MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages General Description Features The MAX6672/MAX6673 are low-current temperature ● Simple Single-Wire PWM Output sensors with a single-wire output. These temperature ● Tiny SC70 Package sensors convert the ambient temperature into a 1.4kHz ● Low 60µA (typ) Supply Current Consumption PWM output, which contains the temperature information in its duty cycle. The MAX6672 has an open-drain output ● 1.4kHz Nominal Frequency and the MAX6673 has a push-pull output. ● Choice of Outputs The MAX6672/MAX6673 operate from 2.4V to 5.5V with a Open Drain (MAX6672) maximum supply current of 150µA. Both devices feature Push-Pull (MAX6673) a single-wire output that minimizes the number of pins ● 2.4V to 5.5V Supply Range necessary to interface with a microprocessor. The MAX6672/MAX6673 are available in 5-pin SC70 packages. Applications Ordering Information ● Industrial and Process Control PIN- TOP ● HVAC PART TEMP RANGE PACKAGE MARK ● Environmental Control MAX6672AXK-T -40°C to +125°C 5 SC70 ACQ ● Isolated Temperature Sensing MAX6673AXK-T -40°C to +125°C 5 SC70 ACR Typical Application Circuit Pin Configuration TOP VIEW µC VCC GPIO TO CONTROL DOUT 1 5 VCC * SHUTDOWN MAX6672 0.1µF MAX6672 MAX6673 INPUT TO TIMER/ N.C. 2 MAX6673 COUNTER GND GND 3 4 GND SC70 * PULLUP RESISTOR REQUIRED ONLY FOR THE MAX6672. 19-2458; Rev 1; 4/14

MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Absolute Maximum Ratings Supply Voltage (VCC to GND) ................................ -0.3V to +6V Operating Temperature Range .........................-40°C to +125°C DOUT to GND (MAX6672) ......................................-0.3V to +6V Storage Temperature Range ............................-65°C to +150°C DOUT to GND (MAX6673) .......................-0.3V to (VCC + 0.3V) Junction Temperature ......................................................+150°C DOUT Short to GND..................................................Continuous SC70 Package ESD Protection (Human Body Model)............................ ±2000V Vapor Phase (60s) ...................................................... +215°C Continuous Power Dissipation (TA = +70°C) Infrared (15s). ............................................................. +220°C 5-Pin SC70 (derate 2.5mW/°C above +70°C). ............200mW 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 (VCC = 2.4V to 5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values specified at +25°C and VCC of 3.3V.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS TA = +25°C to +100°C -3 +3 Temperature Error TA = 0°C to +125°C -4 +4 VCC = 3.3V °C (Note 2) TA = -20°C to +125°C -5 +5 TA = -40°C to -20°C ±3 Nominal t1 Pulse Width 280 µs Output Low Voltage VOL ISINK = 3mA 0.4 V Output High Voltage VOH ISOURCE = 800µA (MAX6673) VCC - 0.5 V Fall Time tFALL CLOAD = 100pF 14 ns Rise Time tRISE CLOAD = 100pF (MAX6673) 96 ns DOUT Open-Drain Leakage VDOUT = 6V (MAX6672) 0.1 µA Current Output Capacitance 2.5 pF Power-Supply Rejection Ratio PSRR 2.4V to 5.5V, TA = -25°C to +125°C 0.3 0.8 °C/V 2.4V to 3.6V 60 100 Supply Current ICC µA 3.6V to 5.5V 70 150 Note 1: All specifications are 100% tested at TA = +25°C. Specification limits over temperature (TA = -40°C to +125°C) are guaranteed by design, not production tested. Note 2: Temperature = -200 × (0.85 - T1/T2)3 + (425 5 T1/T2) - 273. T1 is the low time period. T2 is the high time period (Figure 1). www.maximintegrated.com Maxim Integrated │ 2

MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Typical Operating Characteristics (VCC = 3.3V, TA = +25°C, unless otherwise noted.) OUTPUT FREQUENCY NORMALIZED OUTPUT FREQUENCY t1 AND t2 TIMES vs. TEMPERATURE vs. SUPPLY VOLTAGE vs. TEMPERATURE FREQUENCY (kHz)112...570050 MAX6672 toc01 MALIZED FREQUENCY (kHz)111...000100050 TTAA = = + +12255°°CC MAX6672 toc02 µt AND t TIMES (s)12456000000 t2 MAX6672 toc03 1.25 NOR0.995 TA = -40°C 300 t1 1.00 0.990 200 -50 -25 0 25 50 75 100 125 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) SUPPLY VOLTAGE (V) TEMPERATURE (°C) OUTPUT ACCURACY SUPPLY CURRENT SUPPLY CURRENT vs. TEMPERATURE vs. TEMPERATURE vs. SUPPLY VOLTAGE 4 VCC = 3.3V MAX6672 toc04 112500 MAX6672 toc05 19000 MAX6672 toc06 2 A) A) µ µ °ACCURACY (C) 0 UPPLY CURRENT ( 9600 VCC = 5V VCC = 3.3V UPPLY CURRENT ( 8700 -2 S S 30 60 -4 0 50 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 2.0 2.5 3.0 3.5 4.0 4.5 5.0 TEMPERATURE (°C) TEMPERATURE (°C) SUPPLY VOLTAGE (V) POWER-SUPPLY REJECTION POWER-SUPPLY REJECTION OUTPUT RISE AND FALL TIMES vs. TEMPERATURE vs. FREQUENCY vs. CAPACITIVE LOAD °POWER-SUPPLY REJECTION (C/V)-001...5050 MAX6672 toc07 °POWER-SUPPLY REJECTION (C/V) -100...0055 VAC = 100mVP-P MAX6672 toc08 OUTPUT RISE AND FALL TIMES (ns)113962500000 FALML ATXIM66E73 RISE TIME MAX6672 toc09 -1.0 -1.0 0 -50 -25 0 25 50 75 100 125 0.01 0.10 1 10 100 1k 10k 0.01 0.10 1 10 TEMPERATURE (°C) FREQUENCY (Hz) CAPACITIVE LOAD (nF) www.maximintegrated.com Maxim Integrated │ 3

MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Typical Operating Characteristics (continued) (VCC = 3.3V, TA = +25°C, unless otherwise noted.) THERMAL RESPONSE OUTPUT SINK CURRENT MAX6673 OUTPUT SOURCE CURRENT IN STIRRED OIL BATH vs. TEMPERATURE vs. TEMPERATURE 100 MAX6672 toc10 2350 VOL = 0.4V MAX6672 toc11 23..50 VOH = VCC - 0.5V MAX6672 toc12 °TEMPERATURE (C) 5705 SINK CURRENT (mA) 121005 VVCCCC == 53V.3V OURCE CURRENT (mA) 121...005 VVCCCC == 35.V3V S TRANSITION FROM +25°C AIR 5 0.5 TO +100°C STIRRED OIL BATH 25 0 0 0 4 8 12 16 20 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 TIME (s) TEMPERATURE (°C) TEMPERATURE (°C) Pin Description PIN NAME FUNCTION 1 DOUT Digital Output Pin. PWM output, open-drain output (MAX6672), or push-pull output (MAX6673). 2 N.C. No Connection. Not internally connected. 3, 4 GND Pin 3 and Pin 4 must be tied together and connected to ground. 5 VCC Positive Supply. Bypass with a 0.1µF capacitor to GND. Detailed Description The MAX6673 has a push-pull output. The rise and fall times of the MAX6673 output are negligible with The MAX6672/MAX6673 are low-current (60µA, typ), respect to the period; therefore, errors caused by local temperature sensors ideal for interfacing with µCs capacitive loading are minimized. or µPs. The MAX6672/MAX6673 convert their own temperature into a ratiometric PWM output. The square- The output load capacitance should be minimized in wave output waveform time ratio contains the MAX6672 applications because the sourcing current is temperature information. The output is a square wave set by the pullup resistor. If the output capacitance with a nominal frequency of 1.4kHz at +25°C. The tem- becomes too large, unequal rise and fall times distort perature is obtained with the following formula: the pulse width, thus delivering inaccurate readings. Temperature (°C) = -200 x (0.85 - t1 / t2)3 Applications Information + (425 x t1 / t2) - 273 Pulse-Width Modulation Where t1 is a fixed value and t2 is modulated with the temperature. Table 1 lists time ratio vs. temperature. Interfacing with a µC For temperatures greater than +50°C, the temperature The Typical Application Circuit shows the MAX6672/ error is primarily first order and the following equation MAX6673 interfaced with a µC. In this example, the can be used: MAX6672/MAX6673 convert the ambient temperature to a PWM waveform. The µC reads the temperature by Temperature (°C) = (425 x t1 / t2) - 273 measuring the t1 and t2 periods in software and hard- ware. The only timing requirements are that the clock frequency used for timing measurements is stable and www.maximintegrated.com Maxim Integrated │ 4

MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Table 1. Time Ratio vs. Temperature TIME RATIO TEMPERATURE t2 t1 (t1/t2) (°C) 0.936 125 0.878 100 0.807 70 Figure 1. PWM Waveform Timing 0.714 30 0.646 0 Block Diagram 0.602 -25 0.560 -40 5 VCC high enough to provide the required measurement res- olution. The interface for the MAX6672 requires a pullup TEMPERATURE PWM DOUT1 resistor. SENSOR MODULATOR Thermal Response Time t2 t1 The time periods t1 (low) and t2 (high) are values that GND are easily read by the µP timer/counter. The temperature reading is then calculated using software. Since both 3, 4 periods are obtained consecutively, using the same clock, performing the division indicated in the above formulae The thermal path between the plastic package and the results in a ratiometric value that is independent of the die is not as good as the path through the leads, so exact frequency. the MAX6672/MAX6673, like all temperature sensors in Sensing Circuit Board and Ambient plastic packages, are less sensitive to the temperature Temperatures of the surrounding air than they are to the temperature Temperature sensor ICs such as the MAX6672/ of their leads. They can be successfully used to sense MAX6673 that sense their own die temperatures must ambient temperature if the circuit board is designed to be mounted on or close to the object whose tempera- track the ambient temperature. ture they are intended to measure. Because there is a As with any IC, the wiring and circuits must be kept good thermal path between the SC70 package's metal insulated and dry to avoid leakage and corrosion, leads and the IC die, the MAX6672/MAX6673 can especially if the part is operated at cold temperatures accurately measure the temperature of the circuit where condensation can occur. board to which they are soldered. If the sensor is The error caused by power dissipation in the MAX6672/ intended to measure the temperature of a heat-generat- MAX6673 is negligible. ing component on the circuit board, it should be mount- ed as close as possible to that component and should share supply and ground traces (if they are not noisy) with that component where possible. This maximizes Chip Information the heat transfer from the component to the sensor. PROCESS: BiCMOS www.maximintegrated.com Maxim Integrated │ 5

MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Package Information For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. LAND PATTERN NO. 5 SC70 X5-1 21-0076 90-0188 www.maximintegrated.com Maxim Integrated │ 6

MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Revision History REVISION REVISION PAGES DESCRIPTION NUMBER DATE CHANGED 0 10/02 Initial release — 1 4/14 Removed automotive reference from Applications 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com. Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc. © 2014 Maxim Integrated Products, Inc. │ 7