Analog Devices dBCool ADT7467 Manual

Remote thermal monitor and fan controller

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FEATURES

Controls and monitors up to 4 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, up to 191°C

Dynamic T

control mode optimizes system acoustics

MIN

intelligently

Automatic fan speed control mode controls system cooling

based on measured temperature

Enhanced acoustic mode dramatically reduces user

perception of changing fan speeds

Thermal protection feature via THERM output

Monitors performance impact of Intel® Pentium™ 4

processor

Thermal control circuit via THERM input

2-wire, 3-wire, and 4-wire fan speed measurement

Limit comparison of all monitored values

Meets SMBus 2.0 electrical specifications

(fully SMBus 1.1 compliant)

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable.

However, no responsibility is assumed by Analog Devices for its use, nor for any

infringements of patents or other rights of third parties that may result from its use.

Specifications subject to change without notice. No license is granted by implication

or otherwise under any patent or patent rights of Analog Devices. Trademarks and

registered trademarks are the property of their respective owners.

FUNCTIONAL BLOCK DIAGRAM

ACOUSTIC

PWM1

PWM REGISTERS

ENHANCEMENT

AND

PWM2

CONTROL

CONTROLLERS

HF & LF

PWM3

TACH1

TACH2

FAN SPEED

COUNTER

TACH3

TACH4

PERFORMANCE

MONITORING

THERMAL

THERM

PROTECTION

TO ADT7467

D1+

D1–

SRC

SIGNAL

D2+

CONDITIONING

D2–

ANALOG

CCP

MULTIPLEXER

BAND GAP

TEMP SENSOR

dBCool

Monitor and Fan Controller

GENERAL DESCRIPTION

The ADT7467 dBCOOL

multiple PWM fan controller for noise-sensitive or power-

sensitive applications requiring active system cooling. The

ADT7467 can drive a fan using either a low or high frequency

drive signal, monitor the temperature of up to two remote

sensor diodes plus its own internal temperature, and measure

and control the speed of up to four fans, so that they operate at

the lowest possible speed for minimum acoustic noise.

The automatic fan speed control loop optimizes fan speed for a

given temperature. A unique dynamic T

enables the system thermals/acoustics to be intelligently

managed. The effectiveness of the system's thermal solution can

be monitored using the THERM input. The ADT7467 also

provides critical thermal protection to the system using the

bidirectional THERM pin as an output to prevent system or

component overheating.

SCL SDA

SERIAL BUS

INTERFACE

AUTOMATIC

FAN SPEED

CONTROL

DYNAMIC

MIN

CONTROL

ADT7467

INPUT

10-BIT

ADC

AND

BAND GAP

REFERENCE

GND

Figure 1.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

Fax: 781.326.8703

™

Remote Thermal

controller is a thermal monitor and

MIN

SMBALERT

ADDRESS

POINTER

PWM

CONFIGURATION

REGISTERS

INTERRUPT

MASKING

INTERRUPT

STATUS

REGISTERS

LIMIT

COMPARATORS

VALUE AND

LIMIT

REGISTERS

ADT7467

control mode

www.analog.com

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Summary of Contents for Analog Devices dBCool ADT7467

