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| VRE202 Precision Surface Mount Reference Supplies THALER CORPORATION * 2015 N. FORBES BOULEVARD * TUCSON, AZ. 85745 * (520) 882-4000 FEATURES * VERY HIGH ACCURACY: 2.5000 V OUTPUT 200 V * EXTREMELY LOW DRIFT: 0.6 ppm/C 55C to +125C * 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: 6ppm/V Typ. * DIGITAL VOLTMETERS * HERMETIC 20 TERMINAL CERAMIC LCC * MILITARY PROCESSING OPTION * HIGH PRECISION TEST and MEASUREMENT INSTRUMENTS DESCRIPTION VRE202 Series Precision Voltage References provide ultrastable +2.5000V outputs with 200 V 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 longterm stability, making the VRE202 series the most accurate and stable 2.5V surface mount references available. VRE202 devices are available in two operating temperature ranges, -25C to +85C and -55C to +125C, and two electrical performance grades. All devices are packaged in 20 terminal ceramic LCC packages for maximum long-term stability. "M" versions are screened for high reliability and quality. VRE202DS REV. D NOV 2000 SELECTION GUIDE Type VRE202C VRE202CA VRE202M VRE202MA Output +2.5V +2.5V +2.5V +2.5V Temperature Operating Range -25C to +85C -25C to +85C -55C to +125C -55C to +125C Max. Volt Deviation 200V 100V 400V 200V ELECTRICAL SPECIFICATIONS Vps =15V, T = 25C, RL = 10k? unless otherwise noted. VRE202 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 * * * * * * * * -55 * * * 125 * * -55 * * * 125 * V C C VRE202 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 Coeff. POWER SUPPLY CURRENTS VRE202 +PS VRE202 -PS 10 +2.5 * * * V 300 2 200 6 1.5 * * 1 200 2 100 * * 300 1 400 * * 200 200 V ppm V ppm/1000hrs Vpp * * * mA 6 3 10 * * * * * * * * * ppm/V ppm/mA 10 4 (2) * * * * * * mV V/C/mV 5 5 7 7 * * * * * * * * * * * * mA mA NOTES: *Same as C Models. 1.Using the box method, the specified value is the maximum deviation from the output voltage at 25C over the specified operating temperature range. 2.The specified values are unloaded. VRE202DS REV. D NOV 2000 TYPICAL PERFORMANCE CURVES VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC VRE202C Temperature oC VRE202CA VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC VRE202M Temperature oC VRE202MA QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS. OUTPUT CURRENT PSRR VS. FREQUENCY Temperature oC Output Current (mA) Frequency (Hz) VRE202DS REV. D 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 6.3 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 2.5000V output. The gain is determined by the resistor networks R3 and R4: G=1 + R4/R3. The 6.3 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 references' 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 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 VRE 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 2 shows the proper connection of the VRE202 series voltage references with the optional trim resistors. Pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. The VRE202 series voltage references have the ground terminal brought out on two pins (pin 9 and pin 10) 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 10 to the power supply ground and pin 9 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 does not effect performance. VRE202 FIGURE 1 VRE202DS REV. D NOV 2000 EXTERNAL CONNECTIONS -15V 3 4 2 1 20 19 18 17 16 15 9 10 11 12 13 14 +15V 5 6 7 8 VOUT = +2.5V Ref. Gnd. ? 10k? FIGURE 2 PIN CONFIGURATION NC -VIN NC NC NC 3 NC +VIN NC NC NC 2 1 20 19 18 NC NC NC VOUT NC 4 5 6 7 8 9 10 11 12 13 TOP VIEW 17 16 15 14 VRE202 REF GND NC TRIM NC GND MECHANICAL INCHES DIM A B D D1 E E1 j h L MIN 0.090 0.022 0.342 0.048 0.342 0.045 MAX 0.110 0.028 0.358 0.052 0.358 0.055 MILLIMETER MIN 2.29 0.56 8.68 1.22 8.68 1.114 .254 REF 1.02 REF 1.14 1.40 MAX 2.79 0.71 9.09 1.32 9.09 1.40 0.010 REF 0.040 REF 0.045 0.055 VRE202DS REV. D NOV 2000 |
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