EVAL-ADT7467EBZ ON Semiconductor, EVAL-ADT7467EBZ Datasheet

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FEATURES Controls and monitors fans High and low frequency fan drive signal 1 on-chip and 2 remote temperature sensors Series resistance cancellation on the remote channel Extended temperature measurement range 191°C Dynamic T control mode ...

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... Status Registers............................................................................22 Interrupts .....................................................................................22 Active Cooling .................................................................................27 Driving the Fan Using PWM Control......................................27 Laying Out 2-Wire and 3-Wire Fans........................................29 REVISION HISTORY 01/08 - Rev 3: Conversion to ON Semiconductor 12/07—Rev Rev. B Changes to Limit Values Section Changes to Table 13 Changes to Figure 34 and Figure 36 Changes to Figure 41 Changes to Step 11: Monitoring THERM Section ...

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SPECIFICATIONS unless otherwise noted. A MIN MAX CC MIN MAX All voltages are measured with respect to GND, unless otherwise specified. Typicals are at T parametric norm. Logic ...

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ADT7467 Parameter OPEN-DRAIN DIGITAL OUTPUTS, PWM1 to PWM3, XTO Current Sink Output Low Voltage High Level Output Current OPEN-DRAIN SERIAL DATA BUS OUTPUT (SDA) Output Low Voltage High Level Output Current, I ...

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ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Positive Supply Voltage ( Voltage on Any Input or Output Pin Input Current at Any Pin Package Input Current Maximum Junction Temperature (T ) JMAX Storage Temperature Range Lead Temperature, Soldering IR ...

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ADT7467 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS Table 3. Pin Function Descriptions Pin No. Mnemonic Description 1 SCL Digital Input (Open Drain). SMBus serial clock input. Requires SMBus pull-up. 2 GND Ground Pin for the ADT7467 Power Supply. Can ...

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TYPICAL PERFORMANCE CHARACTERISTICS 0 –10 –20 –30 –40 –50 – 2.2 3.3 CAPACITANCE (nF) Figure 4. Temperature Error vs. Capacitance Between D+ and D− 0 –10 –20 –30 –40 –50 –60 –70 –80 –90 –100 ...

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ADT7467 3.0 3.2 3.4 3.6 3.8 4.0 4.2 4.4 POWER SUPPLY VOLTAGE (V) Figure 10. Shutdown I vs. Power Supply –5 –10 INT ERROR, 100mV –15 ...

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PRODUCT DESCRIPTION The ADT7467 is a complete thermal monitor and multiple fan controller for systems requiring thermal monitoring and cooling. The device communicates with the system via a serial system management bus. The serial bus controller has a serial data ...

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ADT7467 Configuration Register 5 Bit 0: If Bit 0 is set to 1, the ADT7467, in terms of temperature, is backward compatible with the ADT7460. Measurements, including T calibration circuit and fan control, work in the MIN range −127°C to ...

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SERIAL BUS INTERFACE On PCs and servers, control of the ADT7467 is carried out using the serial system management bus (SMBus). The ADT7467 is connected to this bus as a slave device under the control of a master controller, which ...

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ADT7467 1 SCL SDA START BY MASTER SERIAL BUS ADDRESS BYTE Figure 16. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register 1 SCL 0 SDA START ...

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WRITE OPERATIONS The SMBus specification defines several protocols for different types of read and write operations. The ones used in the ADT7467 are discussed here. The following abbreviations are used in Figure 19 through Figure 21 start P ...

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ADT7467 Alert Response Address Alert response address (ARA feature of SMBus devices that allows an interrupting device to identify itself to the host when multiple devices exist on the same bus. The SMBALERT output can be used as ...

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ANALOG-TO-DIGITAL CONVERTER All analog inputs are multiplexed into the on-chip, successive approximation, analog-to-digital converter, which has a resolu- tion of 10 bits. The basic input range 2.25 V, but the input has built-in attenuators to allow ...

