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| 1.2875 V Micropower, Shunt Voltage Reference ADR1500 FEATURES Wide operating range: 50 A to 10 mA Initial accuracy: 0.2% max Output impedance: 1 max Wideband noise (10 Hz to 10 kHz): 20 V rms Operating temperature: -40C to +85C Compact, surface-mount SC70 package PIN CONFIGURATION ADR1500 TOP VIEW (Not to Scale) V- 1 3 NC (OR V-) 05749-001 V+ 2 NC = NO CONNECT APPLICATIONS Computer servers Battery-powered instrumentation Portable medical equipment Automotive Figure 1. 3-Lead SC70 (KS Suffix) GENERAL DESCRIPTION The ADR1500 is a low cost, 2-terminal (shunt), precision band gap reference. It provides an accurate 1.2875 V output for input currents between 50 A to 10 mA. The low minimum operating current makes the ADR1500 ideal for use in battery-powered 3 V or 5 V systems. However, the wide operating current range means the ADR1500 is extremely versatile and suitable for use in a wide variety of high current applications. The ADR1500 is available in the tiny SC70 package and is specified over the -40C to +85C operating temperature range. 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. Specifications subject to change without notice. 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 owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 (c)2006 Analog Devices, Inc. All rights reserved. ADR1500 TABLE OF CONTENTS Features .............................................................................................. 1 Applications....................................................................................... 1 Pin Configuration............................................................................. 1 General Description ......................................................................... 1 Revision History ............................................................................... 2 Specifications..................................................................................... 3 Electrical Characteristics............................................................. 3 Absolute Maximum Ratings............................................................ 4 ESD Caution.................................................................................. 4 Typical Performance Characteristics ..............................................5 Theory of Operation .........................................................................6 Applying the ADR1500 ................................................................6 Turn-On Time ...............................................................................6 Transient Response .......................................................................7 Outline Dimensions ..........................................................................8 Ordering Guide .............................................................................8 REVISION HISTORY 1/06--Revision 0: Initial Version Rev. 0 | Page 2 of 8 ADR1500 SPECIFICATIONS ELECTRICAL CHARACTERISTICS TA = 25C, IIN = 100 A, unless otherwise noted. Table 1. Parameter REVERSE VOLTAGE OUTPUT REVERSE VOLTAGE TEMPERATURE DRIFT, -40C to +85C MINUMUM OPERATING CURRENT, -40C to +85C REVERSE VOLTAGE CHANGE WITH REVERSE CURRENT 50 A < IIN < 10 mA, -40C to +85C 50 A < IIN < 1 mA, -40C to +85C DYNAMIC OUTPUT IMPEDANCE (VR/IR) IIN = 1 mA 100 A (f = 120 Hz) OUTPUT NOISE RMS Noise Voltage: 10 Hz to 10 kHz Low Frequency Noise Voltage: 0.1 Hz to 10 Hz TURN-ON SETTLING TIME TO 0.1%, NO COUT OUTPUT VOLTAGE HYSTERESIS TEMPERATURE RANGE Specified Range Operating Range Min 1.2849 Typ 1.2875 170 Max 1.2901 220 50 6 Unit V ppm/C A mV mV V rms V p-p s V +85 +125 C C 3.0 0.7 0.4 20 5 5 80 -40 -55 1 Rev. 0 | Page 3 of 8 ADR1500 ABSOLUTE MAXIMUM RATINGS Table 2. Parameter Reverse Current Forward Current SC70 (KS) Package Dissipation JA JC Storage Temperature Range Operating Temperature Range Lead Temperature, Soldering Vapor Phase (60 sec) Infrared (15 sec) Rating 25 mA 20 mA 376C/W 189C/W -65C to +150C -55C to +150C 215C 220C 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. ESD 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 this product 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. Rev. 0 | Page 4 of 8 ADR1500 TYPICAL PERFORMANCE CHARACTERISTICS 1.310 1.305 80 1.300 1.295 1.290 1.285 1.280 05749-002 100 REVERSE CURRENT (A) REVERSE VOLTAGE (V) 60 40 +85C +25C 20 -40C 0 0 0.2 0.4 0.6 0.8 1.0 1.2 05749-005 1.275 1.270 -50 -25 0 25 50 75 100 125 1.4 TEMPERATURE (C) REVERSE VOLTAGE (V) Figure 2. Output Drift for Different Temperature Characteristics 6 5 1.0 0.9 +125C +85C +25C -40C 0.8 Figure 5. Reverse Current vs. Reverse Voltage -40C +25C OUTPUT VOLTAGE ERROR (mV) FORWARD VOLTAGE (V) 4 3 2 1 0 0.7 0.6 0.5 0.4 0.3 0.2 +85C 05749-003 0.1 0 0.01 0.1 1 FORWARD CURRENT (mA) 10 -2 0.01 0.1 1 10 100 REVERSE CURRENT (mA) Figure 3. Output Voltage Error vs. Reverse Current 1000 Figure 6. Forward Voltage vs. Forward Current NOISE VOLTAGE (nV/ Hz) 100 10 1 1 10 100 1000 10000 100000 1000000 FREQUENCY (Hz) Figure 4. Noise Spectral Density 05749-004 Rev. 0 | Page 5 of 8 05749-006 -1 ADR1500 THEORY OF OPERATION The ADR1500 uses the band gap concept to produce a stable voltage