ADT7461 ONSEMI | Alldatasheet

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© Semiconductor Components Industries, LLC, 2009 December, 2009 − Rev. 6

1 Publication Order Number:

/C00431/C0053C Temperature Monitor with Series Resistance Cancellation The ADT7461 is a dual-channel digital thermometer and under/over temperature alarm intended for use in PCs and thermal management systems. It is pin- and register-compatible with the ADM1032. The ADT7461 has three additional features: series resistance cancellation (where up to 3 k/C0087 (typical) of resistance in series with the temperature monitoring diode may be automatically cancelled from the temperature result, allowing noise filtering); configurable ALERT output; and an extended, switchable temperature measurement range. The ADT7461 can accurately measure the temperature of a remote thermal diode to ±1°C and the ambient temperature to ±3°C. The temperature measurement range defaults to 0 °C to +127 °C, compatible with the ADM1032, but can be switched to a wider measurement range of −55°C to +150°C. The ADT7461 communicates over a 2-wire serial interface compatible with system management bus (SMBus) standards. An ALERT output signals when the on-chip or remote temperature is out of range. The THERM output is a comparator output that allows on/off control of a cooling fan. The ALERT output can be reconfigured as a second THERM output, if required. The SMBus address of the ADT7461 is 0x4C. An ADT7461-2 is also available, which uses SMBus Address 0x4D.

FEATURES

  • On-Chip and Remote Temperature Sensor
  • 0.25°C Resolution/1°C Accuracy on Remote Channel
  • 1°C Resolution/3°C Accuracy on Local Channel
  • Automatically Cancels Up to 3 k/C0087 (Typ) of Resistance in Series with Remote Diode to Allow Noise Filtering
  • Extended, Switchable Temperature Measurement Range 0°C to +127°C (Default) or –55°C to +150°C
  • Pin− and Register−Compatible with the ADM1032
  • 2−Wire SMBus Serial Interface with SMBus Alert Support
  • Two SMBus Address Versions Available: ♦ ADT7461 SMBus Address is 0x4C ♦ ADT7461-2 SMBus Address is 0x4D
  • Programmable Over/Undertemperature Limits
  • Offset Registers for System Calibration
  • Up to Two Overtemperature Fail−Safe THERM Outputs
  • Small 8−Lead SOIC or 8−Lead MSOP Packages
  • 170 /C0109A Operating Current, 5.5 /C0109A Standby Current
  • These are Pb−Free Devices

APPLICATIONS

  • Desktop and Notebook Computers
  • Industrial Controllers
  • Smart Batteries
  • Embedded Systems
  • Instrumentation MARKING DIAGRAMS http://onsemi.com PIN ASSIGNMENT SOIC−8 CASE 751 ADT74 61A #YWW ADT7461A = Device Code # = Pb −Free Package Y = Year W = Work Week See detailed ordering and shipping information in the package dimensions section on page 18 of this data sheet.

ORDERING INFORMATION

(Top View) SCLK SDATA T1x = Refer to Order Info Table A = Assembly Location Y = Year W = Work Week /C0071= Pb−Free Package (Note: Microdot may be in either location) T1x AYW/C0071 /C0071MSOP−8 CASE 846AB

Figure 1. Functional Block Diagram NOTE: This device is ESD sensitive. Use standard ESD precautions when handling.

1 VDD Positive Supply, 3.0 V to 5.5 V. 2 D+ Positive Connection to Remote Temperature Sensor. 3 D− Negative Connection to Remote Temperature Sensor. overtemperature condition. Requires pullup to VDD. 5 GND Supply Ground Connection. second THERM output. Requires pullup resistor. 7 SDATA Logic Input/Output, SMBus Serial Data. Open−drain output. Requires pullup resistor. 8 SCLK Logic Input, SMBus Serial Clock. Requires pullup resistor. tLOW 1.3 /C0109s min Clock low period, between 10% points. tHIGH 0.6 /C0109s min Clock high period, between 90% points. tR 300 ns max Clock/data rise time. tF 300 ns max Clock/data fall time. tSU; STA 600 ns min Start condition setup time. tHD; STA (Note 2) 600 ns min Start condition hold time. tSU; DAT (Note 3) 100 ns min Data setup time. tHD; DAT 300 ns min Data hold time. tSU; STO (Note 4) 600 ns min Stop condition setup time. tBUF 1.3 /C0109s min Bus free time between stop and start conditions.

