MAX6673AXK+T

MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages General Description The MAX6672/MAX6673 are low-current temperature sensors with a single-wire output. These temperature sensors convert the ambient temperature into a 1.4kHz PWM output, which contains the temperature information in its duty cycle. The MAX6672 has an open-drain output and the MAX6673 has a push-pull output. The MAX6672/MAX6673 operate from 2.4V to 5.5V with a maximum supply current of 150µA. Both devices feature a single-wire output that minimizes the number of pins necessary to interface with a microprocessor. Features ●● Simple Single-Wire PWM Output ●● Tiny SC70 Package ●● Low 60µA (typ) Supply Current Consumption ●● 1.4kHz Nominal Frequency ●● Choice of Outputs Open Drain (MAX6672) Push-Pull (MAX6673) ●● 2.4V to 5.5V Supply Range The MAX6672/MAX6673 are available in 5-pin SC70 packages. Ordering Information Applications ●● ●● ●● ●● Industrial and Process Control HVAC Environmental Control Isolated Temperature Sensing PART Typical Application Circuit MAX6672 MAX6673 0.1µF GND * GPIO TO CONTROL SHUTDOWN INPUT TO TIMER/ COUNTER * PULLUP RESISTOR REQUIRED ONLY FOR THE MAX6672. TOP MARK MAX6672AXK-T -40°C to +125°C 5 SC70 ACQ MAX6673AXK-T -40°C to +125°C 5 SC70 ACR TOP VIEW DOUT 1 N.C. 2 5 VCC 4 GND MAX6672 MAX6673 GND 3 19-2458; Rev 1; 4/14 PINPACKAGE Pin Configuration µC VCC TEMP RANGE SC70 MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Absolute Maximum Ratings Supply Voltage (VCC to GND)................................. -0.3V to +6V DOUT to GND (MAX6672).......................................-0.3V to +6V DOUT to GND (MAX6673)........................ -0.3V to (VCC + 0.3V) DOUT Short to GND..................................................Continuous ESD Protection (Human Body Model)............................ ±2000V Continuous Power Dissipation (TA = +70°C) 5-Pin SC70 (derate 2.5mW/°C above +70°C)..............200mW Operating Temperature Range.......................... -40°C to +125°C Storage Temperature Range............................. -65°C to +150°C Junction Temperature.......................................................+150°C SC70 Package Vapor Phase (60s)....................................................... +215°C Infrared (15s)............................................................... +220°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 (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 Temperature Error (Note 2) CONDITIONS VCC = 3.3V MIN TYP MAX TA = +25°C to +100°C -3 +3 TA = 0°C to +125°C -4 +4 TA = -20°C to +125°C -5 +5 TA = -40°C to -20°C UNITS °C ±3 Nominal t1 Pulse Width 280 µs Output Low Voltage VOL ISINK = 3mA Output High Voltage VOH ISOURCE = 800µA (MAX6673) Fall Time tFALL CLOAD = 100pF 14 ns Rise Time tRISE CLOAD = 100pF (MAX6673) 96 ns VDOUT = 6V (MAX6672) 0.1 µA 2.5 pF DOUT Open-Drain Leakage Current Output Capacitance Power-Supply Rejection Ratio Supply Current PSRR ICC 0.4 VCC - 0.5 V V 2.4V to 5.5V, TA = -25°C to +125°C 0.3 0.8 2.4V to 3.6V 60 100 3.6V to 5.5V 70 150 °C/V µA 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.) 1.25 -25 0 25 50 75 100 125 MAX6672 toc02 3.0 3.5 4.0 4.5 200 5.0 0 25 50 75 100 25 50 75 SUPPLY CURRENT (µA) 90 VCC = 5V 60 VCC = 3.3V 0 125 4.5 5.0 MAX6672 toc06 120 125 100 MAX6672 toc05 150 100 90 80 70 60 -50 -25 0 25 50 75 100 50 125 2.0 2.5 3.0 3.5 4.0 TEMPERATURE (°C) TEMPERATURE (°C) SUPPLY VOLTAGE (V) POWER-SUPPLY REJECTION vs. TEMPERATURE POWER-SUPPLY REJECTION vs. FREQUENCY OUTPUT RISE AND FALL TIMES vs. CAPACITIVE LOAD 0.5 0 -0.5 -25 0 25 50 75 TEMPERATURE (°C) www.maximintegrated.com 100 125 0.5 0 -0.5 150 MAX6672 toc09 1.0 OUTPUT RISE AND FALL TIMES (ns) MAX6672 toc07 1.0 -50 0 SUPPLY CURRENT vs. SUPPLY VOLTAGE 30 -25 -25 SUPPLY CURRENT vs. TEMPERATURE VCC = 3.3V -50 -50 OUTPUT ACCURACY vs. TEMPERATURE SUPPLY CURRENT (µA) ACCURACY (°C) 2.5 t1 TEMPERATURE (°C) -2 POWER-SUPPLY REJECTION (°C/V) 300 TA = -40°C 2.0 t2 400 SUPPLY VOLTAGE (V) 0 -1.0 0.990 500 TEMPERATURE (°C) 2 -4 TA = +25°C 0.995 MAX6672 toc08 4 -50 TA = +125°C 1.000 MAX6672 toc04 1.00 1.005 t1 AND t2 TIMES vs. TEMPERATURE 600 t1 AND t2 TIMES (µs) 1.50 NORMALIZED FREQUENCY (kHz) MAX6672 toc01 1.75 1.010 POWER-SUPPLY REJECTION (°C/V) FREQUENCY (kHz) 2.00 NORMALIZED OUTPUT FREQUENCY vs. SUPPLY VOLTAGE MAX6672 toc03 OUTPUT FREQUENCY vs. TEMPERATURE 120 90 MAX6673 RISE TIME 60 30 FALL TIME VAC = 100mVP-P -1.0 0.01 0.10 1 10 100 FREQUENCY (Hz) 1k 10k 0 0.01 0.10 1 10 CAPACITIVE LOAD (nF) 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.) 