Page 1 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use.
Page 2: Table Of Contents
ADT7467 TABLE OF CONTENTS Specifications..................3 Laying Out 2-Wire and 3-Wire Fans ........28 Absolute Maximum Ratings............5 Operating from 3.3 V Standby..........32 Thermal Characteristics .............. 5 XNOR Tree Test Mode .............. 33 ESD Caution.................. 5 Power-On Default ..............33 Pin Configuration and Function Descriptions......
Page 3: Specifications
ADT7467 SPECIFICATIONS to T to V , unless otherwise noted. All voltages are measured with respect to GND, unless otherwise specified. Typicals are at T = 25°C and represent most likely parametric norm. Logic inputs accept input high voltages up to V even when device is operating down to V .
Page 4 ADT7467 Parameter Unit Test Conditions/Comments OPEN-DRAIN DIGITAL OUTPUTS, PWM1 to PWM3, XTO Current Sink, I Output Low Voltage, V = −8.0 mA, V = +3.3 V High Level Output Current, I µA OPEN-DRAIN SERIAL DATA BUS OUTPUT (SDA) Output Low Voltage, V = −4.0 mA, V = +3.3 V High Level Output Current, I...
Page 5: Absolute Maximum Ratings
ADT7467 ABSOLUTE MAXIMUM RATINGS Table 2. Stresses above those listed under Absolute Maximum Ratings Parameter Rating may cause permanent damage to the device. This is a stress Positive Supply Voltage (V 5.5 V rating only; functional operation of the device at these or any Voltage on Any Input or Output Pin −0.3 V to +6.5 V other conditions above those indicated in the operational...
Page 6: Pin Configuration And Function Descriptions
ADT7467 PIN CONFIGURATION AND FUNCTION DESCRIPTIONS PWM1/XTO ADT7467 TACH3 TOP VIEW PWM2/SMBALERT (NOT TO SCALE) D1– TACH1 D2– TACH2 PWM3 TACH4/GPIO/THERM/SMBALERT Figure 3. Pin Configuration Table 3. Pin Function Descriptions Mnemonic Description Digital Input (Open Drain). SMBus serial clock input. Requires SMBus pull-up. Ground Pin for the ADT7467.
Page 7: Typical Performance Characteristics
ADT7467 TYPICAL PERFORMANCE CHARACTERISTICS 100mV –10 –20 40mV –30 –40 –50 –5 60mV –60 –10 100M CAPACITANCE (nF) FREQUENCY (kHz) Figure 4. Temperature Error vs. Capacitance between D+ and D− Figure 7. Remote Temperature Error vs. Common Mode Noise Frequency –10 20mV –20...
Page 8 ADT7467 –0.5 –1.0 –1.5 –2.0 –2.5 –3.0 –3.5 –4.0 –40 –20 TEMPERATURE (°C) POWER SUPPLY VOLTAGE (V) Figure 10. Shutdown I vs. Power Supply Figure 13. Internal Temperature Error vs. ADT7467 Temperature INT ERROR, 250mV –0.5 –1.0 –1.5 –2.0 –5 –2.5 –10 INT ERROR, 100mV...
Page 9: Product Description
ADT7467 PRODUCT DESCRIPTION The ADT7467 is a complete thermal monitor and multiple fan The ADT7467 has an extended temperature measurement controller for any system requiring thermal monitoring and range. The measurement range goes from–64°C to +191°C. cooling. The device communicates with the system via a serial On the ADT7460, the measurement range is from −127°C system management bus.
Page 10: Recommended Implementation
ADT7467 Configuration Register 5 Table 4. Pin 9 Settings Bit 0 Bit 1 Function Bit 0: If Bit 0 is set to 1, the ADT7467 is backward compatible TACH4 temperature-wise with the ADT7460. Measurements, T THERM calibration circuit, fan control, etc., work in the range −127°C to +127°C.
Page 11: Serial Bus Interface
ADT7467 SERIAL BUS INTERFACE In the ADT7467, write operations contain either one or two bytes, and read operations contain one byte and perform the On PCs and servers, control of the ADT7467 is carried out following functions. To write data to one of the device data using the serial system management bus (SMBus).
Page 12: Write Operations
ADT7467 START BY ACK. BY ACK. BY STOP BY MASTER ADT7467 ADT7467 MASTER FRAME 1 FRAME 2 SERIAL BUS ADDRESS BYTE ADDRESS POINTER REGISTER BYTE Figure 17. Writing to the Address Pointer Register Only ACK. BY START BY NO ACK. BY STOP BY MASTER ADT7467...
