ADR421ARZ-REEL7 IC

Technical Specifications of ADR421ARZ-REEL7

Datasheet	ADR421ARZ-REEL7 datasheet
Category	Integrated Circuits (ICs)
Family	PMIC – Voltage Reference
Manufacturer	Analog Devices Inc.
Series	XFET?
Packaging	Tape & Reel (TR)
Part Status	Active
Reference Type	Series
Output Type	Fixed
Voltage – Output (Min/Fixed)	2.5V
Voltage – Output (Max)	–
Current – Output	10mA
Tolerance	±0.12%
Temperature Coefficient	10ppm/°C
Noise – 0.1Hz to 10Hz	1.75μVp-p
Noise – 10Hz to 10kHz	–
Voltage – Input	4.5 V ~ 18 V
Current – Supply	600μA
Current – Cathode	–
Operating Temperature	-40°C ~ 125°C (TA)
Mounting Type	Surface Mount
Package / Case	8-SOIC (0.154″, 3.90mm Width)
Supplier Device Package	8-SOIC

ADR421ARZ-REEL7 General Description

Featuring both a small outline integrated circuit (SOIC) and a Microsemi surface-mount package (MSOP), the ADR42x are a set of ultraprecise, second-generation eXtra implanted junction FET (XFET) voltage references. These standards have excellent noise immunity, pinpoint accuracy, and remarkable durability. XFET technology and a unique technique for adjusting temperature drift curvature have greatly minimized the nonlinearity of the voltage change induced by temperature. The XFET design offers superior thermal hysteresis and more precise outcomes than the band gap references. Additionally, compared to the hidden Zener references, it consumes less power and requires less space in the supply.

The ADR42x is highly suited for applications that demand precise conversion, such as optical networks and medical equipment, because of its low noise and reliable performance. The output voltage of the ADR42x can be adjusted within a 0.5% range using the trim connector without impacting the functionality of the amplifier. The ADR42x series of voltage references are defined throughout a wide temperature range (-40 to 125 degrees Celsius) with two different electrical classes. The 8-lead SOIC and 8-lead MSOP packages are 30% smaller to accommodate the devices.

Theory Of Operation

To create the ADR42x reference set, the XFET technique of reference generation is used (eXtra implanted junction FET). The resulting reference has low noise, excellent thermal hysteresis, and low supply current. The XFET reference device relies on two junction field-effect transistors (JFET) with a higher pinch-off voltage achieved by implanting an extra channel into one of the JFETs. Using the same drain current in both JFETs yields an extremely stable voltage reference. This makes it possible to amplify the pinch-off voltage differential and utilize it as the reference. The inherent reference voltage is about 0.5 V, and its temperature coefficient is about -120 ppm/°C.

This practically constant slope of silicon dielectric constant can be explained by including a correction term computed similarly to the proportional-to-temperature (PTAT) term used to adjust bandgap references. The primary benefit of this reference over a band gap reference is the approximately 30 times smaller inherent temperature coefficient (therefore requiring less correction). This dramatically reduces noise because much of the noise in a band gap reference comes from the circuitry that regulates the temperature. Figure 38 shows the core architecture of the ADR42x families. The temperature adjustment term is provided by a calibrated current source whose value is directly proportional to the absolute temperature.

Reference For Converters in Optical Network Control Circuits

Each tiny micromechanical mirror is positioned to reflect light at a particular wavelength, carrying specific data that may be routed to any combination of input and output fibres.

Controlled by high-precision ADCs and DACs, the system’s dual-axis actuators tilt the mirrors. Due to the mirrors’ microscopic motion, the precision of the converters is crucial. Still, the noise associated with these regulating converters is even more so, as the total noise inside the system can be increased by the number of converters. Since this application requires exceptionally stable control loops, the ADR42x’s low noise is necessary.

Kelvin Connections

Because of the high cost of PC boards and the limited space available, the circuit interconnects in portable instrumentation applications are often relatively small. There is a possibility of experiencing considerable voltage dips along these small lines if the voltage reference is being utilized to supply load currents to many functions. In practice, the line resistance of interconnects in a circuit is typically just 0.45 m/square. This is a relatively low value (1 oz. Cu, for example).

Kelvin connections, also known as force and sense connections, are a straightforward solution to the issues brought on by voltage drops along the wires of an electrical circuit. The presence of a current flow (IL) via the resistance of the wire results in the creation of a voltage drop at the load, denoted by the equation VERROR = R IL. The Kelvin connection seen in Figure 43 can solve this problem, as it incorporates the wiring resistance into the forcing loop of the operational amplifier (op-amp). The output is forced to adjust for the wiring problem and create the correct voltage at the load when using the op amp loop control.

Precision Voltage Reference for Data Converters

Because of its many valuable characteristics, the ADR42x family is ideally suited for integration with digital to analog converters (DACs and ADCs). The ADR42x is ideally suited for low-noise cellular base station applications due to its extraordinarily low noise, tight temperature coefficient, and excellent accuracy.

Precision Boosted Output Regulator

Using the circuit depicted in Figure 49, one can produce a precise voltage output that can boost current. U2 controls when N1 is turned on to keep the output voltage equal to VREF. Because of this, VIN is the one that supplies the load current. When set up in this manner, the load current that can be drawn at 5 VIN is 50 mA. The MOSFET generates heat, but not excessively, and exchanging the larger device for a smaller one makes it possible to increase the current. In addition, to improve the transient response, it is possible to include a buffer at the output in the case of a high capacitive load with a step input.

Precision Voltage Reference for Data Converters

The ADR42x family possesses various characteristics that make it an excellent choice for integration with ADCs and DACs. Because of its incredibly low noise, tight temperature coefficient, and high accuracy, the ADR42x is a superb choice for low-noise applications such as those used in cellular base station applications.

Conclusion

The Analog Devices ADR421ARZ-REEL7 voltage reference power management device can generate and maintain an exact DC voltage despite the power supply’s large fluctuations. Under 18 volts, this component is safe to use. This state-of-the-art power management outputs a regulated 2.5 V. Initially, and it is only 0.13 percent accurate. For your circuit to maintain a constant output current, load regulation of 70ppm/mA and line regulation of 35ppm/V are required. Using a series topology is possible with this voltage reference circuit. This item will be supplied on tape and reel for transport and assembly convenience.

This voltage reference circuit can operate at temperatures ranging from -40 degrees Celsius to 125 degrees Celsius. It can withstand a maximum temperature coefficient of 10ppm/°C.

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