ADM1021A ONSEMI | Alldatasheet
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© Semiconductor Components Industries, LLC, 2010 June, 2010 − Rev. 8
1 Publication Order Number:
The ADM1021A is a two−channel digital thermometer and under/overtemperature alarm, intended for use in personal computers and other systems requiring thermal monitoring and management. The device can measure the temperature of a microprocessor using a diode−connected PNP transistor, which can be provided on−chip with the Pentium® III or similar processors, or can be a low cost discrete NPN/PNP device, such as the 2N3904/2N3906. A novel measurement technique cancels out the absolute value of the transistor’s base emitter voltage so that no calibration is required. The second measurement channel measures the output of an on−chip temperature sensor to monitor the temperature of the device and its environment. The ADM1021A communicates over a two−wire serial interface compatible with SMBus standards. Under/overtemperature limits can be programmed into the device over the serial bus, and an ALERT output signals when the on−chip or remote temperature is out of range. This output can be used as an interrupt or as an SMBus alert.
FEATURES
- Alternative to the ADM1021
- On−Chip and Remote Temperature Sensing
- No Calibration Necessary
- 1°C Accuracy for On−Chip Sensor
- 3°C Accuracy for Remote Sensor
- Programmable Over/Undertemperature Limits
- Programmable Conversion rate
- 2−Wire SMBus Serial Interface
- Supports System Management Bus (SMBus) Alert
- 200 /C0109A Max Operating Current
- 1 /C0109A Standby Current
- 3.0 V to 5.5 V Supply
- Small 16−Lead QSOP Package
APPLICATIONS
- Desktop Computers
- Notebook Computers
- Smart Batteries
- Industrial Controllers
- Telecom Equipment
- Instrumentation http://onsemi.com See detailed ordering and shipping information in the package dimensions section on page 14 of this data sheet.
ORDERING INFORMATION
xxx = Device Code # = Pb−Free Package YYWW = Date Code MARKING DIAGRAM QSOP−16 CASE 492 1021AA RQZ #YYWW ADM1021A TOP VIEW VDD GND ADD1 NC NC ADD0 GND NC ALERT SDATA NC16 NC STBY SCLK PIN ASSIGNMENT
Figure 1. Functional Block Diagram NOTE: This device is ESD sensitive. Use standard ESD precautions when handling.
http://onsemi.com PIN ASSIGNMENT Pin No. Mnemonic Description 1 NC No Connect. 2 VDD Positive Supply, 3.0 V to 5.5 V. 3 D+ Positive Connection to Remote Temperature Sensor. 4 D− Negative Connection to Remote Temperature Sensor. 5 NC No Connect. 6 ADD1 Three−State Logic Input, Higher Bit of Device Address. 7 GND Supply 0 V Connection. 8 GND Supply 0 V Connection. 9 NC No Connect. 10 ADD0 Three−State Logic Input, Lower Bit of Device Address. 11 ALERT Open−Drain Logic Output Used as Interrupt or SMBus ALERT. 12 SDATA Logic Input/Output, SMBus Serial Data. Open−drain output. 13 NC No Connect. 14 SCLK Logic Input, SMBus Serial Clock. 15 STBY Logic Input Selecting Normal Operation (High) or Standby Mode (Low). 16 NC No Connect. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VDD = 3.0 V to 3.6 V, unless otherwise noted. (Note 1) Parameter Test Conditions / Comments Min Typ Max Unit Power Supply and ADC Temperature Resolution Guaranteed no missed codes 1.0 °C Temperature Error, Local Sensor −3.0 ±1.0 +3.0 °C Temperature Error, Remote Sensor TA = 60°C to 100°C −3.0 −5.0 +3.0 +5.0 Supply Voltage Range (Note 2) 3.0 3.6 V Undervoltage Lockout Threshold VDD input, disables ADC, rising edge 2.5 2.7 2.95 V Undervoltage Lockout Hysteresis 25 mV Power−On Reset Threshold VDD, falling edge (Note 3) 0.9 1.7 2.2 V POR Threshold Hysteresis 50 mV Standby Supply Current VDD = 3.3 V, no SMBus activity SCLK at 10 kHz 1.0 4.0 5.0 /C0109A Average Operating Supply Current 0.25 conversions/sec rate 130 200 /C0109A Auto−convert Mode, Averaged Over 4 Sec 2 conversions/sec rate 225 370 /C0109A Conversion Time From stop bit to conversion complete (both channels) D+ forced to D− + 0.65 V 65 115 170 ms Remote Sensor Source Current High level (Note 3) Low level (Note 3) 120 7.0 205 300 /C0109A D− Source Voltage 0.7 V Address Pin Bias Current (ADD0, ADD1) Momentary at power−on reset 50 /C0109A
- Operation at V DD = 5.0 V guaranteed by design; not production tested.
