ADT7460 Analog Devices, Inc., ADT7460 Datasheet
ADT7460
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ADT7460 Summary of contents
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... 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. ...
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... Serial Bus Interface..................................................................... 11 Voltage Measurement Input...................................................... 15 REVISION HISTORY 3/05—Rev Rev. C Updated Format.................................................................. Universal Changes to Absolute Maximum Ratings Table..............................5 Changes to ADT7460 Register Map Summary Section .............34 Updated Ordering Guide................................................................51 9/03—Rev Rev. B Changed XOR Tree Test Mode to XNOR ............................ Universal Changes to SPECIFICATIONS............................................................. 2 Changes to TPC 7.................................................................................... 7 Additional ADC Functions for Voltage Measurements ...
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... V 0.1 1 µA 0.4 V 0.1 1 µA 2.0 V 0.4 V 500 mV Rev Page ADT7460 Test Conditions/Comments Interface inactive, ADC active Standby mode 0°C ≤ T ≤ 70°C A −40°C ≤ T ≤ +120°C A 0°C ≤ T ≤ 70°C; 0°C ≤ T ≤ 120° 0°C ≤ T ≤ ...
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... ADT7460 Parameter DIGITAL INPUT LOGIC LEVELS (TACH INPUTS) Input High Voltage Input Low Voltage Hysteresis DIGITAL INPUT LOGIC LEVELS (THERM) Input High Voltage Input Low Voltage DIGITAL INPUT CURRENT Input High Current Input Low Current, I ...
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... Exposure to absolute ±20 mA maximum rating conditions for extended periods may affect 150°C device reliability. −65°C to +150°C THERMAL CHARACTERISTICS 220°C 16-Lead QSOP Package: 260°C θ = 150°C/W JA 300°C θ = 39°C/W JC 1500 V Rev Page ADT7460 ...
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... V Power Supply. Can be powered by 3.3 V standby if monitoring in low power states is required monitored through this pin. The ADT7460 can also be powered from supply. Setting Bit 7 of Configuration Register 1 (Reg. 0x40) rescales the V 4 TACH3 Digital Input (Open Drain). Fan tachometer input to measu analog input (AIN3) to measure the speed of 2-wire fans ...
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... HIGH LIMIT 1 +3 SIGMA 0 –3 SIGMA –1 –2 LOW LIMIT –3 – TEMPERATURE (°C) Figure 7. Local Temperature Error vs. Actual Temperature 250mV 4 2 100mV 0 –2 100k 550k 5M FREQUENCY (Hz) 12.5 10.0 7.5 250mV 5.0 2.5 100mV 0 –2.5 –5.0 100k 550k 5M FREQUENCY (Hz) ADT7460 110 50M 50M ...
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... ADT7460 1.90 1.85 1.80 1.75 1.70 1.65 1.60 1.55 1.50 1.45 1.40 2.6 3.0 3.4 3.8 4.2 2.5 SUPPLY VOLTAGE (V) Figure 10. Supply Current vs. Supply Voltage 16 20mV 10mV –2 60k 110k 1M FREQUENCY (Hz) Figure 11. Remote Temperature Error vs. Differential Mode Noise Frequency –5 –10 4.6 5.0 5.4 5.5 Figure 12. Remote Temperature Error vs. Common-Mode Noise Frequency 10M 50M Rev Page ...
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... All control and programming functions of the ADT7460 are performed over the serial bus. In addition, two of the pins can be reconfigured as an SMBALERT output to indicate out-of-limit conditions. ...
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... 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. ...
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... Pin 8 (PWM3/ ADDRESS ENABLE ) high, the ADT7460 has a default SMBus address of 0101110 or 0x2E. If more than one ADT7460 used in a system, each ADT7460 should be placed in address select mode by strapping Pin 8 low on power-up. The logic state of Pin 9 then determines the device’ ...
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... Figure 18. Writing a Register Address to the Address Pointer Register, Then Writing Data to the Selected Register the beginning and cannot subsequently be changed without starting a new operation the case of the ADT7460, write operations contain either one or two bytes, and read operations contain one byte. op signal. The number To write data to one of the device data re from it, the address pointer register must be set so that the correct data register is addressed ...
