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19-3975; Rev 0; 4/06
Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner
General Description
The MAX6603 dual-channel, platinum RTD-to-voltage signal conditioner excites and amplifies the signal from two external 200 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 -40C to +1000C temperature range and provides the temperature information as two independent analog voltages. The MAX6603 features a 6C (max) accuracy over the +400C to +600C 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 -40C to +125C automotive temperature range from a single +3V to +5.5V power supply. 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: 6C (max) from +400C to +600C
Features
Amplifies Pt RTD Temperature Signals
MAX6603
Ordering Information
PART MAX6603ATB+ PIN-PACKAGE 10 TDFN-EP* RTD 200** PKG CODE T1033-1
Note: Device is specified over the -40C to +125C temperature range. *EP = Exposed pad. +Denotes lead-free package. **Other base resistance values can be accommodated. Contact the factory for more information.
Applications
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
Pin Configuration
VCC RS2RS2+ RS1+ RS1-
1 2 3 4 5
+
10 9
DG2 OUT2 OUT1 DG1 GND
MAX6603
8 7 6
TDFN 3mm x 3mm x 0.8mm
________________________________________________________________ Maxim Integrated Products
1
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.
Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner MAX6603
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 = +70C) 10-Pin TDFN Single-Layer Board (derate 18.5 mW/C above +70C) .........................1481.5mW 10-Pin TDFN Multilayer Board (derate 24.4 mW/C above +70C) .........................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 .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C 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 = 3.0V to 5.5V, resistor connected between RS1+ and RS1- = 560, resistor connected between RS2+ and RS2- = 560, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = 5.0V, RL = 47k between OUT_ and GND, TA = +25C.) (Note 1)
PARAMETER Supply Voltage Input Over Voltage Supply Current CURRENT SOURCES Excitation Current Excitation-Current Temperature Coefficient Minimum RS_- Voltage Maximum RS_+ Voltage Supply Ratiometric IEXC TCIEXC VRS_VRS_+ IRATIO VCC = +3V to +5.5V +400C to +600C, VCC = 5.0V -40C to +400C, VCC = 5.0V RTD +600C to +1000C, VCC = 5.0V +400C to +600C, VCC = 3.0V -40C to +400C, VCC = 3.0V +600C to +1000C, VCC = 3.0V (Note 2) (Note 2) 0.58 1.0 -7 3.4 4.0 0.2 6 8 12 10 13.3 20 C 1.12 mA ppm/C V V mA/V SYMBOL VCC VRS ICC RS1+, RS1-, RS2+, RS23.9 Sink current during overvoltage fault VRS1+ = VRS1 - = VRS2+ = VRS2- = +16V 36.2 CONDITIONS MIN 3.0 TYP MAX 5.5 16 5.5 47.1 mA UNITS V V
MAXIMUM TEMPERATURE ERROR (Note 3)
2
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Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner
ELECTRICAL CHARACTERISTICS (continued)
(VCC = 3.0V to 5.5V, resistor connected between RS1+ and RS1- = 560, resistor connected between RS2+ and RS2- = 560, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = 5.0V, RL = 47k between OUT_ and GND, TA = +25C.) (Note 1)
PARAMETER SYMBOL CONDITIONS 494 to 627, VCC = 5.0V 200 to 494, VCC = 5.0V RTD (Note 4) 627 to 866, VCC = 5.0V 494 to 627, VCC = 3.0V 200 to 494, VCC = 3.0V 627 to 866, VCC = 3.0V ANALOG OUTPUTS (OUT1, OUT2) Output-Voltage Low (Max) Output-Voltage High (Min) Short-Circuit Current Maximum Capacitive Load Minimum Resistive Load DIAGNOSTIC OUTPUTS (DG1, DG2) Output-Voltage Low Output-Voltage High Minimum Resistance for RS+, RS - Open Maximum Resistance for RS+, RS - Short VOL VOH RRS - OPEN RRS - SHORT ISOURCE = 1mA ISINK = 1mA VCC 0.2 8000 60 0.2 V V VOL VOH ISC CL RL Between OUT_ and GND RL = 47k between OUT_ and VCC (Note 5) RL = 47k between OUT_ and GND (Note 5) VOUT = VCC VOUT = GND 500 20 0.1 VCC 0.1 22 12 V V mA mA pF k MIN TYP MAX 19 27 33 19 27 33 mV UNITS MAXIMUM INPUT RESISTANCE-TO-OUTPUT VOLTAGE ERROR
MAX6603
Note 1: All parameters are tested at TA = +25C. Specifications over temperature are guaranteed by design. Note 2: RTD resistance range is 150 to 900 for constant excitation current. Note 3: A typical 200 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 = 200, 560, 845. The range is guaranteed by design. Note 5: Parameters are tested in special test mode.
