19-2133; Rev 2; 11/02 Remote Temperature Switches with Integrated Fan Controller/Driver Features ♦ +12V, 250mA Integrated Fan Driver ♦ No Calibration Required ♦ Pin-Selectable 4°C, 8°C, or 12°C Hysteresis (MAX6670) ♦ Factory-Programmed Temperature Thresholds from +40°C to +75°C ♦ Overtemperature Warning Signals ♦ 110µA (typ) Supply Current ♦ Space-Saving 8-Pin and 10-Pin µMAX Packages Ordering Information TEMP RANGE PART PI NPA CK AG E THRESHOLD ( ° C) MAX6668AUA40 -40°C to +125°C 8 µMAX 40 MAX6668AUA45 -40°C to +125°C 8 µMAX 45 MAX6668AUA50 -40°C to +125°C 8 µMAX 50 MAX6668AUA60 -40°C to +125°C 8 µMAX 60 MAX6668AUA70 -40°C to +125°C 8 µMAX 70 MAX6668AUA75 -40°C to +125°C 8 µMAX 75 Ordering Information continued at end of data sheet. Typical Application Circuit Applications +12V Notebook and Desktop Computers Network Switches PC Power Supplies DXP Laboratory Instruments CS 2200pF Card Racks Temperature Alarms 250mA FAN +3.3V 2N3904 VDD FANOUT VDD 10kΩ MAX6670 DXN WARN Fan Controls VDD 10kΩ HYST GND OT PGND FORCEON VDD Pin Configuration appears at end of data sheet. Typical Operating Circuit appears at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX6668/MAX6670 General Description The MAX6668/MAX6670 remote-junction thermal switches with an internal power transistor drive a cooling fan rated for supply voltages up to +12V and 250mA. These devices measure the temperature of an external P-N junction (typically a diode-connected transistor) and turn on the fan power switch when the remote temperature rises above a factory-programmed threshold. Self-contained and requiring no software development, the MAX6668/MAX6670 are simple “drop-in” fan-control solutions for a variety of systems. The MAX6670 features an open-drain WARN output that goes active when the remote temperature exceeds the factory-programmed fan activation threshold by +15°C. The MAX6670 features an open-drain OT output that goes active when the remote temperature exceeds the factory-programmed threshold by +30°C. The MAX6668/MAX6670 provide a fan-control input, FORCEON, that allows the fan to be driven externally, regardless of temperature. Available temperature thresholds range from +40°C to +75°C in 5°C increments. Hysteresis is preset to 8°C on the MAX6668 or pin selectable to 4°C, 8°C, or 12°C using a three-level logic input on the MAX6670. Temperature threshold accuracy is ±1°C (typ) and ±2.2°C (max) for remote-junction temperatures from +40°C to +75°C. The MAX6668/MAX6670 operate from a +3V to +3.6V power supply, and are specified over the automotive temperature range (-40°C to +125°C). The MAX6668 is offered in an 8-pin µMAX package and the MAX6670 is available in a space-saving 10-pin µMAX package. MAX6668/MAX6670 Remote Temperature Switches with Integrated Fan Controller/Driver ABSOLUTE MAXIMUM RATINGS VDD to GND ..............................................................-0.3V to +6V PGND to GND .......................................................-0.3V to +0.3V FANOUT to GND ....................................................-0.3V to +15V DXN to GND ..........................................................-0.3V to +0.8V DXP, WARN, HYST, FORCEON, OT...........-0.3V to (VDD + 0.3V) Current into VDD, GND, DXP, DXN, WARN, HYST, FORCEON, OT..............................................................±20mA Current into FANOUT, PGND ........................................ ±300mA Continuous Power Dissipation (TA = +70°C) 8-Pin µMAX (derate 4.1mW/°C above +70°C) .............333mW 10-Pin µMAX (derate 5.6mW/°C above +70°C) ...........444mW Operating Temperature Range .........................-40°C to +125°C Storage Temperature Range .............................-60°C to +150°C Junction Temperature ......................................................