Analog Devices ADT7460 Manual

Dbcool remote thermal controller and fan controller

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FEATURES

Controls and monitors up to 4 fan speeds

1 on-chip and 2 remote temperature sensors

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 and 3-wire fan speed measurement

Limit comparison of all monitored values

Meets SMBus 2.0 electrical specifications (fully

SMBus 1.1-compliant)

APPLICATIONS

Low acoustic noise PCs

Networking and telecommunications equipment

PWM1

PWM2

PWM3

TACH1

TACH2

TACH3

TACH4

THERM

D1+

D1–

D2+

D2–

+2.5V

Protected by U.S. Patent Nos. 6,188,189; 6,169,442; 6,097,239; 5,982,221; and 5,867,012. Other patents pending.

Rev. C

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

PWM REGISTERS

ENHANCEMENT

AND

CONTROL

CONTROLLERS

FAN SPEED

COUNTER

PERFORMANCE

MONITORING

THERMAL

PROTECTION

TO ADT7460

SIGNAL

CONDITIONING

ANALOG

MULTIPLEXER

BAND GAP

TEMP SENSOR

Controller and Fan Controller

GENERAL DESCRIPTION

The ADT7460

multiple PWM fan controller for noise-sensitive applications

requiring active system cooling. It can monitor the temperature

of up to two remote sensor diodes plus its own internal temp-

erature. It can 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

control mode 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

ADT7460 also provides critical thermal protection to the

system by using the bidirectional THERM pin as an output

to prevent system or component overheating.

ADDR

SELECT

ADDR_EN

SCL SDA

SMBUS

SERIAL BUS

ADDRESS

INTERFACE

SELECTION

AUTOMATIC

FAN SPEED

CONTROL

DYNAMIC

MIN

CONTROL

ADT7460

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: 781.461.3113

COOL™ Remote Thermal

dBCOOL controller is a thermal monitor and

SMBALERT

ADDRESS

POINTER

PWM

CONFIGURATION

REGISTERS

INTERRUPT

MASKING

INTERRUPT

STATUS

REGISTERS

LIMIT

COMPARATORS

VALUE AND

LIMIT

REGISTERS

ADT7460

MIN

www.analog.com

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Summary of Contents for Analog Devices ADT7460