Page 13: Read Operations
ADT7467 The slave asserts ACK on SDA. master. If a device’s SMBALERT line goes low, the following procedure occurs: The master sends a data byte. SMBALERT is pulled low. The slave asserts ACK on SDA. The master initiates a read operation and sends the alert The master asserts a stop condition on SDA to end the response address (ARA = 0001 100).
Page 14: Input Circuitry
ADT7467 INPUT CIRCUITRY ADDITIONAL ADC FUNCTIONS FOR VOLTAGE MEASUREMENTS The internal structure for the V analog input is shown in Figure 22. The input circuit consists of an input protection A number of other functions are available on the ADT7467 to diode, an attenuator, plus a capacitor to form a first-order low- offer the system designer increased flexibility.
Page 15: Temperature Measurement Method
ADT7467 Table 5. 10-Bit A/D Output Code vs. V Input Voltage A/D Output (+5 V (3.3 V Decimal Binary (10 Bits) <0.0065 <0.0042 <0.00293 00000000 00 0.0065–0.0130 0.0042–0.0085 0.0293–0.0058 00000000 01 0.0130–0.0195 0.0085–0.0128 0.0058–0.0087 00000000 10 0.0195–0.0260 0.0128–0.0171 0.0087–0.0117 00000000 11 0.0260–0.0325 0.0171–0.0214 0.0117–0.0146...
Page 16 ADT7467 Local Temperature Measurement If a discrete transistor is used, the collector is not grounded and should be linked to the base. If a PNP transistor is used, the base The ADT7467 contains an on-chip band gap temperature is connected to the D– input and the emitter to the D+ input. If sensor whose output is digitized by the on-chip 10-bit ADC.
Page 17: Series Resistance Cancellation
ADT7467 The ADT7467 has a major advantage over other devices for To reduce the error due to variations in both substrate and eliminating the effects of noise on the external sensor. Using the discrete transistors, a number of factors should be taken into consideration: series resistance cancellation feature, a filter can be constructed between the external temperature sensor and the part.
Page 18 ADT7467 Table 6. Temperature Data Format Nulling Out Temperature Errors Temperature Digital Output (10-Bit) As CPUs run faster, it is getting more difficult to avoid high –128°C 1000 0000 00 frequency clocks when routing the D+/D– traces around a –125°C 1000 0011 00 system board.
Page 19: Additional Adc Functions For Temperature Measurement
ADT7467 Temperature Measurement Limit Registers Table 9. Conversion Time with Averaging Enabled Channel Measurement Time Associated with each temperature measurement channel are Voltage Channels 11 ms high and low limit registers. Exceeding the programmed high or Remote Temperature 39 ms low limit causes the appropriate status bit to be set.
Page 20: Limits, Status Registers, And Interrupts
ADT7467 LIMITS, STATUS REGISTERS, AND INTERRUPTS LIMIT VALUES Reg. 0x57 TACH2 Minimum High Byte = 0x00 default Associated with each measurement channel on the ADT7467 Reg. 0x58 TACH3 Minimum Low Byte = 0x00 default are high and low limits. These can form the basis of system status monitoring;...
Page 21: Status Registers
ADT7467 As mentioned previously, the ADC performs round-robin Status Register 2 (Reg. 0x42) conversions . The total monitoring cycle time for averaged Bit 7 (D2) = 1 , indicates an open or short on D2+/D2– inputs. voltage and temperature monitoring is 145 ms. The total Bit 6 (D1) = 1 , indicates an open or short on D1+/D1–...
Page 22 ADT7467 Handling SMBALERT Interrupts ) = 1 , masks SMBALERT for V Bit 2 (V channel. To prevent the system from being tied up servicing interrupts, it ) = 1 , masks SMBALERT for V channel. Bit 0 (V is recommend to handle the SMBALERT interrupt as follows: Interrupt Mask Register 2 (Reg.