+150°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VDD = +3V to +3.6V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = +3.3V and TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 3.6 V 110 200 µA 400 650 µA 1.5 2.0 POWER SUPPLY Power-Supply Range VDD Average Supply Current IDD Operating Current Power-On Reset (POR) Threshold 3 During sampling POR VDD falling edge 1 POR Threshold Hysteresis 50 V mV TEMPERATURE SENSOR FANOUT Temperature Threshold Accuracy FANOUT Temperature Threshold Hysteresis ∆TTH THYST TRJ = +40°C to +75°C (Note 1), TA = 0°C to +85°C, VDD = +3.3V ±1 ±2.2 TRJ = +40°C to +75°C (Note 1), TA = -40°C to +125°C, VDD = +3.3V ±1 ±4 MAX6670 °C HYST = GND 4 HYST = float 8 HYST = VDD 12 MAX6668 °C 8 WARN Temperature Threshold (MAX6670 Only) Relative to FANOUT temperature threshold +15 °C OT Temperature Threshold (MAX6670 Only) Relative to FANOUT temperature threshold +30 °C Supply Sensitivity of Temperature Threshold 1 Temperature Sample Frequency 3.3 1.6 4 °C/V Hz FAN DRIVE OUTPUT FANOUT Output Voltage Low VOL ISINK = 250mA 0.5 1 V Thermal Shutdown 170 °C Thermal Shutdown Hysteresis 20 °C LOGIC INPUT/OUTPUT FORCEON Input High Voltage 2 VIH 0.8 x VDD _______________________________________________________________________________________ V Remote Temperature Switches with Integrated Fan Controller/Driver (VDD = +3V to +3.6V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VDD = +3.3V and TA = +25°C.) PARAMETER SYMBOL FORCEON Input Low Voltage CONDITIONS MIN TYP VIL FORCEON Input Bias Current MAX UNITS 0.2 x VDD V 1 µA 0.5 V 1 µA V FORCEON = VDD or GND WARN, OT Output Voltage Low VOL ISINK = 6mA WARN, OT Output High Leakage Current IOH V WARN or V OT = +5.5V Note 1: TRJ is the temperature of the remote P-N junction. Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) 0.6 IFANOUT = 250mA 1.8 1.6 100 0.3 1.2 IDD (µA) VFANOUT (V) 0.4 TA = +105°C 1.0 TA = +65°C 0.8 0.6 0.2 0.1 0 0 150 200 250 300 2.0 IFANOUT (mA) 2.5 3.0 0 3.5 SUPPLY CURRENT vs. SUPPLY VOLTAGE 100 80 60 40 30 PERCENTAGE OF SAMPLES (%) 120 50 75 TEMPERATURE (°C) 100 TEMPERATURE THRESHOLD ERROR MAX6668/70 toc04 140 IDD (µA) 25 VDD (V) MAX6668/70 toc05 100 60 20 TA = +25°C 0.2 0 80 40 0.4 50 VDD = +3.3V, IFANOUT = 250mA 120 1.4 VDD = +3.3V 0 140 MAX6668/70 toc02 TA = +25°C VFANOUT (V) 2.0 MAX6668/70 toc01 0.7 0.5 SUPPLY CURRENT vs. TEMPERATURE FANOUT VOLTAGE vs. SUPPLY VOLTAGE MAX6668/70 toc03 FANOUT CURRENT vs. FANOUT VOLTAGE MAX6670AUB040 119 SAMPLES 25 20 15 10 5 20 FORCEON = VDD 0 3.0 3.3 VDD (V) 3.6 0 -1.00 -0.75 -0.50 -0.25 0 0.25 0.50 0.75 1.00 THRESHOLD ERROR (°C) _______________________________________________________________________________________ 3 MAX6668/MAX6670 ELECTRICAL CHARACTERISTICS (continued) Remote Temperature Switches with Integrated Fan Controller/Driver MAX6668/MAX6670 Pin Description PIN NAME MAX6668 MAX6670 1 1 FUNCTION PGND Power Ground. PGND is the power ground for the FANOUT power MOSFET switch. Fan-Control Input. Drive FORCEON high for normal operation. Drive FORCEON low to force fan on. 2 5 FORCEON 3 3 DXP Current Source Positive Input. Connect to the anode of the external diodeconnected transistor. Do not leave DXP floating. Connect a 2200pF capacitor between DXP and DXN for noise filtering. 4 4 DXN Current Sink Negative Input. Connect to the cathode of the external diodeconnected transistor. DXN is internally biased to a diode voltage drop. 5, 7 7 GND Ground 6 8 VDD Positive Power Supply 8 10 FANOUT — 2 WARN — 6 OT Overtemperature Output. OT is an open-drain output that goes low when the sensed junction temperature is 30°C higher than the fan trip threshold. — 9 HYST Hysteresis Control Input. HYST is a three-level logic input for controlling the fandrive comparator’s hysteresis. Connect HYST to GND for 4°C hysteresis, to VDD for 12°C hysteresis, or leave floating for 8°C hysteresis. Fan-Drive Output. FANOUT is an open-drain power MOSFET that sinks up to 250mA current to turn on the fan when the sensed temperature exceeds the fan trip threshold or the fan is forced on by driving FORCEON low. Temperature Warning Output. WARN is an open-drain output that goes low when the sensed junction temperature is 15°C higher than the fan trip threshold. Detailed Description Overtemperature Alarm Outputs The MAX6668/MAX6670 are simple fan controllers/drivers that turn on an internal power transistor when the sensed temperature of an external P-N junction exceeds a factory-set threshold. By connecting a small (up to +12V/250mA nominal) cooling fan to FANOUT, a simple on/off fan-control system is created. Do not connect the fan to a power supply of higher than 12V nominal, 15V maximum. WARN Output (MAX6670 Only) WARN is an active-low, open-drain digital output that indicates when the external P-N junction’s temperature exceeds 15°C above the fan trip threshold. The WARN output serves as a warning that the system temperature has