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Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner MAX6603
Typical Operating Characteristics
(VCC = 5.0V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
TA = +125C TA = +85C 3.2 2.9 2.6 TA = 0C 2.3 2.0 3.0 3.5 4.0 4.5 5.0 5.5 SUPPLY VOLTAGE (V) -20 -40 TA = -40C TA = +25C
MAX6603 toc01
OUTPUT-VOLTAGE DRIFT vs. TEMPERATURE
MAX6603 toc02
3.8 3.5 SUPPLY CURRENT (mA)
20
OUTPUT-VOLTAGE DRIFT (mV)
10
0
-10
-10
20
50
80
110
TEMPERATURE (C)
POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX6603 toc03
OUTPUT VOLTAGE vs. RTD RESISTANCE
TA = 25C
MAX6603 toc04
0 -10 -20 -30 PSRR (dB) -40 -50 -60 -70 -80 -90 -100 0.01 0.10 1.00 10.00
5
4 OUTPUT VOLTAGE (V)
3
2
1
0 100.00 1000.00 100 300 500 700 900 FREQUENCY (kHz) RTD RESISTANCE ()
4
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Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner
Pin Description
PIN 1 2 3 4 5 6 7 8 9 10 -- NAME VCC RS2RS2+ RS1+ RS1GND DG1 OUT1 OUT2 DG2 EP Sense Resistor 2 Negative Input Sense Resistor 2 Positive Input Sense Resistor 1 Positive Input Sense Resistor 1 Negative Input Ground Diagnostic Output Signal 1. DG1 asserts low upon fault detection. Output Analog Voltage 1. OUT1 is high impedance upon DG1 assertion. Output Analog Voltage 2. OUT2 is high impedance upon DG2 assertion. Diagnostic Output Signal 2. DG2 asserts low upon fault detection. Exposed Pad. Connect to GND. FUNCTION Power-Supply Input. Bypass to GND with a 0.1F capacitor as close to VCC as possible.
MAX6603
Functional Block Diagram
VCC VCC
Detailed Description
The MAX6603 converts a Deutsche Institute for Normung (DIN) standard 200 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: R(T) = RO[1 + AT + BT2+ CT3]
RSRC RS1+ ESD CLAMP RS1ESD CLAMP IEXC HI-V DETECT VCC
MAX6603
AMP
OUT1
where:
FAULT DETECT
DG1
R(T) = Resistance of Pt RTD at temperature (T) R0 = Base resistance in ohms at 0C T = Temperature in C 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 > 0C)
RSRC RS2+ ESD CLAMP RS2ESD CLAMP IEXC HI-V DETECT FAULT DETECT DG2 AMP OUT2
GND
(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
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Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner MAX6603
Using Other Pt RTDs
200 Pt RTD
1000 900 800 700 RESISTANCE () 600 500 400 300 200 100 0 0 200 400 600 800 1000 TEMPERATURE (C)
The MAX6603 is designed for a 200 Pt RTD, but the device can work with any RTD as long as the resistance is in the 150 to 900 range. A 500 Pt RTD can be used for temperatures up to +208C because that temperature results in R(T) = 900.
