19-3975; Rev 0; 4/06 Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner The MAX6603 dual-channel, platinum RTD-to-voltage signal conditioner excites and amplifies the signal from two external 200Ω platinum-resistive temperature devices (Pt RTD) to achieve high-voltage, level-filtered signals for temperature measurements. The MAX6603 provides a direct ratiometric output voltage to simplify the interface to microcontrollers with integrated analogto-digital converters (ADCs). External precision resistors and calibration processes are not needed. The MAX6603 provides the necessary signal-conditioning functions, including ratiometric excitation current, amplification, buffered voltage outputs, diagnostic fault detections, and input protection. The MAX6603 amplifies signals from two RTDs operating over the -40°C to +1000°C temperature range and provides the temperature information as two independent analog voltages. The MAX6603 features a ±6°C (max) accuracy over the +400°C to +600°C temperature range. The MAX6603 has overvoltage protection up to +16V on RTD inputs, and ±5kV electrostatic discharge (ESD) protection at RTD input pins for reliable operation where RTD temperature-sensing probes are used. The MAX6603 monitors the RTD for faults and asserts the respective DG output low for fault conditions. The analog voltage outputs can be readily connected to a variety of microcontrollers. The MAX6603 is available in a small, 10-pin TDFN-EP package and operates over the -40°C to +125°C automotive temperature range from a single +3V to +5.5V power supply. Features ♦ Amplifies Pt RTD Temperature Signals ♦ ±5kV ESD Protection on RTD Inputs ♦ +16V Overvoltage Fault Protection on RTD Inputs ♦ Low RTD Excitation Current Minimizes SelfHeating Errors ♦ Small, 10-Pin TDFN Package ♦ Fully Ratiometric Operation ♦ No Calibration Required for Standard RTDs ♦ RTD Diagnostic Check ♦ High Accuracy: ±6°C (max) from +400°C to +600°C Ordering Information PART PIN-PACKAGE RTD PKG CODE 10 TDFN-EP* 200Ω** T1033-1 MAX6603ATB+ Note: Device is specified over the -40°C to +125°C temperature range. *EP = Exposed pad. +Denotes lead-free package. **Other base resistance values can be accommodated. Contact the factory for more information. Applications Pin Configuration Automotive Exhaust Temperature Monitoring Engine Control Management to Meet EURO IV Regulations Braking Systems Industrial Temperature Sensors Food Transportation Monitoring Systems Industrial Process Measurements TOP VIEW + 10 DG2 9 OUT2 8 OUT1 4 7 DG1 5 6 GND VCC 1 RS2- 2 RS2+ 3 RS1+ RS1- MAX6603 TDFN 3mm x 3mm x 0.8mm ________________________________________________________________ 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 MAX6603 General Description MAX6603 Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND, unless otherwise noted.) VCC ........................................................................-0.3V to +6.0V RS1+, RS1-, RS2+, RS2- .....................................-0.3V to +18.0V OUT1, OUT2, DG1, DG2 ............................-0.3V to (VCC + 0.3V) Continuous Power Dissipation (TA = +70°C) 10-Pin TDFN Single-Layer Board (derate 18.5 mW/°C above +70°C) .........................1481.5mW 10-Pin TDFN Multilayer Board (derate 24.4 mW/°C above +70°C) .........................1951.2mW ESD Protection (OUT1, OUT2, DG1, DG2, Human Body Model) .....................................................> ±2kV ESD Protection (RS1+, RS2+, RS1-, RS2-, VCC, GND, Human Body Model) ..................................