  1. Guaranteed by design, but not production tested.
  2. Time from 10% of SDATA to 90% of SCLK.
  3. Time for 10% or 90% of SDATA to 10% of SCLK.
  4. Time for 90% of SCLK to 10% of SDATA.

Figure 2. Serial Bus Timing

http://onsemi.com ELECTRICAL CHARACTERISTICS TA = −40°C to +120°C, VDD = 3.0 V to 5.5 V, unless otherwise noted. Parameter Conditions Min Typ Max Unit Power Supply Supply Voltage, VDD 3.0 3.30 5.5 V Average Operating Supply Current, IDD 0.0625 Conversions/Sec Rate (Note 1) Standby mode, –40°C ≤ TA ≤ +85°C Standby mode, +85°C ≤ TA ≤ +120°C − 170 5.5 5.5 215 /C0109A Undervoltage Lockout Threshold VDD input, disables ADC, rising edge 2.2 2.55 2.8 V Power-On-Reset Threshold 1.0 − 2.5 V Temperature-To-Digital Converter Local Sensor Accuracy −40°C ≤ TA ≤ +100°C, 3.0 V ≤ VDD ≤ 3.6 V − ±1.0 ±3.0 °C Resolution − 1.0 − °C Remote Diode Sensor Accuracy +60°C ≤ TA ≤ +100°C, −55°C ≤ TD (Note 2) ≤ +150°C, 3.0 V ≤ VDD ≤ 3.6 V −55°C ≤ TD (Note 2) ≤ +150°C, 3.0 V ≤ VDD ≤ 5.5 V − − ±1.0 ±3.0 Resolution − 0.25 − °C Remote Sensor Source Current High level (Note 3) − 96 − /C0109A Middle level (Note 3) − 36 − /C0109A Low level (Note 3) − 6.0 − /C0109A Conversion Time From stop bit to conversion complete (both channels), one-shot mode with averaging switched on 32.13 − 114.6 ms One-shot mode with averaging off (that is, conversion rate = 16, 32, or 64 conversions per second) 3.2 − 12.56 ms Maximum Series Resistance Cancelled Resistance split evenly on both the D+ and D– inputs − 3.0 − k/C0087 Open-Drain Digital Outputs (THERM, ALERT/THERM2) Output Low Voltage, VOL IOUT = −6.0 mA (Note 3) − − 0.4 V High Level Output Leakage Current, IOH VOUT = VDD (Note 3) − 0.1 1.0 /C0109A ALERT Output Low Sink Current ALERT forced to 0.4 V 1.0 − − mA SMBus Interface (Note 3 and 4) Logic Input High Voltage, VIH SCLK, SDATA 3.0 V ≤ VDD ≤ 3.6 V 2.1 − − V Logic Input Low Voltage, VIL SCLK, SDATA 3.0 V ≤ VDD ≤ 3.6 V − − 0.8 V Hysteresis − 500 − mV SMBus Output Low Sink Current SDATA forced to 0.6 V 6.0 − − mA Logic Input Current, IIH, IIL −1.0 − +1.0 /C0109A SMBus Input Capacitance, SCLK, SDATA − 5.0 − pF SMBus Clock Frequency − − 400 kHz SMBus Timeout (Note 5) User programmable − 25 64 ms SCLK Falling Edge to SDATA Valid Time Master clocking in data − − 1.0 /C0109s 1. See Table 4 for information on other conversion rates. 2. Guaranteed by characterization, but not production tested. 3. Guaranteed by design, but not production tested. 4. See the SMBUS Timing Specifications section for more information. 5. Disabled by default; see the Serial Bus Interface section for details on enabling it.

