IC REMOTE THERMAL CTRLR 24QSOP

ADT7476ARQZ

Manufacturer Part NumberADT7476ARQZ
DescriptionIC REMOTE THERMAL CTRLR 24QSOP
ManufacturerON Semiconductor
SeriesdBCool®
ADT7476ARQZ datasheet
Product Change Notification
 

Specifications of ADT7476ARQZ

FunctionFan Control, Temp MonitorTopologyADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
Sensor TypeExternal & InternalSensing Temperature-40°C ~ 125°C, External Sensor
Output TypeSMBus™Output AlarmNo
Output FanYesVoltage - Supply3 V ~ 3.6 V
Operating Temperature-40°C ~ 125°CMounting TypeSurface Mount
Package / Case24-QSOPFull Temp Accuracy+/- 0.5 C
Digital Output - Bus InterfaceSerial (3-Wire, 4-Wire)Maximum Operating Temperature+ 125 C
Minimum Operating Temperature- 40 CLead Free Status / RoHS StatusLead free / RoHS Compliant
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ADT7476
R
dBCOOL
Remote Thermal
Controller and Voltage
Monitor
The ADT7476 dBCOOL controller is a thermal monitor
and multiple PWM fan controller for noise−sensitive or
power−sensitive applications requiring active system cooling. The
ADT7476 can drive a fan using either a low or high frequency drive
signal and can monitor the temperature of up to two remote sensor
diodes plus its own internal temperature. The part also measures and
controls the speed of up to four fans, so the fans operate at the lowest
possible speed for minimum acoustic noise.
The automatic fan speed control loop optimizes fan speed
for a given temperature. The effectiveness of the system’s thermal
solution can be monitored using the THERM input. The ADT7476
also provides critical thermal protection to the system using the
bidirectional THERM pin as an output to prevent system or
component overheating.
Features
Monitors Up to Five Voltages
Controls and Monitors Up to Four Fans
High and Low Frequency Fan Drive Signal
One On−Chip and Two Remote Temperature Sensors
Extended Temperature Measurement Range Up to 191°C
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
3−Wire and 4−Wire Fan Speed Measurement
Limit Comparison of All Monitored Values
Meets SMBus 2.0 Electrical Specifications
Pb−Free Package is Available
Halide−Free Packages are Available
© Semiconductor Components Industries, LLC, 2010
May, 2010 − Rev. 6
http://onsemi.com
QSOP−24 NB
CASE 492B
MARKING DIAGRAMS
ADT7476RQZ
#YYWW
xxxx
XX
= Specific Device Code
#
= Pb−Free Package
YYWW = Date Code
xxxx
= Assembly Lot Code
PIN ASSIGNMENT
SDA
1
SCL
2
GND
3
V
4
CC
VID0/GPIO0
5
VID1/GPIO1
6
ADT7476
VID2/GPIO2
7
VID3/GPIO3
8
TACH3
9
PWM2/
10
SMBALERT
TACH1
11
TACH2
12
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 66 of this data sheet.
1
Publication Order Number:
PWM1/XTO
24
V
23
CCP
+2.5V
/THERM
22
IN
+12V
/VID5
21
IN
+5V
20
IN
VID4/GPIO4
19
D1+
18
17
D1−
D2+
16
D2−
15
TACH4/THERM/SMBALERT/
14
GPIO6/ADDR SELECT
PWM3/ADDREN
13
ADT7476/D

ADT7476ARQZ Summary of contents

  • Page 1

    ADT7476 R dBCOOL Remote Thermal Controller and Voltage Monitor The ADT7476 dBCOOL controller is a thermal monitor and multiple PWM fan controller for noise−sensitive or power−sensitive applications requiring active system cooling. The ADT7476 can drive a fan using either a ...

  • Page 2

    VID5/GPIO5 VID4/GPIO4 VID3/GPIO3 VID/GPIO VID2/GPIO2 REGISTER VID1/GPIO1 VID0/GPIO0 GPIO6 PWM PWM1 REGISTERS AUTOMATIC PWM2 AND FAN SPEED CONTROLLERS CONTROL PWM3 (HF AND LF) TACH1 FAN TACH2 SPEED TACH3 COUNTER TACH4 PERFORMANCE MONITORING THERMAL THERM PROTECTION V TO ADT7476 CC V ...

