2.5 V/3.0 V High Precision Reference AD780 Data Sheet FEATURES FUNCTIONAL BLOCK DIAGRAM Pin programmable 2.5 V or 3.0 V output Ultralow drift: 3 ppm/°C max High accuracy: 2.5 V or 3.0 V ±1 mV max Low noise: 100 nV/√Hz Noise reduction capability Low quiescent current: 1 mA max Output trim capability Plug-in upgrade for present references Temperature output pin Series or shunt mode operation (±2.5 V, ±3.0 V) +VIN DNC 2 7 AD780 R10 R11 DNC 1 6 VOUT 5 TRIM R13 Q6 Q7 R16 R5 R14 TEMP 3 R15 R4 DNC = DO NOT CONNECT TO THIS PIN 8 O/P SELECT 2.5V – DNC 3.0V – GND 00841-001 4 GND Figure 1. GENERAL DESCRIPTION The AD780 is an ultrahigh precision band gap reference voltage that provides a 2.5 V or 3.0 V output from inputs between 4.0 V and 36 V. Low initial error and temperature drift combined with low output noise and the ability to drive any value of capacitance make the AD780 the ideal choice for enhancing the performance of high resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs), and for any general-purpose precision reference application. A unique low headroom design facilitates a 3.0 V output from a 5.0 V 10% input, providing a 20% boost to the dynamic range of an ADC over performance with existing 2.5 V references. The AD780 is a pin compatible performance upgrade for the LT1019(A)–2.5 and the AD680. The latter is targeted toward low power applications. The AD780 is available in three grades in PDIP and SOIC packages. The AD780AN, AD780AR, AD780BN, AD780BR, and AD780CR are specified for operation from −40°C to +85°C. PRODUCT HIGHLIGHTS 1. 2. The AD780 can be used to source or sink up to 10 mA, and can be used in series or shunt mode, thus allowing positive or negative output voltages without external components. This makes it suitable for virtually any high performance reference application. Unlike some competing references, the AD780 has no region of possible instability. The part is stable under all load conditions when a 1 µF bypass capacitor is used on the supply. 3. A temperature output pin on the AD780 provides an output voltage that varies linearly with temperature, allowing the part to be configured as a temperature transducer while providing a stable 2.5 V or 3.0 V output. 5. Rev. H 4. The AD780 provides a pin programmable 2.5 V or 3.0 V output from a 4 V to 36 V input. Laser trimming of both initial accuracy and temperature coefficients results in low errors over temperature without the use of external components. The AD780BN has a maximum variation of 0.9 mV from −40°C to +85°C. For applications that require even higher accuracy, an optional fine-trim connection is provided. The AD780 noise is extremely low, typically 4 mV p-p from 0.1 Hz to 10 Hz and a wideband spectral noise density of typically 100 nV/√Hz. This can be further reduced, if desired, by using two external capacitors. The temperature output pin enables the AD780 to be configured as a temperature transducer while providing a stable output reference. Document Feedback 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 ©1993–2015 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com AD780 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 Temperature Output Pin ..............................................................7 Functional Block Diagram .............................................................. 1 Temperature Transducer Circuit .................................................8 General Description ......................................................................... 1 Supply Current Over Temperature .............................................8 Product Highlights ........................................................................... 1 Turn-On Time ...............................................................................8 Revision History ............................................................................... 