a FEATURES Laser Trimmed to High Accuracy: 10.000 V ⴞ5 mV (L and U Grades) Trimmed Temperature Coefficient: 5 ppm/ⴗC max, (L and U Grades) Noise Reduction Capability Low Quiescent Current: 4 mA max Output Trim Capability MIL-STD-883 Compliant Versions Available High Precision 10 V Reference AD587 FUNCTIONAL BLOCK DIAGRAM +VIN NOISE REDUCTION 2 8 RS A1 6 VOUT RF RT 5 TRIM RI AD587 4 GND NOTE: PINS 1,3, AND 7 ARE INTERNAL TEST POINTS. NO CONNECTIONS TO THESE POINTS. PRODUCT DESCRIPTION PRODUCT HIGHLIGHTS The AD587 represents a major advance in the state-of-the-art in monolithic voltage references. Using a proprietary ion-implanted buried Zener diode and laser wafer trimming of high stability thin-film resistors, the AD587 provides outstanding performance at low cost. 1. Laser trimming of both initial accuracy and temperature coefficients results in very low errors over temperature without the use of external components. The AD587L has a maximum deviation from 10.000 V of ± 8.5 mV between 0°C and +70°C, and the AD587U guarantees ± 14 mV maximum total error between –55°C and +125°C. The AD587 offers much higher performance than most other 10 V references. Because the AD587 uses an industry standard pinout, many systems can be upgraded instantly with the AD587. The buried Zener approach to reference design provides lower noise and drift than bandgap voltage references. The AD587 offers a noise reduction pin which can be used to further reduce the noise level generated by the buried Zener. The AD587 is recommended for use as a reference for 8-, 10-, 12-, 14- or 16-bit D/A converters which require an external precision reference. The device is also ideal for successive approximation or integrating A/D converters with up to 14 bits of accuracy and, in general, can offer better performance than the standard on-chip references. 2. For applications requiring higher precision, an optional fine trim connection is provided. 3. Any system using an industry standard pinout 10 volt reference can be upgraded instantly with the AD587. 4. Output noise of the AD587 is very low, typically 4 µV p-p. A noise reduction pin is provided for additional noise filtering using an external capacitor. 5. The AD587 is available in versions compliant with MILSTD-883. Refer to the Analog Devices Military Products Databook or current AD587/883B data sheet for detailed specifications. The AD587J, K and L are specified for operation from 0°C to +70°C, and the AD587S, T and U are specified for –55°C to +125°C operation. All grades are available in 8-pin cerdip. The J and K versions are also available in an 8-pin Small Outline IC (SOIC) package for surface mount applications, while the J, K, and L grades also come in an 8-pin plastic package. REV. D 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 which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2000 AD587–SPECIFICATIONS (T = +25ⴗC, V A Model AD587J/S Typ Min OUTPUT VOLTAGE 9.990 OUTPUT VOLTAGE DRIFT 1 0°C to +70°C –55°C to +125°C IN = +15 V unless otherwise noted) Max Min 10.010 9.995 AD587K/T Typ 20 20 GAIN ADJUSTMENT +3 –1 Max Min 10.005 9.995 10 10 +3 –1 LINE REGULATION 1 13.5 V ≤ + VIN ≤ 36 V TMIN to TMAX LOAD REGULATION1 Sourcing 0 < I OUT < 10 mA TMIN to TMAX Sourcing –10 < I OUT < 0 mA2 TMIN to TMAX AD587L/U Typ Max Units 10.005 V 5 5 ppm/°C +3 –1 % 100 100 100 ±µV/V 100 100 100 ±µV/mA 100 100 4 2 100 QUIESCENT CURRENT 2 4 2 POWER DISSIPATION 30 30 30 mW OUTPUT NOISE 0.1 Hz to 10 Hz Spectral Density, 100 Hz 4 100 4 100 4 100 µV p-p nV/√Hz mA ± ppm/1000 Hr. LONG-TERM STABILITY 15 SHORT-CIRCUIT CURRENT-TO-GROUND 30 70 30 70 30 70 mA SHORT-CIRCUIT CURRENT-TO-V IN 30 70 30 70 30 70 mA +70 +85 +125 +125 °C TEMPERATURE RANGE Specified Performance (J, K, L) Operating Performance (J, K, L) 3 Specified Performance (S, T, U) Operating Performance (S, T, U) 3 0 –40 –55 –55 15 4 +70 +85 +125 +125 15 0 –40 –55 –55 +70 +85 +125 +125 0 –40 –55 –55 NOTES 1Spec is guaranteed for all packages and grades. Cerdip packaged parts are 100% production test. 2 Load Regulation (Sinking) specification for SOIC (R) package is ±200 µV/mA. 3 The operating temperature ranged is defined as the temperatures extremes at which the device will still function. Parts may deviate from their specified performance outside their specified temperature range. Specifications subject to change without notice. ORDERING GUIDE Model1 Initial Error Temperature Coefficient Temperature Range Package Options2 AD587JQ AD587JR AD587JN AD587KQ AD587KR AD587KN AD587LQ AD587LN AD587SQ AD587TQ AD587UQ AD587JCHIPS 10 mV 10 mV 10 mV 5 mV 5 mV 5 mV 5 mV 5 mV 10 mV 10 mV 5 mV 10 mV 20 ppm/°C 20 ppm/°C 20 ppm/°C 10 ppm/°C 10 ppm/°C 10 ppm/°C 5 ppm/°C 5 ppm/°C 20 ppm/°C 10 ppm/°C 5 ppm/°C 20 ppm/°C 0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C 0°C to +70°C –55°C to +125°C –55°C to +125°C –55°C to +125°C 0°C to +70°C Q-8 SO-8 N-8 Q-8 SO-8 N-8 Q-8 N-8 Q-8 Q-8 Q-8 NOTES 1 For details on grade and package offerings screened in accordance with MIL-STD-883, refer to the Analog Devices Military Products Databook or current AD587/883B data sheet. 