- Guaranteed by design; not production tested.
Figure 2. Diagram for Serial Bus Timing
results of 16 measurement cycles. temperature sensor is performed in a similar manner.
- The ADM1021A forces a larger current through
- As a result of the greater remote sensor source
- The temperature measurement range of the
temperature measurement is required.
- The power−on reset values of the remote and local
temperature and writes these to the registers.
- The four MSBs of the revision register can be used
reads 0x0x, and the ADM1021A reads 0x3x.
- The power−on default value of the address pointer
temperature measurement register at powerup.
- Setting the mask bit (Bit 7 Config Reg) on the
ADM1021A masks current and future ALERTs. into the local and remote high and low limit registers. Table 1. Temperature Data Format Table 4. It should be noted that the ADM1021A’s registers factory test purposes and should not be written to. data byte of every write operation is written automatically. for a subsequent read operation. the results of the limit comparisons.
conditions that caused the flags to be set have gone away. contains an in−limit measurement, or the sensor is good. Table 2. Status Register Bit Assignments
7 BUSY 1 when ADC converting
6 LHIGH* 1 when local high temp limit tripped
5 LLOW* 1 when local low temp limit tripped
4 RHIGH* 1 when remote high temp limit tripped
3 RLOW* 1 when remote low temp limit tripped
2 OPEN* 1 when remote sensor open−circuit
Table 3. List of ADM1021A Registers
00 Not applicable Local temperature value 1000 0000 (0x80) (−128°C)
01 Not applicable Remote temperature value 1000 0000 (0x80) (−128°C)
02 Not applicable Status Undefined
10 Not applicable Reserved Reserved for future versions
19 Not applicable Reserved Reserved for future versions
- Writing to Address 0F causes the ADM1021A to perform a single measurement. It is not a data register and data written to it is irrelevant.
the part was placed in standby.
Table 4. Configuration Register Bit Assignments
7 MASK1 0 = ALERT Enabled
6 RUN/STOP 0 = Run
consumption, as shown in Table 5. Table 5. Conversion Rate Register Code possible to program the limit register with negative values. This is for backwards compatibility with the ADM1021. Table 6. Offset Values in standby mode, after which the device returns to standby. address is irrelevant and is not stored. Control of the ADM1021A is carried out via the serial bus. powered down and will not pull down the SMBus. over the bus, the slave device with that address responds. addresses are possible, as shown in Table 7. Table 7. Device Addresses (Note 1)
0 NC 0011 001
1 NC 1001 101
- ADD0 and ADD1 are sampled at powerup only.
- The master initiates data transfer by establishing a
to or read from the slave device. master reads from the slave device.
- Data is sent over the serial bus in sequences of
Acknowledge Bit from the slave device. master and slave devices can handle.