2 Dynamic Performance ..................................................................9 Specifications..................................................................................... 3 Line Regulation..............................................................................9 Absolute Maximum Ratings............................................................ 4 Notes............................................................................................... 4 Precision Reference for High Resolution 5 V Data Converters ................................................................................... 10 ESD Caution .................................................................................. 4 4.5 V Reference from 5 V Supply ............................................. 10 Theory of Operation ........................................................................ 5 Negative (–2.5 V) Reference ..................................................... 10 Applying the AD780......................................................................... 6 Outline Dimensions ....................................................................... 11 Noise Performance ....................................................................... 6 Ordering Guide .......................................................................... 12 Noise Comparison ........................................................................ 7 Temperature Performance ........................................................... 7 REVISION HISTORY 10/15—Rev. G to Rev. H Changes to Table 3 ............................................................................ 4 Changes to Notes Section ................................................................ 4 8/15—Rev. F to Rev. G Changed NC to DNC .................................................... Throughout Added Solder Heat Shift Parameter, Table 1 ................................. 3 Added Table 3, Renumbered Sequentially .................................... 4 Changes to Figure 3 .......................................................................... 4 Change to Notes Section .................................................................. 4 Changes to Ordering Guide .......................................................... 12 12/12—Rev. E to Rev. F Updated Outline Dimensions ....................................................... 11 Changes to Ordering Guide .......................................................... 12 5/04—Rev. D to Rev. E Updated Format .................................................................. Universal Changes to Temperature Transducer Circuit Section ..................8 Changes to Ordering Guide .......................................................... 12 1/04—Rev. C to Rev. D Changes to Specifications .................................................................2 Updated Ordering Guide .................................................................3 Updated Outline Dimensions ....................................................... 10 5/02—Rev. B to Rev. C Updates to Packages ....................................................................... 10 Rev. H | Page 2 of 12 Data Sheet AD780 SPECIFICATIONS TA = 25°C, VIN = 5 V, unless otherwise noted. Table 1. Parameter OUTPUT VOLTAGE 2.5 V Out 3.0 V Out SOLDER HEAT SHIFT Mean Sigma OUTPUT VOLTAGE DRIFT 1 −40°C to +85°C −55°C to +125°C LINE REGULATION 2.5 V Output, 4 V ≤+VIN ≤ 36 V, TMIN to TMAX 3.0 V Output, 4.5 V ≤+VIN ≤ 36 V, TMIN to TMAX LOAD REGULATION, SERIES MODE Sourcing 0 mA < IOUT< 10 mA TMIN to TMAX Sinking −10 mA < IOUT< 0 mA −40°C to +85°C −55°C to +125°C LOAD REGULATION, SHUNT MODE I < ISHUNT< 10 mA QUIESCENT CURRENT, 2.5 V SERIES MODE 2 –40°C to +85°C −55°C to +125°C MINIMUM SHUNT CURRENT OUTPUT NOISE 0.1 Hz to 10 Hz Spectral Density, 100 Hz