VRE204

rom P r o d u c t IIn n o v a t i o n FF r o m nnova VRE204 VRE204 DESCRIPTION Precision Voltage Reference FEaTuRES ♦ Very High Accuracy: +4.5 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 ±22.0 V ♦ Hermetic 20-terminal Ceramic LCC ♦ Military Processing Available VRE204 Series Precision Voltage References provide ultrastable +4.5 V outputs with up to ±0.4 mV initial accuracy and temperature coefficient as low as 0.6 ppm/°C over the full military temperature range. These references are specifically designed to be used with successive-approximation type Analog-to-Digital Converters (ADCs). Specify an ADC with exceptional temperature drift, which can only be as good as the external reference used. The VRE204 combined with the right ADC will provide the lowest drift data conversion obtainable. The VRE204 series is available in the military operating temperature range -55°C to +125°C, and two performance grades. All devices are packaged in 20-terminal LCC ceramic packages for maximum long-term stability. These “M” versions are screened for high reliability and quality. Superior stability, accuracy, and quality make the VRE204 ideal for all precision applications which may require a 4.5 V reference. High-accuracy test and measurement instrumentation, and transducer excitation are some other applications which can benefit from the high accuracy of the VRE204. 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 Figure 1. BlOCK DIaGRaM 11 SElECTION GuIDE Model VRE204M VRE204MA Output (V) +4.5V +4.5V Temperature Operating Range -55°C to +125°C -55°C to +125°C Volt Deviation (MaX) ±0.6mV ±0.3mV 20-terminal Ceramic lCC Package Style HD Jul 2009 1 APEX − VRE204DSREVG VRE204DS http://www.cirrus.com Copyright © Cirrus Logic, Inc. 2009 (All Rights Reserved) VRE204 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 Power Supply Operating Temperature Storage Temperature Short Circuit Protection OuTPuT VOlTaGE VRE204 OuTPuT VOlTaGE ERRORS Initial Error Warmup Drift TMIn - TMAX (note1) 6 3 ±10 6 3 10 4 5 7 10 * * * * * * * * Long-Term Stability noise (0.1 - 10Hz) OuTPuT CuRRENT Range REGulaTION Line Load OuTPuT aDJuSTMENT Range Temperature Coefficient POWER SuPPlY CuRRENT (note 2) VRE204 +PS mA mV µV/ºC/mV ppm/V ppm/mA mA 2 600 * * ±800 1 300 ±400 µV ppm µV ppm/1000hrs. µVpp +4.5 * V Min +13.5 -55 -65 Continuous aBSOluTE MaXIMuM RaTINGS +22 +125 +150 * * * * * * * V ºC ºC M Typ Max Min Ma Typ Max units nOTES: * Same as M 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 VRE204DS P r o d u c t I n n o v a t i o nF r o m VRE204 2. TYPICal PERFORMaNCE GRaPHS VOUT vs. TEMPERATURE VOUT vs. TEMPERATURE Temperature oC VRE204M Temperature oC VRE204MA QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS OUTPUT CURRENT . PSRR VS. FREQUENCY Temperature oC Output Current (mA) Frequency (Hz) 3. THEORY OF OPERaTION The following discussion refers to the block diagram in Figure 1. 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 4.5 V 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. A nonlinear compensation network of thermistors and resistors 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, the VRE204 series 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. VRE204DS 3 VRE204 4. aPPlICaTION INFORMaTION P r o d u c t I n n o v a t i o nF r o m The proper connection of the VRE204 series voltage references with the optional trim resistors is shown below. Pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. The VRE204 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. EXTERNal CONNECTIONS 3 4 2 1 20 19 18 17 16 15 9 10 11 12 13 14 PIN CONFIGuRaTION NC NC NC VOUT NC 18 17 16 15 14 NC 19 NC 20 +15V 5 6 7 8 13 NC VOUT = +4.5V NC NC NC 1 2 3 VRE204 TOP VIEW 12 NC 11 TRIM 10 GND 9 REF GND Ref. Gnd. Δ 4 5 6 7 8 NC VIN NC NC NC 10KΩ 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 tucson.support@cirrus.com. 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. This document is the property of Cirrus and by furnishing this information, Cirrus grants no license, express or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual property rights. 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