19-2546; Rev 0; 7/02 High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package Features ♦ Optimized for Use with ADCs ♦ High Temperature-to-Voltage Slope ♦ Able to Drive High-Capacitive Loads ♦ Operates Up to +150°C ♦ Low Current Consumption (35µA max) ♦ No Calibration Required ♦ Space-Saving SC70 Package Ordering Information PART TEMP RANGE MAX6612MXK-T -55°C to +150°C The operating temperature range varies with the supply voltage, with a higher supply voltage enabling a wider temperature range. The MAX6612 can be used over a range of -10°C to +125°C with a supply voltage of 3.3V or greater. For applications with a supply voltage of 2.4V, the MAX6612 can be used over a temperature range of -10°C to +70°C. PINPACKAGE 5 SC70-5 TOP MARK ADG Pin Configuration TOP VIEW A Applications 1 GND 2 5 B 4 VCC MAX6612 Base Stations Industrial Equipment OUT 3 Home Appliances SC70 Battery Packs Medical Instruments Portable Equipment GPS Equipment Typical Application Circuit VSUPPLY RPU1 VCC OUT CS AIN_ VDD RPU2 SDA CLOAD MAX6612 GND MAX1137 CREF GND SCL ________________________________________________________________ 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 MAX6612 General Description The MAX6612 is a low-power precision analog output temperature sensor in a tiny 5-pin SC70 package. The sensitivity of the output voltage to temperature is a high 19.53mV/°C. This sensitivity provides superior noise immunity. The voltage/temperature slope is chosen to provide convenient bit weights when the MAX6612 drives the input of an ADC with a 2.5V or 5V reference. The MAX6612 provides an analog voltage output proportional to temperature. Accuracy is ±1.2°C (max) at +25°C, ±3.0 (max) from TA = 0°C to +70°C, and ±5.5°C (max) from TA = -10°C to +125°C. Useful measurements can be obtained at temperatures as high as +150°C. Self-heating effects are negligible due to the low current consumption of the part. Unlike many analog temperature sensors, the MAX6612 is stable with large capacitive loads. Any capacitive load greater than or equal to 1000pF yields stable operation, providing broad flexibility in board-level design. ABSOLUTE MAXIMUM RATINGS VCC to GND ..............................................................-0.3V to +6V OUT to GND..................................................-0.3V to VCC + 0.3V ESD Protection (Human Body)...........................................2000V Current into Any Pin ............................................................20mA Output Short-Circuit Duration.....................................Continuous Continuous Power Dissipation (TA = +70°C) 5-Pin SC70 (derate 3.1mW/°C above +70°C) ..............245mW Operating Temperature Range .........................-55°C to +150°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +165°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, CLOAD = 1000pF, TA = -10°C to +150°C, unless otherwise specified.) PARAMETER SYMBOL Temperature Error VOUT = 0.4 + (0.01953 ✕ T) – (2 ✕ 10-6 ✕ T2) (Notes 1, 2) CONDITIONS MIN TYP Supply Voltage Range -1.2 TA = +60°C to +70°C, VCC = 3.3V -3.0 +3.0 TA = +60°C to +100°C, VCC = 3.3V -4.3 +4.3 TA = -10°C to +125°C, VCC = 3.3V -5.5 +1.2 IQ No load Output Voltage VOUT TA = 0°C °C +5.5 2.4 Supply Current UNITS ±5 VCC Sensor Gain (Average Slope) MAX TA = +25°C, VCC = 3.3V TA = -10°C to +150°C, VCC = 5.5V 2.3 5.5 35 TA = -10°C to +150°C V µA 400 mV 19.53 mV/°C Capacitive Load No sustained oscillations (Note 3) Turn-On Time CLOAD = 1000pF 80 µs Shutdown Current VCC < 0.8V 1 µA Supply Sensitivity VCC = 2.4V to 5.5V 0.5 Load Regulation IOUT = 2µA to 100µA 0.03 1000 pF 0.8 °C/V °C/µA Note 1: 100% production tested at +25°C. Guaranteed by design through temperature. Note 2: T is in °C. Note 3: Guaranteed by design. Typical Operating Characteristics (VCC = 3.3V, CS = 0.1µF, CLOAD = 1000pF, unless otherwise specified.) OUTPUT VOLTAGE vs. AMBIENT TEMPERATURE 2500 VCC = 5.5V 2000 1500 1000 MAX6612 toc02 TA = +25°C 20 SUPPLY CURRENT (µA) 3000 15 10 5 500 0 0 -25 0 25 50 75 100 AMBIENT TEMPERATURE (°C) 2 SUPPLY CURRENT vs. SUPPLY VOLTAGE 25 MAX6612 toc01 3500 OUTPUT VOLTAGE (mV) MAX6612 High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package 125 150 1 2 3 4 5 6 SUPPLY VOLTAGE (V) _______________________________________________________________________________________ High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package STEP RESPONSE FROM +25°C TO +100°C IN FLOURINERT BATH SUPPLY CURRENT (µA) 30 VCC = 3.3V MAX6612 toc04 35 MAX6612 toc03 SUPPLY CURRENT vs. AMBIENT TEMPERATURE 25 VCC = 5.5V 20 VOUT 500mV/div 15 VCC = 2.4V 10 5 0 0 -75 -50 -25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) Pin Description PIN NAME FUNCTION 1 A 2 GND GND Must be connected to GND. 3 OUT Temperature Sensor Output. Connect a capacitor (at least 1000pF) from this pin to GND. 4 VCC Power-Supply Input. Bypass VCC to GND with a 0.1µF ceramic capacitor. 