4 8 12 16 20 VCC = 5V 15 VCC = 3.3V 10 20 0 MAX6672 toc12 25 VOH = VCC - 0.5V 2.5 2.0 VCC = 5V 1.5 1.0 VCC = 3.3V 0.5 5 TRANSITION FROM +25°C AIR TO +100°C STIRRED OIL BATH 0 VOL = 0.4V SOURCE CURRENT (mA) 50 3.0 MAX6672 toc11 MAX6672 toc10 75 25 30 SINK CURRENT (mA) TEMPERATURE (°C) 100 MAX6673 OUTPUT SOURCE CURRENT vs. TEMPERATURE OUTPUT SINK CURRENT vs. TEMPERATURE THERMAL RESPONSE IN STIRRED OIL BATH -50 TIME (s) -25 0 25 50 75 100 125 0 -50 -25 0 25 50 75 100 125 TEMPERATURE (°C) TEMPERATURE (°C) Pin Description PIN NAME 1 DOUT FUNCTION 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 MAX6672/MAX6673 are low-current (60µA, typ), local temperature sensors ideal for interfacing with µCs or µPs. The MAX6672/MAX6673 convert their own temperature into a ratiometric PWM output. The squarewave output waveform time ratio contains the temperature information. The output is a square wave with a nominal frequency of 1.4kHz at +25°C. The temperature is obtained with the following formula: Temperature (°C) = -200 x (0.85 - t1 / t2)3 + (425 x t1 / t2) - 273 The MAX6673 has a push-pull output. The rise and fall times of the MAX6673 output are negligible with respect to the period; therefore, errors caused by capacitive loading are minimized. The output load capacitance should be minimized in MAX6672 applications because the sourcing current is set by the pullup resistor. If the output capacitance becomes too large, unequal rise and fall times distort the pulse width, thus delivering inaccurate readings. Applications Information Where t1 is a fixed value and t2 is modulated with the temperature. Table 1 lists time ratio vs. temperature. Pulse-Width Modulation For temperatures greater than +50°C, the temperature error is primarily first order and the following equation can be used: The Typical Application Circuit shows the MAX6672/ MAX6673 interfaced with a µC. In this example, the MAX6672/MAX6673 convert the ambient temperature to a PWM waveform. The µC reads the temperature by measuring the t1 and t2 periods in software and hardware. The only timing requirements are that the clock frequency used for timing measurements is stable and Temperature (°C) = (425 x t1 / t2) - 273 www.maximintegrated.com Interfacing with a µC Maxim Integrated │  4 MAX6672/MAX6673 PWM Output Temperature Sensors in SC70 Packages Table 1. Time Ratio vs. Temperature TIME RATIO (t1/t2) TEMPERATURE (°C) 0.936 125 0.878 100 0.807 70 0.714 30 0.646 0 0.602 -25 0.560 -40 t2 t1 Figure 1. PWM Waveform Timing Block Diagram 5 VCC high enough to provide the required measurement resolution. The interface for the MAX6672 requires a pullup resistor. PWM MODULATOR TEMPERATURE SENSOR Thermal Response Time The time periods t1 (low) and t2 (high) are values that are easily read by the µP timer/counter. The temperature reading is then calculated using software. Since both periods are obtained consecutively, using the same clock, performing the division indicated in the above formulae results in a ratiometric value that is independent of the exact frequency. Sensing Circuit Board and Ambient Temperatures Temperature sensor ICs such as the MAX6672/ MAX6673 that sense their own die temperatures must be mounted on or close to the object whose temperature they are intended to measure. Because there is a good thermal path between the SC70 package's metal leads and the IC die, the MAX6672/MAX6673 can accurately measure the temperature of the circuit board to which they are soldered. If the sensor is intended to measure the temperature of a heat-generating component on the circuit board, it should be mounted 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 the heat transfer from the component to the sensor. www.maximintegrated.com DOUT 1 t2 t1 GND 3, 4 The thermal path between the plastic package and the die is not as good as the path through the leads, so the MAX6672/MAX6673, like all temperature sensors in plastic packages, are less sensitive to the temperature of the surrounding air than they are to the temperature of their leads. They can be successfully used to sense ambient temperature if the circuit board is designed to track the ambient temperature. As with any IC, the wiring and circuits must be kept insulated and dry to avoid leakage and corrosion, especially if the part is operated at cold temperatures where condensation can occur. The error caused by power dissipation in the MAX6672/ MAX6673 is negligible. Chip Information PROCESS: BiCMOS 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 NUMBER REVISION DATE 0 10/02 Initial release — 1 4/14 Removed automotive reference from Applications 1 DESCRIPTION PAGES CHANGED 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