MAX31785ETL+ Maxim Integrated Products, MAX31785ETL+ Datasheet

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... Smart Grid Network Systems Industrial Controls Ordering Information PART TEMP RANGE MAX31785ETL+ -40NC to +85NC MAX31785ETL+T -40NC to +85NC +Denotes a lead(Pb)-free/RoHS-compliant package Tape and reel. *EP = Exposed pad. PMBus is a trademark of SMIF, Inc. SMBus is a trademark of Intel Corp. Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any device may be simultaneously available through various sales channels ...

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Intelligent Fan Controller Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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Intelligent Fan Controller TABLE OF CONTENTS (continued) Fan Control Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...

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Intelligent Fan Controller TABLE OF CONTENTS (continued) MFR_DATE (9Dh ...

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Intelligent Fan Controller Figure 1. Automatic Fan Control ...

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Intelligent Fan Controller ABSOLUTE MAXIMUM RATINGS ...........................................................-0.3V to +5. RS ............................................................-0.3V to +0.3V SS All Other Pins Except REG18 and REG25 Relative to V ........................ -0. Continuous Power Dissipation ...

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Intelligent Fan Controller DC ELECTRICAL CHARACTERISTICS (continued 2.7V to 5.5V -40NC to +85NC, unless otherwise noted. Typical values are PARAMETER SYMBOL ADC Internal Reference Temperature Drift ADC Internal Reference Initial Accuracy ...

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Intelligent Fan Controller 2 I C/SMBUS INTERFACE ELECTRICAL CHARACTERISTICS (V = 2.7V to 5.5V -40NC to +85NC, unless otherwise noted. Typical values are PARAMETER SYMBOL SCL Clock Frequency Bus Free Time Between STOP ...

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Intelligent Fan Controller (T = +25°C, unless otherwise noted.) A SUPPLY CURRENT vs. SUPPLY VOLTAGE (NO PWM SWITCHING) 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 2.7 3.1 3.5 3.9 V WEAK PULLUP VOLTAGE vs. TIME ...

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Intelligent Fan Controller TOP VIEW CONTROL A1/TACHSEL PIN NAME 1 RS-4 Ground Reference for Thermal Diode or Remote Voltage ADC4 Measurement 2, 21 Digital-Supply Return Node (Ground RS+4 Thermal Diode or Remote Voltage ADC Input, ...

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Intelligent Fan Controller PIN NAME Fan PWM Output #3. CMOS push-pull output. Low when the fan is disabled. A 100% duty cycle 20 PWM3 implies this pin is continuously high. Regulator for Low-Voltage Digital Circuitry. Bypass REG18 to V ...

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Intelligent Fan Controller REG25 V SS REG18 V SS MSDA MSCL RST SDA SCL ALERT CONTROL FAULT A0 A1/TACHSEL MAXQ is a registered trademark of Maxim Integrated Products, Inc. 12 POWER MAX31785 CONTROL PULSE- 2.5V ...

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Intelligent Fan Controller +3.3V ALERT CLOCK HOST DATA INTERFACE CONTROL RST ADDITIONAL DEVICES Multiple Device Connection Diagram SDA SCL RST MAX31785 ALERT #0 FAULT CONTROL A1/TACHSEL A0 +3.3V SDA SCL RST MAX31785 ALERT #1 FAULT CONTROL A1/TACHSEL A0 13 ...

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Intelligent Fan Controller Detailed Description The MAX31785 is a closed-loop fan controller. Automatic closed-loop fan control saves system power by operat- ing the fans at the lowest possible speeds. Added ben- efits of slower fan speeds include lower audible ...

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Intelligent Fan Controller Table 1. PMBus Command Codes (continued) CODE COMMAND NAME 9Dh MFR_DATE 9Eh MFR_SERIAL D1h MFR_MODE D4h MFR_VOUT_PEAK D6h MFR_TEMPERATURE_PEAK D7h MFR_VOUT_MIN D9h MFR_FAULT_RESPONSE DCh MFR_NV_FAULT_LOG DDh MFR_TIME_COUNT F0h MFR_TEMP_SENSOR_CONFIG F1h MFR_FAN_CONFIG F2h MFR_FAN_LUT F3h MFR_READ_FAN_PWM F5h ...

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Intelligent Fan Controller Table 2. PMBus/SMBus Serial-Port Address A1 A0 100kI 100kI 100kI 100kI 100kI 100kI READ WORD FORMAT 1 7 ...

