VRE304CS

VRE304 RoHS Precision Voltage Reference COMPLIANT FEATURES • • • • • • +4.5V Output, ± 0.90mV (.02%) Temperature Drift: 2.0ppm/°C Low Noise: 3μVp-p (0.1-10 Hz) Industry Standard Pinout: 8-Pin Surface Mount Package Excellent Line Regulation: 6ppm/V Typical Output Trim Capability APPLICATIONS The VRE304 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 VRE304 offers superior performance over monolithic references. DESCRIPTION The VRE304 is a low cost, high precision +4.5V reference. Available in an industry standard 8-pin surface mount package, the device is ideal for upgrading systems that use lower performance references. The device provides ultrastable +4.5V output with ±0.90mV (0.02%) initial accuracy and a temperature coefficient of 2.0ppm/°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. For enhanced performance, the VRE304 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 Model VRE304CS www.apexanalog.com Initial Error (mV) Temp. Coeff. (ppm/°C) Temp Range (°C) ±0.90 2.0 0°C to +70°C © Apex Microtechnology Inc. All rights reserved Nov 2020 VRE304DS Rev L VRE304 TYPICAL CONNECTION Figure 1: Typical Connection PIN DESCRIPTIONS 2 Pin Number Name Description 1 No connection. 2 NC VIN The supply voltage connection. 3 4 5 6 7 8 TEMP GND TRIM OUT REF_GND NOISE Provides voltage proportional to package temperature for monitoring purposes. Ground. Optional fine adjustment. Connect to a voltage divider between OUT and GND. 4.5V output. Provided for accurate ground sensing. Internally connected to GND. Optional noise reduction. Connect a µF capacitor between this pin and GND. VRE304DS Rev L VRE304 SPECIFICATIONS VIN = +15V, T = +25°C, RL = 10 kΩ unless otherwise noted. ABSOLUTE MAXIMUM RATINGS Parameter Power Supply Operating Temperature Storage Temperature Short Circuit Protection Soldering Temperature (10 sec max) Min Typ Max Units +13.5 0 -65 +15 +22 +70 +150 V °C °C +260 °C Max Units Continuous ELECTRICAL SPECIFICATIONS Parameter Min Output Voltage1 Temp. Sensor Voltage Typ +4.5 V 630 mV 2 ±0.90 Initial Error Warmup Drift TMIN - TMAX 3 3 mV ppm 2.0 ppm/°C Long-Term Stability 6 ppm/1000h Noise (0.1 - 10 Hz) 4 Output Current Line Regulation Load Regulation Output Adjustment 3 µVpp ±10 Power Supply Current, +PS 5 6 3 10 10 5 7 mA ppm/V ppm/mA mV mA 1. The temperature coefficient is -2.1mV/°C. 2. The specified values are without external trim. 3. The temperature coefficient (TC) is determined by the box method using the following formula: V MAX – V MIN 6 TC = ----------------------------------------------------------------------  10 V NOMINAL   T MAX – T MIN  4. The specified values are without the external noise reduction capacitor. 5. The specified values are unloaded. VRE304DS Rev L 3 VRE304 TYPICAL PERFORMANCE GRAPHS Figure 2: VOUT vs. Temperature Figure 3: Power Supply Current vs. Temp. 7.0 1.00 0.75 Quiescent Current (mA) Upper Limit ѐVOUT (mV) 0.50 0.25 0 -0.25 -0.50 -0.75 -1.00 6.0 5.0 4.0 Lower Limit 0 20 30 40 50 60 3.0 70 -50 50 100 Temperature (°C) Temperature (°C) Figure 5: PSRR vs. Frequency Figure 4: Junction Temp Rise vs. Output Current 40 120 100 30 80 5V =1 PSSR (dB) :ƵŶĐƟŽŶdĞŵƉĞƌĂƚƵƌĞ ZŝƐĞďŽǀĞŵďŝĞŶƚ;ΣͿ 0 V CC 20 60 40 10 20 0 0 2 4 6 Output Current (mA) 4 8 10 0 10 100 1k 10k 100k 1M 10M Frequency (Hz) VRE304DS Rev L VRE304 BLOCK DIAGRAM Figure 6: Block Diagram VIN VOUT VRE304DS Rev L 5 VRE304 THEORY OF OPERATION The following discussion refers to the block diagram in Figure 6. A FET current source is used to bias a 6.3V 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 4.5V output. The gain is determined by the resistor networks R3 and R4: G=1 + R4/R3. The 6.3V 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 adjusting the slope, a very stable voltage is produced 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. The proper connection of the VRE304 series voltage references with the optional trim resistor for initial error and the optional capacitor for noise reduction is shown in Figure 1. The VRE304 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. PIN CONFIGURATION Figure 7: Pin Configuration 6 VRE304DS Rev L VRE304 PACKAGE OPTIONS Part Number Apex Package Style Description VRE304CS GD 8-pin Surface Mount PACKAGE STYLE GD ϲ͘ƉŽdžLJƐĞĂůĞĚ͕ŶŽŶͲŚĞƌŵĞƟĐƉĂĐŬĂŐĞ 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, go to www.apexanalog.com IMPORTANT NOTICE Apex Microtechnology, Inc. has made every effort to insure the accuracy of the content contained in this document. However, the information is subject to change without notice and is provided "AS IS" without warranty of any kind (expressed or implied). Apex Microtechnology reserves the right to make changes without further notice to any specifications or products mentioned herein to improve reliability. This document is the property of Apex Microtechnology and by furnishing this information, Apex Microtechnology grants no license, expressed or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual property rights. Apex Microtechnology owns the copyrights associated with the information contained herein and gives consent for copies to be made of the information only for use within your organization with respect to Apex Microtechnology integrated circuits or other products of Apex Microtechnology. 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. APEX MICROTECHNOLOGY PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN PRODUCTS USED FOR LIFE SUPPORT, AUTOMOTIVE SAFETY, SECURITY DEVICES, OR OTHER CRITICAL APPLICATIONS. PRODUCTS IN SUCH APPLICATIONS ARE UNDERSTOOD TO BE FULLY AT THE CUSTOMER OR THE CUSTOMER’S RISK. Apex Microtechnology, Apex and Apex Precision Power are trademarks of Apex Microtechnology, Inc. All other corporate names noted herein may be trademarks of their respective holders. VRE304DS Rev L 7