause INT to be reasserted and PWM_OUT to be brought high (following a status register 1 read) for a spin-up period each time to restart the fan. Once the fifth tachometer failure occurs, the FAN_FAULT is asserted to indicate a critical fan failure. A MAX6653/MAX6664 example is somewhat simpler. Again assume the fan is stalled or under speed. The MAX6653/MAX6664 initially indicate the failure by generating an interrupt on the INT pin. The fan fault bit of the interrupt status register is set to 1. PWM_OUT goes high for the programmed spin-up time (2s default) to restart the fan. Each subsequent fan failure causes another spinup. Once the fifth tachometer failure occurs, the FAN_FAULT output is asserted (if enabled) and the PWM output is driven to 100%. When the FAN_FAULT output is disabled (register 00h, bit 4), spin-ups are still attempted whenever the tach count is greater than the value in the fan tachometer high-limit register (10h). If fan faults and their associated spin-ups are not desired, the fan tachometer highlimit register (10h) to FF. This prevents the tach count from ever exceeding the limit and faults are not detected. Simply disabling the tachometer input (register 01h, bit 2) leaves the fan fault function enabled and can result in fan faults. ______________________________________________________________________________________ 13 MAX6653/MAX6663/MAX6664 Figure 5 shows a schematic using a current-sensing resistor and a coupling capacitor to derive the tachometer information from the power-supply current of a 2-wire fan. This circuit allows the speed of a 2-wire fan to be measured even though the fan has no tachometer signal output. The sensing resistor, RSENSE, converts the fan commutation pulses into a voltage and this voltage is AC-coupled into the TACH/AIN input through coupling capacitor C1. The value of RSENSE is on the order of 1Ω to 5Ω, depending on the fan, and the value of the coupling capacitor C1 is 0.01µF. When using this method, set bit 2 of configuration register 1 to 1. MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers Alarm Speed memory buses, and ISA/PCI buses. For the MAX6663, the alarm speed bit, bit 0 of status register 1 (02h), indicates that the PWM duty cycle is 100%, excluding the case of fan spin-up. For the MAX6653/MAX6664, this bit indicates that the THERM output is low. Once this bit is set, the only way to clear it is by reading status register 1. However, the bit does not reassert on the next monitoring cycle if the condition still exists. It does assert if the condition is discontinued and then returns. 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 30°C 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 20MΩ leakage path from DXP to ground causes about 1°C error. If high-voltage traces are unavoidable, connect guard traces to GND on either side of the DXP-DXN traces (Figure 6). Power-On Default Conditions At power-up, the MAX6653/MAX6663/MAX6664 are monitoring temperature to protect the system against thermal damage. The PWM outputs are in known states. Note that although the "Monitoring" bit (Configuration register 1, Bit 0) is enabled, automatic fan speed control does not begin until a 1 is rewritten to Bit 0. Other default conditions as listed in the Register Summary section. 4) The 10-mil widths and spacing recommended in Figure 6 are not absolutely necessary, as they offer only a minor improvement in leakage and noise over narrow traces. Use wider traces when practical. 5) Add a 200Ω resistor in series with VCC for best noise filtering (see Typical Operating Circuits). After applying power to the MAX6653/MAX6663/ MAX6664, set the desired operating characteristics (fan configuration, alarm thresholds, etc.). Write to Configuration register 1 last. When a 1 is first written to Bit 0 of this register, fan control will commence as determined by the register contents. GND 10 MILS PC Board Layout 10 MILS DXP 10 MILS DXN Follow these guidelines to reduce the measurement error of the temperature sensors: MINIMUM 1) Place the MAX6653/MAX6663/MAX6664 as close as is practical to the remote diode. In noisy environments, such