continued to rise well above the fan activation temperature. FANOUT Driver and FORCEON Controller FANOUT Fan-Driver Output FANOUT is an open-drain output that sinks greater than 250mA of current to turn on the fan, either when the fan trip threshold is exceeded or the fan is forced on by driving FORCEON low. FORCEON Fan-Control Input Drive FORCEON low to turn on the fan when the MAX6670’s remote-sensing junction temperature is less than the fan trip threshold temperature. This overrides the internal control circuitry and allows for an external device to activate the fan. 4 OT Output (MAX6670 Only) OT is an active-low, open-drain digital output that indicates when the external P-N junction’s temperature exceeds 30°C above the fan trip threshold. OT serves as a thermal shutdown output to the system in case of excessive temperature rise. Hysteresis Input The temperature comparator has hysteresis to prevent small temperature changes near the threshold temperature from causing the fan to turn on and off repeatedly over short periods of time. The FANOUT pin goes active and powers the fan when the external P-N junction’s temperature exceeds the factory-programmed _______________________________________________________________________________________ Remote Temperature Switches with Integrated Fan Controller/Driver Applications Information Remote-Diode Selection The MAX6668/MAX6670 directly measure the die temperature of CPUs and other ICs that have on-board temperature-sensing diodes (see Typical Operating Circuit) or they can measure the temperature of a discrete diode-connected transistor. For best accuracy, the discrete transistor should be a small-signal device with its collector and base connected together. Several satisfactory discrete sensing transistors are shown in Table 1. The sensing transistor must be a small-signal type with a relatively high forward voltage. Otherwise, the DXP input voltage range may be violated. The forward voltage at the highest expected temperature must be greater than 0.25V at 10µA, and at the lowest expected temperature, forward voltage must be less than 0.95V at 100µA. Do not use large power transistors. Also, ensure that the base resistance is less than 100Ω. Tight specifications for forward current gain (50 < BF < 150, for example) indicate that the manufacturer has good process controls and that the transistors have consistent VBE characteristics. Noise-Filtering Capacitor In noisy environments, high-frequency noise can be attenuated using an external 2200pF capacitor located at the DXP and DXN pins. Larger capacitor values may be used for additional filtering, but do not exceed 3300pF; excessive capacitance increases error. Figure 2 shows the recommended DXP/DXN PC traces. Bypassing and Layout The location of the remote-sensing junction in the system affects the MAX6668/MAX6670s’ operation. When using a discrete temperature-sensing transistor, place the sensing junction close to major heat-generating components, such as a high-speed CPU or a power device. Table 1. Remote-Sensor Transistor Manufacturers MANUFACTURER Central Semiconductor (USA) MODEL NO. CMPT3904 ON Semiconductor (USA) 2N3904, 2N3906 Rohm Semiconductor (USA) SST3904 Samsung (Korea) KST3904-TF Siemens (Germany) SMBT3904 Zetex (England) FMMT3904CT-ND To minimize noise and other errors, follow the guidelines below: 1) Place the MAX6668/MAX6670 as close as possible to the remote diode. In a noisy environment, such as a computer motherboard, this distance can be 10cm to 20cm (typ) or more as long as the worst noise sources (such as CRTs, clock generators, memory buses, and ISA/PCI buses) are avoided. In general, minimize the distance to the remote-sensing junction. 2) Do not route the DXP/DXN traces next to the deflection coils of a CRT. Also, do not route the traces across a fast memory bus, which can introduce +30°C error or more, even with good filtering. 3) Route the DXP and DXN traces in parallel and in close proximity to each other, away from any highvoltage traces, such as +12VDC. Avoid leakage currents from PC board contamination, since a 20MΩ leakage path from DXP to GND causes about +1°C error. 4) Connect guard traces to GND on either side of the DXP/DXN traces (Figure 2). With guard traces in place, routing near high-voltage traces is no longer an issue. 