Page 23: Therm Timer
ADT7467 The user can also set up the ADT7467 so that, when the The 8-bit THERM timer register (Reg. 0x79) is designed such THERM pin is driven low externally, the fans run at 100%. The that Bit 0 is set to 1 on the first THERM assertion. Once the fans run at 100% for the duration of the time that the THERM cumulative THERM assertion time has exceeded 45.52 ms, Bit 1 pin is pulled low.
Page 24 ADT7467 Generating SMBALERT Interrupts from THERM Timer value, then the F4P bit (Bit 5) of Status Register 2 is set, and an Events SMBALERT is generated. Note that the F4P bit (Bit 5) of Mask Register 2 (Reg. 0x75) masks out SMBALERT s, if this bit is set The ADT7467 can generate SMBALERT s when a programma- to 1;...
Page 25 ADT7467 Configuring the THERM Behavior Alternatively, OS or BIOS level software can timestamp when the system is powered on. If an SMBALERT is Configure the relevant pin as the THERM timer input. generated due to the THERM timer limit being exceeded, Setting Bit 1 ( THERM timer enable) of Configuration another timestamp can be taken.
Page 26 ADT7467 FAN DRIVE USING PWM CONTROL Figure 35 shows a fan drive circuit using an NPN transistor such as a general-purpose MMBT2222. While these devices are The ADT7467 uses pulse-width modulation (PWM) to control inexpensive, they tend to have much lower current handling fan speed.
Page 27 ADT7467 ADT7467 3.3V 3.3V TACH3 TACH4 1kΩ PWM3 MMBT3904 2.2kΩ 10Ω MMBT2222 10Ω MMBT2222 Figure 37. Interfacing Two Fans in Parallel to the PWM3 Output Using Low Cost NPN Transistors 3.3V 10kΩ TYPICAL TACH4 3.3V ADT7467 10kΩ TYPICAL 1N4148 5V OR 5V OR TACH3 12V FAN...
Page 28: Laying Out 2-Wire And 3-Wire Fans
ADT7467 Note that when the voltage spikes (either negative going or TACH Inputs positive going) are more than 40 mV in amplitude, the fan Pins 4, 6, 7, and 9 (when configured as TACH inputs) are open- speed can be reliably determined. drain TACH inputs intended for fan speed measurement.
Page 29 ADT7467 5V OR 12V CLOCK PULL-UP TYP <1kΩ OR TACH 10kΩ TOTEM POLE FAN SPEED COUNTER TACH OUTPUT ZENER* ADT7467 TACH *CHOOSE ZD1 VOLTAGE APPROXIMATELY 0.8 × V Figure 44. Fan with Strong TACH Pull-Up to > V or Totem-Pole Output, Clamped with Zener and Resistor Alternatively, a resistive attenuator can be used, as shown in Figure 46.
Page 30 ADT7467 Fan TACH Limit Registers Fan Pulses per Revolution The fan TACH limit registers are 16-bit values consisting of two Different fan models can output either 1, 2, 3, or 4 TACH pulses bytes. per revolution. Once the number of fan TACH pulses has been determined, it can be programmed into the fan pulses per Reg.
Page 31 ADT7467 Configuration Register 4 (Reg. 0x7D) 101 = 1 s <3:2> AINL, input threshold for 2-wire fan speed 110 = 2 s measurements. 111 = 4 s 00 = ±20 mV PWM3 Configuration (Reg. 0x5E) 01 = ±40 mV <2:0> SPIN , start-up timeout for PWM3. 10 = ±80 mV 000 = no startup timeout 11 = ±130 mV...
Page 32: Operating From 3.3 V Standby
ADT7467 PWM1 Frequency Registers (Reg. 0x5F to Reg. 0x61) Example 1 : For a PWM duty cycle of 50%, <2:0> FREQ . Value (decimal) = 50/0.39 = 128 (decimal) 000 = 11.0 Hz Value = 128 (decimal) or 0x80 (hex) 001 = 14.7 Hz Example 2 : For a PWM duty cycle of 33%, 010 = 22.1 Hz...
Page 33: Xnor Tree Test Mode
ADT7467 If V goes high (the system processor power rail is powered XNOR TREE TEST MODE up), then a fail-safe timer begins to count down. If the ADT7467 The ADT7467 includes an XNOR tree test mode. This mode is is addressed by a valid SMBus transaction before the fail-safe useful for in-circuit test equipment at board-level testing.
Page 34: Programming The Automatic Fan Speed Control Loop