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... This is done by performing a write to the ADT7460 as before, but only the data byte containing the register address is sent because data is not to be written to the register ...
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... The master asserts NO ACK The master asserts a stop condition on SDA and the transaction ends. In the ADT7460, the receive byte protocol is used to read a ely after single byte of data from a register whose address has previously art been set by nd carry out a ...
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... It can also measure its own supply voltage, V Pin 14 may be configured to measure a 2.5 V supply. The V supply voltage measurement is carried out through the V (Pin 3). Setting Bit 7 of Configuration Register 1 (Reg. 0x40) allows supply to power the ADT7460 and be measured without overranging the V measurement channel. The 2 input can be used to monitor a chipset supply voltage in computer systems ...
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... ADT7460 Table 9. 10-Bit A/D Output Code vs. V Input Voltage (3 <0.0065 <0.0042 0.0065–0.0130 0.0042–0.0085 0.0130–0.0195 0.0085–0.0128 0.0195–0.0260 0.0128–0.0171 0.0260–0.0325 0.0171–0.0214 0.0325–0.0390 0.0214–0.0257 0.0390– ...
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... ADDITIONAL ADC FUNCTIONS FOR VOLTAGE MEASUREMENTS A number of other functions are available on the ADT7460 to offer the systems designer increased flexibility. Turn-Off Averaging For each voltage measurement read from a value register, 16 readings have actually been made internally and the results averaged before being placed into the value register. If the user wants to speed up conversion, setting Bit 4 of Configuration Register 2 (Reg ...
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... TDM1 Reading Temperature from the ADT7460 It is important to note that temperature can be read from the ADT7460 as an 8-bit value (with 1°C resolution 10-bit value (with 0.25 C resolution). If only 1°C resolution is required, the temperature readings can be read back at any time and in no particular order ...
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... Singl e-Ch annel ADC Con Settin g Bit 6 of Configuration Register DT7460 into single-channel ADC conversion mode. In this m ode, the ADT7460 can be made to read a single temperature channel only. The appropriate ADC channel is selected its < 7:5> of the TA (Reg. 0 55). x Default Table 17 ...
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... TACH4 minimum low byte 0x5B TACH4 minimum high byte Out-of-Limit Comparisons Once all limits have been programmed, the ADT7460 can be enabled for monitoring. The ADT7460 measures all parameters system in round-robin format and sets the appropriate status bit for -of-lim it out-of-limit conditions ...
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... Ho weve limit, its associated statu Rev Page ADT7460 ) CC s 11.38 ms for each volt age measurement, d 25.5 ms for each rea ding. toring cy cle time for averaged voltage and monitorin g is, therefore, nominally × ...
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... Unused SMBALERT Interrupt Behavior The ADT7460 can be polled for status SMBALERT interrupt can be generated for out-of-limit conditions important to note how the SMBALERT output and status bits behave when writing interrupt handler software. Figure 35 shows how the SMBALERT output and sticky statu bits behave ...
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... CLEARED (SMBALERT REARMED) To Assign THERM Functionality to Pin 9 Pin 9 can be configured as the THERM pin on the ADT7460. To configure Pin 9 as the THERM pin, set the THERM ENABLE Bit (Bit 1) in Configuration Reg er 3 (Address 0x78 THERM When configured as an input, the THERM pin allows the user to time assertions on the pin ...
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... The THERM connected to the output of a trip point temperature sensor. The timer is started on the assertion of the ADT7460’s THERM input and stopped on the negation of the pin. The timer counts THERM times cumulatively, therefore, the timer resumes counting on the next THERM assertion. The THERM timer continues to accumulate THERM assertion times until the timer is read (it is cleared on read) or until it reaches full scale ...