Input Overvoltage Protection to +16V
The input pins RS1+, RS1-, RS2+, and RS2- protect the MAX6603 from overvoltage conditions up to +16V without damaging the device.
Diagnostic Outputs (DG1, DG2)
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.
Figure 1. Typical 200 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.
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.
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 150 and 900, covering a -40C to +1000C temperature range. When R(T) goes too low or too high, a fault condition is asserted and the respective DG_ goes low.
Output Voltage
The following equation describes the output voltage: PROCESS: BiCMOS VOUT = where: VCC = supply voltage R(T) = RTD resistance given by CallendarVan Dusen equation. VCC x R(T) 1000
Chip Information
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Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner MAX6603
5kV ESD 0.1F +5V 0.1F
VCC VCC SHORT TO BAT SHORT TO GND (16V) RS1+ ESD CLAMP RS1RTD SENSOR OPEN SHORT TO BAT (16V) SHORT TOGETHER SHORT TO GND CHASSIS GND ESD CLAMP IEXC HI-V DETECT VCC FAULT DETECT DG1 OUT1 ADC-REF VCC
OPEN
RSRC
MAX6603
AMP
ADC1
INPUT1
MICROCONTROLLER
RSRC RS2+ ESD CLAMP RS2ESD CLAMP IEXC HI-V DETECT FAULT DETECT DG2 AMP OUT2 ADC2
INPUT2
GND
Figure 2. The various fault conditions that cause the diagnostic output to assert low are shown for a single channel.
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Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner MAX6603
0.1F +5V 0.1F
VCC VCC ADC-REF
RSRC RS1+ ESD CLAMP Pt RTD PROBE CONNECTOR RS1ESD CLAMP IEXC HI-V DETECT VCC
MAX6603
AMP
OUT1
ADC1
FAULT DETECT
DG1
INPUT1
MICROCONTROLLER
RSRC RS2+ ESD CLAMP Pt RTD PROBE CONNECTOR RS2ESD CLAMP IEXC HI-V DETECT FAULT DETECT OUT2
AMP
ADC2
DG2
INPUT2
GND
Figure 3. A Typical Application Circuit with Ratiometric Output Coupled to Ratiometric Microcontroller ADC
8
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Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner
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.)
6, 8, &10L, DFN THIN.EPS
MAX6603
D2 D A2
N
PIN 1 ID
0.35x0.35 b
PIN 1 INDEX AREA
E DETAIL A
E2 e
[(N/2)-1] x e REF.
A1
k
C L
C L
A
L e e
L
PACKAGE OUTLINE, 6,8,10 & 14L, TDFN, EXPOSED PAD, 3x3x0.80 mm
-DRAWING NOT TO SCALE-
21-0137
G
1
2
COMMON DIMENSIONS SYMBOL A D E A1 L k A2 MIN. 0.70 2.90 2.90 0.00 MAX. 0.80 3.10 3.10 0.05
0.20 0.40 0.25 MIN. 0.20 REF.
PACKAGE VARIATIONS PKG. CODE T633-1 T633-2 T833-1 T833-2 T833-3 T1033-1 T1433-1 T1433-2 N 6 6 8 8 8 10 14 14 D2 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.500.10 1.700.10 1.700.10 E2 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 2.300.10 e 0.95 BSC 0.95 BSC 0.65 BSC 0.65 BSC 0.65 BSC 0.50 BSC 0.40 BSC 0.40 BSC JEDEC SPEC MO229 / WEEA MO229 / WEEA MO229 / WEEC MO229 / WEEC MO229 / WEEC MO229 / WEED-3 ------b 0.400.05 0.400.05 0.300.05 0.300.05 0.300.05 0.250.05 0.200.05 0.200.05 [(N/2)-1] x e 1.90 REF 1.90 REF 1.95 REF 1.95 REF 1.95 REF 2.00 REF 2.40 REF 2.40 REF
DOWNBONDS ALLOWED
NO NO NO NO YES NO YES 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 (c) 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

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