19-1484; Rev 0; 4/99 SOT Temperature Sensors with Period/Frequency Output The MAX6576/MAX6577 are low-cost, low-current temperature sensors with a single-wire output. The MAX6576 converts the ambient temperature into a square wave with a period proportional to absolute temperature (°K). The MAX6577 converts the ambient temperature into a square wave with a frequency proportional to absolute temperature. The MAX6576 offers accuracy of ±3°C at +25°C, ±4.5°C at +85°C, and ±5°C at +125°C. The MAX6577 offers accuracy of ±3°C at +25°C, ±3.5°C at +85°C, and ±4.5°C at +125°C. Both devices feature a single-wire output that minimizes the number of pins necessary to interface with a microprocessor. The period/frequency range of the output square wave can be selected by hard-wiring the two time-select pins (TS0, TS1) to either VDD or GND. The MAX6576/MAX6577 are available in space-saving 6-pin SOT23 packages. Features ♦ Simple Single-Wire Output ♦ Two Output Types Available Temperature to Period (µs) (MAX6576) Temperature to Frequency (Hz) (MAX6577) ♦ ±0.8°C Accuracy at +25°C (±3°C max) ♦ No External Components ♦ Operates from +2.7V to +5.5V Supply Voltage ♦ Low 140µA Typical Supply Current ♦ Standard Operating Temperature Range: -40°C to +125°C ♦ Small 6-Pin SOT23 Package Applications Ordering Information Critical µP and µC Temperature Monitoring Portable Battery-Powered Equipment PART TEMP. RANGE Cell Phones Battery Packs PINPACKAGE MAX6576ZUT -40°C to +125°C 6 SOT23 MAX6577ZUT -40°C to +125°C 6 SOT23 SOT TOP MARK AABI AABJ Hard Drives/Tape Drives Networking and Telecom Equipment Medical Equipment Automotive Typical Operating Circuit Pin Configuration TOP VIEW +2.7V TO +5.5V 0.1µF VDD 1 GND 2 MAX6576 MAX6577 6 OUT 5 TS1 µP MAX6576 4 TS0 VCC TS1 MAX6577 TS0 N.C. 3 0.1µF VDD GND OUT GND I/O SOT23-6 ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 1-800-835-8769. MAX6576/MAX6577 General Description MAX6576/MAX6577 SOT Temperature Sensors with Period/Frequency Output ABSOLUTE MAXIMUM RATINGS Terminal Voltage (with respect to GND) VDD ......................................................................-0.3V to +6V TS1, TS0, OUT.......................................-0.3V to (VDD + 0.3V) Input/Output Current, All Pins...........................................±20mA Continuous Power Dissipation (TA = +70°C) 6-pin SOT23 (derate 7.10mW/°C above +70°C).........571mW Operating Temperature Range .........................-40°C to +125°C Storage Temperature Range.. ...........................-65°C to +150°C Lead Temperature (soldering, 10sec) .............................+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 = +2.7V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are specified at TA = +25°C and VDD = +5V, unless otherwise noted.) PARAMETER VDD Range Supply Current SYMBOL CONDITIONS VDD IDD MIN VDD = 5.5V Temperature Sensor Error (Note 1) MAX6577 TA = -40°C to +85°C Output Clock Frequency fOUT 5.5 V 140 250 400 TA = -20°C -7.5 ±1.1 +7.5 TA = 0°C -5.5 ±0.9 +5.5 TA = +25°C -3.0 ±0.8 +3.0 TA = +85°C -4.5 ±0.5 +4.5 TA = +125°C -5.0 ±0.5 +5.0 TA = -20°C -7.5 ±1.1 +7.5 TA = 0°C -6.5 ±0.9 +6.5 TA = +25°C -3.0 ±0.8 +3.0 TA = +85°C -3.5 ±0.5 +3.5 TA = +125°C -4.5 ±0.5 +4.5 MAX6576, T (temp) in °K, Figure 1 MAX6577, T (temp) in °K, Figure 2 40T VTS1 = VDD, VTS0 = GND 160T VTS1 = VDD, VTS0 = VDD 640T VTS1 = GND, VTS0 = GND 4T VTS1 = GND, VTS0 = VDD 1T VTS1 = VDD, VTS0 = GND T/4 VTS1 = VDD, VTS0 = VDD T/16 °C °C µs Hz 0.5 VIL VIH VOL OUT Voltage VOH 0.8 2.3 VDD > 4.5V, ISINK = 3.2mA VDD > 2.7V, ISINK = 1.2mA VDD > 4.5V, ISRC = 800µA VDD > 2.7V, ISRC = 500µA 0.4 0.3 VDD - 1.5 0.8VDD Note 1: See the Temperature Accuracy histograms in the Typical Operating Characteristics. Note 2: The output duty cycle is guaranteed to be 50% by an internal flip-flop. 2 µA 10T VTS1 = GND, VTS0 = VDD OUT Duty Cycle (Note 2) Time-Select Pin