MAX6676AUT5+T

EVALUATION KIT AVAILABLE MAX6676/MAX6677 Low-Voltage, 1.8kHz PWM Output Temperature Sensors General Description The MAX6676/MAX6677 are high-accuracy, low-power temperature sensors with a single-wire output. The MAX6676/MAX6677 convert the ambient temperature into a ratiometric PWM output with temperature information contained in the duty cycle of the output square wave. The MAX6676 has an open-drain output and the MAX6677 has a push-pull output. The MAX6676/MAX6677 are specified for operation with power-supply voltages from 1.8V to 3.6V, or from 3.6V to 5.5V (MAX6676 only). The typical unloaded supply current is 80µA. All devices feature a single-wire output that minimizes the number of pins necessary to interface with a microprocessor (µP). The output is a square wave with a nominal frequency of 1.8kHz (±20%) at +25°C. The output format is decoded as follows: Temperature (°C) = 398.15 5 (t1/t2) - 273.15 Where t1 is fixed with a typical value of 0.24ms and t2 is modulated by the temperature. The MAX6676/MAX6677 operate from -40°C to +125°C and are available in space-saving 6-pin SOT23 packages. Applications ●● ●● ●● ●● ●● ●● Process Control Industrial HVAC and Environmental Control Portable Devices µP and µC Temperature Monitoring Isolated Temperature Sensing Features ●● Simple Single-Wire, 1.8kHz PWM Output ●● Operates Down to 1.8V ●● High Accuracy ±1.5°C at TA = +25°C ±3.0°C at TA = 0°C to +85°C ●● Operates from -40°C to +125°C ●● Low 80µA Typical Current Consumption ●● Small 6-Pin SOT23 Package Ordering Information PART TEMP RANGE MAX6676AUT3-T -40°C to +125°C PIN-PACKAGE 6 SOT23 MAX6676AUT5-T -40°C to +125°C 6 SOT23 MAX6677AUT3-T -40°C to +125°C 6 SOT23 Selector Guide PART OUTPUT TYPE SUPPLY VOLTAGE RANGE (V) TOP MARK MAX6676AUT3 Open drain 1.8 to 3.6 ABBF MAX6676AUT5 Open drain 3.6 to 5.5 ABBG MAX6677AUT3 Push-pull 1.8 to 3.6 ABBH Pin Configuration Typical Operating Circuit VCC TOP VIEW VCC 5.1kΩ* DOUT MAX6676 0.1µF t2 INPUT TO TIMER/ COUNTER µC DOUT 1 GND 2 MAX6676 MAX6677 6 GND 5 GND 4 GND t1 GND VCC 3 SOT23 *REQUIRED ONLY FOR MAX6676. 19-2660; Rev 2; 4/15 MAX6676/MAX6677 Low-Voltage, 1.8kHz PWM Output Temperature Sensors Absolute Maximum Ratings (Voltages Referenced to GND) VCC........................................................................-0.3V to +6.0V DOUT (MAX6676).................................................-0.3V to +6.0V DOUT (MAX6677)..................................... -0.3V to (VCC + 0.3V) DOUT Current..................................................... -1mA to +50mA ESD Protection (DOUT, Human Body Model)..................±2000V Continuous Power Dissipation (TA = +70°C) 6-Pin SOT23 (derate 8.7mW/°C above +70°C)........695.7mW Operating Temperature Range.......................... -40°C to +125°C Storage Temperature Range............................. -65°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 (VCC = 1.8V to 3.6V (MAX6676AUT3/MAX6677AUT3), VCC = 3.6V to 5.5V (MAX6676AUT5), TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = 3.0V (MAX6676AUT3/MAX6677AUT3), VCC = 5.0V (MAX6676AUT5), TA = +25°C.) PARAMETER SYMBOL Supply Voltage Range VCC Supply Current ICC Temperature Error CONDITIONS MIN 3.6 MAX6676AUT5 3.6 5.5 RL = ∞ 80 Fall Time Rise Time 200 TA = +25°C -1.5 +1.5 TA = 0°C to +85°C -3.0 +3.0 TA = -20°C to +100°C -4.2 +4.2 TA = -40°C to +125°C -5.5 VOH IOH = 800µA, MAX6677 VOL tF tR Digital Output Capacitance COUT Power-Supply Rejection Ratio PSRR 0.1 °C µA 0.3 CL = 100pF, RL = 10kΩ 20 MAX6676, CL = 15pF, RL = 10kW 300 MAX6677, CL = 100pF, RL = 10kW 30 +0.4 V ns ns 15 -1.2 µA V IOL = 3mA VCC = 1.8V - 3.6V V µs VCC 0.3 VOUT = VCC UNITS +5.5 240 Output Leakage Current Output Low Voltage MAX 1.8 Nominal t1 Pulse Width Output High Voltage TYP MAX6676AUT3/MAX6677AUT3 pF +1.2 °C/V Note 1: Parts are tested at +25°C. Specifications are guaranteed by design over temperature. www.maximintegrated.com Maxim Integrated │  2 MAX6676/MAX6677 Low-Voltage, 1.8kHz PWM Output Temperature Sensors Typical Operating Characteristics (VCC = 3.0V, TA = +25°C, unless otherwise noted.) 