- When all data bytes have been read or written,
during the low period before the ninth clock pulse. 10th clock pulse to assert a stop condition. changed without starting a new operation. or two bytes, while read operations contain one byte. to the register selected by the address pointer register. be written to the internal data register. Figure 14. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register
http://onsemi.com 5. Once the ADM1021A has responded to the alert response address, it resets its ALERT output, provided that the error condition that caused the ALERT no longer exists. If the SMBALERT line remains low, the master sends the ARA again, and so on until all devices whose ALERT outputs were low have responded. Low Power Standby Modes The ADM1021A can be put into a low power standby mode using hardware or software, that is, by taking the STBY input low, or by setting Bit 6 of the configuration register. When STBY is high or Bit 6 is low, the ADM1021A operates normally. When STBY is pulled low or Bit 6 is high, the ADC is inhibited, so any conversion in progress is terminated without writing the result to the corresponding value register. The SMBus is still enabled. Power consumption in the standby mode is reduced to less than 10 /C0109A if there is no SMBus activity or 100 /C0109A if there are clock and data signals on the bus. These two modes are similar but not identical. When STBY is low, conversions are completely inhibited. When Bit 6 is set but STBY is high, a one−shot conversion of both channels can be initiated by writing 0xXX to the one−shot register (Address 0x0F). Sensor Fault Detection The ADM1021A has a fault detector at the D+ input that detects if the external sensor diode is open−circuit. This is a simple voltage comparator that trips if the voltage at D+ exceeds V CC – 1.0 V (typical). The output of this comparator is checked when a conversion is initiated and sets Bit 2 of the status register if a fault is detected. If the remote sensor voltage falls below the normal measuring range, for example due to the diode being short−circuited, the ADC outputs −128 °C (1000 0000). Since the normal operating temperature range of the device only extends down to 0°C, this output code is never seen in normal operation; therefore, it can be interpreted as a fault condition. In this respect, the ADM1021A differs from and improves upon competitive devices that output 0 if the external sensor goes short−circuit. These devices can misinterpret a genuine 0°C measurement as a fault condition. If the external diode channel is not being used and is shorted out, the resulting ALERT can be cleared by writing 0x80 (−128°C) to the low limit register. Factors Affecting Accuracy Remote Sensing Diode The ADM1021A is designed to work with substrate transistors built into processors, or with discrete transistors. Substrate transistors are generally PNP types with the collector connected to the substrate. Discrete types can be either PNP or NPN, connected as a diode (base shorted to collector). If an NPN transistor is used, the collector and base are connected to D+ and the emitter to D−. If a PNP transistor is used, the collector and base are connected to D− and the emitter to D+. The user has no choice in the case of substrate transistors, but if a discrete transistor is used, the best accuracy is obtained by choosing devices according to the following criteria: 1. Base−emitter voltage greater than 0.25 V at 6 /C0109A, at the highest operating temperature. 2. Base−emitter voltage less than 0.95 V at 100 /C0109A, at the lowest operating temperature. 3. Base resistance less than 100 /C0087. 4. Small variation in h FE (such as 50 to 150), which indicates tight control of VBE characteristics. Transistors, such as 2N3904, 2N3906, or equivalents, in SOT−23 package are suitable devices to use. Thermal Inertia and Self−Heating Accuracy depends on the temperature of the remote−sensing diode and/or the internal temperature sensor being at the same temperature as that being measured, and a number of factors can affect this. Ideally, the sensor should be in good thermal contact with the part of the system being measured, for example the processor. If it is not, the thermal inertia caused by the mass of the sensor causes a lag in the response of the sensor to a temperature change. For the remote sensor, this should not be a problem, because it is either a substrate transistor in the processor or a small package device, such as SOT−23, placed in close proximity to it. The on−chip sensor is, however, often remote from the processor and only monitors the general ambient temperature around the package. The thermal time constant of the QSOP−16 package is approximately 10 seconds. In practice, the package will have an electrical, and hence a thermal, connection to the printed circuit board, so the temperature rise due to self−heating is negligible. Layout Considerations Digital boards can be electrically noisy environments, and because the ADM1021A is measuring very small voltages from the remote sensor, care must be taken to minimize noise induced at the sensor inputs. The following precautions should be taken: 1. Place the ADM1021A as close as possible to the remote sensing diode. Provided that the worst noise sources, such as clock generators, data/address buses, and CRTs, are avoided, this distance can be four to eight inches. 2. Route the D+ and D− tracks close together, in parallel, with grounded guard tracks on each side. Provide a ground plane under the tracks, if possible. 3. Use wide tracks to minimize inductance and reduce noise pickup. 10 mil track minimum width and spacing is recommended. 4. Try to minimize the number of copper/solder joints, which can cause thermocouple effects.