http://onsemi.com Functional Description The ADT7461 is a local and remote temperature sensor and over/under temperature alarm, with the added ability to automatically cancel the effect of 3 k /C0087 (typical) of resistance in series with the temperature monitoring diode. When the ADT7461 is operating normally, the on-board ADC operates in a free-running mode. The analog input multiplexer alternately selects either the on-chip temperature sensor to measure its local temperature or the remote temperature sensor. The ADC digitizes these signals and the results are stored in the local and remote temperature value registers. The local and remote measurement results are compared with the corresponding high, low, and THERM temperature limits, stored in eight on-chip registers. Out-of-limit comparisons generate flags that are stored in the status register. A result that exceeds the high temperature limit, the low temperature limit, or an external diode fault causes the ALERT output to assert low. Exceeding THERM temperature limits causes the THERM output to assert low. The ALERT output can be reprogrammed as a second THERM output. The limit registers can be programmed and the device controlled and configured via the serial SMBus. The contents of any register can also be read back via the SMBus. Control and configuration functions consist of switching the device between normal operation and standby mode, selecting the temperature measurement scale, masking or enabling the ALERT output, switching Pin 6 between ALERT and THERM2, and selecting the conversion rate. Series Resistance Cancellation Parasitic resistance to the D+ and D − inputs to the ADT7461, seen in series with the remote diode, is caused by a variety of factors, including PCB track resistance and track length. This series resistance appears as a temperature offset in the remote sensor’s temperature measurement. This error typically causes a 0.5°C offset per ohm of parasitic resistance in series with the remote diode. The ADT7461 automatically cancels out the effect of this series resistance on the temperature reading, giving a more accurate result, without the need for user characterization of this resistance. The ADT7461 is designed to automatically cancel typically up to 3 k /C0087 of resistance. By using an advanced temperature measurement method, this is transparent to the user. This feature allows resistances to be added to the sensor path to produce a filter, allowing the part to be used in noisy environments. See the Noise Filtering section for more details. Temperature Measurement Method A simple method of measuring temperature is to exploit the negative temperature coefficient of a diode by measuring the base-emitter voltage (V BE) of a transistor operated at constant current. However, this technique requires calibration to null out the effect of the absolute value of V BE, which varies from device to device. The technique used in the ADT7461 is to measure the change in VBE when the device is operated at three different currents. Previous devices have used only two operating currents, but it is the use of a third current that allows automatic cancellation of resistances in series with the external temperature sensor. Figure 15 shows the input signal conditioning used to measure the output of an external temperature sensor. This figure shows the external sensor as a substrate transistor, but it could equally be a discrete transistor. If a discrete transistor is used, the collector will not be grounded and should be linked to the base. To prevent ground noise interfering with the measurement, the more negative terminal of the sensor is not referenced to ground, but is biased above ground by an internal diode at the D− input. C1 may be added as a noise filter (a recommended maximum value of 1,000 pF). However, a better option in noisy environments is to add a filter, as described in the Noise Filtering section. See the Layout Considerations section for more information on C1. To measure /C0068V BE, the operating current through the sensor is switched among three related currents. Figure 15 shows N1 x I and N2 x I as different multiples of the current, I. The currents through the temperature diode are switched between I and N1 x I, giving /C0068V BE1, and then between I and N2 x I, giving /C0068VBE2. The temperature may then be calculated using the two /C0068VBE measurements. This method can also be shown to cancel the effect of any series resistance on the temperature measurement. The resulting /C0068V BE waveforms are passed through a 65 kHz low-pass filter to remove noise and then to a chopper-stabilized amplifier. This amplifies and rectifies the waveform to produce a dc voltage proportional to /C0068V BE. The ADC digitizes this voltage and a temperature measurement is produced. To reduce the effects of noise, digital filtering is performed by averaging the results of 16 measurement cycles for low conversion rates. At rates of 16, 32, and 64 conversions per second, no digital averaging takes place. Signal conditioning and measurement of the internal temperature sensor is performed in the same manner.

Figure 15. Input Signal Conditioning Error vs. Series Resistance *CAPACITOR C1 IS OPTIONAL. IT SHOULD ONLY BE USED IN NOISY ENVIRONMENTS. into the local and remote high and low limit registers. shows the data format for the external temperature low byte. Table 1. Extended Temperature Resolution faster than a conversion time. external measurements is, by default, 0 °C to +127 °C. registers themselves can have values from −64°C to +191°C. maximum temperature range of −55°C to +150°C. result register gives the last good temperature measurement. that are outside the operating range of the remote sensor. as specified at ambient temperatures from −40°C to +120°C. temperatures in both data formats are shown in Table 2.