LONG-TERM STABILITY 3 TRIM RANGE TEMPERATURE PIN Voltage Output @ 25°C Temperature Sensitivity Output Resistance SHORT-CIRCUIT CURRENT TO GROUND TEMPERATURE RANGE Specified Performance (A, B, C) Operating Performance (A, B, C) 4 AD780AN/AD780AR Min Typ Max Min 2.495 2.995 2.4985 2.9950 2.505 3.005 −1.1 0.4 0.75 0.8 0.7 2.499 2.999 V V 2.501 3.001 −1.1 0.4 mV mV 7 20 3 ppm/°C ppm/°C 10 10 10 10 10 10 µV/V µV/V 50 75 75 75 150 50 75 75 75 150 50 75 75 75 150 µV/mA µV/mA µV/mA µV/mA µV/mA 75 75 75 µV/mA 1.0 1.3 1.0 mA mA mA 1.0 1.3 1.0 0.75 0.8 0.7 1.0 1.3 1.0 0.75 0.8 0.7 4 100 20 20 4.0 560 1.9 3 30 Unit 7 20 4.0 −40 −55 2.5015 3.0050 AD780BN/AD780BR Min Typ Max −1.1 0.4 4 100 500 AD780CR Typ Max 620 500 +85 +125 −40 −55 4 100 µV p-p nV/√Hz 20 ± ppm/1000 Hr ±% 4.0 560 1.9 3 30 620 500 +85 +125 −40 −55 560 1.9 3 30 620 mV mV/°C kΩ mA +85 +125 °C °C Maximum output voltage drift is guaranteed for all packages. 3.0 V mode typically adds 100 µA to the quiescent current. Also, Iq increases by 2 µA/V above an input voltage of 5 V. 3 The long-term stability specification is noncumulative. The drift in subsequent 1,000 hour periods is significantly lower than in the first 1,000 hour period. 4 The operating temperature range is defined as the temperature extremes at which the device will still function. Parts may deviate from their specified performance outside their specified temperature range. 1 2 Rev. H | Page 3 of 12 AD780 Data Sheet ABSOLUTE MAXIMUM RATINGS 96 mils Table 2. GND ESD Classification Values 36 V 36 V 36 V 500 mW −65°C to +150°C 300°C 67 mils GND Output safe for indefinite short to ground and momentary short to VIN. Class 1 (1000 V) Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. DNC 1 8 +VIN 2 7 AD780 2.5V/3.0V O/PSELECT (DNC OR GND) DNC 6 VOUT TOP VIEW GND 4 (Not to Scale) 5 TRIM Figure 2. Pin Configuration, 8-Lead PDIP and SOIC Packages Table 3. Die Physical Characteristics Value 67 × 96 10 89 × 136 AlCu (0.5%) Oxynitride None 780 GND VOUT 2.5V/3.0V O/P SELECT Figure 3. Die Layout NOTES Both VOUT pads must be connected to the output. Die Thickness: The standard thickness of Analog Devices, Inc. bipolar dice is 10 mil ± 1 mil. Backing: The standard backside surface is silicon (not plated). Analog Devices does not recommend gold-backed dice for most applications. 00841-002 NOTES 1. DNC = DO NOT CONNECT TO THIS PIN. TRIM Die Dimensions: The dimensions given are the maximum possible die size. TEMP 3 Parameter Die Size Back Grind Thickness Bond Pad Opening Size Top Metal Composition Passivation Polyimide Die Marker Substrate Bias +VIN 00841-003 Parameter +VIN to Ground TRIM Pin to Ground TEMP Pin to Ground Power Dissipation (25°C) Storage Temperature Lead Temperature (Soldering 10 sec) Output Protection TEMP Units mil mil µm % µm V 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 pickup), while the uniform shape and size simplify substrate design and die attach. Top Surface: The standard top surface of the die is covered by a layer of passivation. All areas are covered except bonding pads and scribe lines. Surface Metallization: The metallization to Analog Devices bipolar dice is aluminum/copper. The minimum thickness is 10,000 Å. Bonding Pads: All bonding pads have a minimum size of 4.0 mil by 6.0 mil. The passivation windows have a minimum size of 3.5 mil by 5.3 mil. ESD CAUTION Rev. H | Page 4 of 12 Data Sheet AD780 THEORY OF OPERATION Band gap references are the high performance solution for low supply voltage and low power voltage reference applications. In this technique, a voltage with a positive temperature coefficient is combined with the negative coefficient of a transistor’s Vbe to produce a constant band gap voltage. In the AD780, the band gap cell contains two NPN transistors (Q6 and Q7) that differ in emitter area by 12×. The difference in their Vbes produces a PTAT current