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19-2546; Rev 0; 7/02
High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package
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 1.2C (max) at +25C, 3.0 (max) from TA = 0C to +70C, and 5.5C (max) from TA = -10C to +125C. Useful measurements can be obtained at temperatures as high as +150C. 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. 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 -10C to +125C 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 -10C to +70C. o Optimized for Use with ADCs o High Temperature-to-Voltage Slope o Able to Drive High-Capacitive Loads o Operates Up to +150C o Low Current Consumption (35A max) o No Calibration Required o Space-Saving SC70 Package
Features
MAX6612
Ordering Information
PART MAX6612MXK-T TEMP RANGE -55C to +150C PINPACKAGE 5 SC70-5 TOP MARK ADG
Pin Configuration
TOP VIEW
A 1 5 B
Applications
Base Stations Industrial Equipment Home Appliances Battery Packs Medical Instruments Portable Equipment GPS Equipment
GND 2
MAX6612
OUT 3
4
VCC
SC70
Typical Application Circuit
VSUPPLY
RPU1 VCC CS OUT CLOAD AIN_ VDD SDA
RPU2
MAX6612
GND CREF GND
MAX1137
SCL
________________________________________________________________ Maxim Integrated Products
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High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package MAX6612
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 = +70C) 5-Pin SC70 (derate 3.1mW/C above +70C) ..............245mW Operating Temperature Range .........................-55C to +150C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +165C Lead Temperature (soldering, 10s) .................................+300C
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 = -10C to +150C, unless otherwise specified.)
PARAMETER Temperature Error VOUT = 0.4 + (0.01953 T) - (2 10-6 T2) (Notes 1, 2) Supply Voltage Range Supply Current Output Voltage Sensor Gain (Average Slope) Capacitive Load Turn-On Time Shutdown Current Supply Sensitivity Load Regulation VCC IQ VOUT No load TA = 0C TA = -10C to +150C No sustained oscillations (Note 3) CLOAD = 1000pF VCC < 0.8V VCC = 2.4V to 5.5V IOUT = 2A to 100A 1000 80 1 0.5 0.03 0.8 400 19.53 SYMBOL CONDITIONS TA = +25C, VCC = 3.3V TA = +60C to +70C, VCC = 3.3V TA = +60C to +100C, VCC = 3.3V TA = -10C to +125C, VCC = 3.3V TA = -10C to +150C, VCC = 5.5V 2.4 MIN -1.2 -3.0 -4.3 -5.5 5 2.3 5.5 35 V A mV mV/C pF s A C/V C/A TYP MAX +1.2 +3.0 +4.3 +5.5 C UNITS
Note 1: 100% production tested at +25C. Guaranteed by design through temperature. Note 2: T is in C. Note 3: Guaranteed by design.
Typical Operating Characteristics
(VCC = 3.3V, CS = 0.1F, CLOAD = 1000pF, unless otherwise specified.)
OUTPUT VOLTAGE vs. AMBIENT TEMPERATURE
MAX6612 toc01
SUPPLY CURRENT vs. SUPPLY VOLTAGE
TA = +25C 20 SUPPLY CURRENT (A)
MAX6612 toc02
3500 3000 OUTPUT VOLTAGE (mV) 2500 VCC = 5.5V 2000 1500 1000 500 0 -25 0 25 50 75 100 125
25
15
10
5
0 150 1 2 3 4 5 6 AMBIENT TEMPERATURE (C) SUPPLY VOLTAGE (V)
2
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High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package
Typical Operating Characteristics (continued)
(VCC = 3.3V, CS = 0.1F, CLOAD = 1000pF, unless otherwise specified.)
SUPPLY CURRENT vs. AMBIENT TEMPERATURE
MAX6612 toc03
MAX6612
STEP RESPONSE FROM +25C TO +100C IN FLOURINERT BATH
MAX6612 toc04
35 30 SUPPLY CURRENT (A) 25 VCC = 5.5V 20 15 VCC = 2.4V 10 5 VCC = 3.3V
VOUT 500mV/div
0
0 -75 -50 -25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (C)
1s/div
Pin Description
PIN 1 2 3 NAME A GND OUT GND Temperature Sensor Output. Connect a capacitor (at least 1000pF) from this pin to GND. Power-Supply Input. Bypass VCC to GND with a 0.1F ceramic capacitor. Must be connected to GND. FUNCTION Must be connected to GND.
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 TC) - (2 10-6 TC2) where T is the MAX6612's die temperature in C. Therefore: T (C) = (VOUT - 0.40V) / 0.01953V/C
4 5
VCC B
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.
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 0C to allow measurement of negative temperatures. The maximum supply current is 35A, and the supply voltage range is from 2.4V to 5.5V for the -10C to +150C temperature range. The temperature error is less than 1.2C at TA = +25C, 3C from TA = 0C to +70C, and 4.5C from TA = -10C to +125C. 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 -10C to +125C 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 -10C to +70C.
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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 +25C (VOUT = 0.888V), driving a 100k load (IOUT = 10A), and in the 5-pin SC70 package, the die temperature increases above the ambient by 0.036C. Therefore, the error caused by power dissipation is negligible.
MAX6612
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 1C change in the MAX6612's temperature. An 8-bit ADC with a 2.5V reference has an LSB value of 9.765mV, or 0.5C.
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
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High-Slope, Low-Power, Analog Temperature Sensor in an SC70 Package
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.)
SC70, 5L.EPS
MAX6612
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 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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