> ±5kV Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +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 = 3.0V to 5.5V, resistor connected between RS1+ and RS1- = 560Ω, resistor connected between RS2+ and RS2- = 560Ω, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = 5.0V, RL = 47kΩ between OUT_ and GND, TA = +25°C.) (Note 1) PARAMETER SYMBOL Supply Voltage VCC Input Over Voltage VRS Supply Current CONDITIONS MIN TYP 3.0 RS1+, RS1-, RS2+, RS2- ICC Sink current during overvoltage fault VRS1+ = VRS1 - = VRS2+ = VRS2- = +16V IEXC (Note 2) TCIEXC (Note 2) MAX UNITS 5.5 V 16 V 3.9 5.5 36.2 47.1 1.0 1.12 mA CURRENT SOURCES Excitation Current Excitation-Current Temperature Coefficient 0.58 mA -7 ppm/°C Minimum RS_- Voltage VRS_- 3.4 V Maximum RS_+ Voltage VRS_+ 4.0 V Supply Ratiometric IRATIO 0.2 mA/V VCC = +3V to +5.5V MAXIMUM TEMPERATURE ERROR (Note 3) +400°C to +600°C, VCC = 5.0V RTD ±8 +600°C to +1000°C, VCC = 5.0V ±12 +400°C to +600°C, VCC = 3.0V ±10 -40°C to +400°C, VCC = 3.0V +600°C to +1000°C, VCC = 3.0V 2 ±6 -40°C to +400°C, VCC = 5.0V _______________________________________________________________________________________ ±13.3 ±20 °C Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner (VCC = 3.0V to 5.5V, resistor connected between RS1+ and RS1- = 560Ω, resistor connected between RS2+ and RS2- = 560Ω, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = 5.0V, RL = 47kΩ between OUT_ and GND, TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS MAXIMUM INPUT RESISTANCE-TO-OUTPUT VOLTAGE ERROR RTD (Note 4) 494Ω to 627Ω, VCC = 5.0V 19 200Ω to 494Ω, VCC = 5.0V 27 627Ω to 866Ω, VCC = 5.0V 33 494Ω to 627Ω, VCC = 3.0V 19 200Ω to 494Ω, VCC = 3.0V 27 627Ω to 866Ω, VCC = 3.0V 33 mV ANALOG OUTPUTS (OUT1, OUT2) Output-Voltage Low (Max) VOL RL = 47kΩ between OUT_ and VCC (Note 5) 0.1 V Output-Voltage High (Min) VOH RL = 47kΩ between OUT_ and GND (Note 5) VCC 0.1 V Short-Circuit Current ISC Maximum Capacitive Load CL Minimum Resistive Load RL VOUT = VCC 22 mA VOUT = GND 12 mA Between OUT_ and GND 500 pF 20 kΩ DIAGNOSTIC OUTPUTS (DG1, DG2) Output-Voltage Low VOL ISOURCE = 1mA Output-Voltage High VOH ISINK = 1mA 0.2 VCC 0.2 V V Minimum Resistance for RS+, RS - Open RRS - OPEN 8000 Ω Maximum Resistance for RS+, RS - Short RRS - SHORT 60 Ω Note 1: All parameters are tested at TA = +25°C. Specifications over temperature are guaranteed by design. Note 2: RTD resistance range is 150Ω to 900Ω for constant excitation current. Note 3: A typical 200Ω RTD: R(T) = RO[1 + AT + BT2] is referenced for probe temperature-probe resistance relation. The parameters in this section are not tested and are for reference only. Note 4: RTD resistance is tested only at RRTD = 200Ω, 560Ω, 845Ω. The range is guaranteed by design. Note 5: Parameters are tested in special test mode. _______________________________________________________________________________________ 3 MAX6603 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = 5.0V, TA = +25°C, unless otherwise noted.) OUTPUT-VOLTAGE DRIFT vs. TEMPERATURE SUPPLY CURRENT (mA) TA = +85°C 3.2 TA = +25°C 2.9 TA = -40°C 2.6 TA = 0°C MAX6603 toc02 TA = +125°C 3.5 20 OUTPUT-VOLTAGE DRIFT (mV) 3.8 MAX6603 toc01 SUPPLY CURRENT vs. SUPPLY VOLTAGE 10 0 -10 2.3 -20 2.0 3.5 4.0 4.5 5.0 -40 5.5 -10 20 50 80 SUPPLY VOLTAGE (V) TEMPERATURE (°C) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY OUTPUT VOLTAGE vs. RTD RESISTANCE 5 MAX6603 toc03 0 -10 -30 -40 -50 -60 -70 TA = 25°C 4 OUTPUT VOLTAGE (V) -20 110 MAX6603 toc04 3.0 PSRR (dB) MAX6603 Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner 3 2 1 -80 -90 0 -100 0.01 0.10 1.00 10.00 FREQUENCY (kHz) 4 100.00 1000.00 100 300 500 RTD RESISTANCE (Ω) _______________________________________________________________________________________ 700 900 Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner PIN NAME 1 VCC Power-Supply Input. Bypass to GND with a 0.1µF capacitor as close to VCC as possible. FUNCTION 2 RS2- Sense Resistor 2 Negative Input 3 RS2+ Sense Resistor 2 Positive Input 4 RS1+ Sense Resistor 1 Positive Input 5 RS1- Sense Resistor 1 Negative Input 6 GND Ground 7 DG1 Diagnostic Output Signal 1. DG1 asserts low upon fault detection. 