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
Updated the SERIAL BUS INTERFACE section........9 Changes to Absolute Maximum Ratings Table......5 Added the To Assign THERM Functionality to a Pin 9 section ..21 Changes to ADT7460 Register Map Summary Section .....34 Added the THERM as an Input section..........21 Updated Ordering Guide..............51 Renamed the Therm Input section to THERM Timer ....21...
Page 3: Specifications
ADT7460 SPECIFICATIONS to T to V , unless otherwise noted. Table 1. 1, , 2 3 Parameter Unit Test Conditions/Comments POWER SUPPLY Supply Voltage Supply Current, I Interface inactive, ADC active µA Standby mode TEMPERATURE-TO-DIGITAL CONVERTER Local Sensor Accuracy ±1.5 °C...
Page 4: Updated Ordering
ADT7460 1, 2, 3 Parameter Unit Test Conditions/Comments DIGITAL INPUT LOGIC LEVELS (TACH INPUTS) Input High Voltage, V Maximum input voltage Input Low Voltage, V +0.8 −0.3 Minimum input voltage Hysteresis V p-p DIGITAL INPUT LOGIC LEVELS (THERM) Input High Voltage, V...
Page 5: Absolute Maximum Ratings
ADT7460 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 6.5 V rating only; functional operation of the device at these or any Voltage on Any Other Input or Output Pin −0.3 V to +6.5 V...
Page 6: Pin Configuration And Function Descriptions
Power Supply. Can be powered by 3.3 V standby if monitoring in low power states is required. V is also monitored through this pin. The ADT7460 can also be powered from a 5 V supply. Setting Bit 7 of Configuration Register 1 (Reg. 0x40) rescales the V input attenuators to correctly measure a 5 V supply.
Page 7: Typical Performance Characteristics
ADT7460 TYPICAL PERFORMANCE CHARACTERISTICS HIGH LIMIT DXP TO GND +3 SIGMA –5 –3 SIGMA DXP TO V (3.3V) –1 –10 –2 –15 LOW LIMIT –3 –20 10.0 30.0 100.0 –40 LEAKAGE RESISTANCE (M Ω ) TEMPERATURE (°C) Figure 4. Remote Temperature Error vs. Leakage Resistance Figure 7.
Page 8 ADT7460 1.90 1.85 100mV 1.80 1.75 1.70 1.65 1.60 40mV 1.55 20mV 1.50 1.45 –5 1.40 –10 100k FREQUENCY (Hz) SUPPLY VOLTAGE (V) Figure 12. Remote Temperature Error vs. Common-Mode Noise Frequency Figure 10. Supply Current vs. Supply Voltage 20mV 10mV –2...
Page 9: Product Description
(Pin 1). All control and programming functions limit registers. The results of out-of-limit comparisons are of the ADT7460 are performed over the serial bus. In addition, stored in the status registers, which can be read over the serial two of the pins can be reconfigured as an SMBALERT output to bus to flag out-of-limit conditions.
Page 10: Adt7460 Address Selection
These registers provide control and configuration of the ADT7460, including alternate pinout functionality. Address Pointer This register contains the address that selects one of the other internal registers. When writing to the ADT7460, the first byte of data is always a register address, which is written to the address pointer register.
Page 11: Theory Of Operation
ADT7460 has a default SMBus address of 0101110 or 0x2E. If ADDRESS = 0x2D more than one ADT7460 is to be used in a system, each ADT7460 should be placed in address select mode by strapping Pin 8 low Figure 16. SMBus Address 0x2D (Pin 9 = 1) on power-up.
Page 12 Transitions on the data line must occ In the case of the ADT7460, write operations contain either one during the low period of the clock signal and remain stable or two bytes, and read operations contain one byte.
Page 13 The SMBus specification defines several protocols for different register. This is done by performing a write to the ADT7460 types of read and write operations. The ones used in the as before, but only the data byte containing the register ADT7460 are discussed below.
Page 14 Figure 21. Settin g a Register Address for Subsequent Read In the ADT7460, the receive byte protocol is used to read a If it is required to read data from the register immediat ely after single byte of data from a register whose address has previously...
Page 15: Voltage Measurement Input
The ADT7460 includes an SMBus timeout feature. If there is no The internal structure for the 2.5 V analog input is shown in SMBus activity for 25 ms, the ADT7460 assumes that the bus is Figure 24. The input circuit consists of an input protection locked and releases the bus.
Page 16 ADT7460 Table 9. 10-Bit A/D Output Code vs. V Input Voltage A/D Output (3.3 V 2.5 V Decimal Binary (10 Bits) <0.0065 <0.0042 <0.0032 00000000 00 0.0065–0.0130 0.0042–0.0085 0.0032–0.0065 00000000 01 0.0130–0.0195 0.0085–0.0128 0.0065–0.0097 00000000 10 0.0195–0.0260 0.0128–0.0171 0.0097–0.0130 00000000 11 0.0260–0.0325...
Page 17: Additional Adc Functions For Voltage Measurements
Local Temperature Measurement VOLTAGE MEASUREMENTS The ADT7460 contains an on-chip band gap temperature A number of other functions are available on the ADT7460 to sensor whose output is digitized by the on-chip 10-bit ADC. offer the systems designer increased flexibility.
