VRE305
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VRE305 Precision Voltage Reference FEATURES • • • • • • +5 V Output, ± 0.5 mV (0.01%) Temperature Drift: 0.6 ppm/°C Low Noise: 3 μVP-P (0.1-10 Hz) Industry Standard Pinout: 8-pin DIP or Surface Mount Package Excellent Line Regulation: 6 ppm/V Typical Output Trim Capability APPLICATIONS The VRE305 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 VRE305 offers superior performance over monolithic references. DESCRIPTION The VRE305 is a low cost, high precision +5 V reference. Packaged in an industry standard 8-pin DIP or SMT, the device is ideal for upgrading systems that use lower performance references. The device provides ultrastable +5 V output with ±0.5 mV (0.01%) 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. 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 VRE305 series the most accurate reference available in a standard 8-pin DIP or SMT. For enhanced performance, the VRE305 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. SELECTION GUIDE Initial Error (mV) Temp. Coeff. (ppm/°C) Package Options © Apex Microtechnology Inc. All rights reserved

TYPICAL CONNECTION Noise Reduction Figure 1: Typical Connection Fine Trim

VRE305 SPECIFICATIONS VIN= +15 V, T = +25°C, RL = 10 kΩ unless otherwise noted. ABSOLUTE MAXIMUM RATINGS Parameter Operating Temperature Storage Temperature Power Supply Short Circuit Protection ELECTRICAL SPECIFICATIONS Parameter Output Voltage Temp. Sensor Voltage 1 Warmup Drift TMIN - TMAX Long-Term Stability Noise (0.1 - 10Hz) Output Current Line Regulation Load Regulation Output Adjustment Power Supply Current, +PS 5 1. The temp. reference TC is 2.1 mV/ °C 2. The specified values are without external trim 3. The temperature coefficient (TC) is determined by the box method using the...

VRE305 TYPICAL PERFORMANCE GRAPHS Figure 2: VOUT vs. Temperature (VRE305A) Figure 3: VOUT vs. Temperature (VRE305C) 1.00 Upper Limit Upper Limit Lower Limit Figure 4: Power Supply Current vs. Temp. Figure 5: Junction Temp. Rise vs. Output Current

Figure 6: PSRR vs. Frequency

VRE305 BLOCK DIAGRAM Figure 7: Block Diagram THEORY OF OPERATION The following discussion refers to the block diagram in Figure 8. A FET current source is used to bias a 6.3 V 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 5 V output. The gain is determined by the resistor networks R3 and R4: G=1 + R4/R3. The 6.3 V zener diode is used because it is the most stable diode over time and temperature. The current source provides a closely...

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 20 ppm. 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....

PACKAGE OPTIONS 1. Dimensions are inches & [millimeters]. 2. Bracketed alternate units are for reference only. 3. Pins: Phosphor bronze, Sn/Ag 96/4 solder dipped. 4. Material: Alumina Ceramic substrate and cover.

1. Dimensions are inches & [millimeters]. 2. Bracketed alternate units are for reference c 3. Pins: Phosphor bronze, Sn/Ag 96/4 solder c 4-. Material: Alumina Ceramic substrate and covi NEED TECHNICAL HELP? CONTACT APEX SUPPORT! For all Apex Microtechnology product questions and inquiries, call toll free 800-546-2739 in North America. For inquiries via email, please contact apex.support@apexanalog.com. International customers can also request support by contacting their local Apex Microtechnology Sales Representative. To find the one nearest to you, IMPORTANT NOTICE Apex Microtechnology,...