AD688BQ Voltage reference IC:Pinout, Specification, Datasheet

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Low tracking error, low initial error, and low-temperature drift give the AD688BQ reference absolute ±10 V accuracy performance previously unavailable in monolithic form. The AD688BQ uses a proprietary ion-implanted buried Zener diode, and laser wafer drift trimming of high stability thin-film resistors to provide outstanding performance.

The AD688BQ includes the basic reference cell and three additional amplifiers. The amplifiers are laser-trimmed for low offset and low drift and maintain the accuracy of the reference. The amplifiers are configured to allow Kelvin connections to the load and/or boosters for driving long lines or high current loads, delivering the full accuracy of the AD688BQ where it is required in the application circuit.

The low initial error allows the AD688BQ to be used as a system reference in precision measurement applications requiring 12-bit absolute accuracy. In such systems, the AD688BQ can provide a known voltage for system calibration; the cost of periodic recalibration can therefore be eliminated. Furthermore, the mechanical instability of a trimming potentiometer and the potential for improper calibration can be eliminated by using the AD688BQ and calibration software.

The AD688BQ is available in the commercial version. Specified over the −40℃ to +85℃ temperature range, the AD688BQ is offered in wide-body 16-lead SOIC and 16-lead CERDIP packages.

±10 V tracking outputs

Kelvin connections

Low tracking error: 1.5 mV

Low initial error: 2.0 mV

Low drift: 1.5 ppm/°C

Low noise: 6 μV p-p

Flexible output force and sense terminals

High impedance ground sense

Precision tracking. The AD688BQ offers precision tracking ±10 V Kelvin output connections with no external components. Tracking error is less than 1.5 mV and fine trim is available for applications requiring exact symmetry between the +10 V and −10 V outputs.

Accuracy. The AD688BQ offers 12-bit absolute accuracy without any user adjustments. Optional fine-trim connections are provided for applications requiring higher precision. The fine trimming does not alter the operating conditions of the Zener or the buffer amplifiers and thus does not increase the temperature drift.

Low output noise. Output noise of the AD688BQ is low— typically 6 μV p-p. A pin is provided for broadband noise filtering using an external capacitor.

The AD688 can be configured to provide e ±10 V reference outputs as shown in Figure. The architecture of the AD688 provides ground sense and uncommitted output buffer amplifiers which offer the user a great deal of functional flexibility.

The AD688 consists of a buried Zener diode reference, amplifiers, and associated thin-film resistors as shown in Figure. The temperature compensation circuitry provides the device with a temperature coefficient of 1.5 ppm/°C or less.

Amplifier A1 performs several functions. A1 primarily acts to amplify the Zener voltage to the required 20 V. In addition, A1 also provides for external adjustment of the 20 V output through Pin 5 (GAIN ADJ). Using the bias compensation resistor between the Zener output and the noninverting input to A1, a capacitor can be added at the noise reduction pin (Pin 7) to form a low-pass filter and reduce the noise contribution of the Zener to the circuit. Two matched 12 kΩ nominal thin-film resistors (R4 and R5) divide the 20 V output in half.

Ground sensing for the circuit is provided by amplifier A2. The noninverting input (Pin 9) senses the system ground and forces the midpoint of resistors R4 and R5 to be a virtual ground. Pin 12 (BAL ADJ) can be used for fine adjustment of this midpoint transfer.

Amplifiers A3 and A4 are internally compensated and are used to buffer the voltages at Pin 6 and Pin 8 as well as to provide a full Kelvin output. Thus, the AD688 has a full Kelvin capability by providing the means to sense a system ground, and forced and sensed outputs referenced to that ground.

Analog Devices Inc. AD688BQ technical specifications, attributes, parameters and parts with similar specifications to Analog Devices Inc. AD688BQ.

Analog Devices (NASDAQ: ADI) is a world leader in the design, manufacture, and marketing of a broad portfolio of high-performance analog, mixed-signal, and digital signal processing (DSP) integrated circuits (ICs) used in virtually all types of electronic equipment. Since our inception in 1965, we have focused on solving the engineering challenges associated with signal processing in electronic equipment. Used by over 100,000 customers worldwide, our signal processing products play a fundamental role in converting, conditioning, and processing real-world phenomena such as temperature, pressure, sound, light, speed, and motion into electrical signals to be used in a wide array of electronic devices.