8 OUT1 Output Analog Voltage 1. OUT1 is high impedance upon DG1 assertion. 9 OUT2 Output Analog Voltage 2. OUT2 is high impedance upon DG2 assertion. 10 DG2 Diagnostic Output Signal 2. DG2 asserts low upon fault detection. — EP Exposed Pad. Connect to GND. Detailed Description Functional Block Diagram The MAX6603 converts a Deutsche Institute for Normung (DIN) standard 200Ω Pt RTD to a high-level analog voltage without the need for external trims or precise discrete components. The Pt RTD resistance conveys temperature information approximated by the CallendarVan Dusen equation and is represented in Figure 1: VCC VCC MAX6603 RSRC RS1+ R(T) = RO[1 + AT + BT2+ CT3] ESD CLAMP AMP OUT1 where: RS1ESD CLAMP IEXC HI-V DETECT FAULT DETECT DG1 A = 3.9083 E-3 °C-1 (alpha coefficient 1) B = -5.7750 E-7 °C-2 (alpha coefficient 2) C = 0 (approximation for temperatures > 0°C) VCC RSRC RS2+ ESD CLAMP AMP OUT2 RS2ESD CLAMP R(T) = Resistance of Pt RTD at temperature (T) R0 = Base resistance in ohms at 0°C T = Temperature in °C IEXC HI-V DETECT GND FAULT DETECT DG2 (Alpha coefficients can vary depending on standards.) The MAX6603 applies a constant excitation current of 1mA (typ) through the Pt RTD, generating a voltage drop that is amplified and results in a high-level output voltage. The excitation current (IEXC) typically varies ratiometrically by 0.2mA/V (typ) with respect to V CC, and therefore, the amplified signal is ratiometric to the power supply. The voltage amplification from input to output is 5 (typ). The output voltage is applied to a ratiometric ADC to produce a digital value independent of supply voltage. For ADCs that use VCC as their reference voltage, sudden changes in the supply voltage do not affect the microcontroller’s reading of the temperature. Ratiometricity simplifies the connection to most _______________________________________________________________________________________ 5 MAX6603 Pin Description Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner MAX6603 Using Other Pt RTDs The MAX6603 is designed for a 200Ω Pt RTD, but the device can work with any RTD as long as the resistance is in the 150Ω to 900Ω range. A 500Ω Pt RTD can be used for temperatures up to +208°C because that temperature results in R(T) = 900Ω. 200Ω Pt RTD 1000 900 800 RESISTANCE (Ω) 700 600 Input Overvoltage Protection to +16V 500 The input pins RS1+, RS1-, RS2+, and RS2- protect the MAX6603 from overvoltage conditions up to +16V without damaging the device. 400 300 200 Diagnostic Outputs (DG1, DG2) 100 The MAX6603 continuously monitors the excitation current to the RTD, the resultant voltage drop, and voltage levels of the inputs to detect fault conditions. Any fault condition causes the respective DG output to assert low. Fault conditions occur for RTD open circuits; RTD short circuits; and RS1+, RS1-, RS2+, and RS2short to ground or supply. If any fault is detected, the respective DG output asserts low. OUT1 and OUT2 are high impedance on assertion of DG1 and DG2, respectively. An example circuit showing potential fault conditions is shown in Figure 2. 