VRE118

VRE117/118/119 Precision Reference Supplies THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000 FEATURES • VERY HIGH ACCURACY: 3.000 V OUTPUT ±200 µV • EXTREMELY LOW DRIFT: 0.6 ppm/°C 55°C to +125°C • LOW WARM-UP DRIFT: 1 ppm Typ. • EXCELLENT STABILITY: 6 ppm/1000 Hrs. Typ. APPLICATIONS • PRECISION A/D and D/A CONVERTERS • TRANSDUCER EXCITATION • ACCURATE COMPARATOR THRESHOLD REFERENCE • HIGH RESOLUTION SERVO SYSTEMS • EXCELLENT LINE REGULATION: 3 ppm/V Typ. • DIGITAL VOLTMETERS • HERMETIC 14-PIN CERAMIC DIP • MILITARY PROCESSING OPTION • HIGH PRECISION TEST and MEASUREMENT INSTRUMENTS DESCRIPTION VRE117 Series Precision Voltage References provide ultrastable +3.000V (VRE117), -3.000V (VRE118) and ±3.000V (VRE119) outputs with ±0.200 mV initial accuracy and temperature coefficient as low as 0.6 ppm/°C over the full military temperature range. This improvement in accuracy is made possible by a unique, proprietary multipoint laser compensation technique developed by Thaler Corporation. Significant improvements have been made in other performance parameters as well, including initial accuracy, warm-up drift, line regulation, and long-term stability, making the VRE117 series the most accurate and stable 3.0V reference available. SELECTION GUIDE Type VRE117C VRE117CA VRE117M VRE117MA VRE118C VRE118CA VRE118M VRE118MA VRE119C VRE119CA VRE119M VRE119MA Output +3.0V +3.0V +3.0V +3.0V -3.0V -3.0V -3.0V -3.0V ±3.0V ±3.0V ±3.0V ±3.0V Temperature Operating Range -25°C to +85°C -25°C to +85°C -55°C to +125°C -55°C to +125°C -25°C to +85°C -25°C to +85°C -55°C to +125°C -55°C to +125°C -25°C to +85°C -25°C to +85°C -55°C to +125°C -55°C to +125°C Max. Volt Deviation 200 µV 100 µV 400 µV 200 µV 200 µV 100 µV 400 µV 200 µV 200 µV 100 µV 400 µV 200 µV VRE117/118/119 devices are available in two operating temperature ranges, -25°C to +85°C and -55°C to +125°C, and two performance grades. All devices are packaged in 14-pin hermetic ceramic packages for maximum long-term stability. "M" versions are screened for high reliability and quality. 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. VRE117DS REV. C NOV 2000 ELECTRICAL SPECIFICATIONS Vps =±15V, T = 25°C, RL = 10kΩ unless otherwise noted. VRE117/118/119 CA MIN TYP MAX MIN MODEL PARAMETERS MIN C TYP MAX M TYP MAX MIN MA TYP MAX UNITS ABSOLUTE MAXIMUM RATINGS Power Supply ±13.5 ±22 Operating Temperature -25 85 Storage Temperature -65 150 Short Circuit Protection Continuous OUTPUT VOLTAGE VRE117 VRE118 VRE119 OUTPUT VOLTAGE ERRORS Initial Error Warmup Drift Tmin - Tmax (1) Long-Term Stability Noise (.1-10Hz) OUTPUT CURRENT Range REGULATION Line Load OUTPUT ADJUSTMENT Range Temperature Coefficient POWER SUPPLY CURRENTS VRE117 +PS/ -PS VRE119 +PS VRE118/119 -PS NOTES: *Same as C Models. (2) * * * * * * * * -55 * * * 125 * * -55 * * * 125 * V °C °C +3.0 -3.0 ±3.0 * * * * * * * * * V V V 300 2 200 6 1.5 * * 1 200 2 100 * * 300 1 400 * * 200 200 µV ppm µV ppm/1000hr. µVpp ±10 * * * mA 3 3 10 * * * * * * * * * ppm/V ppm/mA 5 1 * * * * * * mV µV/°C/mV 5 7 4 7 9 6 * * * * * * * * * * * * * * * * * * 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. VRE117DS REV. C NOV 2000 TYPICAL PERFORMANCE CURVES VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC VRE117/118/119C Temperature oC VRE117/118/119CA Temperature oC VRE117/118/119M Temperature oC VRE117/118/119MA VRE117/118 QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS. OUTPUT CURRENT PSRR VS. FREQUENCY Temperature oC Output Current (mA) Frequency (Hz) VRE119 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) VRE117DS REV. C NOV 2000 DISCUSSION OF PERFORMANCE THEORY OF OPERATION The following discussion refers to the schematic below. A FET current source is used to bias a 6.3V zener diode. The zener voltage is divided by the resistor network R1 and R2. This voltage is then applied to the noninverting input of the operational amplifier which amplifies the voltage to produce a 3.000V output. The gain is determined by the resistor networks R3 and R4: G=1 + R4/R3. The 6.3V zener diode is used because it is the most stable diode over time and temperature. The current source provides a closely regulated zener current, which determines the slope of the reference's voltage vs. temperature function. By trimming the zener current, a lower drift over temperature can be achieved. But since the voltage vs. temperature function is nonlinear, this method leaves a residual error over wide temperature ranges. To remove this residual error, Thaler Corporation has developed a nonlinear compensation network of thermistors and resistors that is used in the VRE117 series 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. APPLICATION INFORMATION Figure 1 shows the proper connection of the VRE117 series voltage reference with the optional trim resistors. When trimming the VRE119, 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. The VRE117 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. VRE117 VRE119 VRE117DS REV. C NOV 2000 EXTERNAL CONNECTIONS FIGURE 1 1. Optional Fine Adjust for approximately ±5mV. VRE118 trim pot center tap connects to -15V. PIN CONFIGURATION TOP VIEW NC NC NC -PS NC REF. GND GND FINE ADJ. +3.0V (-3.0V) FINE ADJ. FINE -ADJ. -3.0V FINE -ADJ. -PS NC REF. GND GND TOP VIEW FINE +ADJ. +3.0V FINE +ADJ. VRE117 (VRE118) +PS (-PS) NC NC NC VRE119 +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 3.0 0.4 N/A 0.2 7.3 MAX 4.0 0.9 0.7 0.3 7.8 VRE117DS REV. C NOV 2000