ADT7467 PROGRAMMING THE AUTOMATIC FAN SPEED CONTROL LOOP temperature. Reducing fan speed can also decrease system Note: To more efficiently understand the automatic fan speed current consumption. The automatic fan speed control mode is control loop, it is strongly recommended to use the ADT7467 very flexible owing to the number of programmable parameters, evaluation board and software while reading this section.
Page 35: Step 1: Hardware Configuration
ADT7467 STEP 1: HARDWARE CONFIGURATION How many fans will be supported in system, three or four? This influences the choice of whether to use the TACH4 During system design, the motherboard sensing and control pin or to reconfigure it for the THERM function. capabilities should be addressed early in the design stages.
Page 36: Recommended Implementation 1
ADT7467 5 V measurement input. RECOMMENDED IMPLEMENTATION 1 Configuring the ADT7467 as in Figure 51 provides the system VRM temperature using local temperature sensor. designer with the following features: CPU temperature measured using the Remote 1 Six VID inputs (VID0 to VID5) for VRM10 support. temperature channel.
Page 37: Recommended Implementation 2
ADT7467 5 V measurement input. RECOMMENDED IMPLEMENTATION 2 Configuring the ADT7467 as in Figure 52 provides the system VRM temperature using local temperature sensor. designer with the following features: CPU temperature measured using the Remote 1 Six VID inputs (VID0 to VID5) for VRM10 support. temperature channel.
Page 38: Step 2: Configuring The Mux
ADT7467 101 = Fastest speed calculated by local and Remote 2 STEP 2: CONFIGURING THE MUX temperature controls PWMx After the system hardware configuration is determined, the fans can be assigned to particular temperature channels. Not only 110 = Fastest speed calculated by all three temperature can fans be assigned to individual channels, but the behavior of channels controls PWMx the fans is also configurable.
Page 39 ADT7467 MUX Configuration Example Example MUX Settings This is an example of how to configure the MUX in a system <7:5> (BHVR), PWM1 Configuration Register 0x5C. using the ADT7467 to control three fans. The CPU fan sink is 101 = Fastest speed calculated by local and Remote 2 controlled by PWM1, the front chassis fan is controlled by temperature controls PWM1 PWM2, and the rear chassis fan is controlled by PWM3.
Page 40: Step 3: Tmin Settings For Thermal Calibration Channels
ADT7467 Registers STEP 3: T SETTINGS FOR THERMAL CALIBRATION CHANNELS Reg. 0x67, Remote 1 Temperature T = 0x9A (90°C) is the temperature at which the fans start to turn on under Reg. 0x68, Local Temperature T = 0x9A (90°C) automatic fan control. The speed at which the fan runs at T Reg.
Page 41: Step 4: Pwm Min For Each Pwm (Fan) Output
ADT7467 Programming the PWM Registers STEP 4: PWM FOR EACH PWM (FAN) OUTPUT The PWM registers are 8-bit registers that allow the is the minimum PWM duty cycle at which each fan in minimum PWM duty cycle for each output to be configured the system runs.
Page 42: Step 6: Trange For Temperature Channels
Using the ADT7467 evaluation software, can graphically Reg. 0x38, PWM1 Maximum Duty Cycle = 0xFF program and visualize this functionality. Ask your local (100% default) Analog Devices representative for details. Reg. 0x39, PWM2 Maximum Duty Cycle = 0xFF (100% default) 100% Reg.
Page 43 ADT7467 is implemented as a slope, which means that as PWM Example: Calculate T , given that T = 30°C, T = 40°C, RANGE RANGE is changed, T changes, but the actual slope remains the and PWM = 33% duty cycle = 85 (decimal). RANGE same.
Page 44 ADT7467 2°C Increasing or decreasing PWM changes the effective T RANGE 2.5°C although the fan control still follows the same PWM duty cycle 3.33°C 4°C to temperature slope. The effective T for different PWM RANGE 5°C values can be calculated using Equation 2: 6.67°C 8°C + (Max DC −...