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... THERM TIMER CLEARED ON READ COMPARATOR F4P BIT (BIT 5) IN OUT STATUS REGISTER 2 L ATCH R ESET CLEARED 1 = MASK ON READ F4P BIT (BIT 5) MASK REGISTER 2 (REG. 0x75) ram of ADT7460’ THERM s Monitoring Circuitry Rev Page ADT7460 THERM TIMER (REG. 0x79) THERM SMBALERT ...
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... Configuring the ADT7460 THERM Pin as an Output In addition to the ADT7460 being able to monitor THERM as an input, the ADT7460 can optionally drive THERM low as a output. The user can preprogram system critical thermal limi If the temperature exceeds a thermal limit by 0.25°C, asserts low ...
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... Driving Two Fans from PWM3 Note that the ADT7460 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 in parallel with the third fan. Figure 43 shows how to drive two fans in parallel using low cost NPN transistors ...
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... TACH4 to PWM3. 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 measured, even though the fan has no dedicated TACH signal. A series resistor the fan circuit converts the fan ...
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... Pins and 9 are open-drain TACH inputs for fan speed measure ment. Signal conditioning in the ADT7460 accommodates the slow rise and fall times typical of fan tachometer outputs. The maxi- mum input signal range even where V than the event that these inputs are supplied from fan ...
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... TACH3 high byte 0x2E TACH4 Low byte 0x2F TACH4 high byte V Reading Fan Speed from the ADT7460 CC If fan speeds are being measured, this involves a 2-register read fo r each measurement. The low byte should be read first. This ADT7460 ca uses the high byte to be frozen until both high and low byte FAN SPEED registers are read from ...
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... Fan Speed Measurements The ADT7460 is capable of measuring the speed of 2-wire fans, that is, fans without TA CH outputs this, the fan must be interfaced as shown in the Fan Drive Circuit case, the TACH inputs need to be reprogram inputs, AIN ...
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... The second fan speed control method is manual fan speed control, which is described next. Manual Fan Speed Control The ADT7460 allows the duty cycle of any PWM output to be manually adjusted. This can be useful if you want to change fan speed in software or if you want to adjust PWM duty cycle output for test purposes. Bits < ...
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... XNOR TREE TEST MODE Def ault The ADT7460 includes an XNOR tree test mode. This mode is 0xFF (100%) useful for in-circuit test equipment at board-level testing. By 0xFF (100%) applying stimulus to the pins included in the XNOR tree 0xFF (100%) ...
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... ADT7460 ADT7460 REGISTER SUMMARY Tabl 7460 Registers T Addre ss R/W Description 0x20 R 2.5 V Reading 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 TACH1 High Byte 0x2A R TACH2 Low Byte 0x2B R TACH2 High Byte ...
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... FAN1 FAN1 0x55 AINL RES AL2.5V 0x00 0x00 0x00 pin (8 MSBs of reading) should be read he extended nded resolution bits of these readings ters are read, all associated MSB ADT7460 Lockable? YES YES YES YES YES YES YES YES YES YES YES YES YES ...
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... Read/Write 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 ...
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... MIN rature, operating po int, and high and low limits for this ue chosen is not adjusted, and the channel behaves Further att empts to write to this register have no ADT7460 is is value is MIN value is MIN ...
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... ADT7460 Table 48. Register 0x37—Dynamic T MIN Bit Nam Descr <2:0> Read/W ite r 3-Bit Remote 1 Cycle Value. These three bits define the delay time between making subse 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 fans and the control loop ...
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... ADT7460 is powered down and powered up again. This prevents rogue programs such as viruses from modifying critical system limit settings. (Lockable.) <2> RDY Read-Only T his bit is set the ADT7460 to indicate that the device is fully powered-up and ready to begin syste m onitoring. <3> FSPD Read/Write When set to 1, all fans run at full speed. Power-on default = 0. (This bit cannot be locked.) < ...
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... ADT7460 Table 51. Register 0x42—Interrupt Status Register 2 (Power-On Defaul Bit Name R/ W Description <0> RES Read-Only Reserved for future use. <1> OVT Read-Only A 1 indicates that one of the THERM overte o f the status re <2> FAN1 Read-Only A 1 indicates output is off. <3> FAN2 Read-Only A 1 indicates output is off ...