2.0 1.5 10 35 60 85 110 MAX6676 toc02 2.1 2.4 2.7 3.0 3.3 MAX6676 toc04 600 500 VCC = 3.6V 400 300 VCC = 3.0V 200 VCC = 1.8V 100 10 35 60 85 0 110 60 85 110 -40 -15 400 10 35 60 85 350 300 250 5.1kΩ PULLUP 200 150 100 NO PULLUP 0 110 1.8 2.1 2.4 2.7 3.0 3.3 TEMPERATURE (°C) SUPPLY VOLTAGE (V) POWER-SUPPLY REJECTION RATIO vs. TEMPERATURE POWER-SUPPLY REJECTION RATIO vs. FREQUENCY OUTPUT FALL TIME (CL = 100pF, RL = 100kΩ) 0 -0.5 1 0 -1 -2 1V/div -3 -4 0V -5 -25 0 25 50 75 TEMPERATURE (°C) www.maximintegrated.com 100 125 3.6 MAX6676 toc09 MAX6676 toc08 2 CHANGE IN TEMPERATURE (C) MAX6676 toc07 TEMPERATURE (°C) 0.5 PSRR (C/V) 35 450 50 5.1kΩ PULLUP RESISTOR -50 10 MAX6676AUT3 SUPPLY CURRENT vs. SUPPLY VOLTAGE -3 -1.0 -15 MAX6676AUT3 SUPPLY CURRENT vs. TEMPERATURE -1 1.0 -40 OUTPUT ACCURACY vs. TEMPERATURE 1 -15 200 3.6 TEMPERATURE (°C) SUPPLY CURRENT (µA) OUTPUT ACCURACY (C) TEMP = -40°C 1.8 SUPPLY VOLTAGE (V) 3 -40 t1 250 TEMPERATURE (°C) 5 -5 300 MAX6676 toc06 -15 1.75 1.50 350 TEMP = +25°C SUPPLY CURRENT (µA) -40 TEMP = +125°C 2.00 t2 400 2.25 MAX6676 toc05 1.0 450 TIME (s) 2.5 2.50 OUTPUT FREQUENCY (Hz) MAX6676 toc01 OUTPUT FREQUENCY (kHz) 3.0 t1 AND t2 TIMES vs. TEMPERATURE MAX6676AUT3 OUTPUT FREQUENCY vs. SUPPLY VOLTAGE MAX6676 toc03 OUTPUT FREQUENCY vs. TEMPERATURE -6 VAC = 100mVP-P 1 10 100 FREQUENCY (Hz) 1k 10k 10ns/div Maxim Integrated │  3 MAX6676/MAX6677 Low-Voltage, 1.8kHz PWM Output Temperature Sensors Typical Operating Characteristics (continued) (VCC = 3.0V, TA = +25°C, unless otherwise noted.) MAX6677 OUTPUT RISE AND FALL TIMES vs. CAPACITIVE LOAD MAX6677 OUTPUT RISE TIME MAX6676 toc10 MAX6676 toc11 200 CLOAD = 100pF RL = 100kΩ 160 TIME (ns) 1V/div 0 120 RISE 80 40 0 40ns/div FALL 0 100 300 200 400 500 600 CLOAD (pF) 3.25 3.00 2.75 350 MAX6676 toc13 ISOURCE = 800µA OUTPUT LOW VOLTAGE (mV) MAX6676 toc12 3.50 OUTPUT HIGH VOLTAGE (V) MAX6677 OUTPUT LOW VOLTAGE vs. TEMPERATURE MAX6677 OUTPUT HIGH VOLTAGE vs. TEMPERATURE ISINK = 5mA 300 250 200 150 100 ISINK = 1.5mA ISINK = 1mA 50 2.50 -40 -15 10 35 60 TEMPERATURE (°C) www.maximintegrated.com 85 110 0 -40 -5 30 65 100 TEMPERATURE (°C) Maxim Integrated │  4 MAX6676/MAX6677 Low-Voltage, 1.8kHz PWM Output Temperature Sensors Pin Description Applications Information PIN NAME FUNCTION 1 DOUT Digital Output Pin. The duty cycle of the output waveform is modulated by temperature 2, 4, 5, 6 GND Ground. All four ground pins must be connected to GND 3 VCC Supply Voltage. Bypass VCC to GND with a 0.1µF capacitor. Detailed Description The MAX6676/MAX6677 are high-accuracy, low-current (80µA, typ) temperature sensors ideal for interfacing with µCs or µPs. The MAX6676/MAX6677 convert the ambient temperature into a ratiometric PWM output at a nominal frequency of 1.8kHz (±20%) at +25°C. The time periods, t1 (low) and t2 (high) (Figure 1), are easily read by a µP’s timer/counter port. To calculate the temperature, use the following expression: Accurate temperature monitoring requires a good thermal contact between the MAX6676/MAX6677 and the object being monitored. A precise temperature measurement depends on the thermal resistance between the object being monitored and the MAX6676/ MAX6677 die. Heat flows in and out of plastic packages primarily through the leads. If the sensor is intended to measure the temperature of a heat-generating