Page 45: Step 7: Ttherm For Temperature Channels
ADT7467 The fans remain running at 100% until the temperature drops below T minus hysteresis, where hysteresis is the number THERM programmed into the Hysteresis Registers 0x6D and 0x6E. The default hysteresis value is 4°C. The T limit should be considered the maximum worst-case THERM operating temperature of the system.
Page 46: Step 8: Thyst For Temperature Channels
ADT7467 RANGE 100% THERM THERMAL CALIBRATION 100% CONFIG RAMP CONTROL PWM1 (ACOUSTIC GENERATOR ENHANCEMENT) TACHOMETER 1 RANGE TACH1 MEASUREMENT CPU FAN SINK THERMAL CALIBRATION CONFIG REMOTE 2 = 100% CPU TEMP RAMP CONTROL PWM2 (ACOUSTIC GENERATOR ENHANCEMENT) TACHOMETER 2 TACH2 MEASUREMENT RANGE CONFIG...
Page 47 ADT7467 RANGE 100% THERM THERMAL CALIBRATION 100% CONFIG RAMP CONTROL PWM1 (ACOUSTIC GENERATOR ENHANCEMENT) TACHOMETER 1 RANGE TACH1 MEASUREMENT CPU FAN SINK THERMAL CALIBRATION CONFIG REMOTE 2 = 100% CPU TEMP RAMP CONTROL PWM2 (ACOUSTIC GENERATOR ENHANCEMENT) TACHOMETER 2 TACH2 MEASUREMENT RANGE CONFIG...
Page 48: Dynamic Tmin Control Mode
ADT7467 VENTS DYNAMIC T CONTROL MODE I/O CARDS In addition to the automatic fan speed control mode described VENTS POWER I/O CARDS POWER in the Automatic Fan Control Overview section, the ADT7467 SUPPLY SUPPLY has a mode that extends the basic automatic fan speed control loop.
Page 49 ADT7467 Dynamic T Control Overview Figure 69 shows an overview of the parameters that affect the Dynamic T control mode builds upon the basic automatic operation of the dynamic T control loop. fan control loop by adjusting the T value based on system performance and measured temperature.
Page 50: Step 9: Operating Points For Temperature Channels
ADT7467 the operating point to be exceeded, and in turn, the ADT7467 STEP 9: OPERATING POINTS FOR TEMPERATURE reduces T to turn the fans on sooner to cool the system. CHANNELS Programming Operating Point Registers The operating point for each temperature channel is the optimal There are three operating point registers, one for each temperature for that thermal zone.
Page 51: Step 10: High And Low Limits For Temperature Channels
ADT7467 Short Cycle and Long Cycle STEP 10: HIGH AND LOW LIMITS FOR TEMPERATURE CHANNELS The ADT7467 implements two loops: a short cycle and a long cycle. The short cycle takes place every n monitoring cycles. The The low limit defines the temperature at which the T value long cycle takes place every 2n monitoring cycles.
Page 52 ADT7467 depends on how much the temperature has increased between WAIT 2n MONITORING this monitoring cycle and the last monitoring cycle, that is, if CYCLES the temperature has increased by 1°C, then T is reduced by CURRENT 2°C. Decreasing T has the effect of increasing the fan speed, TEMPERATURE MEASUREMENT...
Page 53: Step 11: Monitoring Therm
ADT7467 THERM LIMIT HIGH TEMP LIMIT OPERATING POINT HYSTERESIS ACTUAL NO CHANGE IN T HERE TEMP DUE TO ANY CYCLE, BECAUSE T1(n) – T1 (n – 1) ≤ 0.25°C AND T1(n) < OP = > T STAYS THE SAME LOW TEMP LIMIT DECREASE HERE DUE TO DECREASE HERE DUE TO...
Page 54: Enhancing System Acoustics
ADT7467 Enabling the THERM Trip Point as the Operating Point R2T = 0, disables dynamic T control. The T value chosen is not adjusted and the channel behaves as described in the Bits <4:2> of dynamic T control Register 1 (Reg. 0x36) Automatic Fan Control Overview section.
Page 55 ADT7467 ACOUSTIC ENHANCEMENT THERMAL CALIBRATION 100% CONFIG RAMP CONTROL PWM1 (ACOUSTIC GENERATOR ENHANCEMENT) TACHOMETER 1 RANGE TACH1 MEASUREMENT CPU FAN SINK THERMAL CALIBRATION CONFIG REMOTE 2 = 100% CPU TEMP RAMP CONTROL PWM2 (ACOUSTIC GENERATOR ENHANCEMENT) TACHOMETER 2 TACH2 MEASUREMENT RANGE CONFIG LOCAL =...