Page 18 D− input, and the base to the D+ input. Figure 26 and −75°C 1011 0101 00 Figure 27 show how to connect the ADT7460 to an NPN or −50°C 1100 1110 00 PNP transistor for temperature measurement. To prevent −25°C...
Page 19: Additional Adc Functions For Temperature Measurement
100% FANS ments that are too high by a constant amount. The ADT7460 has temperature offset registers at Addresses 0x70, 0x72 for the Remote 1 and Remote 2 temperature channels. By doing a one- Figure 28.
Page 20: Limits, Status Registers, And Interrupts
ADT7460 LIMITS, STATUS REGISTERS, AND INTERRUPTS Out-of-Limit Comparisons Limit Val Once all limits have been programmed, the ADT7460 can be Associ ated with ea ch measuremen t channel on the ADT7460 enabled for monitoring. The ADT7460 measures all parameters are hig h and low li mits.
Page 21: Status Registers
ADT7460 The total number of channels measured is • Two supply voltage inputs (2.5 V and V NO INT • Local temperature • Two remote temperatures As mentioned previously, the ADC performs round-robin conversions and take s 11.38 ms for each volt...
Page 22: Handling Smbalert Interrupts
SMBALERT Interrupt Behavior Mnemonic Descriptio The ADT7460 can be polled for status, or an SMBALERT 1 denotes a bit in Status Register 2 is set interrupt can be generated for out-of-limit conditions. It is and Status Register 2 should be read.
Page 23 To Assign THERM Functionality to Pin 9 Figure 36. How Masking the Interrupt Source Affects SMBALERT Output Pin 9 can be configured as the THERM pin on the ADT7460. Masking Interrupt Sources To configure Pin 9 as the THERM pin, set the THERM ENABLE Interrupt Mask Registers 1 and 2 are located at Addresses 0x74 Bit (Bit 1) in Configuration Reg er 3 (Address 0x78) = 1.
Page 24: Therm Timer
If the THERM timer is read during a THERM assertion The timer is started on the assertion of the ADT7460’s THERM input and stopped on the negation of the pin. The timer counts •...
Page 25 F4P BIT (BIT 5) STATUS REGISTER 2 SMBALERT ATCH ESET CLEARED 1 = MASK ON READ F4P BIT (BIT 5) MASK REGISTER 2 (REG. 0x75) ram of ADT7460’ THERM Figure 39. Functional Diag Monitoring Circuitry Rev. C | Page 25 of 52...
Page 26 ADT7460 Configuring the Desired THERM Behavior Configuring the ADT7460 THERM Pin as an Output In addition to the ADT7460 being able to monitor THERM as Configure the THERM input. an input, the ADT7460 can optionally drive THERM low as a Setting Bit 1 ( THERM ENABLE) of Configuration output.
Page 27: Fan Drive Using Pwm Control
-wire fan can be driven using PWM control. Note that the ADT7460 has four TACH inputs available for fan speed measurement, but only three PWM drive outputs. If a fourth fan is being used in the system, it should be driven from the PWM3 output in parallel with the third fan.
Page 28: Updated The Fan Speed Control Section
40 mV in amplitude. This allows fan speed to be reliably determined. Driving 2-Wire Fans Figure 45 shows how a 2-wire fan may be connected to the ADT7460. This circuit allows the speed of a 2-wire fan to be 1N4148 3.3V 5V OR measured, even though the fan has no dedicated TACH signal.
Page 29: Added The Power-On Default Section
3.83 V. measure ment. 5V OR 12V Signal conditioning in the ADT7460 accommodates the slow rise and fall times typical of fan tachometer outputs. The maxi- mum input signal range is 0 V to 5 V, even where V is less...
Page 30: Updated Table Iv
ADT7460 Reading Fan Speed from the ADT7460 If fan speeds are being measured, this involves a 2-register read r each measurement. The low byte should be read first. This ADT7460 <1kΩ uses the high byte to be frozen until both high and low byte...
Page 31 <7:6> FAN4 Default 2 pulses per revolution The ADT7460 has a unique fan spin-up function. It spins the fan at 100% PWM duty cycle until two TACH pulses are detected on the TACH input. Once two pulses are detected, the Table 33.
Page 32 Manual Fan Speed Control up for the fixed time as selected in Registers 0x5C to 0x5E. The ADT7460 allows the duty cycle of any PWM output to be PWM Logic State manually adjusted. This can be useful if you want to change fan...
Page 33: Operating From 3.3 V Standby
Table 40. PWM Duty Cycle Registers XNOR TREE TEST MODE Register Description ault The ADT7460 includes an XNOR tree test mode. This mode is 0x30 PWM1 duty cycle 0xFF (100%) useful for in-circuit test equipment at board-level testing. By 0x31...
Page 34: Changes To Adt7460 Register Map Summary Section
ADT7460 ADT7460 REGISTER SUMMARY Tabl e 41 . AD 7460 Registers Addre Description Defau Lock able? 0x20 2.5 V Reading 0x00 0x22 Reading 0x00 0x25 Remote 1 Temperature 0x80 0x26 Local Temperature 0x80 0x27 Remote 2 Temperature 0x80 0x28 TACH1...
Page 35 ADT7460 Address Description Bit 7 Bit 6 Bit 5 Bit 4 Bit 2 Bit 1 Bit 0 Default Lockable? 0x67 Remote 1 Tem 0x5A 0x68 Local Temp T 0x5A 0x69 Remote 2 Tem 0x5A 0x6A Remote 1 THERM Limit 0x64...