http://onsemi.com Where copper/solder joints are used, ensure they are in both the D+ and D− paths and at the same temperature. Thermocouple effects should not be a major problem as 1°C corresponds to about 240 /C0109V , and thermocouple voltages are about 3 /C0109V/°C of temperature difference. Unless there are two thermocouples with a big temperature differential between them, thermocouple voltages should be much less than 240 /C0109V. 5. Place a 0.1 /C0109F bypass capacitor close to the V DD pin, and 2200 pF input filter capacitors across D+, D− close to the ADM1021A. 6. If the distance to the remote sensor is more than eight inches, the use of twisted pair cable is recommended. This works up to about 6 to 12 feet. 7. For very long distances (up to 100 feet), use shielded twisted pair, such as Belden #8451 microphone cable. Connect the twisted pair to D+ and D− and the shield to GND close to the ADM1021A. Leave the remote end of the shield unconnected to avoid ground loops. Figure 18. Arrangement of Signal Tracks filter capacitor can be reduced or removed. resistance of 1 /C0087 introduces about 1°C error. already provided elsewhere in the system. system using this type of I/O controller. Figure 19. Typical Application Circuit Figure 20. Typical System Using ADM1021A
2 USB PORTS
2 IDE PORTS
Device Number Temperature Range Package Type Package Option Shipping† ADM1021AARQZ 0°C to +100°C 16−Lead QSOP RQ−16 98 Tube ADM1021AARQZ−R 0°C to +100°C 16−Lead QSOP RQ−16 2500 Tape & Reel ADM1021AARQZ−R7 0°C to +100°C 16−Lead QSOP RQ−16 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 part.
http://onsemi.com PACKAGE DIMENSIONS QSOP16 CASE 492−01 ISSUE O MAX MILLIMETERS G R −B− −A− L M0.25 (0.010) T U −T− SEATING PLANE K D16 PL C M0.25 (0.010) T BAS S V N J M F 8 PL DETAIL E DETAIL E H x 45/C0095 RAD. MOLD PIN DIM MIN MAXMIN INCHES A 4.80 4.980.189 0.196 B 3.81 3.990.150 0.157 C 1.55 1.730.061 0.068 D 0.20 0.310.008 0.012 F 0.41 0.890.016 0.035 G 0.64 BSC0.025 BSC H 0.20 0.460.008 0.018 J 0.249 0.1910.0098 0.0075 K 0.10 0.250.004 0.010 L 5.84 6.200.230 0.244 M 0 8 0 N 0 7 0 7 P 0.18 0.280.007 0.011 Q 0.51 DIA0.020 DIA R 0.64 0.890.025 0.035 U 0.64 0.890.025 0.035 V NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. THE BOTTOM PACKAGE SHALL BE BIGGER THAN THE TOP PACKAGE BY 4 MILS (NOTE: LEAD SIDE ONLY). BOTTOM PACKAGE DIMENSION SHALL FOLLOW THE DIMENSION STATED IN THIS DRAWING. 4. PLASTIC DIMENSIONS DOES NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 6 MILS PER SIDE. 5. BOTTOM EJECTOR PIN WILL INCLUDE THE COUNTRY OF ORIGIN (COO) AND MOLD CAVITY I.D./C0095/C0095/C0095 /C00950 8 0 /C0095/C0095/C0095 8 /C0095 /C0095/C0095/C0095/C0095 MARK Q P 0.013 X 0.005 DP. MAX RAD. 0.005−0.010 TYP 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 ADM1021A/D Protected by U.S. Patents 5,195,827; 5,867,012; 5,982,221; 6,097,239; 6,133,753; 6,169,442; other patents pending. Pentium is a registered trademark of Intel Corporation. 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