in R5. This, in turn, produces a PTAT voltage across R4 that, when combined with the Vbe of Q7, produces a voltage (Vbg) that does not vary with temperature. Precision laser trimming of the resistors and other patented circuit techniques are used to further enhance the drift performance. +VIN 7 AD780 R10 R11 DNC 1 6 VOUT 5 TRIM R13 Q6 A unique feature of the AD780 is the low headroom design of the high gain amplifier, which produces a precision 3 V output from an input voltage as low as 4.5 V (or 2.5 V from a 4.0 V input). The amplifier design also allows the part to work with +VIN = VOUT when current is forced into the output terminal. This allows the AD780 to work as a 2-terminal shunt regulator, providing a −2.5 V or −3.0 V reference voltage output without external components. The PTAT voltage is also used to provide the user with a thermometer output voltage (at Pin 3) that increases at a rate of approximately 2 mV/°C. DNC 2 The output voltage of the AD780 is determined by the configuration of Resistors R13, R14, and R15 in the amplifier’s feedback loop. This sets the output to either 2.5 V or 3.0 V, depending on whether R15 (Pin 8) is grounded or not connected. Q7 R16 R5 The DNC (Pin 7) of the AD780 is a 20 kΩ resistor to +VIN that is used solely for production test purposes. Users who are currently using the LT1019 self-heater pin (Pin 7) must take into account the different load on the heater supply. R14 TEMP 3 R15 R4 8 O/P SELECT 2.5V – NC 3.0V – GND DNC = DO NOT CONNECT TO THIS PIN 00841-004 4 GND Figure 4. Schematic Diagram Rev. H | Page 5 of 12 AD780 Data Sheet APPLYING THE AD780 The AD780 can be used without any external components to achieve specified performance. If power is supplied to Pin 2 and Pin 4 is grounded, Pin 6 provides a 2.5 V or 3.0 V output depending on whether Pin 8 is left unconnected or grounded. A bypass capacitor of 1 µF (+VIN to GND) should be used if the load capacitance in the application is expected to be greater than 1 nF. The AD780 in 2.5 V mode typically draws 700 µA of Iq at 5 V. This increases by ~2 µA/V up to 36 V. 1 2 7 +VIN DNC VOUT 6 DNC RNULL TRIM 5 R POT 4 8 DNC = DO NOT CONNECT TO THIS PIN 100 C1 and C2 also improve the settling performance of the AD780 when subjected to load transients. The improvement in noise performance is shown in Figure 7, Figure 8, Figure 9, and Figure 10. 00841-005 GND 1 10 LOAD CAPACITOR, C1 (µF) Figure 6. Compensation and Load Capacitor Combinations TEMP O/P SELECT 2.5V – DNC 3.0V – GND 1 0.1 0.1 AD780 3 10 00841-006 COMPENSATION CAPACITOR, C2 (nF) 100 AMPLIFIER GAIN = 100 100µV Figure 5. Optional Fine-Trim Circuit 100 90 10 0% 00841-007 Initial error can be nulled using a single 25 kΩ potentiometer connected between VOUT, TRIM, and GND. This is a coarse trim with an adjustment range of 4%, and is only included here for compatibility purposes with other references. A fine trim can be implemented by inserting a large value resistor (e.g., 1 MΩ to 5 MΩ) in series with the wiper of the potentiometer (see Figure 5). The trim range, expressed as a fraction of the output, is simply greater than or equal to 2.1 kΩ/RNULL for either the 2.5 V or 3.0 V mode. The external null resistor affects the overall temperature coefficient by a factor equal to the percentage of VOUT nulled. For example, a 1 mV (0.03%) shift in the output caused by the trim circuit, with a 100 ppm/°C null resistor, adds less than 0.06 ppm/°C to the output drift (0.03% × 200 ppm/°C, since the resistors internal to the AD780 also have temperature coefficients of less than 100 ppm/°C). 1s 0.1 TO 10Hz Figure 7. Standalone Noise Performance NO AMPLIFIER 20µV 10ms 100 90 NOISE PERFORMANCE 10 0% 00841-008 The impressive noise performance of the AD780 can be further improved, if desired, by adding two capacitors: a load capacitor (C1) between the output and ground, and a compensation capacitor (C2) between the TEMP pin and ground. Suitable values are shown in Figure 6. 