VRE205 VRE205 P r o d u c t IInnnnoovvaa t i o n FFr roomm Precision Voltage Reference Features DESCRIPTION ♦ Very High Accuracy: ±5 V Output, ±0.4 mV ♦ Extremely Low Drift: 0.6 ppm/°C (-55°C to +125°C) ♦ Excellent Stability: 6 ppm/1000 Hrs. Typical ♦ Excellent Line Regulation: 6 ppm/V Typical ♦ Wide Supply Range: ±13.5 V to ±22 V ♦ Hermetic 20-terminal Ceramic LCC ♦ Military Processing Option 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 VRE205 Series Precision Voltage References provides ultrastable ±5 V outputs with ±0.4 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. Significant improvements have been made in other performance parameters as well, including initial accuracy, warm-up drift, line regulation, and longterm stability, making the VRE205 series the most accurate and stable 5 V references available. VRE205 series 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 20-terminal ceramic LCC packages for maximum long-term stability. “M” versions are screened for high reliability and quality. Figure 1. BLOCK DIAGRAM 11 Selection Guide Output (V) Temperature Operating Range Volt Deviation (Max) VRE205C VRE205CA ±5V ±5V -25°C to +85°C -25°C to +85°C 0.4mV 0.2mV VRE205M VRE205MA ±5V ±5V -55°C to +125°C -55°C to +125°C 0.6mV 0.3mV Model VRE205DS http://www.cirrus.com Copyright © Cirrus Logic, Inc. 2009 (All Rights Reserved) 20-terminal Ceramic LCC Package Style HD JUL 20091 APEX − VRE205DSREVG VRE205 P r o d u c t I n n o v a t i o nF r o m 1. Characteristics and Specifications ELECTRICAL Specifications Vps =+15V, T = +25°C, RL = 10K Ω Unless Otherwise Noted. Model Parameter C Min Typ CA Max Min +13.5 +22 Operating Temperature -25 Storage Temperature -65 Typ M Max Min * * +85 * +150 * Typ MA Max Min * * * -55 * * Typ Max Units * * V +125 -55 +125 ºC * * * ºC ABSOLUTE MAXIMUM RATINGS Power Supply Short Circuit Protection Continuous * * * ±5 * * * OUTPUT VOLTAGE VRE205 V OUTPUT VOLTAGE ERRORS Initial Error ±800 Warmup Drift TMIN - TMAX ±400 2 (Note1) ±800 1 400 ±400 2 200 1 600 µV ppm 300 µV Long-Term Stability 6 * * * ppm/1000hrs Noise (0.1 - 10Hz) 3 * * * µVpp OUTPUT CURRENT Range ±10 * * * mA REGULATION Line 6 10 * * * * * * ppm/V Load 3 * * * ppm/mA Range 10 * * * mV Temperature Coefficient 4 * * * µV/ºC/mV OUTPUT ADJUSTMENT POWER SUPPLY CURRENT (Note 2) VRE205 +PS 5 7 * * * * * * mA NOTES: * Same as C Models. 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. 2 VRE205DS VRE205 P r o d u c t I n n o v a t i o nF r o m 2. TYPICAL PERFORMANCE GRAPHS VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC VRE205C Temperature oC VRE205CA Temperature oC VRE205M Temperature oC VRE205MA QUIESCENT CURRENT VS. TEMP Temperature oC JUNCTION TEMP. RISE VS. OUTPUT CURRENT Output Current (mA) PSRR VS. FREQUENCY Frequency (Hz) 3. THEORY OF OPERATION The following discussion refers to the schematic in Figure 1. 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 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. A nonlinear compensation network of thermistors and resistors is used in the VRE series voltage. This proprietary network eliminates most of the nonlinearity in the voltage vs. temperature function. By then adjusting the slope, a very stable voltage over wide temperature ranges is produced. 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. VRE205DS 3 VRE205 P r o d u c t I n n o v a t i o nF r o m 4. APPLICATION INFORMATION The proper connection of the VRE205 series voltage references with the optional trim resistor is shown below. Pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. The VRE205 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 20 ppm. 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. PIN CONFIGURATION EXTERNAL CONNECTIONS 3 +15V 1 20 19 18 5 17 6 16 7 15 8 Ref. Gnd. 2 4 9 10 11 12 13 NC NC NC VOUT NC 18 17 16 15 14 13 NC NC 19 NC 20 VOUT = +5V 14 10KΩ NC 1 NC 2 NC 3 12 NC VRE205 11 TRIM TOP VIEW 10 GND Δ 4 9 5 NC VIN 6 7 REF GND 8 NC NC NC Contacting Cirrus Logic Support For all Apex Precision Power product questions and inquiries, call toll free 800-546-2739 in North America. For inquiries via email, please contact [email protected]. International customers can also request support by contacting their local Cirrus Logic Sales Representative. To find the one nearest to you, go to www.cirrus.com IMPORTANT NOTICE Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe that the information contained in this document is accurate and reliable. However, the information is subject to change without notice and is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third parties. 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Cirrus Logic, Cirrus, and the Cirrus Logic logo designs, Apex Precision Power, Apex and the Apex Precision Power logo designs are trademarks of Cirrus Logic, Inc. All other brand and product names in this document may be trademarks or service marks of their respective owners. 4 VRE205DS