as a computer motherboard, this distance can be 4in to 8in (typ). This length can be increased if the worst noise sources are avoided. Noise sources include CRTs, clock generators, 10 MILS GND Figure 6. Recommended DXP/DXN PC Traces Table 15. Power-On Default Conditions MAX6653 MAX6663 MAX6664 Temperature Monitoring Monitoring at 4Hz Monitoring at 4Hz Monitoring at 4Hz PWM Output Low High High PWM Mode PWM duty cycle control mode PWM duty cycle control mode Automatic fan speed control mode Duty cycle setting (not enabled until a 1 is written to Bit 0 of Register 00h) 33% 100% Automatic PWM Polarity Inverted (100% duty cycle = output high) Not Inverted (100% duty cycle = output low) Not Inverted (100% duty cycle = output low) 14 ______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers Addr(H) READ/WRITE POR STATE MAX6653 0000 1001 00 R/W MAX6663 00000001 MAX6664 10010001 01 R/W 0111 1111 DESCRIPTION Configuration register 1: Bits [7:5]: Setting the fan-speed control mode: Bit 7 = 1: Enables automatic fan-speed control mode. Bits [6:5] = 00: Remote temperature controls the fan speed. Bits [6:5] =11: Both remote and local temperature control the fan speed. Bit 7 = 0, Enables PWM control mode or RPM control mode. Bits [6:5] = X0: PWM duty cycle control mode. Bits [6:5] = X1: RPM control mode. Bit 4: FAN_FAULT output enable: 1: FAN_FAULT output enabled; 0: (default) FAN_FAULT output disabled. Bit 3: Invert the PWM output: 0: (default) PWM active low; 1: (inverted) PWM active high. Bit 2: TACHOMETER digital/analog input selection: 0: (default) TACHOMETER is a logic input; 1: TACHOMETER is an analog input. Bit 1: INT output enable: 0: INT output disabled; 1: INT output enabled. Bit 0: Monitoring: 0: sleep mode; 1: (default) active temperature monitoring and fan-speed control. (Keep this bit set to 1 for MAX6663.) Although the default value of this bit is 1, fan speed control for the MAX6653 and MAX6664 is inactive until a 1 is written to this bit. Configuration register 2: Bit 7: Reset: Setting this bit to 1 restores all registers to POR default states; self-clears to zero after reset. Bit 6: Unused. Bit 5: Remote temperature enable: 0: interrupts disabled for remote channel; 1: interrupts enabled for remote channel; defaults to 1 unless a diode fault is detected on power-up. Bit 4: Local temperature enable: 0: interrupts disabled for local channel; 1: (default) interrupts enabled for local channel. Bit 3: INT input function mask: 0: enable INT input function; 1: (default) disable INT input function. Bit 2: TACHOMETER input enable: 0: disable TACHOMETER input; 1: (default) enable the TACHOMETER input. (Keep this bit set to 1 for MAX6663.) Bit 1: SMBus timeout enable: 0: SMBus timeout disabled; 1: (default) SMBus timeout enabled. Bit 0: PWM out enable: 0: PWM output disabled; 1: (default) PWM output enabled. ______________________________________________________________________________________ 15 MAX6653/MAX6663/MAX6664 Register Summary MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers Register Summary (continued) Addr(H) 02 03 16 READ/WRITE POR STATE R R DESCRIPTION 0000 0000 Status register 1: Bit 7: Local temp low: 1: Local temp low interrupt limit has been exceeded. This bit is cleared by reading status register 1 for the MAX6653/MAX6663/MAX6664 or completing an alert response protocol for the MAX6664. This bit is asserted on the next cycle if the local temperature is still less than the limit. Bit 6: Local temp high: 1: Local temp high interrupt limit has been exceeded. This bit is cleared by reading status register 1 for the MAX6653/MAX6663/MAX6664 or completing an alert response protocol for the MAX6664. This bit is asserted on the next cycle if the local temperature is still greater than the limit. Bit 5: Remote-diode error: 1: remote-diode short circuit or open circuit detected. Bit 4: Remote temp THERM: 1: Remote temp THERM limit has been exceeded. This bit is cleared by reading status register 1. Bit 3: Remote temp low: 1: Remote temp low interrupt limit has been exceeded. This bit is cleared by reading status register 1 for the MAX6653/MAX6663/MAX6664 or