  • Page 3

    ABSOLUTE MAXIMUM RATINGS Parameter Positive Supply Voltage ( Maximum Voltage on +12 V Pin IN Maximum Voltage on +5.0 V Pin IN Maximum Voltage on All Open−Drain Outputs Input Current at Any Pin Package Input Current Maximum Junction ...

  • Page 4

    ELECTRICAL CHARACTERISTICS Parameter Power Supply Supply Voltage Supply Current Temperature−to−Digital Converter Local Sensor Accuracy Resolution Remote Diode Sensor Accuracy Resolution Remote Sensor Source Current Analog−to−Digital Converter (Including MUX and Attentuators) Total Unadjusted Error (TUE) Differential Non−linearity (DNL) Power ...

  • Page 5

    ELECTRICAL CHARACTERISTICS Parameter Digital Input Logic Levels (THERM) ADTL+ Input High Voltage Input Low Voltage Digital Input Current Input High Current Input Low Current Input Capacitance Serial Bus Timing Clock ...

  • Page 6

    PIN ASSIGNMENT Pin No. Mnemonic 1 SDA Digital I/O (Open Drain). SMBus bidirectional serial data. Requires SMBus pullup. 2 SCL Digital Input (Open Drain). SMBus serial clock input. Requires SMBus pullup. 3 GND Ground Pin. 4 VCC Power Supply. Powered ...

  • Page 7

    CAPACITANCE (nF) Figure 3. Temperature Error vs. Capacitance Between D+ and D− 100mV 20 15 60mV 40mV –5 0 ...

  • Page 8

    FREQUENCY (Hz) Figure 9. Remote Temperature Error vs. Power Supply Noise Frequency 3.0 2.5 2.0 1.5 1.0 0.5 –0.5 –1.0 –1.5 –2.0 Figure ...

  • Page 9

    Product Description The ADT7476 is a complete thermal monitor and multiple fan controller for any system requiring thermal monitoring and cooling. The device communicates with the system via a serial system management bus. The serial bus controller has a serial ...

  • Page 10

    Serial Bus Interface Control of the ADT7476 is carried out using the serial system management bus (SMBus). The ADT7476 is connected to this bus as a slave device, under the control of a master controller. The ADT7476 has a 7−bit ...

  • Page 11

    In read mode, the master device overrides the acknowledge bit by pulling the data line high during the low period before the ninth clock pulse. This is known as no acknowledge. The master then ...

  • Page 12

    SCL SDA START BY MASTER SERIAL BUS ADDRESS BYTE Figure 20. Reading Data from a Previously Selected Register Write Operations The SMBus specification defines several protocols for different types of read and write operations. The ones ...

  • Page 13

    The master initiates a read operation and sends the alert response address (ARA = 0001 100). This is a general call address that must not be used as a specific device address. 3. The device whose SMBALERT output is ...

  • Page 14

    When the ADC is running, it samples and converts a voltage input in 0.7 ms and averages 16 conversions to reduce noise; a measurement takes nominally 11 ms. Extended Resolution Registers Voltage measurements can be made with higher accuracy using ...

  • Page 15

    Table 5. 10−Bit ADC Output Code <0.0156 <0.0065 <0.0042 0.0156 to 0.0065 to 0.0042 to 0.0312 0.0130 0.0085 0.0312 to 0.0130 to 0.0085 to 0.0469 0.0195 0.0128 0.0469 ...

  • Page 16

    VID Code Monitoring The ADT7476 has five dedicated voltage ID (VID code) inputs. These are digital inputs that can be read back through the VID/GPIO register (0x43) to determine the processor voltage required or the system being used. Five VID ...

  • Page 17

    Table 6. Twos Complement Temperature Data Format Temperature Digital Output (10−Bit) (Note 1) –128°C 1000 0000 00 (diode fault) –50°C 1100 1110 00 –25°C 1110 0111 00 –10°C 1111 0110 00 0°C 0000 0000 00 +10.25°C 0000 1010 01 +25.5°C ...

  • Page 18

    ADT7476 D+ 2N3906 D– PNP Figure 27. Measuring Temperature Using an PNP Transistor To measure DV , the sensor switches between operating BE currents of I and The resulting waveform passes through a 65 kHz low−pass filter ...

  • Page 19

    Temperature Offset Registers Register 0x70, Remote 1 Temperature Offset = 0x00 (0°C default) Register 0x71, Local Temperature Offset = 0x00 (0°C default) Register 0x72, Remote 2 Temperature Offset = 0x00 ...