2 N = Plastic DIP; Q = Cerdip; SO = SOIC. –2– REV. D AD587 PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS* VIN to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V Power Dissipation (+25°C) . . . . . . . . . . . . . . . . . . . . . 500 mW Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300°C Package Thermal Resistance θJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22°C/W θJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110°C/W Output Protection: Output safe for indefinite short to ground and momentary short to VIN. NOISE 8 REDUCTION TP* 1 +VIN 2 AD587 7 TP* TOP VIEW TP* 3 (Not to Scale) 6 VOUT GND 4 5 TRIM *TP DENOTES FACTORY TEST POINT. NO CONNECTIONS SHOULD BE MADE TO THESE PINS. *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 sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. The following specifications are tested at the die level for AD587JCHIPS. These die are probed at +25°C only. A IN = +15 V unless otherwise noted) DIE SPECIFICATIONS (T = +25°C, V DIE LAYOUT Parameter AD587JCHIPS Min Typ Max Output Voltage 9.990 10.010 V Gain Adjustment –1 3 % Line Regulation 13.5 V < + VIN < 36 V 100 ±µV/V Load Regulation Sourcing 0 < IOUT < 10 mA Sinking –10 < IOUT < 0 mA 100 100 µV/mA µV/mA 4 mA Short-Circuit Current-to-Ground 70 mA Short-Circuit Currrent-to-V OUT 70 mA Quiescent Current 2 Units Die Size: 0.081 × 0.060 Inches NOTES 1 Both V OUT pads should be connected to the output. 2 Sense and force grounds must be tied together. Die Thickness: The standard thickness of Analog Devices Bipolar dice is 24 mils ± 2 mils. Die Dimensions: The dimensions given have a tolerance of ± 2 mils. Backing: The standard backside surface is silicon (not plated). Analog Devices does not recommend gold-backed dice for most applications. Edges: A diamond saw is used to separate wafers into dice thus providing perpendicular edges halfway through the die. In contrast to scribed dice, this technique provides a more uniform die shape and size . The perpendicular edges facilitate handling (such as tweezer pick-up) while the uniform shape and size simplifies substrate design and die attach. Top Surface: The standard top surface of the die is covered by a layer of glassivation . All areas are covered except bonding pads and scribe lines. Surface Metalization: The metalization to Analog Devices bipolar dice is aluminum. Minimum thickness is 10,000Å. Bonding Pads: All bonding pads have a minimum size of 4 mils by 4 mils. The passivation windows have 3.5 mils by 3.5 mils minimum. REV. D –3– AD587 THEORY OF OPERATION NOISE PERFORMANCE AND REDUCTION The AD587 consists of a proprietary buried Zener diode reference, an amplifier to buffer the output and several high stability thin-film resistors as shown in the block diagram in Figure 1. This design results in a high precision monolithic 10 V output reference with initial offset of 5 mV or less. The temperature compensation circuitry provides the device with a temperature coefficient of under 5 ppm/°C. NOISE REDUCTION +VIN 2 8 The noise generated by the AD587 is typically less than 4 µV p-p over the 0.1 Hz to 10 Hz band. Noise in a 1 MHz bandwidth is approximately 200 µV p-p. The dominant source of this noise is the buried Zener which contributes approximately 100 nV/√Hz. In comparison, the op amp’s contribution is negligible. Figure 3 shows the 0.1 Hz to 10 Hz noise of a typical AD587. The noise measurement is made with a bandpass filter made of a 1-pole high-pass filter with a corner frequency at 0.1 Hz and a 2-pole low-pass filter with a corner frequency at 12.6 Hz to create a filter with a 9.922 Hz bandwidth. RS A1 6 VOUT RF RT 5 TRIM RI AD587 4 GND NOTE: PINS 1,3, AND 7 ARE INTERNAL TEST POINTS. NO CONNECTIONS TO THESE POINTS. Figure 1. AD587 Functional Block Diagram A capacitor can be added at the NOISE REDUCTION pin (Pin 8) to form a low-pass filter with RS to reduce the noise contribution of the Zener to the circuit. APPLYING THE AD587 The AD587 is simple to use in virtually all precision reference applications. When power is applied to Pin 2, and Pin 4 is grounded, Pin 6 provides a 10 V output. No external components are required; the degree of desired absolute accuracy is achieved simply by selecting the required device grade. The AD587 requires less than 4 mA quiescent current from an operating supply of +15 V. Figure 3. 