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ADT7467 Table 6. 10-Bit Analog-to-Digital Output Code vs. V Input Voltage (3 <0.0065 <0.0042 0.0065 to 0.0130 0.0042 to 0.0085 0.0130 to 0.0195 0.0085 to 0.0128 0.0195 to 0.0260 ...

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Remote Temperature Measurement The ADT7467 can measure the temperature of two remote diode sensors or diode-connected transistors connected to Pin 10 and Pin Pin 12 and Pin 13. The forward voltage of a diode or diode-connected transistor ...

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ADT7467 The construction of a filter allows the ADT7467 and the remote temperature sensor to operate in noisy environments. Figure 24 shows a low-pass R-C-R filter with the following values 100 Ω This filtering ...

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ADT7467 2N3904 D+ NPN D– Figure 25. Measuring Temperature Using an NPN Transistor ADT7467 2N3906 D+ PNP D– Figure 26. Measuring Temperature Using a PNP Transistor Nulling Temperature Errors As CPUs run faster more difficult to avoid high ...

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ADT7467 Table 9. Conversion Time with Averaging Disabled Channel Measurement Time Voltage Channels 0.7 ms Remote Temperature Remote Temperature Local Temperature 1.3 ms Table 10. Conversion Time with Averaging Enabled Channel Measurement Time Voltage ...

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LIMITS, STATUS REGISTERS, AND INTERRUPTS LIMIT VALUES High and low limits are associated with each measurement channel on the ADT7467. These limits form the basis of system-status monitoring in that a status bit can be set for any out-of-limit condition ...

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ADT7467 Fan TACH measurements are made in parallel and are not synchronized with the analog measurements in any way. STATUS REGISTERS The results of limit comparisons are stored in Interrupt Status Register 1 and Interrupt Status Register 2. The status ...

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Mask the interrupt source by setting the appropriate mask bit in the interrupt mask registers (Register 0x74 and Register 0x75). 5. Take the appropriate action for a given interrupt source. 6. Exit the interrupt handler. 7. Periodically poll the ...

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ADT7467 T MIN THERM THERM ASSERTED TO LOW AS AN INPUT: FANS DO NOT GO TO 100% BECAUSE TEMPERATURE IS BELOW T MIN THERM ASSERTED TO LOW AS AN INPUT: FANS DO NOT GO TO 100% BECAUSE TEMPERATURE IS ABOVE ...

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Generating SMBALERT Interrupts From THERM Timer Events The ADT7467 can generate SMBALERTs when a programma- ble THERM timer limit has been exceeded. This allows the system designer to ignore brief, infrequent THERM assertions while capturing longer THERM timer events. Register ...

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ADT7467 Configuring THERM Behavior 1. Configure the relevant pin as the THERM timer input. Setting Bit 1 (THERM timer enable) of Configuration Register 3 (0x78) enables the THERM timer monitoring functionality. This is disabled on Pin 9 by default. Setting ...

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ACTIVE COOLING DRIVING THE FAN USING PWM CONTROL The ADT7467 uses pulse-width modulation (PWM) to control fan speed. This relies on varying the duty cycle (or on/off ratio square wave applied to the fan to vary the fan ...

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ADT7467 Figure 37. Interfacing Two Fans in Parallel to the PWM3 Output Using Low Cost NPN Transistors ADT7467 Figure 38. Interfacing Two Fans in Parallel to the PWM3 Output Using a Single N-Channel MOSFET Because the MOSFET can handle up ...

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Note that when the voltage spikes (either negative going or positive going) are more than amplitude, the fan speed can be reliably determined. 3. ADT7467 12V FAN 10k Ω TYPICAL PWMx 0.01μF TACHx Figure 39. ...

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ADT7467 Clamped with Zener and Resistor Alternatively, a resistive attenuator can be used, as shown in Figure 45. R1 and R2 should be chosen such that 2 V < V × R2/( R2) < PULL-UP ...