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Intelligent Fan Controller The device supports the group command. With the group command, a host can write different data to multiple devices on the same serial bus with one long SLAVE ADDRESS, COMMAND BYTE, AND DATA WORD FOR DEVICE ...

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Intelligent Fan Controller 1 S 0001100 Host Sends or Reads Too Few Bits If for any reason the host does not complete writing a full byte or reading a full byte from the device before a START or STOP ...

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Intelligent Fan Controller Host Reads from a Write-Only Command When a read request is issued to a write-only command (CLEAR_FAULTS, STORE_DEFAULT_ALL, RESTORE_DEFAULT_ALL), the device does the following: 1) ACKs the address byte. 2) Ignores the command. 3) Sends all ...

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Intelligent Fan Controller Table 3. PMBus Command Code Coefficients PARAMETER COMMANDS VOUT_OV_FAULT_LIMIT VOUT_OV_WARN_LIMIT VOUT_UV_WARN_LIMIT Voltage VOUT_UV_FAULT_LIMIT READ_VOUT MFR_VOUT_PEAK MFR_VOUT_MIN Voltage Scaling VOUT_SCALE_MONITOR OT_FAULT_LIMIT OT_WARN_LIMIT Temperature READ_TEMPERATURE_1 MFR_TEMPERATURE_PEAK READ_FAN_SPEED_1 FAN_COMMAND_1 MFR_FAN_FAULT_LIMIT MFR_FAN_WARN_LIMIT Fan Speed FAN_COMMAND_1 MFR_READ_FAN_PWM MFR_FAN_FAULT_LIMIT MFR_FAN_WARN_LIMIT MFR_FAN_PWM_AVG Interpreting ...

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Intelligent Fan Controller Table 5. Device Parametric Monitoring States PARAMETER REQUIRED CONDITIONS FOR ACTIVE MONITORING Overvoltage Voltage Monitoring Enabled (ADC_ENABLE in MFR_MODE = 1) Undervoltage Voltage Monitoring Enabled (ADC_ENABLE in MFR_MODE = 1) Overtemperature Temp Sensor Enabled (ENABLE in ...

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Intelligent Fan Controller Fan Control Operation Fan control has four operational modes. The mode is determined by the combination of FAN_COMMAND_1 and bit 6 of FAN_CONFIG_1_2 (see Table 7). Fan control can be disabled by setting bit 7 in ...

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Intelligent Fan Controller OFFSET ADJUSTMENT ALLOWS TEMPERATURE ZONE NORMALIZATION REMOTE DIODE TEMP SENSOR 0 REMOTE DIODE TEMP SENSOR 1 REMOTE DIODE TEMP SENSOR REMOTE TEMP SENSOR 3 INTERNAL TEMP SENSOR Figure 1. Automatic Fan Control ...

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Intelligent Fan Controller At temperature sample 2, the temperature has increased to greater than temperature level 4 so again the PWM duty cycle must be increased. At temperature sample 3, the temperature has dropped but not below the ther- ...

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Intelligent Fan Controller Fan Power-On Sequencing Multiple fans are not started at the same time. Fans are started in increments of 200ms to relieve the strain on the power supply. This sequencing occurs both at initial fan power-up and ...

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Intelligent Fan Controller fan’s PWM duty cycle is between 40% and 80%. The masured fan speed is also compared to the expected at 100% duty cycle. In the 40% to 80% range, a fan’s expected fan-speed profile is approximately ...

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Intelligent Fan Controller A summary of the PMBus commands supported by the device are described in the following sections. The device can control up to six fans temperature sensors, and measure up to six remote voltages ...

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Intelligent Fan Controller The CLEAR_FAULTS command is used to clear any fault or warning bits in the status registers that have been set. This command clears all bits simultaneously fault is still present after the CLEAR_FAULTS command ...

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Intelligent Fan Controller The VOUT_MODE command is used to report the data format of the device. The device uses the DIRECT format for all the voltage-related commands. The value returned is 40h, indicating DIRECT data format. This command is ...

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Intelligent Fan Controller The FAN_COMMAND_1 command is used to override the device’s automatic fan-control function and force the fan to either a fixed PWM duty-cycle value or a target fan speed (in RPM). The units of FAN_COMMAND_1 are either ...

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Intelligent Fan Controller The VOUT_UV_WARN_LIMIT command sets the value of the output voltage that causes an output-voltage low warning. This value is typically greater than the output undervoltage fault threshold in VOUT_UV_FAULT_LIMIT. The monitored voltage must increase by at ...

