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| 1.2 V Precision Low Noise Shunt Voltage Reference ADR512 FEATURES Precision 1.200 V Voltage Reference Ultracompact 3 mm 3 mm SOT-23 Package No External Capacitor Required Low Output Noise: 4 V p-p (0.1 Hz to 10 Hz) Initial Accuracy: 0.3% Max Temperature Coefficient: 60 ppm/ C Max Operating Current Range: 100 A to 10 mA Output Impedance: 0.3 Max Temperature Range: -40 C to +85 C APPLICATIONS Precision Data Acquisition Systems Battery-Powered Equipment: Cellular Phone, Notebook Computer, PDA, and GPS 3 V/5 V, 8-/12-Bit Data Converters Portable Medical Instruments Industrial Process Control Systems Precision Instruments GENERAL DESCRIPTION PIN CONFIGURATION 3-Lead SOT-23 V+ 1 ADR512 3 TRIM/NC V- 2 ADR512 Model Output Voltage (VO) Initial Accuracy (mV) (%) 3.5 0.3 Temperature Coefficient (ppm/ C) 60 ADR512ART-REEL7 1.200 Designed for space critical applications, the ADR512 is a low voltage (1.200 V), precision shunt-mode voltage reference in the ultracompact (3 mm 3 mm) SOT-23 package. The ADR512 features low temperature drift (60 ppm/ C), high accuracy ( 0.30%), and ultralow noise (4 V p-p) performance. The ADR512's advanced design eliminates the need for an external capacitor, yet it is stable with any capacitive load. The minimum operating current increases from a scant 100 A to a maximum of 10 mA. This low operating current and ease of use make the ADR512 ideally suited for handheld battery-powered applications. VS IL + IQ RBIAS IL A TRIM terminal is available on the ADR512 to provide adjustment of the output voltage over 0.5% without affecting the temperature coefficient of the device. This feature provides users with the flexibility to trim out any system errors. VOUT = 1.2V ADR512 IQ COUT (OPTIONAL) VS - VOUT IL + IQ RBIAS = Figure 1. Typical Operating Circuit REV. 0 Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective companies. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 www.analog.com Fax: 781/326-8703 (c) 2003 Analog Devices, Inc. All rights reserved. ADR512-SPECIFICATIONS ELECTRICAL CHARACTERISTICS (I Parameter Output Voltage Initial Accuracy 1 IN = 100 A to 10 mA @ TA = 25 C, unless otherwise noted.) Conditions Min Typ Max 1.2035 +3.5 +0.3 60 3 0.3 Unit V mV % ppm/C mV A V p-p s ppm Symbol VO VOERR VOERR% TCVO VR (VR/IR) IIN eN p-p tR VO_HYS 1.1965 1.2 -3.5 -0.3 -40C < TA < +85C IIN = 0.1 mA to 10 mA IIN = 1 mA 100 A -40C < TA < +85C f = 0.1 Hz to 10 Hz To within 0.1% of Output Temperature Coefficient A Grade Output Voltage Change vs. IIN Dynamic Output Impedence Minimum Operating Current Voltage Noise Turn-On Settling Time2 Output Voltage Hysteresis 100 4 10 50 NOTES 1 The forward diode voltage characteristic at -1 mA is typically 0.65 V. 2 Measured without a load capacitor. Specifications subject to change without notice. ABSOLUTE MAXIMUM RATINGS* Reverse Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 mA Forward Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 mA Storage Temperature Range RT Package . . . . . . . . . . . . . . . . . . . . . . . . -65C to +150C Operating Temperature Range . . . . . . . . . . . . -40C to +85C Junction Temperature Range RT Package . . . . . . . . . . . . . . . . . . . . . . . . -65C to +150C Lead Temperature Range (Soldering, 60 Sec) . . . . . . . . 300C *Absolute maximum ratings apply at 25C, unless otherwise noted. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Package Type1 3-SOT-23 (RT) 2 JA JC Unit C/W 230 146 NOTES 1 Package power dissipation = (T JMAX - TA)/JA. 2 JA is specified for worst-case conditions, i.e., JA is specified for device soldered. ORDERING GUIDE Model Output Voltage (VO) Initial Accuracy (mV) (%) 3.5 3.5 0.3 0.3 Temperature Number Coefficient Package Package of Parts (ppm/ C) Description Option Branding per Reel 60 60 SOT-23 SOT-23 RT-3 RT-3 RGA RGA 3,000 250 Temperature Range -40C to +85C -40C to +85C ADR512ART-REEL7 1.2 ADR512ART-R2 1.2 CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although the ADR512 features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. -2- REV. 0 Typical Performance Characteristics-ADR512 1.204 1.203 1.202 1.201 VIN = 2V/DIV VOUT (V) 1.200 1.199 1.198 1.197 1.196 -40 -15 10 35 TEMPERATURE ( C) 60 85 VOUT = 1V/DIV TIME (400 s/DIV) TPC 1. Typical VOUT vs. Temperature TPC 4. Turn Off Time VIN = 2V/DIV VIN = 2V/DIV VOUT = 1V/DIV VOUT = 1V/DIV TIME (100 s/DIV) TIME (200 s/DIV) TPC 2. Turn On Time TPC 5. Turn Off Time with 1 F Input Capacitor IIN = 100 A VIN = 2V/DIV VOUT = 1V/DIV VOUT = 20mV/DIV TIME (100 s/DIV) TIME (2 s/DIV) TPC 3. Turn On Time with 1 F Input Capacitor TPC 6. Output Response to 100 A Input Current Change REV. 0 -3- ADR512 IIN = 100 A 2 V/DIV VOUT = 20mV/DIV TIME (2 s/DIV) TIME (400ms/DIV) TPC 7. Output Response to 100 A Input Current Change With 1 F Capacitor TPC 8. 