Logic Levels UNITS TA = -40°C to +125°C VTS1 = GND, VTS0 = GND tOUT MAX 2.7 MAX6576 Output Clock Period TYP _______________________________________________________________________________________ V V SOT Temperature Sensors with Period/Frequency Output SAMPLE SIZE = 200 MAX6576 MAX6577 30 25 20 15 10 5 60 PERCENTAGE OF PARTS SAMPLED (%) MAX6576 toc01 PERCENTAGE OF PARTS SAMPLED (%) 35 SAMPLE SIZE = 200 MAX6576 MAX6577 50 40 30 20 10 0 0 -5 -4 -3 -2 -1 0 1 2 3 4 -5 -4 -3 -2 -1 5 SUPPLY CURRENT vs. TEMPERATURE 1 2 3 4 5 ACCURACY vs. TEMPERATURE 170 160 1.0 ACCURACY (°C) MAX6576 140 130 MAX6575 toc04 1.5 MAX6576/77toc02 180 SUPPLY CURRENT (µA) 0 ACCURACY (°C) ACCURACY (°C) 150 MAX6576 toc01 TEMPERATURE ACCURACY (TA = +85°C) TEMPERATURE ACCURACY (TA = +25°C) 0.5 MAX6577 0 120 MAX6577 -0.5 110 MAX6576 100 -40 -25 -10 5 20 35 50 65 80 95 110 125 -1.0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TEMPERATURE (°C) TEMPERATURE (°C) THERMAL STEP RESPONSE IN PERFLUORINATED FLUID THERMAL STEP RESPONSE IN STILL AIR MAX6576/77 toc06 MAX6576/77 toc05 +100°C +100°C +12.5°C/div +15°C/div MOUNTED ON 0.75 in.2 OF 2oz. COPPER MOUNTED ON 0.75 in.2 OF 2oz. COPPER +25°C +25°C 5sec/div 20sec/div _______________________________________________________________________________________ 3 MAX6576/MAX6577 Typical Operating Characteristics (VDD = +5V, TA = +25°C, unless otherwise noted.) MAX6576/MAX6577 SOT Temperature Sensors with Period/Frequency Output Pin Description PIN NAME 1 VDD Positive Supply Voltage FUNCTION 2 GND Ground 3 N.C. No Connection. Connect pin to GND or leave open. 4, 5 TS1, TS0 6 OUT Time-Select Pins. TS1 and TS0 set the temperature scale factor by connecting TS1 and TS0 to either VDD or GND. See Tables 1 and 2. Square-Wave Output with a Clock Period Proportional to Absolute Temperature (°K) (MAX6576) Square-Wave Output with a Clock Frequency Proportional to Absolute Temperature (°K) (MAX6577) Table 1. MAX6576 Time-Select Pin Configuration TS1 TS0 SCALAR MULTIPLIER (µs/°K) TS1 TS0 SCALAR MULTIPLIER (Hz/°K) GND GND 10 GND GND 4 GND VDD 40 GND VDD 1 VDD GND 160 VDD GND 1/4 VDD VDD 640 VDD VDD 1/16 Note: The temperature, in °C, may be calculated as follows: T(°C) = period(µs) scalar mulitplier(µs/ °K) − 273.15°K Detailed Description The MAX6576/MAX6577 low-cost, low-current (140µA typ) temperature sensors are ideal for interfacing with microcontrollers (µCs) or microprocessors (µPs). The MAX6576 converts ambient temperature into a 50% dutycycle square wave with a period proportional to absolute temperature. The MAX6577 converts ambient temperature into a 50% duty-cycle square wave with a frequency proportional to absolute temperature. Time-select pins (TS1, TS0) permit the internal temperature-controlled oscillator (TCO) to be scaled by four preset multipliers. The MAX6576/MAX6577 feature a single-wire interface to minimize the number of port pins necessary for interfacing with a µP. MAX6576 Characteristics The MAX6576 temperature sensor converts temperature to period. The output of the device is a freerunning, 50% duty-cycle square wave with a period that 4 Table 2. MAX6577 Time-Select Pin Configuration Note: The temperature, in °C, may be calculated as follows: T(°C) = frequency(Hz) scalar mulitplier(Hz/°K) − 273.15°K is proportional to the absolute temperature (°K) of the device (Figure 1). The MAX6576 has a push/pull CMOS output with sharp edges. The speed of the output square wave can be selected by hard-wiring TS1 and TS0 as shown in Table 1. One of four scaled output periods can be selected using TS1 and TS0. MAX6577 Characteristics The MAX6577 temperature sensor converts temperature to frequency. The output of the device is a freerunning, 50% duty-cycle square wave with a frequency that is proportional to the absolute temperature (°K) of the device (Figure 2). The MAX6577 has a push/pull CMOS output with sharp