0 0 200 400 600 800 1000 TEMPERATURE (°C) Figure 1. Typical 200Ω Pt RTD Representation by the Simplified Callender-Van Dusen Equation microcontrollers that incorporate an ADC and enables a low-cost, low-complexity solution. Ratiometricity is an important consideration for battery-operated instruments, automotive, and some industrial applications. Temperature Information The MAX6603 measures the resistance between the RTD and translates that into a high-level output voltage. The resistance range of the MAX6603 is between 150Ω and 900Ω, covering a -40°C to +1000°C temperature range. When R(T) goes too low or too high, a fault condition is asserted and the respective DG_ goes low. Applications Information Ratiometric Output Coupled to a Microcontroller The circuit of Figure 3 shows the MAX6603 connected to the microcontroller using VCC as the ADC reference voltage. The output is ratiometric to VCC, and temperature measurements are independent of the supply voltage. Output Voltage Chip Information The following equation describes the output voltage: PROCESS: BiCMOS VOUT = VCC × R(T) 1000 where: VCC = supply voltage R(T) = RTD resistance given by CallendarVan Dusen equation. 6 _______________________________________________________________________________________ Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner +5V 0.1µF MAX6603 ±5kV ESD 0.1µF VCC ADC-REF VCC VCC OPEN SHORT TO BAT SHORT TO GND (16V) MAX6603 RSRC RS1+ ESD CLAMP AMP OUT1 ADC1 RS1RTD SENSOR OPEN SHORT TO BAT (16V) ESD CLAMP SHORT TOGETHER SHORT TO GND CHASSIS GND IEXC HI-V DETECT FAULT DETECT DG1 VCC INPUT1 MICROCONTROLLER RSRC RS2+ ESD CLAMP AMP OUT2 ADC2 RS2ESD CLAMP IEXC HI-V DETECT FAULT DETECT DG2 INPUT2 GND Figure 2. The various fault conditions that cause the diagnostic output to assert low are shown for a single channel. _______________________________________________________________________________________ 7 MAX6603 Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner +5V 0.1µF 0.1µF VCC ADC-REF VCC MAX6603 RSRC RS1+ ESD CLAMP AMP OUT1 ADC1 RS1- Pt RTD PROBE ESD CLAMP CONNECTOR IEXC HI-V DETECT FAULT DETECT DG1 INPUT1 VCC MICROCONTROLLER RSRC RS2+ ESD CLAMP AMP OUT2 ADC2 RS2- Pt RTD PROBE CONNECTOR ESD CLAMP IEXC HI-V DETECT FAULT DETECT DG2 INPUT2 GND Figure 3. A Typical Application Circuit with Ratiometric Output Coupled to Ratiometric Microcontroller ADC 8 _______________________________________________________________________________________ Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner 6, 8, &10L, DFN THIN.EPS D2 D A2 PIN 1 ID N 0.35x0.35 b PIN 1 INDEX AREA E [(N/2)-1] x e REF. E2 DETAIL A e k A1 CL CL A L L e e PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm -DRAWING NOT TO SCALE- 21-0137 G 1 2 COMMON DIMENSIONS MIN. MAX. D 0.70 2.90 0.80 3.10 E A1 2.90 0.00 3.10 0.05 L k 0.20 0.40 0.25 MIN. A2 0.20 REF. SYMBOL A PACKAGE VARIATIONS PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e DOWNBONDS ALLOWED T633-1 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF NO T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF NO T833-1 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF NO T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF NO T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF YES T1033-1 10 1.50±0.10 2.30±0.10 0.50 BSC MO229 / WEED-3 0.25±0.05 2.00 REF NO T1433-1 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF YES T1433-2 14 1.70±0.10 2.30±0.10 0.40 BSC ---- 0.20±0.05 2.40 REF NO PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm -DRAWING NOT TO SCALE- 21-0137 G 2 2 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 _____________________ 9 © 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX6603 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.)