VRE120

RHOPOINT COMPONENTS VRE120/121/122 Precision High Temperature Reference Supplies Tel: +44/01883 717988, Fax: +44/01883 712938, Email: sales@rhopointcomponents.com Website: www.rhopointcomponents.com FEATURES • WIDE OPERATING RANGE: -55°C TO +180°C • EXTREMELY LOW DRIFT: 1 ppm /°C -55°C to +150°C • LOW WARM-UP DRIFT: 1 ppm Typ. • EXCELLENT STABILITY: 6 ppm / 1000 Hrs. Typ. • EXCELLENT LINE REGULATION: 3 ppm / V Typ. • HERMETIC 14-PIN CERAMIC DIP • PIN & FUNCTION COMPATIBLE WITH AD2700, AD2710, MAX 670/671 REFERENCES APPLICATIONS • PRECISION A/D and D/A CONVERTERS • TRANSDUCER EXCITATION • ACCURATE COMPARATOR THRESHOLD REFERENCE • HIGH RESOLUTION SERVO SYSTEMS • DIGITAL VOLTMETERS • HIGH PRECISION TEST and MEASUREMENT INSTRUMENTS • GEOLOGICAL EQUIPMENT DESCRIPTION VRE120 series references are designed to operate over an extremely wide temperature range (-55°C to +180°C) and still provide excellent accuracy. The VRE120 provides a +10V output, the VRE121 provides a -10V and the VRE122 provides a ±10V output. All types are available in commercial (C suffix) and military (M suffix) models. The "M" models are screened for high reliability and quality. Two accuracy grades (standard and "A") are available for all models. SELECTION GUIDE Max. Volt Deviation (-55°C to +150°C) Type Output Max. Volt Deviation (150°C to +180°C) Initial Accuracy (Max) VRE120C VRE120CA VRE120M VRE120MA +10V +10V +10V +10V 1.5mV 1.0mV 1.5mV 1.0mV 5.0mV 3.0mV 5.0mV 3.0mV 1.0mV 0.5mV 1.5mV 0.8mV The adjacent selector guide shows the limits of the VRE121C -10V 1.5mV 5.0mV 1.0mV most important parameters of the VRE120 series VRE121CA -10V 1.0mV 3.0mV 0.5mV voltage references. The maximum voltage VRE121M -10V 1.5mV 5.0mV 1.5mV deviation increases linearly with temperature from VRE121MA -10V 1.0mV 3.0mV 0.8mV the 150°C specification to the 180°C specification. For example, the A grade maximum voltage VRE122C ±10V 1.5mV 5.0mV 1.0mV deviation of 1mV increases to 2mV at 175°C and is VRE122CA ±10V 1.0mV 3.0mV 0.5mV 3mV at 180°C. This degree of accuracy over such VRE122M ±10V 1.5mV 5.0mV 1.5mV a large temperature range has been achieved VRE122MA ±10V 1.0mV 3.0mV 0.8mV using the Thaler Corporation patented multipoint compensation technique. All devices are packaged in 14-pin hermetic ceramic packages for maximum long term stability. They are pin and function compatible with other Thaler references and AD2700, AD2710 and MAX 670/671 References Superior stability, accuracy, and quality make these references ideal for precision applications such as A/D and D/A converters, high-accuracy test and measurement instrumentation, and transducer excitation. VRE120DS REV. C SEPT 1994 4-56 ELECTRICAL SPECIFICATIONS Vps =±15V, T = 25°C, RL = 10KΩ unless otherwise noted. VRE120/121/122 CA MIN TYP MAX MIN MODEL PARAMETERS MIN C TYP MAX M MA UNITS TYP MAX MIN TYP MAX ABSOLUTE MAXIMUM RATINGS Power Supply ±13.5 ±22 Operating Temperature -55 180 Storage Temperature -65 150 Short Circuit Protection Continuous OUTPUT VOLTAGE VRE120 VRE121 VRE122 OUTPUT VOLTAGE ERRORS Initial Error Warmup Drift (1) -55°C to 150°C (3) 150°C to 180°C Long-Term Stability Noise (.1-10Hz) OUTPUT CURRENT Range REGULATION Line Load OUTPUT ADJUSTMENT Range Temperature Coefficient POWER SUPPLY CURRENTS VRE120 +PS VRE121 -PS VRE122 +PS VRE122 -PS NOTES: *Same as C Models. (2) * * * * * * * * * * * * * * * * * * * * * V °C °C +10 -10 ±10 * * * * * * * * * V V V 1.0 2 1.5 5.0 6 6 * * 1 0.5 2 1.0 3.0 * * 1.5 1 * * * * 0.8 * * mV ppm mV mV ppm/1000hr. µVpp ±10 * * * mA 3 3 10 * * * * * * * * * ppm/V ppm/mA 10 4 * * * * * * mV µV/°C/mV 5 5 7 4 7 7 9 6 * * * * * * * * * * * * * * * * * * * * * * * * mA mA mA mA 1.Using the box method, the specified value is the maximum deviation from the output voltage at 25°C over the specified operating temperature range. 2.The specified values are unloaded. 