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Fan Speed Measurement Rate The fan TACH readings are normally updated once every second. When set, the FAST bit (Bit 3) of Configuration Register 3 (0x78) updates the fan TACH readings every 250 ms fan is powered directly ...

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ADT7467 Bit 5 (FSPDIS), the functionality of this bit can be changed (see the Disabling Fan Start-Up Timeout section). PWM1 Configuration Register (0x5C) <2:0> SPIN, start-up timeout for PWM1 000 = no start-up timeout 001 = 100 ms 010 = ...

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FAN SPEED CONTROL The ADT7467 controls fan speed using two modes: automatic and manual. In automatic fan speed control mode, fan speed is varied with temperature without CPU intervention once initial parameters are set up. The advantage of this is ...

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ADT7467 MISCELLANEOUS FUNCTIONS OPERATING FROM 3.3 V STANDBY The ADT7467 has been specifically designed to operate from a 3.3 V STANDBY supply. In computers that support S3 and S5 states, the core voltage of the processor is lowered in these ...

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AUTOMATIC FAN CONTROL OVERVIEW The ADT7467 can automatically control the speed of fans based on the measured temperature. This is done independently of CPU intervention once initial parameters are set up. The ADT7467 has a local temperature sensor and two ...

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ADT7467 DYNAMIC T CONTROL MODE MIN In addition to the automatic fan speed control mode, the ADT7467 has a mode that extends the basic automatic fan speed control loop. Dynamic T control allows the ADT7467 MIN to intelligently adapt the ...

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Dynamic T Control Overview MIN Dynamic T control mode builds on the basic automatic fan MIN control loop by adjusting the T value based on system MIN performance and measured temperature. Therefore, instead of designing for the worst case, the ...

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... This section provides the system designer with an understand- ing of the automatic fan control loop and provides step-by-step guidance on effectively evaluating and selecting critical system parameters. To optimize the system characteristics, the designer should consider several aspects of the system configuration, including the number of fans, where fans are located, and what temperatures are measured ...

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Recommended Implementation Configuring the ADT7467 as shown in Figure 54 provides the system designer with the following features: • Two PWM outputs for control three fans. (The front and rear chassis fans are connected in parallel.) • ...

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ADT7467 STEP 2: CONFIGURING THE MUX After the system hardware configuration is determined, the fans can be assigned to particular temperature channels. Not only can fans be assigned to individual channels, but the behavior of the fans is also configurable. ...

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Mux Configuration Example This is an example of how to configure the mux in a system using the ADT7467 to control three fans. The CPU fan sink is controlled by PWM1, the front chassis fan is controlled by PWM2, and ...

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ADT7467 STEP 3: T SETTINGS FOR THERMAL MIN CALIBRATION CHANNELS T is the temperature at which the fans start to turn on when MIN using automatic fan control mode. The speed at which the fan runs programmed ...

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T MIN THERMAL CALIBRATION T MIN THERMAL CALIBRATION REMOTE 2 = CPU TEMP T MIN LOCAL = THERMAL CALIBRATION VRM TEMP T MIN REMOTE 1 = AMBIENT TEMP STEP 4: PWM FOR PWM (FAN) OUTPUTS MIN PWM is ...

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ADT7467 Programming the PWM Registers MIN The PWM registers are 8-bit registers that allow the MIN minimum PWM duty cycle for each output to be configured from 0% to 100%. This allows the minimum PWM duty cycle to be set ...

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... PWM duty cycle.) 3. Determine the slope of the required control loop to meet these requirements. 4. The ADT7467 evaluation software can graphically program and visualize this functionality. Ask your local Analog Devices sales representative for details. 100% 50% 33% 0% 30° ...

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ADT7467 Example 4: Calculate T , given that T MAX MIN and PWM = 50% duty cycle = 128 (decimal). MIN (Max DC − Min DC) × T MAX MIN T = 30°C + (100% − ...

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TEMPERATURE ABOVE T MIN 100 TEMPERATURE ABOVE T MIN ...