5) Route through as few vias and crossunders as possible to minimize copper/solder thermocouple effects. 6) Use wide traces where possible. Narrow traces are more inductive and tend to pick up radiated noise. 7) Do not use copper as an EMI shield. Only ferrous materials such as steel work well. Placing a copper ground plane between the DXP/DXN traces and other traces carrying high-frequency noise signals does not help reduce EMI. The MAX6668/MAX6670s’ PGND is the ground return for the fan driver. Bypass V DD to GND with a 1µF capacitor located as close to VDD as possible. Add additional bypass capacitors for long VDD and GND lines. _______________________________________________________________________________________ 5 MAX6668/MAX6670 trip temperature. As the cooling fan operates, the circuit board temperature should decrease, which causes the external P-N junction’s temperature to decrease. When the P-N junction’s temperature is equal to the trip threshold minus the hysteresis, the FANOUT pin turns the fan off, removing power from the fan. For the MAX6670, HYST is a three-level logic input for controlling the fan-drive comparator’s hysteresis. Connect HYST to GND to select 4°C hysteresis, to VDD to select 12°C hysteresis, or leave floating to select 8°C hysteresis. The MAX6668 has a built-in hysteresis of 8°C. This allows the amount of hysteresis to be matched to the cooling and noise requirements of the system. Figure 1 shows the temperature trip threshold hysteresis. MAX6668/MAX6670 Remote Temperature Switches with Integrated Fan Controller/Driver Pin Configurations TRIP TEMPERATURE TOP VIEW TRIP TEMPERATURE – HYSTERESIS FANOUT PGND MAX6668 MAX6670 1 8 FANOUT 7 GND 3 6 VDD DXN 4 5 GND FORCEON 2 MAX6668 TIME DXP Figure 1. Temperature Trip Threshold Hysteresis µMAX PGND 1 GND 10MILS DXP 10MILS MINIMUM WARN 2 DXP 3 DXN FORCEON 10 FANOUT 9 HYST 8 VDD 4 7 GND 5 6 OT MAX6670 DXN 10MILS 10MILS GND µMAX Figure 2. Recommended DXP/DXN PC Traces Chip Information Typical Operating Circuit +4.5V TO +12V TRANSISTOR COUNT: 8113 PROCESS: BiCMOS +3V TO +3.6V CPU DXP VDD Ordering Information FANOUT VDD PART MAX6670 DXN WARN VDD HYST GND 6 OT PGND FORCEON VDD TEMP RANGE PI NPA CK AG E THRESHOLD ( ° C) MAX6670AUB40 -40°C to +125°C 10 µMAX 40 MAX6670AUB45 -40°C to +125°C 10 µMAX 45 MAX6670AUB50 -40°C to +125°C 10 µMAX 50 MAX6670AUB55 -40°C to +125°C 10 µMAX 55 MAX6670AUB60 -40°C to +125°C 10 µMAX 60 MAX6670AUB65 -40°C to +125°C 10 µMAX 65 MAX6670AUB70 -40°C to +125°C 10 µMAX 70 MAX6670AUB75 -40°C to +125°C 10 µMAX 75 _______________________________________________________________________________________ Remote Temperature Switches with Integrated Fan Controller/Driver VDD DXP FANOUT TEMP SENSOR CS TFAN PGND DXN HYST 4°C, 8°C, 12°C HYSTERESIS WARN FORCEON TFAN +15°C OT MAX6670 TFAN +30°C GND VDD DXP FANOUT TEMP SENSOR CS TFAN PGND DXN 8°C HYSTERESIS MAX6668 FORCEON GND _______________________________________________________________________________________ 7 MAX6668/MAX6670 Functional Diagrams Package Information 4X S 8 E ÿ 0.50±0.1 8 H MIN 0.002 0.030 0.6±0.1 L 1 α 0.6±0.1 S BOTTOM VIEW D MAX 0.043 0.006 0.037 0.05 0.75 1.10 0.15 0.95 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0∞ 6∞ 0.5250 BSC 0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 6∞ 0∞ 0.0207 BSC c D e E H 1 MILLIMETERS MAX MIN INCHES DIM A A1 A2 b 8LUMAXD.EPS (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) TOP VIEW A1 A2 A α c e L b SIDE VIEW FRONT VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 8L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0036 e REV. 1 J 1 10LUMAX.EPS MAX6668/MAX6670 Remote Temperature Switches with Integrated Fan Controller/Driver 4X S 10 INCHES 10 H ÿ 0.50±0.1 0.6±0.1 1 1 0.6±0.1 BOTTOM VIEW TOP VIEW D2 MILLIMETERS MAX DIM MIN 0.043 A 0.006 A1 0.002 A2 0.030 0.037 D1 0.116 0.120 0.114 0.118 D2 0.116 E1 0.120 0.118 E2 0.114 0.199 H 0.187 L 0.0157 0.0275 L1 0.037 REF b 0.007 0.0106 e 0.0197 BSC c 0.0035 0.0078 0.0196 REF S α 0∞ 6∞ MAX MIN 1.10 0.15 0.05 0.75 0.95 3.05 2.95 3.00 2.89 3.05 2.95 2.89 3.00 4.75 5.05 0.40 0.70 0.940 REF 0.177 0.270 0.500 BSC 0.090 0.200 0.498 REF 0∞ 6∞ E2 GAGE PLANE A2 c A b A1 D1 FRONT VIEW α E1 L L1 SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 10L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0061 REV. I 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.