1 Hz to 10 Hz Noise PARAMETER DEFINITIONS Temperature Coefficient APPLICATIONS SECTION This is the change of output voltage with respect to operating temperature changes, normalized by the output voltage at 25C. This parameter is expressed in ppm/C and can be determined with the following equation: The ADR512 is a 1.2 V precision shunt voltage reference. It is designed to operate without an external output capacitor between the positive and negative terminals for stability. An external capacitor can be used for additional filtering of the supply. As with all shunt voltage references, an external bias resistor (RBIAS) is required between the supply voltage and the ADR512 (see Figure 1). RBIAS sets the current that is required to pass through the load (IL) and the ADR512 (IQ). The load and the supply voltage can vary, thus RBIAS is chosen based on * RBIAS must be small enough to supply the minimum IQ current to the ADR512 even when the supply voltage is at its minimum and the load current is at its maximum value. RBIAS also needs to be large enough so that IQ does not exceed 10 mA when the supply voltage is at its maximum and the load current is at its minimum. VO (T2 ) - VO (T1 ) ppm TCVO x 106 = C VO (25C ) x (T2 - T1 ) where: VO(25C) = VO at 25C VO(T1 ) = VO at Temperature 1 VO(T2) = VO at Temperature 2 Thermal Hysteresis (1) * Thermal hysteresis is defined as the change of output voltage after the device is cycled through the temperature from +25C to -40C to +85C and back to +25C. This is a typical value from a sample of parts put through such a cycle. VO _ HYS = VO (25C ) -VO _ TC VO _ HYS [ ppm ] = where: VO(25C) = VO at 25C VO_TC = VO at 25C after temperature cycle at +25C to -40C to +85C and back to +25C VO (25C ) -VO _ TC VO (25C ) Given these conditions, RBIAS is determined by the supply voltage (Vs), the load and operating current (IL and IQ) of the ADR512, and the ADR512's output voltage. RBIAS = (VS - VOUT ) / (IL + IQ ) (3) x 106 (2) -4- REV. 0 ADR512 Adjustable Precision Voltage Source The ADR512, combined with a precision low input bias op amp such as the AD8610, can be used to output a precise adjustable voltage. Figure 2 illustrates the implementation of this application using the ADR512. The output of the op amp, VOUT, is determined by the gain of the circuit, which is completely dependent on resistors R2 and R1. VOUT = 1 + R2 R1 (4) Figure 4 shows the ADR512 serving as an external reference to the AD7533, a CMOS multiplying DAC. Such a DAC requires a negative voltage input in order to provide a positive output range. In this application, the ADR512 is supplying a -1.2 V reference to the REF input of the AD7533. 0 MSB 9 LSB ADR512 VDD 1 1 AD7533 An additional capacitor in parallel with R2 can be added to filter out high frequency noise. The value of C2 is dependent on the value of R2. VCC RBIAS 1.2V R2 GN 3 2 1 15 -VDD VOUT = 0V TO 1.2V AD8610 VOUT = 1.2(1 + R2/R1) Figure 4. ADR512 as a Reference for a 10-Bit CMOS DAC (AD7533) Precise Negative Voltage Reference ADR512 R2 R1 C2 (OPTIONAL) The ADR512 is suitable for use in applications where a precise negative voltage reference is desired, including the application detailed in Figure 4. Figure 5 shows the ADR512 configured to provide a -1.2 V output. Figure 2. Adjustable Precision Voltage Source Output Voltage Trim Using a mechanical or digital potentiometer, the output voltage of the ADR512 can be trimmed 0.5%. The circuit in Figure 3 illustrates how the output voltage can be trimmed, using a 10 k potentiometer. VCC ADR512 - -1.2V R1 -VDD RBIAS VOUT Figure 5. Precise -1.2 V Reference Configuration ADR512 R1 100k POT 50k Since the ADR512 characteristics resemble those of a Zener diode, the cathode shown in Figure 5 will be 1.2 V higher with respect to the anode (V+ with respect to V- on the ADR512 package). Since the cathode of the ADR512 is tied to ground, the anode must be -1.2 V. R1 in Figure 5 should be chosen so that 100 A to 10 mA is provided to properly bias the ADR512. VDD (5) I The resistor R1 should be chosen so that power dissipation is at a minimum. An ideal resistor value can be determined through manipulation of Equation 5. R1 = Figure 3. Output Voltage Trim Using the ADR512 with Precision Data Converters The compact ADR512 package and the device's low minimum operating current requirement make it ideal for use in batterypowered portable instruments, such as the AD7533 CMOS multiplying DAC, that use precision data converters. REV. 0 -5- ADR512 OUTLINE DIMENSIONS 3-Lead Small Outline Transistor Package [SOT-23] (RT-3) Dimensions shown in millimeters 3.04 2.90 2.80 1.40 1.30 1.20 1 3 2.64 2.10 2 PIN 1 0.95 BSC 1.90 BSC 1.12 0.89 0.10 0.01 SEATING PLANE 0.50 0.30 0.60 0.50 0.40 0.20 0.08 COMPLIANT TO JEDEC STANDARDS TO-236AB -6- REV. 0 -7- -8- C03700-0-7/03(0) |
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