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ADT7467 Note that the T limits are nonmaskable and affect the fan THERM speed regardless of the configuration of the automatic fan control settings. This allows some flexibility, because a T value can be selected based on its slope, and ...

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STEP 8: T FOR TEMPERATURE CHANNELS HYST T is the amount of extra cooling a fan provides after the HYST temperature measured drops below T MIN off. The premise for temperature hysteresis (T without it, the fan would merely chatter ...

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ADT7467 Enhanced Acoustics Register 1 (0x62) Bit 7 (MIN3 PWM3 is off (0% PWM duty cycle) when the temperature is below T − MIN HYST Bit 7 (MIN3 PWM3 runs at PWM3 minimum duty ...

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STEP 10: HIGH AND LOW LIMITS FOR TEMPERATURE CHANNELS If the temperature falls below the temperature channel’s low limit, T increases. This reduces fan speed, allowing the MIN system to heat up. An interrupt can be generated when the temperature ...

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ADT7467 Figure 71 shows the steps taken during the long cycle. WAIT 2n MONITORING CYCLES CURRENT TEMPERATURE MEASUREMENT T1(n) YES IS T1(n) > OP1 OPERATING POINT TEMPERATURE NO OP1 IS T1(n) < LOW TEMP LIMIT AND T < HIGH TEMP ...

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THERM LIMIT HIGH TEMP LIMIT OPERATING POINT T MIN LOW TEMP LIMIT Figure 73. Effect of Exceeding Operating Point Minus Hysteresis Temperature Figure 74 shows how T increases when the current tempera- MIN ture is above T but below the ...

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ADT7467 Enabling the THERM Trip Point as the Operating Point Bits <4:2> of the dynamic T control Register 1 (0x36) MIN enable/disable THERM monitoring to program the operating point. Dynamic T Control Register 1 (0x36) MIN <2> PHTR1 = 1 ...

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ADT7467 into manual mode and changing the PWM output from 0% to 100% PWM duty cycle. The PWM output takes 35 sec to reach 100% when a ramp rate of 1 time slot is selected. Figure 76 shows ...

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ADT7467 Figure 80 shows the behavior of the PWM output as tempera- ture varies. As the temperature increases, the fan speed ramps up. Small drops in temperature do not affect the ramp-up function because the newly calculated fan speed is ...

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... Acoustic enhancement is intended as a postdesign tweak made by a system or mechanical engineer evaluating the best settings for the system. Having determined the optimal settings for the thermal solution, the engineer can adjust the system acoustics. ...

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ADT7467 Approaches to System Acoustic Enhancement There are two different approaches to implementing system acoustic enhancement: temperature-centric and fan-centric. The ADT7467 uses the fan-centric approach. The temperature-centric approach involves smoothing transient temperatures as they are measured by a temperature source ...

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REGISTER MAP Table 17. ADT7467 Registers Address R/W Description 0x21 R V reading CCP 0x22 R V reading CC 0x25 R Remote 1 temperature 0x26 R Local temperature 0x27 R Remote 2 temperature 0x28 R TACH1 low byte 0x29 R ...

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ADT7467 Address R/W Description high limit 0x50 R/W Local temperature low limit 0x51 R/W Local temperature high limit 0x52 R/W Remote 2 temperature low limit 0x53 R/W Remote 2 temperature high limit 0x54 R/W TACH1 minimum low byte 0x55 R/W ...

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Address R/W Description temp/T hysteresis MIN 0x6E R/W Remote 2 temp/T MIN hysteresis 0x6F R/W XNOR tree test enable 0x70 R/W Remote 1 temperature offset 0x71 R/W Local temperature offset 0x72 R/W Remote 2 temperature offset 0x73 R/W Configuration Register ...

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ADT7467 Table 20. Fan Tachometer Reading Registers (Power-On Default = 0x00) Register Address 0x28 0x29 0x2A 0x2B 0x2C 0x2D 0x2E 0x2F 1 These registers count the number of 11.11 μs periods (based on an internal 90 kHz clock) that occur ...