3. Cone widening from 150 °C value to specified value. VRE120DS REV. C SEPT 1994 4-57 TYPICAL PERFORMANCE CURVES VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC VRE120/121/122C Temperature oC VRE120/121/122CA Temperature oC VRE120/121/122M Temperature oC VRE120/121/122MA VRE120/121 QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS. OUTPUT CURRENT PSRR VS. FREQUENCY Temperature oC Output Current (mA) Frequency (Hz) VRE122 POSITIVE OUTPUT QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS. OUTPUT CURRENT PSRR VS. FREQUENCY Temperature oC Output Current (mA) NEGATIVE OUTPUT Frequency (Hz) QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS. OUTPUT CURRENT PSRR VS. FREQUENCY Temperature oC Output Current (mA) Frequency (Hz) VRE120DS REV. C SEPT.1994 4-58 DISCUSSION OF PERFORMANCE THEORY OF OPERATION The following discussion refers to the schematic below. In operation, approximately 6.3 volts is applied to the noninverting input of the op amp. The voltage is amplified by the op amp to produce a 10.000V output. The gain is determined by the networks R1 and R2: G=1 + R2/R1. The 6.3V zener diode is used because it is the most stable diode over time and temperature. The zener operating current is derived from the regulated output voltage through R3. This feedback arrangement provides a closely regulated zener current. This current determines the slope of the reference's voltage vs. temperature function. By trimming the zener current lower drift over temperature can be achieved. But since the voltage vs. temperature function is nonlinear this compensation technique is not well suited for wide temperature ranges. Thaler Corporation has developed a nonlinear compensation network of thermistors and resistors that is used in the VRE120 series voltage references. This proprietary network eliminates most of the nonlinearity in the voltage vs. temperature function. By then adjusting the slope, Thaler Corporation produces a very stable voltage over wide temperature ranges. This network is less than 2% of the overall network resistance so it has a negligible effect on long term stability. By using highly stable resistors in our network, we produce a voltage reference that also has very good long term stability. APPLICATION INFORMATION Figure 1 shows the proper connection of the VRE120 series voltage reference with the optional trim resistors. When trimming the VRE122, the positive voltage should be trimmed first since the negative voltage tracks the positive side. Pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. When using the precision voltage references at high temperatures it is best to keep them powered up. If the zener diode isn't powered up at high temperatures the junction will collect ions, and then when power is applied, the voltage will drift until the charge build up is depleted. The VRE120 series voltage references have the ground terminal brought out on two pins (pin 6 and pin 7) which are connected together internally. This allows the user to achieve greater accuracy when using a socket. Voltage references have a voltage drop across their power supply ground pin due to quiescent current flowing through the contact resistance. If the contact resistance was constant with time and temperature, this voltage drop could be trimmed out. When the reference is plugged into a socket, this source of error can be as high as 20ppm. By connecting pin 7 to the power supply ground and pin 6 to a high impedance ground point in the measurement circuit, the error due to the contact resistance can be eliminated. If the unit is soldered into place the contact resistance is sufficiently small that it doesn't effect performance. VRE120 FIGURE 2 VRE122 FIGURE 3 VRE120DS REV. C SEPT 1994 4-59 EXTERNAL CONNECTIONS FIGURE 1 1. Optional Fine Adjust for approximately ±10mV. VRE122 center tap connects to -PS. 2. Pin 6 is internally connected to Pin 7 and can be used as Ref. GND. PIN CONFIGURATION TOP VIEW NC NC NC NC NC REF. GND GND FINE ADJ. +10V FINE ADJ. NC NC NC NC NC REF. GND GND TOP VIEW FINE ADJ. -10V FINE ADJ. -ADJ. -10V -ADJ. -PS NC REF. GND GND TOP VIEW +ADJ. +10V +ADJ. VRE120 +PS NC NC NC VRE121 -PS NC NC NC VRE122 +PS NC NC NC MECHANICAL 14-PIN HYBRID PACKAGE INCHES DIM E L D B B1 B2 S P MIN .480 .195 .775 .016 .038 .095 .085 .004 MAX .500 .215 .805 .020 .042 .105 .105 .006 MILLIMETER MIN 12.1 4.9 19.7 0.4 0.9 2.4 2.1 0.10 MAX 12.7 5.4 20.4 0.5 1.0 2.6 2.6 0.15 DIM A Q Q1 C G1 INCHES MIN .120 .015 N/A .009 .290 MAX .155 .035 .030 .012 .310 MILLIMETER MIN MAX 3.0 0.4 N/A 0.2 7.3 4.0 0.9 0.7 0.3 7.8 VRE120DS REV. C SEPT 1994 4-60