5 B Must be connected to GND. Detailed Description The MAX6612 is an analog output temperature sensor whose output voltage is a linear function of its die temperature. The slope of the output voltage is 19.53mV/°C and there is a 400mV offset at 0°C to allow measurement of negative temperatures. The maximum supply current is 35µA, and the supply voltage range is from 2.4V to 5.5V for the -10°C to +150°C temperature range. The temperature error is less than ±1.2°C at TA = +25°C, ±3°C from TA = 0°C to +70°C, and ±4.5°C from TA = -10°C to +125°C. The operating temperature range varies with the supply voltage with higher supply voltages enabling wider temperature ranges. The MAX6612 can be used over a range of -10°C to +125°C with a supply voltage of 3.3V or greater. For applications with a supply voltage of 2.4V, the MAX6612 can be used over a temperature range of -10°C to +70°C. 1s/div Transfer Function The temperature-to-voltage transfer function has a linear positive slope and can be approximated by the equation: VOUT = 0.40V + (0.01953V/°C ✕ T°C) - (2 ✕ 10-6 ✕ T°C2) where T is the MAX6612’s die temperature in °C. Therefore: T (°C) = (VOUT - 0.40V) / 0.01953V/°C Applications Information Sensing Circuit Board and Ambient Temperatures Temperature sensor ICs like the MAX6612 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 MAX6612 can accurately measure the temperature of the circuit board to which it is 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. _______________________________________________________________________________________ 3 MAX6612 Typical Operating Characteristics (continued) (VCC = 3.3V, CS = 0.1µF, CLOAD = 1000pF, unless otherwise specified.) MAX6612 High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package The thermal path between the plastic package and the die is not as good as the path through the leads, so the MAX6612, like all temperature sensors in plastic packages, is less sensitive to the temperature of the surrounding air than it is to the temperature of its leads. It 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 MAX6612 is a very low-power temperature sensor and is intended to drive very light loads. As a result, the temperature rise due to power dissipation on the die is insignificant under normal conditions. For example, with the MAX6612 operating from a 3V supply at +25°C (VOUT = 0.888V), driving a 100kΩ load (IOUT = 10µA), and in the 5-pin SC70 package, the die temperature increases above the ambient by 0.036°C. Therefore, the error caused by power dissipation is negligible. 4 Driving ADC Inputs The MAX6612’s temperature-to-voltage transfer function provides convenient LSB weights when driving ADCs with 2.5V or 5V references. With a 5V reference, an 8-bit ADC has an LSB value equal to 19.53mV, which corresponds exactly to the voltage produced by a 1°C change in the MAX6612’s temperature. An 8-bit ADC with a 2.5V reference has an LSB value of 9.765mV, or 0.5°C. Capacitive Loads The MAX6612 is optimized for stability with large capacitive loads such as noise-filtering capacitors at the input of an ADC. For stable operation, ensure that the MAX6612 has a load capacitance of at least 1000pF located near its output pin. Chip Information TRANSISTOR COUNT: 257 PROCESS: BiCMOS _______________________________________________________________________________________ High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package SC70, 5L.EPS 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 5 © 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX6612 Package Information (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.)