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Table 23. Register 0x36—Dynamic T MIN Bit Name R/W Description <0> CYR2 Read/write MSB of 3-bit Remote 2 cycle value. The other two bits of the code reside in Dynamic T (0x37). These three bits define the delay time, in ...

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ADT7467 Table 24. Register 0x37—Dynamic T MIN Bit Name R/W Description <2:0> CYR1 Read/write 3-bit Remote 1 cycle value. These three bits define the delay time, in terms of the number of monitoring cycles, for making subsequent T associated with ...

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Table 26. Register 0x40—Configuration Register 1 (Power-On Default = 0x01) Bit Name R/W Description <0> STRT Read/write Logic 1 enables monitoring and PWM control outputs based on the limit settings programmed. Logic 0 disables monitoring and PWM control based on ...

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ADT7467 Table 28. Register 0x42—Interrupt Status Register 2 (Power-On Default = 0x00) Bit Name R/W Description <1> OVT Read only OVT = 1 indicates that one of the THERM overtemperature limits has been exceeded. This bit is cleared upon a ...

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Table 32. Register 0x55—TACH 1 Minimum High Byte (Power-On Default = 0xFF) Bit Name R/W <4:0> Reserved Read only <7:5> SCADC Read/write Table 33. PWM Configuration Registers 1 Register Address R/W 0x5C Read/write 0x5D Read/write 0x5E Read/write 1 These registers ...

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ADT7467 Table 35. T /PWM Frequency Registers RANGE 1 Register Address R/W 0x5F Read/write 0x60 Read/write 0x61 Read/write 1 These registers become read-only registers when the Configuration Register 1 LOCK bit is set to 1. Any subsequent attempts to write ...

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Table 37. Register 0x62—Enhanced Acoustics Register 1 (Power-On Default = 0x00) 1 Bit Name R/W Description <2:0> ACOU Read/write These bits select the ramp rate applied to the PWM1 output. Instead of PWM1 jumping instantaneously to its newly calculated speed, ...

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ADT7467 Table 38. Register 0x63—Enhanced Acoustics Register 2 (Power-On Default = 0x00) 1 Bit Name R/W Description <2:0> ACOU3 Read/write These bits select the ramp rate applied to the PWM3 output. Instead of PWM3 jumping instantaneously to its newly calculated ...

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Table 41. T Registers MIN 2 Register Address R/W 0x67 Read/write 0x68 Read/write 0x69 Read/write 1 These are the T registers for each temperature channel. When the temperature measured exceeds T MIN with temperature according RANGE ...

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ADT7467 Table 47. Register 0x70—Remote 1 Temperature Offset (Power-On Default = 0x00) 1 Bit R/W Description <7:0> Read/write Allows a twos complement offset value to be automatically added to or subtracted from the Remote 1 temperature reading. This is to ...

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Table 51. Register 0x74—Interrupt Mask 1 Register (Power-On Default = 0x00) Bit Name R/W Description <1> V Read/write V CCP <2> V Read/write V CC <4> R1T Read/write R1T = 1 masks SMBALERT for out-of-limit conditions on the Remote 1 ...

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ADT7467 Table 56. Register 0x79— THERM Timer Status Register (Power-On Default = 0x00) Bit Name R/W Description <7:1> TMR Read only Times how long THERM input is asserted. These seven bits read 0 until the THERM assertion time exceeds 45.52 ...

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Table 60. Register 0x7D—Configuration Register 4 (Power-On Default = 0x00) 1 Bit Name R/W Description <1:0> Pin 9 Func Read/write These bits set the functionality of Pin TACH4 (default bidirectional THERM . 10 = SMBALERT ...

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ADT7467 ADT7467 PROGRAMMING BLOCK DIAGRAM Figure 84.Block Diagram Rev Page www.onsemi.com 04498-044 SPEED FAN CYCLE/RELATIVE DUTY PWM ...

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