  • Page 20

    Table 10. Programming Single−Channel ADC Mode for Temperatures Bits [7:5], Register 0x55 Channel Selected 101 Remote 1 Temperature 110 Local Temperature 111 Remote 2 Temperature Configuration Register 2 (0x73) [ averaging off. [ single−channel convert mode. ...

  • Page 21

    Fan Limit Registers Register 0x54, TACH1 Minimum Low Byte = 0xFF default Register 0x55, TACH1 Minimum High Byte = 0xFF default Register 0x56, TACH2 Minimum Low Byte = 0xFF default Register 0x57, TACH2 Minimum High Byte = 0xFF default Register ...

  • Page 22

    Bit 5 (F4P indicates Fan 4 has dropped below minimum speed. Alternatively, indicates that the THERM limit has been exceeded, if the THERM function is used. Alternatively, indicates the status of GPIO6. Bit 4 (FAN3 indicates ...

  • Page 23

    Interrupt Mask Register 2 (0x75) Bit 7 (D2 masks SMBALERT for Diode 2 errors. Bit 6 (D1 masks SMBALERT for Diode 1 errors. Bit 5 (FAN4 masks SMBALERT for Fan 4 failure. If the ...

  • Page 24

    THERM THERM TIMER (REG. 0x79) THERM ASSERTED THERM ACCUMULATE THERM LOW ASSERTION TIMES THERM TIMER 7 ...

  • Page 25

    Configuring the Relevant THERM Behavior 1. Configure the desired pin as the THERM timer input. Setting Bit 1 (THERM Configuration Register 3 (0x78) enables the THERM timer monitoring functionality. This is disabled on Pin 14 and Pin 22 by default. ...

  • Page 26

    THERM event occurs. If THERM hysteresis is disabled and THERM is disabled (Bit 2 of Configuration Register 4, 0x7D) and assuming the appropriate pin is configured as THERM), the THERM pin asserts low when ...

  • Page 27

    Driving Two Fans from PWM3 The ADT7476 has four TACH inputs available for fan speed measurement, but only three PWM drive outputs fourth fan is being used in the system, it should be driven from the PWM3 output ...

  • Page 28

    If the fan output has a resistive pullup other voltage greater than 5.5 V, the fan output can be clamped with a Zener diode, as shown in Figure 42. The Zener diode voltage should be chosen ...

  • Page 29

    Because the actual fan TACH period is being measured, falling below a fan TACH limit by 1 sets the appropriate status bit and can be used to generate an SMBALERT. Measuring fan TACH has the following caveat: When the ADT7476 ...

  • Page 30

    PWM1, PWM2, PWM3 Configuration (0x5C, 0x5D, 0x5E) [2:0] SPIN, startup timeout for PWM1 = 0x5C, PWM2 = 0x5D, and PWM3 = 0x5E. 000 = No startup timeout 001 = 100 ms 010 = 250 ms default 011 = 400 ms ...

  • Page 31

    Programming T RANGE T defines the distance between T RANGE PWM. For the ADT7467, ADT7468 and ADT7473 effectively a slope. For the ADT7475 andADT7476 longer a slope, but defines the temperature RANGE region where the ...

  • Page 32

    THERMAL CALIBRATION 100 REMOTE 1 MIN RANGE TEMP THERMAL CALIBRATION 100 LOCAL MIN RANGE TEMP THERMAL CALIBRATION 100 REMOTE 2 MIN RANGE TEMP Figure 47. Automatic Fan Control Block Diagram PWM ...

  • Page 33

    Step 1—Hardware Configuration During system design, the motherboard sensing and control capabilities should be addressed early in the design stages. Decisions about how these capabilities are used should involve the system thermal/mechanical engineer. Ask the following questions: 1. What ADT7476 ...

  • Page 34

    Recommended Implementation 1 Configuring the ADT7476 as shown in Figure 49 provides the system designer with the following features: • Six VID inputs (VID0, VID1, VID2, VID3, VID4, and VID6) for VRM10 support. • Two PWM outputs for fan control ...

  • Page 35

    Recommended Implementation 2 Configuring the ADT7476 as shown in Figure 50 provides the system designer with the following features: • Six VID inputs (VID0, VID1, VID2, VID3, VID4, and VID6) for VRM10 support. • Three PWM outputs for fan control ...

  • Page 36

    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. For example, ...