Page 56: Step 12: Ramp Rate For Acoustic Enhancement
ADT7467 cycle is, therefore, high for 1/3 × 255 time slots and low for 2/3 STEP 12: RAMP RATE FOR ACOUSTIC × 255 time slots. Therefore, a 33% PWM duty cycle corresponds ENHANCEMENT to a signal that is high for 85 time slots and low for 170 time The optimal ramp rate for acoustic enhancement can be found slots.
Page 57 ADT7467 Figure 80 shows remote temperature plotted against PWM duty (°C) TEMP cycle for enhanced acoustics mode. The ramp rate is set to 48, which corresponds to the fastest ramp rate. Assume that a new temperature reading is available every 115 ms. With these settings, it takes approximately 0.76 s to go from 33% duty cycle PWM DUTY CYCLE (%) to 100% duty cycle (full speed).
Page 58 ADT7467 Enhanced Acoustics Register 1 (Reg. 0x62) <2:0> ACOU, selects the ramp rate for PWM1. PWM DUTY CYCLE (%) 000 = 140 s 001 = 70.4 s 010 = 47.2 s (°C) TEMP 011 = 28 s 100 = 17.6 s 101 = 12 s 110 = 6.4 s 111 = 3.2 s...
Page 59: Register Tables
ADT7467 REGISTER TABLES Table 16. ADT7467 Registers Address Description Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default Lockable? 0x21 Vccp Reading 0x00 0x22 Reading 0x00 0x25 Remote 1 0x01 Temperature 0x26 Local 0x01 Temperature...
Page 60 ADT7467 Address Description Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default Lockable? 0x41 Interrupt Status 0x00 Register 1 0x42 Interrupt Status FAN3 FAN2 FAN1 0x00 Register 2 0x46 Low Limit 0x00 0x47 High Limit 0xFF...
Page 61 ADT7467 Address Description Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default Lockable? 0x61 Remote 2 RANGE RANGE RANGE RANGE THRM FREQ FREQ FREQ 0XC4 /PWM3 RANGE Frequency 0x62 Enhance MIN3 MIN2 MIN1 SYNC ACOU...
Page 62 ADT7467 Address Description Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default Lockable? 0x7C Configuration GPIOP GPIOD LF/HF Twos 0X00 Register 5 Compl 0x7D Configuration BpAtt AINL AINL Pin 9 Pin 9 0X00 Register 4 Func...
Page 63 ADT7467 1, 2, 3 Table 21. Operating Point Registers (Power-On Default = 0x64) Register Address Description 0x33 Read/write Remote 1 operating point register (default = 100°C). 0x34 Read/write Local temperature operating point register (default = 100°C). 0x35 Read/write Remote 2 operating point register (default = 100°C). These registers set the target operating point for each temperature channel when the dynamic T control feature is enabled.
Page 64 ADT7467 Table 23. Register 0x37—Dynamic T Control Register 2 (Power-On Default = 0x00) Name Description <2:0> CYR1 Read/write 3-Bit Remote 1 Cycle Value. These three bits define the delay time between making subsequent T adjustments in the control loop for the Remote 1 channel, in terms of number of monitoring cycles. The system has associated thermal time constants that need to be found to optimize the response of fans and the control loop.
Page 65 ADT7467 Table 25. Register 0x40—Configuration Register 1 (Power-On Default = 0x01) Name 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 the default power-up limit settings. Note that the limit values programmed are preserved even if a Logic 0 is written to this bit and the default settings are enabled.
Page 66 ADT7467 Table 27. Register 0x42—Interrupt Status Register 2 (Power-On Default = 0x00) Name Description <1> Read-only OVT = 1 indicates that one of the THERM overtemperature limits has been exceeded. This bit is cleared on a read of the status register when the temperature drops below THERM –T HYST <2>...
Page 67 ADT7467 Table 31. Register 0x55—TACH 1 Minimum High Byte (Power-On Default = 0xFF) Name Description <4:0> Reserved Read-only These bits are reserved when Bit 6 of Config 2 Register (0x73) is set (single-channel ADC mode). Otherwise, these bits represent Bits <4:0> of the TACH1 minimum high byte. <7:5>...