reference suitable for high accuracy data acquisition components and systems. This device makes use of the underlying physical nature of the silicon transistor base emitter voltage in the forward-biased operating region. All such transistors have an approximate -2 mV/C temperature coefficient, which is not suitable for use as a low TC reference; however, extrapolation of the temperature characteristic of any one of these devices to absolute zero (with collector current proportional to absolute temperature) reveals that VBE goes to approximately the silicon band gap voltage. Therefore, if a voltage could be developed with an opposing temperature coefficient to the sum with the VBE, than a zero TC reference would result. The ADR1500 circuit in Figure 7 provides such a compensating voltage, V1, by deriving two transistors at different current densities and amplifying the resultant VBE difference (VBE, which has a positive TC). The sum of the VBE and V1 provides a stable voltage reference. + V+ VS RS VR IR IR + IL IL + VOUT - +5V (+3V) 10% RS VR 2.94k (1.30k) + VOUT - 05749-009 (A) (B) Figure 8. Typical Connection Diagram Figure 8 shows a typical connection of the ADR1500 operating at a minimum of 100 A. This connection can provide 1 mA to the load, while accommodating 10% power supply variations. TURN-ON TIME The turn-on time is a critical parameter for applications demanding a large amount of processing. Figure 9 shows the turn-on characteristics of the ADR1500. 2.4V 0V VIN V1 CL = 200pF - + VBE - + VBE - 05749-008 V- APPLYING THE ADR1500 The ADR1500 is simple to use in virtually all applications. To operate the ADR1500 as a conventional shunt reference, see Figure 8. An external series resistor is connected between the supply voltage and the ADR1500. For a given supply voltage, the series resistor, RS, determines the reverse current flowing through the ADR1500. The value of RS must be chosen to accommodate the expected variations of the supply voltage, VS, load current, IL, and the ADR1500 reverse voltage, VR, while maintaining an acceptable reverse current, IR, through the ADR1500. The minimum value for RS should be enough to limit IR to 10 mA when VS is at its maximum, and IL and VR are at their minimum. The equation for selecting RS is 250mV/DIV 5s/DIV Figure 9. Response Time Upon application of power (cold start), the time required for the output voltage to reach its final value within a specified error is the turn-on settling time. Tow components are normally associated with the time for active circuits to settle and the time for the thermal gradients on the chip to stabilize. This characteristic is generated from cold start operation and represents the true turn-on waveform after power up. Figure 10 shows both the course and fine turn-on settling characteristics of the device; the total settling time to within 1.0 mV is about 6 s, and there is no long thermal tail when the horizontal scale is expanded to 2 s/DIV. The output turn-on time is modified when an external noise reduction filter is used. When present, the time constant of the filter dominates the overall settling. RS = (VS - VR ) (I R + I L ) Rev. 0 | Page 6 of 8 05749-010 Figure 7. Schematic Diagram ADR1500 2.4V TRANSIENT RESPONSE Many ADCs and DACs present transient current loads to the reference. Poor reference response can degrade the converter's performance. Figure 12 displays both the coarse and fine settling characteristics of the device to load transient of 50 A. It shows the settling characteristics of the device for an increased reverse current of 50 A and the response when the reverse current is decreased by 50 A. The transients settle to 1 mV in about 3 s. 05749-011 VIN 0V OUTPUT ERROR 1mV/DIV 2s/DIV OUTPUT 0.5mV/DIV 2ms/DIV 20mV/DIV 1mV/DIV Figure 10. Turn-On Settling Time Attempts to drive a large capacitive load (in excess of 1000 pF) can result in ringing. This is due to the additional poles formed by the load capacitance and the output impedance of the reference. A recommended method for driving capacitive loads of this magnitude is shown in Figure 11. RS = 11.5k VIN + VR - RL VOUT 05749-012 IR = 100A + 50A STEP IR = 100A - 50A STEP 05749-013 CL 20mV/DIV 1mV/DIV 1s/DIV Figure 11. Turn-On, Settling, and Transient Test Circuit Figure 12. Transient Settling Time A resistor isolates the capacitive load from the output stage, while the capacitor provides a single-pole, low-pass filter and lowers the output noise. Rev. 0 | Page 7 of 8 ADR1500 OUTLINE DIMENSIONS 2.20 2.00 1.80 2.40 2.10 1.80 1.35 1.25 1.15 1 3 2 PIN 1 1.00 0.80 0.65 BSC 1.10 0.80 0.40 0.10 0.30 0.20 0.10 111505-0 0.10 MAX 0.40 0.25 0.10 COPLANARITY SEATING PLANE 0.26 0.10 ALL DIMENSIONS COMPLIANT WITH EIAJ SC70 Figure 13. 3-Lead Thin Shrink Small Outline Transistor Package [SC70] (KS-3) Dimensions shown in millimeters ORDERING GUIDE Model ADR1500BKSZ-REEL 1 1 Initial Output Error 2.6 mV Temperature Coefficient (Typ) 170 ppm/C Temperature Range -40C to +85C Package Description 3-Lead SC70 Package Option KS-3 Branding R2F Z = Pb-free part. (c)2006 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D05749-0-1/06(0) Rev. 0 | Page 8 of 8 |
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