0.1 Hz to 10 Hz Noise If further noise reduction is desired, an external capacitor may be added between the NOISE REDUCTION pin and ground as shown in Figure 2. This capacitor, combined with the 4 kΩ RS and the Zener resistances, form a low-pass filter on the output of the Zener cell. A 1 µF capacitor will have a 3 dB point at 40 Hz, and it will reduce the high frequency (to 1 MHz) noise to about 160 µV p-p. Figure 4 shows the 1 MHz noise of a typical AD587 both with and without a 1 µF capacitor. Fine trimming may be desired to set the output level to exactly 10.000 V (calibrated to a main system reference). System calibration may also require a reference voltage that is slightly different from 10.000 V, for example, 10.24 V for binary applications. In either case, the optional trim circuit shown in Figure 2 can offset the output by as much as 300 mV, if desired, with minimal effect on other device characteristics. +VIN 2 OPTIONAL NOISE REDUCTION CAPACITOR CN 1µF Figure 4. Effect of 1 µ F Noise Reduction Capacitor on Broadband Noise VIN 8 NOISE VO REDUCTION 6 OUTPUT AD587 TRIM 5 10kΩ GND 4 Figure 2. Optional Fine Trim Configuration TURN-ON TIME Upon application of power (cold start), the time required for the output voltage to reach its final value within a specified error band is defined as the turn-on settling time. Two components normally associated with this are: the time for the active circuits to settle, and the time for the thermal gradients on the chip to stabilize. Figure 5 shows the turn-on characteristics of the AD587. It shows the settling to be about 60 µs to 0.01%. Note the absence of any thermal tails when the horizontal scale is expanded to 1 ms/cm in Figure 5b. –4– REV. D AD587 DYNAMIC PERFORMANCE Output turn-on time is modified when an external noise reduction capacitor is used. When present, this capacitor acts as an additional load to the internal Zener diode’s current source, resulting in a somewhat longer turn-on time. In the case of a 1 µF capacitor, the initial turn-on time is approximately 400 ms to 0.01% (see Figure 5c). The output buffer amplifier is designed to provide the AD587 with static and dynamic load regulation superior to less complete references. Many A/D and D/A converters present transient current loads to the reference, and poor reference response can degrade the converter’s performance. Figure 6 displays the characteristics of the AD587 output amplifier driving a 0 mA to 10 mA load. VOUT 7.0V 1kΩ AD587 REV. D VL 10V 0V a. Electrical Turn-On Figure 6a. Transient Load Test Circuit b. Extended Time Scale Figure 6b. Large-Scale Transient Response c. Turn-On with 1 µ F CN Figure 5. Turn-On Characteristics Figure 6c. Fine Scale Settling for Transient Load –5– AD587 In some applications, a varying load may be both resistive and capacitive in nature, or the load may be connected to the AD587 by a long capacitive cable. Figure 7 displays the output amplifier characteristics driving a 1000 pF, 0 mA to 10 mA load. VOUT CL 1000pF 7.0V AD587 VL 1kΩ 10V 0V Figure 7a. Capacitive Load Transient /Response Test Circuit Some confusion exists in the area of defining and specifying reference voltage error over temperature. Historically, references have been characterized using a maximum deviation per degree Centrigrade; i.e., ppm/°C. However, because of nonlinearities in temperature characteristics which originated in standard Zener references (such as “S” type characteristics), most manufacturers have begun to use a maximum limit error band approach to specify devices. This technique involves the measurement of the output at three or more different temperatures to specify an output voltage error band. Figure 9 shows the typical output voltage drift for the AD587L and illustrates the test methodology. The box in Figure 9 is bounded on the sides by thc operating temperature extremes, and on the top and the bottom by the maximum and minimum output voltages measured over the operating temperature range. The slope of the diagonal drawn from the lower left to the upper right