completing an alert response protocol for the MAX6664. This bit is asserted on the next cycle if the remote temperature is still less than the limit. Bit 2: Remote temp high: 1: Remote temp high interrupt limit has been exceeded. This bit is cleared by reading status register 1 for the MAX6653/MAX6663/ MAX6664 or completing an alert response protocol for the MAX6664. This bit is asserted on the next cycle if the remote temperature is still greater than the limit. Bit 1: Fan fault: 1: The fan is running under speed. This bit is cleared by reading status register 1 or completing an alert response protocol. This bit is asserted again on the next cycle if the fan fault still exists. Bit 0: Alarm speed: For MAX6663, this bit is set to 1 when the PWM duty cycle = 100%. Once read, this bit does not reassert on the next monitoring cycle, even if the condition still exists. It is asserted again if the condition is discontinued and then returns. For the MAX6653/MAX6664, this bit is set to 1 when the THERM output goes to low. 0000 0000 Status register 2: Bit 7: THERM: 1: THERM has been pulled low externally. This bit clears on a read of status register 2. Bit 6: Local temp THERM: 1: Local temp THERM limit has been exceeded. This bit is cleared by reading status register 2. Bits [5:0]: Unused. 06 R 0000 0000 Extended bits of temperature data: Bits [7:5]: Extended bits for local temperature data. Bits [4:3]: Unused. Bits [2:0]: Extended bits for remote temperature data. 08 R 1111 1111 Fan-speed reading register: This register contains the fan-speed tachometer measurement. ______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers Addr(H) READ/WRITE POR STATE DESCRIPTION 0A R 0001 1110 (30°C) Local temperature data: This register contains the 8 MSBs of the local temperature measurement. 0B R 0001 1110 (30°C) Remote temperature data: This register contains the 8 MSBs of the local temperature measurement. 0000 0000 Local temperature offset: Bit 7: Sign bit; when zero, the offset value in bits [3:0] is added to the measured local temperature reading. When this bit is 1, the offset value in bits [3:0] is subtracted from the local temperature reading. Bits [6:4] Unused. This bits normally reads back zeros. Bits [3:0] Offset value. This is added to or subtracted from the measured local temperature reading. 0D R/W 0E R/W 0000 0000 Remote temperature offset: Bit 7: Sign bit: When 0, the offset value in bits [3:0] is added to the measured remote temperature reading. When this bit is 1, the offset value in bits [3:0] is subtracted from the remote temperature reading. Bits [6:4] Unused: These bits normally read back zeros. Bits [3:0] Offset value: This is added to or subtracted from the measured remote temperature reading. 10 R/W 1111 1111 Fan tachometer high-limit register: Contains the limit of the fan-speed measurement. It detects a stalled fan if the measured fan-speed data (reg_08h; proportional to fan period) is larger than the limit. 14 R/W 0011 1100 (60°C) Local temp high limit: Contains the local high-temperature interrupt limit. 15 R/W 0000 0000 (0°C) Local temp low limit: Contains the local low-temperature interrupt limit. 16 R/W 0100 0110 (70°C) Local temp THERM limit: Contains the local high-temperature limit for the THERM output. Default is +70°C for the MAX6663/MAX6664; CRIT0 and CRIT1 determine the default value for the MAX6653 (see Table 1). 18 R/W 0101 0000 (80°C) Remote temp high limit: Contains the remote high-temperature interrupt limit. 19 R/W 0000 0000 (0°C) Remote temp low limit: Contains the remote low-temperature interrupt limit. 1A R/W 0110 0100 (100°C) Remote temp THERM limit: Contains the remote high-temperature limit for the THERM output. Default is +100°C for the MAX6663/MAX6664; CRIT0 and CRIT1 determine the default value for the MAX6653 (see Table 1). 1B R/W 0101 1111 (95°C) Local temp shutdown limit: Contains the local high-temperature limit for the SDL output. CRIT0 and CRIT1 determine the default value for the MAX6653 (see Table 1). 