10Hz TO 10kHz Figure 8. Standalone Noise Performance Rev. H | Page 6 of 12 Data Sheet AD780 2.0 2 7 +VIN DNC 1.6 VOUT 6 1 DNC 1.2 ERROR (mV) AD780 TRIM 5 3 TEMP 4 8 0.8 0.4 0 DNC = DO NOT CONNECT TO THIS PIN –0.4 Figure 9. Noise Reduction Circuit –0.8 –60 00841-011 O/P SELECT 2.5V – DNC 3.0V – GND 00841-009 GND C2 C1 –40 –20 NOISE COMPARISON The wideband noise performance of the AD780 can also be expressed in ppm. The typical performance with C1 and C2 is 0.6 ppm; without external capacitors, typical performance is 1.2 ppm. This performance is, respectively, 7× and 3× lower than the specified performance of the LT1019. NO AMPLIFIER 20µV 0 20 40 60 80 TEMPERATURE (°C) 100 120 140 Figure 11. Typical AD780BN Temperature Drift TEMPERATURE OUTPUT PIN The AD780 provides a TEMP output (Pin 3) that varies linearly with temperature. This output can be used to monitor changes in system ambient temperature, and to initiate calibration of the system, if desired. The voltage VTEMP is 560 mV at 25°C, and the temperature coefficient is approximately 2 mV/°C. Figure 12 shows the typical VTEMP characteristic curve over temperature taken at the output of the op amp with a noninverting gain of 5. 10ms 100 90 4.25 4.00 CIRCUIT CALIBRATED AT 25°C REFER TO FIGURE 13 VOLTAGE (VOUT) 3.75 00841-010 10 0% 3.50 10mV PER °C 3.25 3.00 2.75 10Hz TO 10kHz 2.50 00841-012 Figure 10. Reduced Noise Performance with C1 = 100 µF, C2 = 100 nF 2.25 TEMPERATURE PERFORMANCE The AD780 provides superior performance over temperature by means of a combination of patented circuit design techniques, precision thin-film resistors, and drift trimming. Temperature performance is specified in terms of ppm/°C; because of nonlinearity in the temperature characteristic, the box test method is used to test and specify the part. The nonlinearity takes the form of the characteristic S-shaped curve shown in Figure 11. The box test method forms a rectangular box around this curve, enclosing the maximum and minimum output voltages over the specified temperature range. The specified drift is equal to the slope of the diagonal of this box. 2.00 –75 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 150 Figure 12. Temperature Pin Transfer Characteristic Since the TEMP voltage is acquired from the band gap core circuit, current pulled from this pin has a significant effect on VOUT. Care must be taken to buffer the TEMP output with a suitable op amp, for example, an OP07, AD820, or AD711 (all of which would result in less than a 100 µV change in VOUT). The relationship between ITEMP and VOUT is Rev. H | Page 7 of 12 ∆VOUT = 5.8 mV/µA ITEMP (2.5 V Range) or ∆VOUT = 6.9 mV/µA ITEMP (3.0 V Range) AD780 Data Sheet Notice how sensitive the current dependent factor on VOUT is. A large amount of current, even in tens of microamps, drawn from the TEMP pin can cause the VOUT and TEMP output to fail. 0.85 –55°C The choice of C1 and C2 was dictated primarily by the need for a relatively flat response that rolled off early in the high frequency noise at the output. However, there is considerable margin in the choice of these capacitors. For example, the user can actually put a huge C2 on the TEMP pin with none on the output pin. However, one must either put very little or a lot of capacitance at the TEMP pin. Intermediate values of capacitance can sometimes cause oscillation. In any case, the user should follow the recommendation in Figure 6. +25°C 0.75 +125°C 0.70 0.65 00841-014 QUIESCENT CURRENT (mA) 0.80 0.60 36 4 TEMPERATURE TRANSDUCER CIRCUIT INPUT VOLTAGE (V) The circuit shown in Figure 13 is a temperature transducer that amplifies the TEMP output voltage by a gain of a little over +5 to provide a wider full-scale output range. The digital potentiometer can be used to adjust