  • Page 37

    Mux Configuration Example This is an example of how to configure the mux in a system using the ADT7476 to control three fans. The CPU fan sink is controlled by PWM1, the front chassis fan is controlled by PWM2, and ...

  • Page 38

    Step 3—T Settings for Thermal Calibration MIN Channels T is the temperature at which the fans start to turn on MIN under automatic fan control. The speed at which the fan runs programmed later. The T MIN ...

  • Page 39

    Step 4—PWM for Each PWM (Fan) Output MIN PWM is the minimum PWM duty cycle at which each MIN fan in the system runs also the start speed for each fan under automatic fan control once the temperature ...

  • Page 40

    Programming the PWM Maximum Duty Cycle Registers The PWM maximum duty cycle registers are 8−bit registers that allow the maximum PWM duty cycle for each output to be configured anywhere from 0% to 100%. This allows the maximum PWM duty ...

  • Page 41

    Selecting T RANGE The T value can be selected for each temperature RANGE channel: Remote 1, local, and Remote 2 temperature. Bits [7: Register 0x5F to Register 0x61 define the RANGE T value for each temperature channel. ...

  • Page 42

    TEMPERATURE ABOVE T MIN (A) 100 TEMPERATURE ABOVE T ...

  • Page 43

    T to that limit (for example, 70°C). THERM THERM Limit Registers Register 0x6A, Remote 1 THERM Limit = 0x64 (100°C default) Register 0x6B, Local THERM Limit = 0x64 (100°C default) ...

  • Page 44

    Step 8—T for Temperature Channels HYST T is the amount of extra cooling a fan provides after HYST the temperature measured has dropped back below T before the fan turns off. The premise for temperature hysteresis ( that ...

  • Page 45

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

  • Page 46

    Fan Sync When two ADT7476s are used in a system possible to synchronize them so that one PWM channel from each device can be effectively OR’ed together to create a PWM output that reflects the maximum speed of ...

  • Page 47

    Register Tables Table 14. ADT7476 Registers Addr R/W Desc Bit 7 0x10 R/W Configuration Extra Register 6 Slow 0x11 R/W Configuration RES Register 7 0x20 R 2 Measurement 0x21 CCP Measurement 0x22 ...

  • Page 48

    Table 14. ADT7476 Registers Addr R/W Desc Bit 7 0x43 R/W VID/GPIO VIDSEL 0x44 R/W 2.5 V Low Limit 7 0x45 R/W 2.5 V High Limit 7 0x46 R/W V Low Limit 7 CCP 0x47 R/W V High Limit 7 ...

  • Page 49

    Table 14. ADT7476 Registers Addr R/W Desc Bit 7 0x64 R/W PWM1 Min Duty 7 Cycle 0x65 R/W PWM2 Min Duty 7 Cycle 0x66 R/W PWM3 Min Duty 7 Cycle 0x67 R/W Remote 1 Temp 7 T MIN 0x68 R/W ...

  • Page 50

    Table 15. Register 0x10 — Configuration Register 6 (Power−On Default = 0x00) Bit No. Mnemonic R/W [0] SlowFan R/W Remote 1 [1] SlowFan R/W Local [2] SlowFan R/W Remote 2 [3] THERM in R/W Manual [4] SlaveEn R/W [5] MasterEn ...

  • Page 51

    Table 19. Fan Tachometer Reading Registers (Power−On Default = 0x00) Register Address R/W 0x28 Read−only 0x29 Read−only 0x2A Read−only 0x2B Read−only 0x2C Read−only 0x2D Read−only 0x2E Read−only 0x2F Read−only 1. These registers count the number of 11.11 ms periods (based ...

  • Page 52

    Table 22. Register 0x40 — Configuration Register 1 (Power−On Default = 0x04) Bit No. Mnemonic R/W [0] STRT R/W (Notes 1, 2) [1] LOCK Write once [2] RDY Read−only [3] FSPD R/W [4] Vx1 R/W [5] FSPDIS R/W [6] TODIS ...

  • Page 53

    Table 24. Register 0x42 — Interrupt Status Register 2 (Power−On Default = 0x00) Bit No. Mnemonic R/W [0] 12 V/VC Read−only [1] OVT Read−only [2] FAN1 Read−only [3] FAN2 Read−only [4] FAN3 Read−only [5] F4P Read−only R/W Read−only [6] D1 ...

  • Page 54

    Table 27. Temperature Limit Registers Register Address R/W 0x4E R/W 0x4F R/W 0x50 R/W 0x51 R/W 0x52 R/W 0x53 R/W 1. Exceeding any of these temperature limits by 1°C causes the appropriate status bit to be set in the interrupt ...