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Intelligent Fan Controller The STATUS_BYTE command returns 1 byte of information with a summary of the most critical faults. A value of 1 indi- cates that a fault or warning event has occurred and a 0 indicates otherwise. Bits ...

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Intelligent Fan Controller The STATUS_CML command returns 1 byte of information with contents as described in Table 19. Table 19. STATUS_CML BIT BIT NAME 7 COMM_FAULT An invalid or unsupported command has been received. 6 DATA_FAULT An invalid or ...

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Intelligent Fan Controller The READ_VOUT command returns the actual measured output voltage. READ_VOUT is measured and updated every 10ms. The 2 data bytes are in DIRECT format. The READ_TEMPERATURE_1 command returns the temperature returned from the temperature sensor. The ...

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Intelligent Fan Controller The MFR_MODE command is used to configure the device to support manufacturer specific commands. The MFR_MODE command is described in Table 22. Table 22. MFR_MODE BIT BIT NAME Setting this bit to 1 forces the device ...

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Intelligent Fan Controller The MFR_VOUT_PEAK command returns the maximum actual measured output voltage. To reset this value to 0, write to this command with a data value of 0. Any values written to this command are used as a ...

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Intelligent Fan Controller Each time the MFR_NV_FAULT_LOG command is executed, the device returns a block of 255 bytes containing one of the 15 nonvolatile fault logs. The MFR_NV_FAULT_LOG command must be executed 15 times to dump the com- plete ...

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Intelligent Fan Controller Table 24. MFR_NV_FAULT_LOG BYTE PARAMETER 0 00h/FAULT_LOG_INDEX 2 FAULT_LOG_COUNT 4 MFR_TIME_COUNT (LSW) 6 MFR_TIME_COUNT (MSW) 8 STATUS_BYTE/STATUS_CML 10 STATUS_WORD 12 STATUS_VOUT Pages 17/18 14 STATUS_VOUT Pages 19/20 16 STATUS_VOUT Pages 21/22 18 STATUS_MFR_SPECIFIC Pages 6/7 20 ...

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Intelligent Fan Controller Table 24. MFR_NV_FAULT_LOG (continued) BYTE PARAMETER 84 RESERVED (0000h) 86 VOLTAGE_INDEX/00h 88 READ_VOUT Index = 0, Page 17 90 READ_VOUT Index = 0, Page 18 92 READ_VOUT Index = 0, Page 19 94 READ_VOUT Index = ...

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Intelligent Fan Controller The MFR_TIME_COUNT command returns the number of seconds of device lifetime operation. Once every hour, the device automatically stores this counter in flash memory. The counter is a 32-bit value that rolls over. The latest stored ...

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Intelligent Fan Controller The MFR_FAN_CONFIG command is used with FAN_CONFIG_1_2 to configure the fan. See the FAN_CONFIG_1_2 description for more details on this command. Table 26 describes the MFR_FAN_CONFIG command. Table 26. MFR_FAN_CONFIG BIT BIT NAME The FREQ bits ...

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Intelligent Fan Controller Table 26. MFR_FAN_CONFIG (continued) BIT BIT NAME The RAMP bits select how fast the device ramps the PWM from one duty cycle to another (either up or down). In PWM mode, the following table always applies. ...

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Intelligent Fan Controller The MFR_FAN_LUT command is used to configure the LUT that controls the fan. The fan has an LUT that maps eight programmable temperature levels to eight programmable fan PWM duty-cycle levels (bit 6 in FAN_CONFIG_1_2 is ...

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Intelligent Fan Controller If bit 6 in FAN_CONFIG_1_2 is set to zero, the FAN SPEED STEP sets the fan PWM duty cycle at each temperature step breakpoint. The valid duty cycle range 100 (inclusive). Any values ...

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Intelligent Fan Controller The MFR_READ_FAN_PWM command returns the latest real-time value for the fan PWM in % duty cycle. MFR_READ_FAN_PWM is updated whenever the PWM duty cycle is updated. This is determined by the RATE bits in MFR_FAN_CONFIG. The ...

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Intelligent Fan Controller The MFR_FAN_RUN_TIME command returns the number of hours of fan lifetime operation. Once every hour, the device automatically stores this counter in flash memory. The counter is a 16-bit value that rolls over. The latest stored ...

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Intelligent Fan Controller CHANNELS DS75LV TEMP SENSOR +3.3V HOST INTERFACE For the latest package outline information and land patterns www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code ...

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