edges. The speed of the output square wave can be selected by hard-wiring TS1 and TS0 as shown in Table 2. One of four scaled output frequencies can be selected using TS1 and TS0. _______________________________________________________________________________________ SOT Temperature Sensors with Period/Frequency Output MAX6577 CLOCK WAVEFORM OUTPUT tOUT tOUT Figure 1. MAX6576 Timing Diagram Applications Information Quick-Look Circuits Figure 3 shows a quick-look application circuit for the MAX6576 using a universal counter measuring period. TS1 and TS0 are both tied to ground to select a scalar multiplier of 10µs/°K. The MAX6576 converts the ambient temperature into a square wave with a period that is 10 times the absolute temperature of the device in µs. At room temperature, the universal counter will display approximately 2980µs. Figure 4 shows a quick-look application circuit for the MAX6577 using a universal counter measuring frequency. TS1 is tied to ground and TS0 is tied to V DD to select a scalar multiplier of 1Hz/°K. The MAX6577 converts the ambient temperature into a square wave with a frequency that is equal to the absolute temperature of the device in Hertz. At room temperature, the universal counter will display approximately 298Hz. Interfacing with a Microcontroller Figure 5 shows the MAX6577 interfaced with an 8051 µC. In this example, TS1 is tied to ground and TS0 is fOUT = 1 / tOUT fOUT (°K) Figure 2. MAX6577 Timing Diagram tied to VDD to select a scalar multiplier of 1Hz/°K. The MAX6577 converts the ambient temperature into a square wave with a frequency that is equal to the absolute temperature of the device in Hertz. The 8051 µC reads the frequency of the square-wave output of the MAX6577 into Timer 0 and displays the temperature as degrees Celsius in binary on Port 1. Listing 1 provides the code for this application. The interface is similar for the MAX6576, except the µC will perform a period measurement. Noise Considerations The accuracy of the MAX6576/MAX6577 is susceptible to noise generated both internally and externally. The effects of external noise can be minimized by placing a 0.1µF ceramic bypass capacitor close to the supply pin of the devices. Internal noise is inherent in the operation of the devices and is detailed in Table 3. Internal averaging minimizes the effect of this noise when using longer scalar timeout multipliers. The effects of this noise are included in the overall accuracy of the devices as specified in the Electrical Characteristics. _______________________________________________________________________________________ 5 MAX6576/MAX6577 MAX6576 CLOCK WAVEFORM OUTPUT MAX6576/MAX6577 SOT Temperature Sensors with Period/Frequency Output VCC +2.7V TO +5.5V 470Ω x 8 P1.0 0.1µF VDD TS0 MAX6576 P1.1 +2.7V TO +5.5V UNIVERSAL COUNTER P1.2 P1.3 "PERIOD" OUT TS1 P1.4 0.1µF VDD P1.5 GND TS0 MAX6577 P1.6 OUT T0 P1.7 TS1 22pF GND Figure 3. MAX6576 Quick-Look Circuit X1 8051 +2.7V TO +5.5V X2 GND 22pF 0.1µF UNIVERSAL COUNTER VDD TS0 12MHz MAX6577 OUT Figure 5. Interfacing with a µC "FREQUENCY" TS1 GND Chip Information TRANSISTOR COUNT: 302 Figure 4. MAX6577 Quick-Look Circuit Table 3. Typical Peak Noise Amplitude PARAMETER 6 MAX6576 MAX6577 Scalar Multiplier 10 40 160 640 4 1 1/4 1/16 Noise Amplitude (°C) ±0.38 ±0.17 ±0.11 ±0.094 ±0.13 ±0.066 ±0.040 ±0.028 _______________________________________________________________________________________ SOT Temperature Sensors with Period/Frequency Output MAX6576/MAX6577 Listing 1. 8051 Code Example _______________________________________________________________________________________ 7 Listing 1. 8051 Code Example (continued) Package Information 6LSOT.EPS MAX6576/MAX6577 SOT Temperature Sensors with Period/Frequency Output 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 © 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.