corner of the box determines the performance grade of the device. Figure 9. Typical AD587L Temperature Drift Figure 7b. Output Response with Capacitive Load LOAD REGULATION The AD587 has excellent load regulation characteristics. Figure 8 shows that varying the load several mA changes the output by only a few µV. Each AD587J, K, L grade unit is tested at 0°C, +25°C and +70°C. Each AD587S, T, and U grade unit is tested at –55°C, +25°C and +125°C. This approach ensures that the variations of output voltage that occur as the temperature changes within the specified range will be contained within a box whose diagonal has a slope equal to the maximum specified drift. The position of the box on the vertical scale will change from device to device as initial error and the shape of the curve vary. The maximum height of the box for the appropriate temperature range and device grade is shown in Figure 10. Duplication of these results requires a combination of high accuracy and stable temperature control in a test system. Evaluation of the AD587 will produce a curve similar to that in Figure 9, but output readings may vary depending on the test methods and equipment utilized. Figure 8. Typical Load Regulation Characteristics TEMPERATURE PERFORMANCE The AD587 is designed for precision reference applications where temperature performance is critical. Extensive temperature testing ensures that the device’s high level of performance is maintained over the operating temperature range. Figure 10. Maximum Output Change in mV –6– REV. D AD587 The AD587 can also be used as a precision reference for multiple DACs. Figure 13 shows the AD587, the AD7628 dual DAC and the AD712 dual op amp hooked up for single supply operation to produce 0 V to –10 V outputs. Because both DACs are on the same die and share a common reference and output op amps; the DAC outputs will exhibit similar gain TCs. NEGATIVE REFERENCE VOLTAGE FROM AN AD587 The AD587 can be used to provide a precision –10.000 V output as shown in Figure 11. The VIN pin is tied to at least a +3.5 V supply, the output pin is grounded, and the AD587 ground pin is connected through a resistor, RS, to a –15 V supply. The –10 V output is now taken from the ground pin (Pin 4) instead of VOUT. It is essential to arrange the output load and the supply resistor RS so that the net current through the AD587 is between 2.5 mA and 10.0 mA. The temperature characteristics and long-term stability of the device will be essentially the same as that of a unit used in the standard +10 V output configuration. +3.5V → +26V 2 VIN VOUT 6 AD587 GND 4 1nF ← IL –10V RS 2.5mA < –15V Figure 13. AD587 as a 10 V Reference for a CMOS Dual DAC 5V –I L <10mA RS PRECISION CURRENT SOURCE Figure 11. AD587 as a Negative 10 V Reference The design of the AD587 allows it to be easily configured as a current source. By choosing the control resistor RC in Figure 14, you can vary the load current from the quiescent current (2 mA typically) to approximately 10 mA. USING THE AD587 WITH CONVERTERS The AD587 is an ideal reference for a wide variety of 8-, 12-, 14- and 16-bit A/D and D/A converters. Several representative examples follow. +VIN 10 V REFERENCE WITH MULTIPLYING CMOS D/A OR A/D CONVERTERS 2 VIN The AD587 is ideal for applications with 10- and 12-bit multiplying CMOS D/A converters. In the standard hookup, as shown in Figure 12, the AD587 is paired with the AD7545 12-bit multiplying DAC and the AD711 high-speed BiFET Op Amp. The amplifier DAC configuration produces a unipolar 0 V to –10 V output range. Bipolar output applications and other operating details can be found on the individual product data sheets. VOUT AD587 GND IL = RC 500Ω MIN 10V + I BIAS RC 4 Figure 14. Precision Current Source Figure 12. Low Power 12-Bit CMOS DAC Application REV. D 6 –7– AD587 PRECISION HIGH CURRENT SUPPLY capacitor is required only if the load has a significant capacitive component. If the load is purely resistive, improved high frequency supply rejection results can be obtained by removing the capacitor. C1136a–0–2/00 (rev. D) For higher currents, the AD587 can easily be connected to a power PNP or power Darlington PNP device. The circuit in Figure 15 can deliver up to 4 amps to the load. The 0.1 µF Figure 15b. Precision High-Current Voltage Source Figure 15a. Precision High-Current Current Source OUTLINE DIMENSIONS Dimensions shown in inches and (mm). Cerdip (Q-8) Package Small Outline (R-8) Package PRINTED IN U.S.A. Mini-DIP (N-8) Package –8– REV. D