  • Page 55

    Table 30. PWM Configuration Registers Register Address R/W (Note 1) 0x5C R/W 0x5D R/W 0x5E R/W Bit No. Name R/W [2:0] SPIN R/W [3] RES N/A [4] INV R/W [7:5] BHVR R/W 1. These registers become read−only when the Configuration ...

  • Page 56

    Table 31. T /PWM Frequency RANGE Register Address R/W (Note 1) 0x5F R/W 0x60 R/W 0x61 R/W Bit No. Name R/W [2:0] FREQ R/W [3] HF/LR R/W [7:4] RANGE R/W 1. These registers become read−only when the Configuration Register 1 ...

  • Page 57

    Table 32. Register 0x62 — Enhanced Acoustics Register 1 (Power−On Default = 0x00) Bit No. Mnemonic R/W (Note 1) [2:0] ACOU R/W (Note 2) [3] EN1 R/W [4] SYNC R/W [5] MIN1 R/W [6] MIN2 R/W [7] MIN3 R/W 1. ...

  • Page 58

    Table 33. Register 0x63 — Enhanced Acoustics Register 2 (Power−On Default = 0x00) Bit No. Mnemonic R/W (Note 1) [2:0] ACOU3 R/W [3] EN3 R/W [6:4] ACOU2 R/W [2:0] ACOU3 R/W [7] EN2 R/W 1. This register becomes read−only when ...

  • Page 59

    Table 34. PWM Minimum Duty Cycle Registers Register Address R/W (Note 1) 0x64 R/W 0x65 R/W 0x66 R/W Bit No. Name R/W [7:0] PWM duty R/W cycle 1. These registers become read−only when the ADT7476 is in automatic fan control ...

  • Page 60

    Table 38. XNOR Tree Test Enable Register Address R/W (Note 1) 0x6F R/W [0] XEN [7:1] Reserved 1. This register becomes read−only when the Configuration Register 1 lock bit is set to 1. Any further attempts to write to this ...

  • Page 61

    Table 42. Register 0x73 — Configuration Register 2 (Power−On Default = 0x00) Bit No. Mnemonic R/W (Note 1) 0 FanPresDT R/W 1 Fan1Detect Read−only 2 Fan2Detect Read−only 3 Fan3Detect Read−only 4 AVG R/W 5 ATTN R/W 6 CONV R/W 7 ...

  • Page 62

    Table 44. Register 0x75 — Interrupt Mask Register 2 (Power−On Default [7:0] = 0x00) Bit No. Mnemonic R/W [0] 12 V/VC R/W [1] OVT R/W [2] FAN1 R/W [3] FAN2 R/W [4] FAN3 R/W [5] F4P R/W [6] D1 R/W ...

  • Page 63

    Table 47. Register 0x78 — Configuration Register 3 (Power−On Default = 0x00) Bit No. Mnemonic R/W (Note 1) [0] ALERT R/W [1] THERM/ R/W 2.5V [2] BOOST R/W [3] FAST R/W [4] DC1 R/W [5] DC2 R/W [6] DC3 R/W ...

  • Page 64

    Table 50. Register 0x7B — TACH Pulses per Revolution Register (Power−On Default = 0x55) Bit No. Mnemonic R/W [1:0] FAN1 R/W [3:2] FAN2 R/W [5:4] FAN3 R/W [7:6] FAN4 R/W Description Sets number of pulses to be counted when measuring ...

  • Page 65

    Table 51. Register 0x7C — Configuration Register 5 (Power−On Default = 0x01) Bit No. Mnemonic R/W (Note 1) [0] 2sC R/W [1] Temp Offset R/W [2] GPIO6D R/W [3] GPIO6P R/W [4] VID/GPIO R/W [5] R1 THERM R/W [6] Local ...

  • Page 66

    ... Read−only ORDERING INFORMATION Device Order Number ADT7476ARQZ ADT7476ARQZ−REEL ADT7476ARQZ−R7 ADT7476ARQH ADT7476ARQH−REEL †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. *The “Z” suffix indicates Pb−Free packages. ...

  • Page 67

    ... C 0.10 C 24X *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. dBCOOL is a registered trademarks of Semiconductor Components Industries, LLC (SCILLC). Pentium is a registered trademark of Intel Corporation. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein ...