VRE310 Low Cost Precision Reference THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000 FEATURES • 10.000 V OUTPUT ± 1.000 mV (.01%) PIN CONFIGURATION • TEMPERATURE DRIFT: 0.6 ppm/°C • LOW NOISE: 6µV p-p (0.1-10Hz) • INDUSTRY STD PINOUT- 8 PIN DIP OR SURFACE MOUNT PACKAGE N/C 1 +VIN 2 TEMP 3 GND 4 VRE310 TOP VIEW 8 NOISE REDUCTION 7 REF. GND 6 VOUT 5 TRIM •EXCELLENT LINE REGULATION: 6ppm/V Typ. • OUTPUT TRIM CAPABILITY FIGURE 1 DESCRIPTION The VRE310 is a low cost, high precision 10.0V reference. Packaged in the industry standard 8 pin DIP, the device is ideal for upgrading systems that use lower performance references. The device provides ultrastable +10.000V output with ±1.000 mV (.01%) initial accuracy and a temperature coefficient of 0.6 ppm/°C. This improvement in accuracy is made possible by a unique, patented 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 VRE310 series the most accurate reference available in the standard 8 pin DIP package. For enhanced performance, the VRE310 has an external trim option for users who want less than 0.01% initial error. For ultra low noise applications, an external capacitor can be attached between the noise reduction pin and the ground pin. A reference ground pin is provided to eliminate socket contact resistance errors. The VRE310 is recommended for use as a reference for 14-, 16-, or 18-bit D/A converters which require an external precision reference. The device is also ideal for calibrating scale factor on high resolution A/D converters. The VRE310 offers superior performance over monolithic references. SELECTION GUIDE Model Initial Error mV VRE310A VRE310B VRE310C VRE310J VRE310K VRE310L 1.0 1.6 2.0 1.0 1.6 2.0 Temp. Coeff. ppm/°C 0.6 1.0 2.0 0.6 1.0 2.0 Temp. Range °C 0°C to +70°C 0°C to +70°C 0°C to +70°C -40°C to +85°C -40°C to +85°C -40°C to +85°C For package option add D for DIP or S for Surface Mount to end of model number. VRE310DS REV. D MAY 2001 ELECTRICAL SPECIFICATIONS VRE310 Vps =+15V, T = 25°C, RL = 10KΩ unless otherwise noted. MODEL A/J PARAMETER MIN TYP +13.5 0 -40 -65 +15 B/K MAX C/L MIN TYP MAX MIN TYP MAX UNITS * * * * * * * * * * * * * * * * * * V °C °C °C ABSOLUTE RATINGS Power Supply Operating Temp. (A,B,C) Operating Temp. (J,K,L) Storage Temperature Short Circuit Protection +22 +70 +85 +150 Continuous * * * * * * OUTPUT VOLTAGE VRE310 (1) Temp. Sensor Voltage 10.000 630 V mV OUTPUT VOLTAGE ERRORS (2) Initial Error Warmup Drift Tmin - Tmax (3) Long-Term Stability Noise (.1-10Hz) (4) 1.00 1.60 1 2.00 2 0.6 3 1.0 6 6 2.0 * * * * mV ppm ppm/°C ppm/1000hrs µVpp OUTPUT CURRENT Range ±10 * * mA REGULATION Line Load 3 3 10 * * * * * * ppm/V ppm/mA OUTPUT ADJUSTMENT Range 20 POWER SUPPLY CURRENTS * mV (5) VRE310 +PS NOTES: * 5 7 *Same as A/J Models. 1. The temp. reference TC is 2.1mV/°C 2. The specified values are without external trim. * * * * mA 4. The specified values are without the external noise reduction capacitor. 5. The specified values are unloaded. 3. The temperature coefficient is determined by the box method using the following formula: Vmax - Vmin x 106 T.C. = Vnominal x (Tmax-Tmin) VRE310DS REV. D MAY 2001 TYPICAL PERFORMANCE CURVES VOUT vs. TEMPERATURE Temperature oC VRE310A VOUT vs. TEMPERATURE Temperature oC VRE310B VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC VRE310J Temperature oC VRE310K QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS. OUTPUT CURRENT Temperature oC Output Current (mA) VOUT vs. TEMPERATURE Temperature oC VRE310C VOUT vs. TEMPERATURE Temperature oC VRE310L PSRR VS. FREQUENCY Frequency (Hz) VRE310DS REV. D MAY 2001 DISCUSSION OF PERFORMANCE THEORY OF OPERATION 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 The following discussion refers to the schematic in figure 2 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. Figure 3 shows the proper connection of the VRE310 series voltage references with the optional trim resistor. The VRE310 reference has the ground terminal brought out on two pins (pin 4 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 4 to the power supply ground and pin 7 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. Pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. 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 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. VRE310 FIGURE 2 EXTERNAL CONNECTIONS + VIN V TEMP OUT 2 3 8 OPTIONAL NOISE REDUCTION CAPACITOR 6 VRE310 CN 1µF 5 7 FIGURE 3 + VOUT 4 10kΩ OPTIONAL FINE TRIM ADJUSTMENT REF. GND VRE310DS REV. D MAY 2001 MECHANICAL FIGURE 3 D D1 INCHES D2 E1 E2 E PIN 1 IDENTIFIER MILLIMETER MILLIMETER MIN MAX MIN MAX DIM MIN MAX MIN MAX A .115 .125 2.92 3.17 D2 .018 .023 0.46 0.58 B .098 .102 2.48 2.59 E .507 .513 12.8 13.0 B1 .046 .051 1.14 1.29 E1 .397 .403 10.0 10.2 C .107 .113 2.71 2.89 E2 .264 .270 6.70 6.85 C1 .009 .012 0.22 0.30 P .085 .095 2.15 2.41 C2 .052 .058 1.32 1.47 Q .020 .030 .508 .762 S .045 .055 1.14 1.39 D .397 .403 10.0 10.2 D1 .372 .380 9.44 9.65 E1 Q A INCHES DIM P BASE SEATING C1 C2 B S C B1 FIGURE 4 INCHES MILLIMETER INCHES MILLIMETER DIM MIN MAX MIN MAX DIM MIN MAX MIN MAX A .115 .125 2.92 3.17 E .397 .403 10.0 10.2 B .018 .022 .457 .558 E1 .264 .270 6.70 6.85 B1 .046 .051 1.14 1.29 G1 .290 .310 7.36 7.87 B2 .098 .102 2.48 2.59 L .195 .215 4.95 5.46 C .009 .012 0.22 0.30 P .085 .095 2.15 2.41 D .397 .403 10.0 10.2 Q .055 .065 1.39 1.65 D1 .372 .380 9.44 9.65 S .045 .055 1.14 1.39 VRE310DS REV. D MAY 2001