a 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)
2.5 V/3.0 V High Precision Reference AD780 FUNCTIONAL BLOCK DIAGRAM +VIN
The AD780 is an ultrahigh precision bandgap reference voltage which 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 is provided on the AD780. This provides an output voltage that varies linearly with temperature, allowing the AD780 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.
4 GND NC = NO CONNECT
8 O/P SELECT 2.5V NC 3.0V GND
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 0.8 mV from –40°C to +85°C. 3. For applications requiring even higher accuracy, an optional fine-trim connection is provided. 4. The AD780 noise is extremely low, typically 4 µV 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 simply 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 voltage.
The AD780 is available in two grades in plastic DIP, SOIC and cerdip packages. The AD780AN, AD780AR, AD780BN and AD780BR are specified for operation from –40°C to +85°C. The AD780SQ and AD780SQ/883B are specified for –55°C to +125°C operation.
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