component on the circuit board, mount the device as close as possible to that component and share the ground traces (if they are not too noisy) with the component. This maximizes the heat transfer from the component to the sensor. Power Supply from µP Port Pin The low quiescent current of the MAX6676/MAX6677 enables them to be powered from a logic line, which meets the requirements for supply voltage range. This provides a simple shutdown function to totally eliminate quiescent current by taking the logic line low. The logic line must be able to withstand the 0.1µ power-supply bypass capacitance. Temperature (°C) = 398.15 x (t1 / t2) - 273.15 The µC or µP measures the output of the MAX6676/ MAX6677 by counting t1 and t2 and computing the temperature based on their ratio. The resolution of the count is a function of the processor clock frequency and the resolution of the counter. Always use the same clock for t1 and t2 counters so that the temperature is strictly based on a ratio of the two times, thus eliminating errors due to different clocks’ frequencies. The MAX6677 (Figure 2a) has a push-pull output with full CMOS output swings. The ability to source and sink current allows the MAX6677 to drive capacitive loads up to 100pF with less than 1°C error. t2 t1 Figure 1. MAX6676/MAX6677 PWM Output VCC The MAX6676 (Figure 2b) has an open-drain output. The output capacitance should be minimized in MAX6676 applications because the sourcing current is set by the pullup resistor. If the output capacitance becomes too large, lengthy rise and fall times distort the pulse width, resulting in inaccurate measurements. VCC P DOUT DOUT N N (a) (b) MAX6677 MAX6676 Figure 2. Output Configurations www.maximintegrated.com Maxim Integrated │  5 MAX6676/MAX6677 3.3V Low-Voltage, 1.8kHz PWM Output Temperature Sensors VISO VDD VCC MAX6676AUT3 MAX6676 DOUT 5.1kΩ DOUT Figure 3. Galvanic Isolation Using an Optocoupler Figure 4. Low-Voltage Logic Galvanic Isolation Multiple Logic Voltages Use an optocoupler to isolate the MAX6676/MAX6677 whenever a high common-mode voltage is present. Choose an optocoupler with equal turn-on and turn-off times. Unequal turn-on/turn-off times produce an error in the temperature reading (Figure 3) Thermal Considerations Self-heating may cause the temperature measurement accuracy of the MAX6676/MAX6677 to degrade in some applications. The quiescent dissipation and the power dissipated by the digital output may cause errors in obtaining the accurate temperature measurement. The temperature errors depend on the thermal conductivity of the package (SOT23, +140°C/W), the mounting technique, and the airflow. Static dissipation is typically 4.0µW operating at 5V with no load. For example, an out load of 3mA creates a maximum error of less than 0.1°C. www.maximintegrated.com Use the MAX6676 open-drain output to drive devices operating at supply voltages other than the MAX6676’s VCC. As shown in Figure 4, connect a pullup resistor from the other supply voltage to the MAX6676 output. Limit the resistor’s current to less than 1mA, thus maintaining an output low logic level of less than 200mV. Chip Information TRANSISTOR COUNT: 2096 PROCESS: BiCMOS 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. 6 SOT23 U6-1 21-0058 90-0175 Maxim Integrated │  6 MAX6676/MAX6677 Low-Voltage, 1.8kHz PWM Output Temperature Sensors Revision History REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 1 10/02 Initial release 1/03 Removed future product designation and revised Typical Operating Characteristics 1, 2, 3 2 4/15 Removed the automotive reference from data sheet — 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. © 2015 Maxim Integrated Products, Inc. │  7