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2.5 V/3.0 V High Precision Reference Data Sheet AD780 Rev. F 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. Tel: 781.329.4700 ©2012 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com
FEATURES
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) FUNCTIONAL BLOCK DIAGRAM 00841-001 R16 R10 +VIN R11 R14 R13 R15 NC VOUT TRIM GND O/P SELECT 2.5V – NC 3.0V – GND TEMP NC NC = NO CONNECT AD780 4 8 Figure 1. PRODUCT 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 ADCs and 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 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. 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. 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. The AD780 provides a pin programmable 2.5 V or 3.0 V output from a 4 V to 36 V input. 2. 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. 3. For applications that require even higher accuracy, an optional fine-trim connection is provided. 4. 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. 5. The temperature output pin enables the AD780 to be configured as a temperature transducer while providing a stable output reference.
Rev. F | Page 2 of 12 TABLE OF CONTENTS Precision Reference for High Resolution 5 V Data Converters
REVISION HISTORY
12/12—Rev. E to Rev. F 5/04—Data Sheet Changed from Rev. D to Rev. E 1/04—Data Sheet Changed from Rev. C to Rev. D. 5/02—Data Sheet Changed from Rev. B to Rev. C.
Rev. F | Page 3 of 12 SPECIFICATIONS TA = 25°C, VIN = 5 V , unless otherwise noted. Table 1. AD780AN/AD780AR AD780CR AD780BN/AD780BR Parameter Min Typ Max Min Typ Max Min Typ Max Unit OUTPUT VOLTAGE OUTPUT VOLTAGE DRIFT1 −40°C to +85°C 7 7 3 ppm/°C −55°C to +125°C 20 20 ppm/°C LINE REGULATION
2.5 V Output, 4 V ≤+VIN ≤ 36 V, TMIN to TMAX 10 10 10 µV/V
3.0 V Output, 4.5 V ≤+VIN ≤ 36 V, TMIN to TMAX 10 10 10 µV/V LOAD REGULATION, SERIES MODE Sourcing 0 mA < IOUT< 10 mA 50 50 50 µV/mA TMIN to TMAX 75 75 75 µV/mA Sinking −10 mA < IOUT< 0 mA 75 75 75 µV/mA −40°C to +85°C 75 75 75 µV/mA −55°C to +125°C 150 150 150 µV/mA LOAD REGULATION, SHUNT MODE I < ISHUNT< 10 mA 75 75 75 µV/mA QUIESCENT CURRENT, 2.5 V SERIES MODE2 OUTPUT NOISE
0.1 Hz to 10 Hz 4 4 4 µV p-p
Spectral Density, 100 Hz 100 100 100 nV/√Hz LONG-TERM STABILITY3 20 20 20 ± ppm/1000 Hr TRIM RANGE 4.0 4.0 4.0 ± % TEMPERATURE PIN Voltage Output @ 25°C 500 560 620 500 560 620 500 560 620 mV Temperature Sensitivity 1.9 1.9 1.9 mV/°C Output Resistance 3 3 3 kΩ SHORT-CIRCUIT CURRENT TO GROUND 30 30 30 mA TEMPERATURE RANGE Specified Performance (A, B, C) –40 +85 –40 +85 –40 +85 °C Operating Performance (A, B, C)4 –55 +125 –55 +125 –55 +125 °C 1 Maximum output voltage drift is guaranteed for all packages. 23.0 V mode typically adds 100 µA to the quiescent current. Also, Iq increases by 2 µA/V above an input voltage of 5 V. 3The 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. 4The 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.
produce a constant band gap voltage. Figure 4. Schematic Diagram IN = VOUT when current is forced into the output terminal. the different load on the heater supply.
depending on whether Pin 8 is left unconnected or grounded. Iq at 5 V . This increases by ~2 µA/V up to 36 V . Figure 5. Optional Fine-Trim Circuit
5 MΩ) in series with the wiper of the potentiometer (see
coefficient by a factor equal to the percentage of VOUT nulled. coefficients of less than 100 ppm/°C). values are shown in Figure 6. Figure 6. Compensation and Load Capacitor Combinations
0.1 TO 10Hz
Figure 7. Standalone Noise Performance Figure 8. Standalone Noise Performance
Figure 16. Transient Resistive Load Test Circuit Figure 17. Settling under Transient Resistive Load Figure 18. Capacitive Load Transient Response Test Circuit Figure 19. Settling under Dynamic Capacitive Load Figure 20. Output Voltage Change vs. Input Voltage
5 V DATA CONVERTERS
3.0 V output provides the converter with the maximum
Figure 21. Precision 3 V Reference for the AD7884 16-Bit, High Speed ADC
- While these parts are specified with a 2.5 V internal
Figure 22. Precision 2.5 V or 3.0 V Reference for the
4.5 V REFERENCE FROM 5 V SUPPLY
output impedance around 50 MHz. Figure 23. 4.5 V Reference from a Single 5 V Supply resistor, as shown in Figure 25.
- IS MIN = MINIMUM SHUNT CURRENT
Figure 24. Negative (−2.5 V Shunt Mode Reference) using the bootstrap circuit shown in Figure 25. Figure 25. −2.5 V High Load Current Reference
Rev. F | Page 12 of 12 ORDERING GUIDE Model1 Initial Error Temperature Range Temperature Coefficient Package Description Package Option Qty. per Tube/Reel AD780ANZ ±5.0 mV −40°C to +85°C 7 ppm/°C 8-Lead PDIP N-8 50 AD780AR ±5.0 mV −40°C to +85°C 7 ppm/°C 8-Lead SOIC_N R-8 98 AD780AR-REEL7 ±5.0 mV −40°C to +85°C 7 ppm/°C 8-Lead SOIC_N R-8 750 AD780ARZ ±5.0 mV −40°C to +85°C 7 ppm/°C 8-Lead SOIC_N R-8 98 AD780ARZ-REEL7 ±5.0 mV −40°C to +85°C 7 ppm/°C 8-Lead SOIC_N R-8 1,000 AD780BNZ ±1.0 mV −40°C to +85°C 3 ppm/°C 8-Lead PDIP N-8 50 AD780BR ±1.0 mV −40°C to +85°C 3 ppm/°C 8-Lead SOIC_N R-8 98 AD780BR-REEL ±1.0 mV −40°C to +85°C 3 ppm/°C 8-Lead SOIC_N R-8 2,500 AD780BR-REEL7 ±1.0 mV −40°C to +85°C 3 ppm/°C 8-Lead SOIC_N R-8 750 AD780BRZ ±1.0 mV −40°C to +85°C 3 ppm/°C 8-Lead SOIC_N R-8 98 AD780BRZ-REEL ±1.0 mV −40°C to +85°C 3 ppm/°C 8-Lead SOIC_N R-8 2,500 AD780BRZ-REEL7 ±1.0 mV −40°C to +85°C 3 ppm/°C 8-Lead SOIC_N R-8 750 AD780CRZ ±1.5 mV −40°C to +85°C 7 ppm/°C 8-Lead SOIC_N R-8 98 AD780CRZ-REEL7 ±1.5 mV −40°C to +85°C 7 ppm/°C 8-Lead SOIC_N R-8 1,000 1 Z = RoHS Compliant Part. ©2012 Analog D evices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D00841-0-12/12(F)