Page 68 ADT7467 Table 33. TEMP T /PWM Frequency Registers RANGE Register Address Description Power-On Default 0x5F Read/write Remote 1 T /PWM1 frequency. 0xC4 RANGE 0x60 Read/write Local temperature T /PWM2 frequency. 0xC4 RANGE 0x61 Read/write Remote 2 T /PWM3 frequency. 0xC4 RANGE Name Description...
Page 69 ADT7467 Table 34. Register 0x62—Enhanced Acoustics Register 1 (Power-On Default = 0x00) Name 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, PWM1 ramps gracefully at the rate determined by these bits. This feature enhances the acoustics of the fan being driven by the PWM1 output.
Page 70 ADT7467 Table 35. Register 0x63—Enhanced Acoustics Register 2 (Power-On Default = 0x00) Name 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 speed, PWM3 ramps gracefully at the rate determined by these bits. This effect enhances the acoustics of the fan being driven by the PWM3 output.
Page 71 ADT7467 Table 38. THERM Limit Registers Register Address Description Power-On Default Remote 1 THERM limit. 0x6A Read/write 0x64 (100°C) 0x6B Read/write Local THERM limit. 0x64 (100°C) Remote 2 THERM limit. 0x6C Read/write 0x64 (100°C) If any temperature measured exceeds its THERM limit, all PWM outputs drive their fans at 100% duty cycle. This is a fail-safe mechanism incorporated to cool the system in the event of a critical overtemperature.
Page 72 ADT7467 Table 42. Local Temperature Offset Register Address Description Power-On Default 0x71 Read/write Local temperature offset. 0x00 <7:0> Read/write Allows a twos complement offset value to be automatically added to or subtracted from the local temperature reading. LSB value = 0.5°C. This register becomes read-only when the Configuration Register 1 lock bit is set to 1.
Page 73 ADT7467 Table 45. Register 0x74—Interrupt Mask Register 1 (Power-On Default <7:0> = 0x00) Name Description Read/write = 1, masks SMBALERT for out-of-limit conditions on the V channel. Read/write = 1, masks SMBALERT for out-of-limit conditions on the V channel. Read/write R1T = 1, masks SMBALERT for out-of-limit conditions on the Remote 1 temperature channel.
Page 74 ADT7467 Table 49. Register 0x78—Configuration Register 3 (Power-On Default = 0x00) Name Description <0> ALERT Read/write ALERT = 1, Pin 5 (PWM2/ SMBALERT ) is configured as an SMBALERT interrupt output to indicate out- of-limit error conditions. <1> THERM Read/write THERM Enable = 1 enables THERM timer monitoring functionality on Pin 9.
Page 75 ADT7467 Table 52. Register 0x7B—TACH Pulses per Revolution Register (Power-On Default = 0x55) Name Description <1:0> FAN1 Read/write Sets number of pulses to be counted when measuring Fan 1 speed. Can be used to determine fan pulses per revolution for unknown fan type. Pulses Counted 00 = 1 01 = 2 (default)
Page 76 ADT7467 Table 54. Register 0x7D—Configuration Register 4 (Power-On Default = 0x00) Name Description <1:0> Pin9FUNC Read/write These bits set the functionality of Pin 9: 00 = TACH4 (default) 01 = Bidirectional THERM 10 = SMBALERT 11 = GPIO <3:2> AINL Read/write These two bits define the input threshold for 2-wire fan speed measurements (low frequency mode only):...
Page 77: Adt7467 Programming Block Diagram
ADT7467 ADT7467 PROGRAMMING BLOCK DIAGRAM Figure 85. Rev. 0| Page 77 of 80...
Page 78: Outline Dimensions
ADT7467 OUTLINE DIMENSIONS 0.193 0.154 0.236 PIN 1 0.069 0.065 0.053 0.049 8° 0.010 0.025 0° 0.012 0.050 0.004 SEATING 0.010 0.008 0.016 PLANE COPLANARITY 0.006 0.004 COMPLIANT TO JEDEC STANDARDS MO-137AB Figure 86. 16-Lead Shrink Small Outline Package [QSOP] (RQ-16) Dimensions shown in inches ORDERING GUIDE...
Page 79 ADT7467 NOTES Rev. 0| Page 79 of 80...

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