1C R/W 0111 1101 (125°C) Remote temp shutdown limit: Contains the remote high-temperature limit for the SDR output. CRIT0 and CRIT1 determine the default value for the MAX6653 (see Table 1). ______________________________________________________________________________________ 17 MAX6653/MAX6663/MAX6664 Register Summary (continued) MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers Register Summary (continued) Addr(H) 20 READ/WRITE POR STATE R/W 0101 1101 MAX6653/ MAX6664 22 R/W 01010101 MAX6663 01011111 18 DESCRIPTION Fan characteristics register: Bits [7:6]: N factor: These bits contain the N factor for the fan-speed range: 00 = 1 (fail speed =2647RPM) 01 = 2 (fail speed =1324RPM) (default) 10 = 4 (fail speed = 662RPM) 11 = 8 (fail speed = 331RPM) Bits [5:3]: PWM frequency: These bits contain the nominal PWM output frequency: 000 = 11.7Hz 001 = 15.6Hz 010 = 23.4Hz 011 = 31.25Hz (default) 100 = 37.5Hz 101 = 46.9Hz 110 = 62.5Hz 111 = 93.5Hz Bits [2:0]: Spin-up: These bits contain the fan spin-up time: 000 = 200ms 001 = 400ms 010 = 600ms 011 = 800ms 100 = 1s 101 = 2s (default) 110 = 4s 111 = 8s Fan-speed configuration register: Bits [7:4]: Unused. Bits [3:0]: PWM duty cycle: These bits contain the PWM duty cycle for the PWM duty cycle fan-control mode. They also contain the minimum duty cycle that is applied to the fan: 0000 = 0% output 0001 = 7% output 0010 = 14% output 0011 = 20% output 0100 = 27% output 0101 = 33% output (default) 0110 = 40% output 0111 = 47% output 1000 = 53% output 1001 = 60% output 1010 = 67% output 1011 = 73% output 1100 = 80% output 1101 = 87% output 1110 = 93% output 1111 =100% output ______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers Addr(H) READ/WRITE POR STATE 23 R/W 0101 1101 24 R/W 0100 0001 25 R/W 0110 0001 DESCRIPTION Fan filter register: Bit 7: Fan spin-up disable: 0: Spin-up enabled; 1: spin-up disabled. Bits [6:5]: Fan ramp rate: These bits set the amount the PWM duty cycle can change on each monitoring cycle: 00 = 1 (0.416%) 01 = 2 (0.833%) 10 = 4 (1.667%) (default) 11 = 8 (3.333%) Bits [4:2]: Temperature measurement rate (see Table 5). Bit 1: Unused. Bit 0: Fan filter enable. Setting the bit to 1 enables the fan filter function. Local temp TMIN/ TRANGE register: Bits [7:3]: Local TMIN: Contains the temp threshold for the automatic fan-speed control mode. When the local temperature exceeds this value, the PWM output becomes active: 00000 = 00C 00001 = +40C | 01000 = +320C (default) | 11110 = +1200C 11111 = +1240C Bits [2:0]: Local TRANGE: Contains the local temperature range for automatic fanspeed control mode. When the temperature reaches TMIN + TRANGE, the PWM duty cycle reaches 100%: 000 = +50C 001 = +100C (default) 010 = +200C 011 = +400C 100 = +800C Remote temp TMIN/TRANGE register: Bits [7:3]: Remote TMIN. Contains the temp threshold for the automatic fan-speed control mode. When the remote temperature exceeds this value, the PWM output becomes active.: 00000 = 00C 00001 = +40C | 01100 = +480C (default) | 11110 = +1200C 1111 = +1240C Bits [2:0]: Remote TRANGE: Contains the remote temperature range for automatic fanspeed control mode. When the temperature reaches TMIN + TRANGE, the PWM duty cycle reaches 100%: 000 = +50C 001 = +100C (default) 010 = +200C 011 = +400C 100 = +800C ______________________________________________________________________________________ 19 MAX6653/MAX6663/MAX6664 Register Summary (continued) MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers Register Summary (continued) Addr(H) READ/WRITE POR STATE DESCRIPTION 3D R 0011 1000 Device ID 3E R 0100 1101 Manufacturer ID 1000 0000 THERM behavior/revision: Bit : THERM behavior: 1: enable THERM as an output. 0: disable THERM as an output. Bits [3:0] revision number. *For MAX6663 bit 7 has to be 1 all the time. 3F R/W Twisted-Pair and Shielded Cables Use a twisted-pair cable to connect the remote sensor for remote-sensor distances 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 1Ω of series resistance, the error is approximately 0.5°C. PC Board Layout Checklist • Place the MAX6653/MAX6663/MAX6664 close to the remote-sense junction. • 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. • Use guard traces flanking DXP and DXN and connecting to GND. • Place the noise filter and the 0.1µF VCC bypass capacitors close to the MAX6653/MAX6663/ MAX6664. 