the output so it varies by exactly 10 mV/°C. To minimize resistance changes with temperature, resistors with low temperature coefficients, such as metal film resistors, should be used. 5V Figure 14. Typical Supply Current over Temperature TURN-ON TIME 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. The two major factors that affect this are the active circuit settling time and the time for the thermal gradients on the chip to stabilize. Typical settling performance is shown in Figure 15. The AD780 settles to within 0.1% of its final value within 10 µs. 2 +VIN VIN 5V TEMP 3 10mV/°C AD820 GND 4 RB 1.27kΩ (1%) 0V VOUT RF 6.04kΩ (1%) RBP 200Ω 2.500V 2.499V 2.498V Figure 13. Differential Temperature Transducer 00841-015 AD780 00841-013 1µF 10µs/DIV SUPPLY CURRENT OVER TEMPERATURE Figure 15. Turn-On Settling Time Performance The quiescent current of the AD780 varies slightly over temperature and input supply range. The test limit is 1 mA over the industrial and 1.3 mA over the military temperature range. Typical performance with input voltage and temperature variation is shown in Figure 14. Rev. H | Page 8 of 12 Data Sheet AD780 DYNAMIC PERFORMANCE ILOAD The output stage of the AD780 has been designed to provide superior static and dynamic load regulation. Figure 16 and Figure 17 show the performance of the AD780 while driving a 0 mA to 10 mA load. +VIN AD780 10mA VOUT (CL = 1000pF) 00841-019 2 OUTPUT CHANGE (50mV/DIV) 0mA VOUT 6 10µs/DIV 1µF Figure 19. Settling under Dynamic Capacitive Load 249Ω LINE REGULATION VOUT 0V VL Line regulation is a measure of change in output voltage due to a specified change in input voltage. It is intended to simulate worst-case unregulated supply conditions and is measured in µV/V. Figure 20 shows typical performance with 4.0 V < VIN < 15.0 V. 00841-016 4 Figure 16. Transient Resistive Load Test Circuit ILOAD 200 10mA T = 25°C VOUT (CL = 0pF) OUTPUT CHANGE (µV) 100 00841-017 OUTPUT CHANGE (50mV/DIV) 0mA 0 –100 Figure 17. Settling Under Transient Resistive Load –200 4 The dynamic load may be resistive and capacitive. For example, the load may be connected via a long capacitive cable. Figure 18 and Figure 19 show the performance of the AD780 driving a 1000 pF, 0 mA to 10 mA load. +VIN 2 AD780 VOUT 6 CL 1000pF 1µF VL VOUT 0V 00841-018 249Ω 4 00841-020 10µs/DIV Figure 18. Capacitive Load Transient Response Test Circuit Rev. H | Page 9 of 12 10 INPUT VOLTAGE (V) Figure 20. Output Voltage Change vs. Input Voltage 15 AD780 Data Sheet PRECISION REFERENCE FOR HIGH RESOLUTION 5 V DATA CONVERTERS VSUPPLY 0.1µF The AD780 is ideally suited to be the reference for most 5 V high resolution ADCs. The AD780 is stable under any capacitive load, has superior dynamic load performance, and its 3.0 V output provides the converter with the maximum dynamic range without requiring an additional and expensive buffer amplifier. One of the many ADCs that the AD780 is suited for is the AD7884, a 16-bit, high speed sampling ADC (see Figure 21). This part previously needed a precision 5 V reference, resistor divider, and buffer amplifier to do this function. 1kΩ 2N2907 2 7 3 + 6 OP90 AD780 2 – 6 VOUT 2.5kΩ 4 10µF 0.1µF 4 0.1µF 3.9Ω 00841-023 4kΩ 0.01% 5kΩ 0.01% 5V Figure 23. 4.5 V Reference from a Single 5 V Supply AD7884 NEGATIVE (–2.5 V) REFERENCE 2 +VIN The AD780 can produce a negative output voltage in shunt mode by connecting the input and output to ground, and connecting the GND pin of the AD780 to a negative supply via a bias resistor, as shown in Figure 25. VREF + F 6 AD780 2.5V/3.0V SELECT 4 8 VREF + S 00841-021 GND 2 7 DNC +VIN Figure 21. Precision 3 V Reference for the AD7884 16-Bit, High Speed ADC VOUT 6 1 DNC The AD780 is also ideal for use with higher resolution converters, such as the AD7710/AD7711/AD7712 (see Figure 22. While these parts are specified with a 2.5 V internal reference, the