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... Rev Page Register 1 lock bit has no effect on th ese regis on ADT7460 set ters. ...
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... ADT7460 Table 57. TEMP T /PWM Frequency Registers (Power-On Default 0xC4) RANGE Reg iste r Addre s s 0x5F 0x60 0x61 These re isters b g ecom es read-o nly fect. Table 58. TEM T P /PWM Freq enc Re u RANGE Bit Name R/W <2:0> FREQ Read/Writ e <3> THRM Read/Write < ...
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... PWM1 minimum duty cycle when the controlling temperature is below its <6> MIN2 Read/Write When the ADT7460 is in automatic fan speed control mode, this bit defines whether PWM2 is off (0% duty cycle PWM2 minimum duty cycle when the controlling temperature is below its T value <7> ...
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... Table 61. PWM Min Duty Cycle Registers Register Address R/W 0x64 Read/Write 0x65 Read/Write 0x66 Read/Write These registers become read-only when the ADT7460 is in automatic fan control mode. Table 62. PWM Min Duty Cycle Register Bits Bit Name Read/Wr <7:0> PWM Duty Cy cle Read /Wri ...
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... MIN 0x5A (90°C) MIN 0x5A (90°C) MIN , the appropriate fan runs at MIN Power-On Default 0x64 (100°C) 0x64 (100°C) 0x64 (100° Further attempts to write to these registers have Power-On Default 0x44 0x40 – Hysteresis 15°C of MIN ADT7460 MIN. ...
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... ADT7460 Table 67. Remote 1 Temperature Offset Register (Power-On Default = 0x00) Reg ter Add R/W 0x70 Read/W e rit <7:0> Read/Writ e This register becomes read-only when the Configuration Register 1 lock bit is set to 1. Further attempts to write to this register ha effe . ct Table 68. Local Temperature O ffset Register (Power-On Default = 0x00) ...
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... PWM current duty cycle registers read 0x00 to indicate that the fans Rev Page ADT7460 al sensing resistor and coupling x7D). fan. AIN4 = 1, Pin 9 is sistor and coupling sion mode. In this mode, the ADT7460 can Remote 1 temperature also possible terize/profile CPU temperature quickly. The ter have no channel. CC ...
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... ADT7460 Table 72. Register 0x75—Interrupt Mask Register 2 (Power-On Default = 0x00 Bit Name R/W Description 0 RES Read/Write Reserved for future use. 1 OVT Read-Only A 1 masks SMBALERT for overtemperature THERM conditions. 2 FAN1 Read/Write A 1 masks SMBALERT for a Fan 1 fault. 3 FAN2 Read/Write A 1 masks SMBALERT for a Fan 2 fault. ...
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... Pulses Counted (Default tion input is asserted. These seven bits read 0 until the THERM assertion time set and becomes the LSB of the 8-bit TMR reading. This allows THERM er-On Default = 0x00) Rev Page ADT7460 assertion 6 ms. ...
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... ADT7460 Table 79. Register 0x7D—Configur ation Register 4 (Power-On Default = 0x00) Bit Name R/W Des cription <0> AL2.5V Read/Write AL2. Pin 14 (2.5V/SMBALERT) is configured as an SMBALERT interrupt output to indicate out-of-limit error conditions. AL2. Pin 14 (2.5V/SMBALERT) is configured as a 2.5 V measurement input. <1> RES Read-Only Reserved for future use. ...
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... ADT7460ARQ −40°C to +120°C ADT7460ARQ-REEL −40°C to +120°C ADT7460ARQ-REEL7 −40°C to +120°C 1 ADT7460ARQZ −40°C to +120°C 1 ADT7460ARQZ-REEL −40°C to +120°C 1 ADT7460ARQZ-REEL7 −40°C to +120°C EVAL-ADT7460EB Pb-free part. 0.193 BSC 16 9 0.154 BSC 0.236 1 BSC ...
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... ADT7460 NOTES © 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03228–0–3/05(C) Rev Page ...