Table 2. Temperature Data Format (Local and Remote

  1. Offset binary scale temperature values are offset by 64 °C.
  2. Binary scale temperature measurement returns 0 °C for all
  3. Binary scale temperature measurement returns 127°C for all

ADT7461, which is stored in the address pointer register. write operation or is used for a subsequent read operation. returned, since its register address is 0x00. register is at Address 0x00. Address 0x01, with the low byte register at Address 0x10. The power-on default for all three registers is 0x00. and 4 are reserved and should not be written to by the user. output. If Bit 7 is 0, the ALERT output is enabled. up as a THERM2 output, then Bit 7 has no effect. measurement range is set to the extended temperature range. Table 3. Configuration Register Bit Assignments

7 MASK1 0 = ALERT Enabled

6 RUN/STOP 0 = Run

5 ALERT/

2 Temperature

consumption, as shown in Table 4. Table 4. Conversion Rate Register Codes of the limit registers and their power-on default values. powerup (Register Address 0x21). limit register should be reprogrammed to be 0100 1010b. The status register is a read-only register at Address 0x02. It contains status information for the ADT7461. Bits 1 to 0) and the remote sensor open circuit (Bit 2). interrupt latch is set and the ALERT output goes low. temperature falls to limit value minus hysteresis value.

behavior of THERM2 is otherwise the same as THERM. Table 5. Status Register Bit Assignments

7 BUSY

6 LHIGH

5 LLOW

4 RHIGH

3 RLOW

2 OPEN

1 RTHRM 1 when remote THERM limit is tripped

0 LTHRM 1 when local THERM limit is tripped

  1. Polling of the BUSY bit is not recommended.
  2. These flags stay high until the status register is read or they

justified). Only the upper 2 bits of Register 0x12 are used. measured value of the remote temperature. and has no effect unless the user writes a different value to it. Table 6. Sample Offset Register Codes irrelevant and is not stored. no averaging takes place. This register is at Address 0x22. Table 7. Consecutive ALERT Register Codes NOTE: x = don’t care bits, and y = SMBus timeout bit. Default = 0. See SMBus section for more information.

Table 8. List of Registers

  1. Writing to Address ox0F causes the ADT7461 to perform a single measurement. It is not a data register, therefore, data writte n to it is

Control of the ADT7461 is carried out via the serial bus. under the control of a master device. conversion time, to allow the next conversion to complete. the conversion rate register. inactivity. However, this feature is not enabled by default. information (www.smbus.org). over the bus, the slave device with that address responds.

  1. The master initiates data transfer by establishing a
  2. Data is sent over the serial bus in a sequence of
  1. If the ADT7461’s address pointer register value is

sent, since data is not to be written to the register.

  1. If the address pointer register is known to be at the

shown in Figure 17 can be omitted. write is always written to the address pointer register. address pointer before data can be read from that register. or more of the ALERT outputs goes low. common SMBALERT line that is connected to the master. devices, the procedure shown in Figure 19 occurs. Figure 19. Use of SMBALERT

  1. Master initiates a read operation and sends the
  2. Once the ADT7461 has responded to the alert

out-puts were low have responded. generated even though the ADT7461 is still in standby.

placed in close proximity to it. temperature to be measured also affects the accuracy. resistance, /C0113JA, of the SOIC-8 package is about 121°C/W.

  1. Place the ADT7461 as close as possible to the
  2. Route the D+ and D– tracks close together, in

parallel, with grounded guard tracks on each side. 5 mil track width and spacing is recommended. Provide a ground plane under the tracks if possible. Figure 23. Typical Arrangement of Signal Tracks

5 MIL

  1. Try to minimize the number of copper/solder
  2. Place a 0.1 /C0109F bypass capacitor close to the V

capacitance between the pins and the sensor diode.