Page 36 PWM3 Current Duty Cycle (0% to 100% Duty Cycle = 0x00 to 0xFF) These registers reflect the PWM duty cycle driving each fan at any given time. When in automatic fan speed control mode, the ADT7460 reports the PWM duty cycles back through these registers. The PWM duty cycle values vary according to temperature in automatic fan speed control mode.
Page 37 ADT7460 Table 47. Register 0x36—Dynamic T Control Register 1 (Power-On Default = 0x00) Desc ription <0> ad/Write of 3-Bit Remote 2 Cycle Value. The other two bits of the code reside in Dynamic T Control Register 2 (Reg. 0x37). These three bits define the delay time between making subsequent T...
Page 38: Updated Table Xviii
ADT7460 Table 48. Register 0x37—Dynamic T Control Register 2 (Power-On Default = 0x00) Descr iption <2:0> Read/W ite 3-Bit Remote 1 Cycle Value. These three bits define the delay time between making subse quent T adjustments in the control loop for the Remote 1 channel, in terms of number of monitoring cycles.
Page 39 ADT7460 is powered down and powered up again. This prevents rogue programs such as viruses from modifying critical system limit settings. (Lockable.) <2> Read-Only his bit is set to 1 by the ADT7460 to indicate that the device is fully powered-up and ready to begin syste onitoring. <3> FSPD Read/Write When set to 1, all fans run at full speed.
Page 40: Updated Table Xx
ADT7460 Table 51. Register 0x42—Interrupt Status Register 2 (Power-On Defaul t = 0x00) Name Description <0> Read-Only Reserved for future use. <1> Read-Only A 1 indicates that one of the THERM overte mperature limits has been ex ceeded. This bit is cleared on a read...
Page 41 ADT7460 Table 54. Fan Tachometer Limit Registers (Power-On Default = 0xFF) Register Address Description 0x54 Read/Write TACH1 Minimum Low Byte 0x55 Read/Write TACH1 Minimum High Byte 0x56 Read/Write TACH2 Minimum Low Byte 0x57 Read/Write TACH2 Minimum High Byte 0x58 Read/Write...
Page 42 ADT7460 Table 57. TEMP T /PWM Frequency Registers (Power-On Default 0xC4) RANGE iste r Addre s Description 0x5F Read/Write Remote 1 T /PWM1 frequency RANGE 0x60 Read/Write Local Temp T /PWM2 frequency RANGE 0x61 Read/Write Remote 2 T /PWM3 frequency...
Page 43 <6> MIN2 Read/Write When the ADT7460 is in automatic fan speed control mode, this bit defines whether PWM2 is off (0% duty cycle) or at PWM2 minimum duty cycle when the controlling temperature is below its T − Hysteresis value.
Page 44 PWM2 Min Duty Cycle 0x80 (50% duty cycle) 0x66 Read/Write PWM3 Min Duty Cycle 0x80 (50% duty cycle) These registers become read-only when the ADT7460 is in automatic fan control mode. Table 62. PWM Min Duty Cycle Register Bits Name Read/Wr Descript <7:0>...
Page 45 ADT7460 Table 63. T Registers Register Address Description Power-On Default 0x67 Read /Write Remote 1 T emperature T 0x5A (90°C) 0x68 Read/Write Local Temperature T 0x5A (90°C) 0x69 Read/Write Remote 2 Temperature T 0x5A (90°C) These are the T registers for each temperature channel. When the temperature measured exceeds T...
Page 46: Updated Table Xxxv
ADT7460 Table 67. Remote 1 Temperature Offset Register (Power-On Default = 0x00) Reg ter Add ss Descr iption 0x70 Read/W e Remote 1 Temperature Offset <7:0> Read/Writ Allows a twos complement offset value to be automatically added to or subtracted from th Remote 1 temperature reading.
Page 47 Read/Write CONV = 1, the A DT7460 is put into a single-channel ADC conver sion mode. In this mode, the ADT7460 can made to read continuously from one input only, for example, Remote 1 temperature. It is also possible to start ADC conversions using an external clock on Pin 6 by setting Bit 2 of Test Register 2 (Reg. 0x7F). This ode could be useful if, for example, users wanted to charac terize/profile CPU temperature quickly.
Page 48 ADT7460 Table 72. Register 0x75—Interrupt Mask Register 2 (Power-On Default = 0x00 Name Description Read/Write Reserved for future use. Read-Only A 1 masks SMBALERT for overtemperature THERM conditions. FAN1 Read/Write A 1 masks SMBALERT for a Fan 1 fault. FAN2 Read/Write A 1 masks SMBALERT for a Fan 2 fault.
Page 49: Updated Outline Dimensions
ADT7460 Table 76. Register 0x79— THERM Status Register (Power-On Default = 0x00) Name Descrip tion <7:1> Read-On Times how long THERM input is asserted. These seven bits read 0 until the THERM assertion time exceeds 45.52 ms. <0> ASRT/TMR0 Read-Only Is set high on the assertion of the THERM input.
Page 50 ADT7460 Table 79. Register 0x7D—Configur ation Register 4 (Power-On Default = 0x00) Name cription <0> AL2.5V Read/Write AL2.5V = 1, Pin 14 (2.5V/SMBALERT) is configured as an SMBALERT interrupt output to indicate out-of-limit error conditions. AL2.5V = 0, Pin 14 (2.5V/SMBALERT) is configured as a 2.5 V measurement input.
Page 51: Updated Ordering Guide
ADT7460 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 55. 16-Lead Shrink Small Outline Package [QSOP]...

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