AD780 in 3 V mode can be used to improve the absolute accuracy, temperature stability, and dynamic range. It is shown in Figure 22 with the two optional noise reduction capacitors. AD780 1µF TRIM 5 3 TEMP 5V R= GND O/P SELECT 2.5V – DNC 3.0V – GND 4 8 –2.5 VOUT NOTES 1. IL = LOAD CURRENT 2. IS MIN = MINIMUM SHUNT CURRENT 3. DNC = DO NOT CONNECT TO THIS PIN VOUT – (V–) IL + IS MIN AD7710 V– 2 +VIN Figure 24. Negative (−2.5 V Shunt Mode Reference) A precise –2.5 V reference capable of supplying up to 100 mA to a load can be implemented with the AD780 in series mode, using the bootstrap circuit shown in Figure 25. AD780 3 100µF GND 2.5V/3.0V O/P SELECT 4 8 +5V REF IN– +VIN 00841-022 100nF REF IN+ 6 2 1kΩ Figure 22. Precision 2.5 V or 3.0 V Reference for the AD7710 High Resolution, Σ-Δ ADC AD780 OUT 6 8 +5V 4.5 V REFERENCE FROM 5 V SUPPLY 4 Some 5 V high resolution ADCs can accommodate reference voltages up to 4.5 V. The AD780 can be used to provide a precision 4.5 V reference voltage from a 5 V supply using the circuit shown in Figure 23. This circuit provides a regulated 4.5 V output from a supply voltage as low as 4.7 V. The high quality tantalum 10 µF capacitor, in parallel with the ceramic AD780 0.1 µF capacitor and the 3.9 Ω resistor, ensures a low output impedance around 50 MHz. Rev. H | Page 10 of 12 CONNECT IF –3V OUTPUT DESIRED –2.5V (IL ≤ 100mA) – OP07 2N3906 + –5V –5V 1000pF Figure 25. −2.5 V High Load Current Reference 00841-025 VOUT 1µF 00841-024 VOUT 1µF Data Sheet AD780 OUTLINE DIMENSIONS 5.00 (0.1968) 4.80 (0.1890) 1 5 4 6.20 (0.2441) 5.80 (0.2284) 1.27 (0.0500) BSC 0.25 (0.0098) 0.10 (0.0040) 1.75 (0.0688) 1.35 (0.0532) 0.51 (0.0201) 0.31 (0.0122) COPLANARITY 0.10 SEATING PLANE 0.50 (0.0196) 0.25 (0.0099) 45° 8° 0° 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) COMPLIANT TO JEDEC STANDARDS MS-012-AA CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. 012407-A 8 4.00 (0.1574) 3.80 (0.1497) Figure 26. 8-Lead Standard Small Outline Package [SOIC_N] Narrow Body (R-8) Dimensions shown in millimeters and (inches) 0.400 (10.16) 0.365 (9.27) 0.355 (9.02) 8 5 1 4 0.280 (7.11) 0.250 (6.35) 0.240 (6.10) 0.100 (2.54) BSC 0.060 (1.52) MAX 0.210 (5.33) MAX 0.015 (0.38) MIN 0.150 (3.81) 0.130 (3.30) 0.115 (2.92) SEATING PLANE 0.022 (0.56) 0.018 (0.46) 0.014 (0.36) 0.325 (8.26) 0.310 (7.87) 0.300 (7.62) 0.195 (4.95) 0.130 (3.30) 0.115 (2.92) 0.015 (0.38) GAUGE PLANE 0.005 (0.13) MIN 0.014 (0.36) 0.010 (0.25) 0.008 (0.20) 0.430 (10.92) MAX COMPLIANT TO JEDEC STANDARDS MS-001 CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS (IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN. CORNER LEADS MAY BE CONFIGURED AS WHOLE OR HALF LEADS. Figure 27. 8-Lead Plastic Dual-In-Line Package [PDIP] Narrow Body (N-8) Dimensions shown in inches and (millimeters) Rev. H | Page 11 of 12 070606-A 0.070 (1.78) 0.060 (1.52) 0.045 (1.14) AD780 Data Sheet ORDERING GUIDE Model 1 AD780ANZ AD780AR AD780AR-REEL7 AD780ARZ AD780ARZ-REEL7 AD780BNZ AD780BR AD780BR-REEL7 AD780BRZ AD780BRZ-REEL AD780BRZ-REEL7 AD780CRZ AD780CRZ-REEL7 AD780-001C 1 Initial Error ±5.0 mV ±5.0 mV ±5.0 mV ±5.0 mV ±5.0 mV ±1.0 mV ±1.0 mV ±1.0 mV ±1.0 mV ±1.0 mV ±1.0 mV ±1.5 mV ±1.5 mV Temperature Range −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C −40°C to +85°C Temperature Coefficient 7 ppm/°C 7 ppm/°C 7 ppm/°C 7 ppm/°C 7 ppm/°C 3 ppm/°C 3 ppm/°C 3 ppm/°C 3 ppm/°C 3 ppm/°C 3 ppm/°C 7 ppm/°C 7 ppm/°C Z = RoHS Compliant Part. ©1993–2015 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D00841-0-10/15(H) Rev. H | Page 12 of 12 Package Description 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead PDIP 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N 8-Lead SOIC_N DIE Package Option N-8 R-8 R-8 R-8 R-8 N-8 R-8 R-8 R-8 R-8 R-8 R-8 R-8 Qty. per Tube/ Reel/Wafflepack 50 98 750 98 750 50 98 750 98 2,500 750 98 750 165