SCM5B34 Linearized 2- or 3-Wire RTD Input Modules FEATURES The SCM5B modules are designed with a completely isolated computer side circuit which can be floated to 50V from Power Common, pin 16. This complete isolation means that no connection is required between I/O Common and Power Common for proper operation of the output switch. If desired, the output switch can be turned on continuously by simply connecting pin 22, the Read-Enable pin to I/O Common, pin 19. INTERFACES TO 100 PLATINUM, 10 COPPER, OR 120 NICKEL RTDs LINEARIZES RTD SIGNAL HIGH LEVEL VOLTAGE OUTPUTS RTD excitation is provided from the module by two matched current sources. When using a three-wire RTD, this method allows an equal current to flow in each RTD lead, which cancels the effects of lead resistances. The excitation currents are very small (0.25mA for 100 Pt and 120 Ni, and 1.0mA for 10 Cu) which minimizes self-heating of the RTD. 1500Vrms TRANSFORMER ISOLATION ANSI/IEEE C37.90.1-1989 TRANSIENT PROTECTION INPUT PROTECTED TO 240VAC CONTINUOUS 160dB CMR Signal filtering is accomplished with a six-pole filter which provides 95dB of normal-mode-rejection at 60Hz and 90dB at 50Hz. Two poles of this filter are on the field side of the isolation barrier, and the other four are on the computer side. After the initial field-side filtering, the input signal is chopped by a proprietary chopper circuit. Isolation is provided by transformer coupling, again using a proprietary technique to suppress transmission of common mode spikes or surges. The module is powered from +5VDC, 5%. 95dB NMR AT 60Hz, 90dB AT 50Hz CSA CERTIFIED, FM APPROVED, CE COMPLIANT MIX AND MATCH SCM5B TYPES ON BACKPANEL DESCRIPTION Each SCM5B34 RTD input module provides a single channel of RTD input which is filtered, isolated, amplified, linearized, and converted to a high level analog voltage output (Figure 1). This voltage output is logic switch controlled, which allows these modules to share a common analog bus without the requirement of external multiplexers. A special input circuit on the SCM5B34 modules provides protection against accidental connection of power-line voltages up to 240VAC. 3 and 4 Wire(1) 2 Wire +EXC Linearizer 4 LPF IsochopperTM Amplifier Pat Pending 4 +In Surge Suppression and Protection 6 3 RTD 5 -In -EXC 2 LPF RZ 20 19 22 +V 3 NC -V VOUT I/O Common RD EN\ Isolated Computer-Side Power 1 4 Wire(1) Backpanel Term Block 1 -V NC -V 2 +V NOTE: (1) 4-wire sensors may be used with this module. However, for true 4-wire measurement, use SCM5B35. -V 17 Isolated Field-Side Power FIGURE 1. SCM5B34 Block Diagram. DATAFORTH A Burr-Brown Company (R) Call 800-444-7644 For Information and Assistance 50 Power Oscillator 16 +5V Power Common SPECIFICATIONS Typical at T = +25C and +5V Power. A Module -200C to +850C (100 Pt) -80C to 320C (120 Ni) -100C to 260C (10 Cu) Input Resistance Normal Power Off Overload Input Protection Continuous Transient Sensor Excitation Current 100 Pt, 120 Ni 10 Cu Lead Resistance Effect 100 Pt, 120 Ni 10 Cu CMV, Input to Output Continuous Transient CMR (50 or 60Hz) NMR 50M 40k 40k 240Vrms max ANSI/IEEE C37.90.1-1989 0.25mA 1.0mA 0.02C/(1) 0.2C/(1) 1500Vrms max ANSI/IEEE C37.90.1-1989 160dB 95dB at 60Hz, 90dB at 50Hz Accuracy Conformity Error Stability Input Offset Output Offset Gain Noise Input, 0.1 to 10Hz Output, 100kHz Bandwidth, -3dB Response Time, 90% Span Output Range Output Resistance Output Protection Output Selection Time (to 1mV of VOUT) Output Current Limit SCM5B Input Range Limits SCM5B34 See Ordering Information 0.05% Span 0.01C/C 20V/C 35ppm of reading/C 0.2Vrms 200Vrms 4Hz 0.2s 0V to +5V 50 Continuous Short to Ground 6s at Cload = 0 to 2000pF +8mA ORDERING INFORMATION MODEL Output Enable Control Max Logic "0" Min Logic "1" Max Logic "1" Input Current, "0,1" 100 Pt ** SCM5B34-01 +0.8V +2.4V +36V 0.5A Power Supply Voltage Power Supply Current Power Supply Sensitivity 100 Pt, 120 Ni 10 Cu +5VDC 5% 30mA Mechanical Dimensions 2.28" x 2.26" x 0.60" (58mm x 57mm x 15mm) SCM5B34-02 SCM5B34-03 SCM5B34-04 0.2C/V 0.5C/V Environmental Operating Temperature Range Storage Temperature Range Relative Humidity Emissions Immunity NOTES: (1) "" refers to the resistance in one lead. 10 Cu ** SCM5B34C-01 SCM5B34C-02 -40C to +85C -40C to +85C 0 to 95% noncondensing EN50081-1, ISM Group 1, Class A (Radiated, Conducted) EN50082-1, ISM Group 1, Class A (ESD, RF, EFT) SCM5B34C-03 120 Ni ** SCM5B34N-01 OUTPUT RANGE ACCURACY INPUT RANGE -100C to +100C (-148F to +212F) 0C to +100C (+32F to 212F) 0C to +200C (+32F to 392F) 0C to +600C (+32F to 1112F) 0V to +5V 0.32C 0V to +5V 0.13C 0V to +5V 0.26C 0V to +5V 0.78C 0C to +120C (10 at 0C) (+32F to +248F) 0C to +120C (10 at 25C) (+32F to +248F) 0C to +160C (10 at 0C) (+32F to +320F) 0V to +5V 0.23C 0V to +5V 0.23C 0V to +5V 0.32C 0C to +300C (+32F to +572F) 0V to +5V 0.40C Includes conformity, hysteresis and repeatability. **RTD STANDARDS TYPE ALPHA COEFFICIENT 100 Pt 120 Ni 10 CU 51 0.00385 0.00672 0.004274 DIN JIS DIN 43760 JIS C 1604-1989 Call 800-444-7644 For Information and Assistance DATAFORTH A Burr-Brown Company (R)