20 Table 16. Remote-Sensor Transistor Manufacturers MANUFACTURER MODEL NO. Central Semiconductor (USA) CMPT3904 Rohm Semiconductor (USA) SST3904 Samsung (Korea) KST3904-TF Siemens (Germany) SMBT3904 Zetex (England) FMMT3904CT-ND Note: Discrete transistors must be diode connected (base shorted to collector). Remote Diode Considerations The accuracy of the remote temperature measurements depends on the ideality factor (n) of the remote “diode” (actually a transistor). The MAX6653/MAX6663/ MAX6664 are optimized for n = 1.008, which is the typical value for the Intel Pentium III. A thermal diode on the substrate of an IC is normally a PNP with its collector grounded. DXP should be connected to the anode (emitter) and DXN should be connected to the cathode (base) of this PNP. When the remote-sensing diode is a discrete transistor, its collector and base should be connected together. Table 16 lists examples of discrete transistors that are appropriate for use with the MAX6653/MAX6663/ MAX6664. 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 ______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers Manufacturers of discrete transistors do not normally specify or guarantee ideality factor. This is normally not a problem since good-quality discrete transistors tend to have ideality factors that fall within a relatively narrow range. We have observed variations in remote temperature readings of less than ±2°C with a variety of discrete transistors. Still, it is sound design practice to verify good consistency of temperature readings with several discrete transistors from any manufacturer under consideration. Typical Operating Circuits +3.3V +5V +3.3V 3-WIRE FAN 10kΩ 2.2kΩ +3.3V +3.3V 2.2kΩ CLOCK 10kΩ 1 PWM_OUT SMBCLK TACH/AIN SMBDATA DATA 16 NDT3055L +3.3V 2 15 10kΩ 3 +3.3V CRIT0 INT INTERRUPT TO µC 14 +3.3V 4 CRIT1 MAX6653 ADD 13 10kΩ 5 GND SDR 12 SYSTEM SHUTDOWN +3.3V 6 VCC SDL THERM DXP 11 10kΩ THERM SIGNAL TO THROTTLE CPU CLOCK 7 CPU 10 +3.3V 2.2nF 10kΩ FAN _FAULT TO SIGNAL FAN-FAILURE CONDITION 8 FAN_FAULT DXN 9 ______________________________________________________________________________________ 21 MAX6653/MAX6663/MAX6664 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. Tight specifications for forward current gain (50 < ß <150, for example) indicate that the manufacturer has good process controls and that the devices have consistent VBE characteristics. Temperature Monitors and PWM Fan Controllers MAX6653/MAX6663/MAX6664 Typical Operating Circuits (continued) +3.3V +5V +3.3V 3-WIRE FAN 10kΩ 2.2kΩ +3.3V +3.3V 2.2kΩ CLOCK 10kΩ 1 PWM_OUT SMBCLK TACH/AIN SMBDATA DATA 16 NDT3055L +3.3V 2 15 10kΩ 3 N.C. INT INTERRUPT TO µC 14 +3.3V 4 +3.3V 5 N.C. GND MAX6663 MAX6664 ADD N.C. 13 12 +3.3V 6 VCC N.C. THERM DXP 11 10kΩ THERM SIGNAL TO THROTTLE CPU CLOCK 7 CPU 10 +3.3V 2.2nF 10kΩ FAN _FAULT TO SIGNAL FAN-FAILURE CONDITION 22 8 FAN_FAULT DXN 9 ______________________________________________________________________________________ Temperature Monitors and PWM Fan Controllers VCC TACH SIGNAL CONDITIONING TACH/AIN SMBCLK SMBus INTERFACE SLAVE ADDRESS DECODER ADD SMBDATA TACHOMETER REGISTER BANK DXP ANALOG MUX DXN ADC INTERNAL TEMPERATURE SENSOR PWM_OUT TEMPERATURE MEASUREMENT BANDGAP REFRENCE (CRIT1) SHUTDOWN AND THERM LIMIT DECODER MUX (CRIT0) INT THERM FAN_FAULT (SDL) (SDR) PWM OUTPUT CONTROLLER ALU ( ) ARE FOR MAX6653 ONLY GND Pin Configurations (continued) Chip Information TRANSISTOR COUNT: 27,074 PROCESS: BiCMOS TOP VIEW PWM_OUT 1 16 SMBCLK TACH/AIN 2 15 SMBDATA N.C. 3 N.C. 4 GND 5 14 INT MAX6663 MAX6664 13 ADD 12 N.C. VCC 6 11 N.C. THERM 7 10 DXP FAN_FAULT 8 9 DXN QSOP ______________________________________________________________________________________ 23 MAX6653/MAX6663/MAX6664 Functional Diagram 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.) QSOP.EPS MAX6653/MAX6663/MAX6664 Temperature Monitors and PWM Fan Controllers PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 E 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. 24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.