vre104 vre104ds 1 vre104 description vre104 series precision voltage references pro - vide ultrastable +4.5 v outputs with up to 0.8 mv initial accuracy and temperature coeffcient as low as 0.74ppm/c over the full military temperature range. these references are specifcally designed to be used with the crystal semiconductor line of successive-ap - proximation type analog to digital converters (adcs). this line of adcs sets new standards for temperature drift, which can only be as good as the external refer - ence used. the vre104 combined with an adc will provide the lowest drift data conversion obtainable. vre104 series devices are available in two operat - ing temperature ranges, -25c to +85c and -55c to +125c, and two performance grades. all devices are packaged in 14-pin hermetic ceramic packages for maximum long-term stability. m versions are screened for high reliability and quality. superior stability, accuracy, and quality make the vre104 ideal for all precision applications which may require a 4.5 v reference. high-accuracy test and measurement instrumentation, and transducer exci - tation are some other applications which can beneft from the high accuracy of the vre104. features ? very high accuracy: +4.5 v output, 0.8 mv ? extremely low drift: 0.74 ppm/c (-55c to +125c) ? excellent stability: 6 ppm/1000 hrs. typical ? excellent line regulation: 6 ppm/v typical ? wide supply range: 13.5 to 22.0 v ? hermetic 14-pin ceramic dip ? military processing options 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 instru - ments precision voltage reference vre104 p r o d u c t i n n o v a t i o n f r o m figure 1. block diagram copyright ? cirrus logic, inc. 2009 (all rights reserved) www.cirrus.com nov 2009 apex ? vre104dsreve p r o d u c t i n n o v a t i o n f r o m
vre104 2 vre104ds 1. characteristics and specifications electrical specifications v ps =+15v, t = 25c, r l = 10k unless otherwise noted. grade vre104c vre104ca vre104m VRE104MA parameter min typ max min typ max min typ max min typ max units absolute maximum ratings power supply 13.5 22 * * * * * * v operating temperature -25 +85 * * -55 +125 -55 +125 oc storage temperature -65 +150 * * * * * * oc short circuit protection continuous * * * output voltage vre104 +4.5 * * * v output voltage errors initial error 890 800 890 800 v warmup drift 2 1 2 1 ppm t min - t max (note1) 490 400 690 600 v long-term stability 6 * * * ppm/1000hrs noise (0.1 - 10hz) 3 * * * vpp output current range 10 * * * ma regulation line 6 10 * * * * * * ppm/v load 3 * * * ppm/ma output adjustment range 10 * * * mv temperature coeffcient 4 * * * v/oc/mv power supply current (note 2) vre104 +ps 5 7 * * * * * * ma model output (v) temperature operating range volt deviation (max) vre104c vre104ca +4.5 +4.5 -25c to +85c -25c to +85c 0.49mv 0.40mv vre104m VRE104MA +4.5 +4.5 -55c to +125c -55c to +125c 0.69mv 0.60mv selection guide notes: * same as c models. 1. using the box method, the specifed value is the maximum deviation from the output voltage at 25c over the specifed operating temperature range. 2. the specifed values are unloaded. hermetic 14-pin ceramic dip package style hc p r o d u c t i n n o v a t i o n f r o m
vre104 vre104ds 3 t e m p e r atu r e o c v r e10 4c v o u t v s . t e m per a t ure v o u t v s . t e m per a t ure v o u t v s . t e m per a t ure v o u t v s . t e m per a t ure t e m p e r atu r e o c v r e10 4c a t e m p e r atu r e o c v r e10 4m t e m p e r atu r e o c v r e10 4m a qu i es c e n t curr en t v s . t e m p t em p erat u re o c j u n c t i on te m p . r i se vs . outpu t c u r r en t outpu t curre nt (m a ) p s rr v s . fr eq uenc y fr e qu e n c y (hz ) 0.49 -0.49 -0.4 0.4 -0.69 0.69 -0.6 0.6 2. typical performance graphs 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 v zener diode. the zener voltage is divided by the resistor network r1 and r2. this voltage is then applied to the noninvert - ing input of the operational amplifer which amplifes 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 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 volt - age 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 method leaves a residual error over wide temperature ranges. to remove this residual error, a nonlinear compensation network of thermistors and resistors has been developed that is used in the vre104 series references. this proprietary network eliminates most of the nonlinearity in the voltage vs. temperature function. by then adjusting the slope, the vre104 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. p r o d u c t i n n o v a t i o n f r o m
vre104 4 vre104ds 4. application information the proper connection of the vre104 series voltage references is shown below with the optional trim resistors. pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. the vre104 series voltage references have the ground terminal brought out on two pins (pin 6 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 fowing 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 con - necting pin 7 to the power supply ground and pin 6 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 suffciently small that it does not effect performance. vre104 used with crystal semiconductor adc suggested reading: crystal semiconductor application note - voltage references for the cs501x/cs25iix series of a/d converters" external connections pin configuration 1 . o p ti on al f i n e a dj us t f or ap pr o x i m atel y 1 0m v . top vi e w v r e 10 4 +p s nc nc nc g n d r ef . gn d nc nc nc nc nc fine adj . fine adj . +4 . 5v p r o d u c t i n n o v a t i o n f r o m
vre104 vre104ds 5 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 apex.support@cirrus.com. international customers can also request support by contacting their local cirrus logic sales representative. to fnd 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, indemnifcation, 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. cirrus owns the copyrights associated with the information contained herein and gives con - sent for copies to be made of the information only for use within your organization with respect to cirrus integrated circuits or other products of cirrus. this consent does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale. certain applications using semiconductor products may involve potential risks of death, personal injury, or severe prop - erty or environmental damage (critical applications). cirrus products are not designed, authorized or warranted to be suitable for use in products surgically implanted into the body, automotive safety or security devices, life support prod - ucts or other critical applications. inclusion of cirrus products in such applications is understood to be fully at the cus - tomers risk and cirrus disclaims and makes no warranty, express, statutory or implied, including the implied warranties of merchantability and fitness for particular purpose, with regard to any cirrus product that is used in such a manner. if the customer or customers customer uses or permits the use of cirrus products in critical applications, customer agrees, by such use, to fully indemnify cirrus, its officers, directors, employees, distributors and other agents from any and all liability, including attorneys fees and costs, that may result from or arise in connection with these uses. 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. p r o d u c t i n n o v a t i o n f r o m
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