VRE306 VRE306 VRE306 Precision Voltage Reference FEATURES +6 V Output, 0.6 mV (.01%) Temperature Drift: 0.6 ppm/C Low Noise: 4 VP-P (0.1-10Hz) Industry Standard Pinout: 8-pin Surface Mount Package Excellent Line Regulation: 6 ppm/V Typical Output Trim Capability APPLICATIONS The VRE306 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 VRE306 offers superior performance over monolithic references. DESCRIPTION The VRE306 is a low cost, high precision +6 V 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 +6 V output with 0.6 mV (.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 VRE306 series the most accurate reference available in a standard 8-pin SMT package. For enhanced performance, the VRE306 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. Figure 1. BLOCK DIAGRAM SELECTION GUIDE Model VRE306AS Initial Error Temp. Coeff. (mV) (ppm/C) 0.6 www.apexanalog.com VRE306DS 0.6 Temp. Range (C) 0C to +70C Copyright (c) Apex Microtechnology, Inc. 2012 (All Rights Reserved) 8-pin Surface Mount Package Style GD SEP 2012 1 VRE306DS REVH VRE306 1. CHARACTERISTICS AND SPECIFICATIONS ELECTRICAL SPECIFICATIONS VPS = +15V, T = +25C, RL = 10K Unless Otherwise Noted. Parameter Min Typ Max Units Power Supply 14 15 16 V Operating Temperature 0 +70 C -65 +150 C ABSOLUTE MAXIMUM RATINGS Storage Temperature Short Circuit Protection Continuous OUTPUT VOLTAGE VRE306 Temp. Sensor Voltage (Note 1) +6.0 V 630 mV OUTPUT VOLTAGE ERRORS Initial Error (Note 2) 0.6 Warmup Drift 1 TMIN - TMAX (Note 3) 0.6 Long-Term Stability Noise (0.1 - 10Hz) (Note 4) mV ppm ppm/C 6 ppm/1000hrs. 4 Vpp OUTPUT CURRENT Range 10 mA REGULATION Line 6 Load 3 35 ppm/mA ppm/V 10 mV OUTPUT ADJUSTMENT Range POWER SUPPLY CURRENT (Note 5) VRE306 +PS 5 7 mA NOTES: 1. The temp. reference TC is 2.1 mV/ C 2. The specified values are without external trim. 3. The temperature coefficient is determined by the box method using the following formula: T.C. = VMAX - VMIN x 106 VNOMINAL x (TMAX - TMIN) 4. The specified values are without the external noise reduction capacitor. 5. The specified values are unloaded. 2 VRE306DS VRE306 2. TYPICAL PERFORMANCE CURVES VOUT vs. TEMPERATURE Temperature oC VRE306AC 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 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 noninverting input of the operational amplifier which amplifies the voltage to produce a 6.0V 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 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. VRE306DS 3 VRE306 The proper connection of the VRE306 series voltage references with the optional trim resistor for initial error and the optional capacitor for noise reduction is shown below. The VRE306 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 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. Pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. PIN CONFIGURATION EXTERNAL CONNECTIONS + VIN V TEMP OUT 2 OPTIONAL NOISE REDUCTION CAPACITOR CN 1F 3 8 6 VRE306 5 7 4 + VOUT 10kW N/C 1 +VIN 2 TEMP 3 GND 4 VRE306 TOP VIEW 8 NOISE REDUCTION 7 REF. GND 6 VOUT 5 TRIM OPTIONAL FINE TRIM ADJUSTMENT REF. GND 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 Microtechnolgy, Inc. All other corporate names noted herein may be trademarks of their respective holders. 4 www.apexanalog.com Copyright (c) Apex Microtechnology, Inc. 2012 (All Rights Reserved) SEP 2012 VRE306DS VRE306DS REVH