  1. If the distance to the remote sensor is more than

recommended. This works up to about 6 to 12 feet. a shielded twisted pair, such as the Belden No. unconnected to avoid ground loops. capacitance may be reduced or removed. as the Intel/C0082 820 chipset.

http://onsemi.com Figure 24. Typical Application Circuit Device Order Number* Package

Description

Shipping† ADT7461AR 8−Lead SOIC_N R−8 − 4C 98 Tube ADT7461AR−REEL − 4C 2500 Tape & Reel ADT7461AR−REEL7 − 4C 1000 Tape & Reel ADT7461ARZ − 4C 98 Tube ADT7461ARZ−REEL − 4C 2500 Tape & Reel ADT7461ARZ−REEL7 − 4C 1000 Tape & Reel ADT7461ARM 8−Lead MSOP RM−8 T1B 4C 50 Tube ADT7461ARM−REEL 4C 3000 Tape & Reel ADT7461ARM−REEL7 4C 1000 Tape & Reel ADT7461ARMZ 4C 50 Tube ADT7461ARMZ−REEL 4C 3000 Tape & Reel ADT7461ARMZ−R7 4C 1000 Tape & Reel ADT7461ARMZ−002 T1F 4D 50 Tube ADT7461ARMZ−2R 4D 3000 Tape & Reel ADT7461ARMZ−2RL7 4D 1000 Tape & 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 package available.

http://onsemi.com PACKAGE DIMENSIONS SEATING PLANE N J X 45/C0095 K NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A AND B DO NOT INCLUDE MOLD PROTRUSION. 4. MAXIMUM MOLD PROTRUSION 0.15 (0.006) PER SIDE. 5. DIMENSION D DOES NOT INCLUDE DAMBAR PROTRUSION. ALLOWABLE DAMBAR PROTRUSION SHALL BE 0.127 (0.005) TOTAL IN EXCESS OF THE D DIMENSION AT MAXIMUM MATERIAL CONDITION. 6. 751 −01 THRU 751−06 ARE OBSOLETE. NEW STANDARD IS 751−07. A B S DH C 0.10 (0.004) DIM A MIN MAX MIN MAX INCHES 4.80 5.00 0.189 0.197 MILLIMETERS B 3.80 4.00 0.150 0.157 C 1.35 1.75 0.053 0.069 D 0.33 0.51 0.013 0.020 G 1.27 BSC 0.050 BSC H 0.10 0.25 0.004 0.010 J 0.19 0.25 0.007 0.010 K 0.40 1.27 0.016 0.050 M 0 8 0 8 N 0.25 0.50 0.010 0.020 S 5.80 6.20 0.228 0.244 −X− −Y− G MYM0.25 (0.010) −Z− YM0.25 (0.010) Z S X S M /C0095/C0095/C0095/C0095 1.52 0.060 7.0 0.275 0.6 0.024 1.270 0.050 4.0 0.155 /C0466mm inches/C0467SCALE 6:1 *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. SOLDERING FOOTPRINT* SOIC−8 NB CASE 751−07 ISSUE AJ

http://onsemi.com PACKAGE DIMENSIONS SBM0.08 (0.003) A ST NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: MILLIMETER. 3. DIMENSION A DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.15 (0.006) PER SIDE. 4. DIMENSION B DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSION. INTERLEAD FLASH OR PROTRUSION SHALL NOT EXCEED 0.25 (0.010) PER SIDE. 5. 846A-01 OBSOLETE, NEW STANDARD 846A-02. b ePIN 1 ID 8 PL 0.038 (0.0015) −T− SEATING PLANE A A1 c L DIM A MIN NOM MAX MIN MILLIMETERS INCHES A1 0.05 0.08 0.15 0.002 b 0.25 0.33 0.40 0.010 c 0.13 0.18 0.23 0.005 D 2.90 3.00 3.10 0.114 E 2.90 3.00 3.10 0.114 e 0.65 BSC L 0.40 0.55 0.70 0.016 −− 0.043 0.003 0.006 0.013 0.016 0.007 0.009 0.118 0.122 0.118 0.122

0.026 BSC

0.021 0.028 NOM MAX HE DD E MSOP8 CASE 846AB−01 ISSUE O *For additional information on our Pb−Free strategy and soldering details, please download the ON Semiconductor Soldering and Mounting Techniques Reference Manual, SOLDERRM/D. SOLDERING FOOTPRINT* 8X 8X 6X /C0466mm inches/C0467SCALE 8:1 1.04 0.041 0.38 0.015 5.28 0.208 4.24 0.167 3.20 0.126 0.65 0.0256 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. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, direct ly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION N. American Technical Support: 800−282−9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81−3−5773−3850 ADT7461/D Protected by US Patents 5,195,827; 5,867,012; 5,982,221; 6,097,239; 6,133,753; 6,169,442; other patents pending. LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada Email: orderlit@onsemi.com ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative