Shunt voltage reference

When designing a system for applications ranging from automobiles to simple temperature measurements, shunt voltage reference, interfacing with the analog world typically requ When designing a system for applications ranging from automobiles to simple temperature measurements, interfacing with the analog world typically requires data converters digital-to-analog and analog-to-digitalsensors, or other application-specific integrated circuits ICs.

There are two types of voltage references, shunt references and series references. Each type has its own usage conditions and the process of selecting between the two can be intimidating. Comparison tables do exist, but they typically provide little insight on how to choose one reference topology over the other for specific applications. This blog series will discuss the applications of both shunt and series references and when to use them, as well as highlight some lesser known use cases for each reference topology. Part 1 - Shunt versus series: Which topology is right for you? The real world is analog for now at least , and the most common way to interface with the real world is to use analog-to-digital converters ADCs , sensors or other application-specific integrated circuits ICs. A voltage-reference IC provides a stable output voltage that can be used as a constant value as system voltage and temperature change.

Shunt voltage reference

You can also set the cathode current using the various resistors in series with the supply. This external resistor quick-start calculator tool lets you easily calculate valid external resistor values relative to voltage reference, supply and load-current bounds. With these inputs, you can instantly view the resulting calculations and use the color-coded indications to understand Use our reference design selection tool to find designs that best match your application and parameters. Minimize idle power consumption with low-quiescent current I Q shunt voltage references. Low idle power consumption in the power supply can help you design Energy Star-rated appliances and small but reliable power adapters. Our low-I Q shunt voltage references can help your power-supply designs achieve low standby power and longer battery run times, while lowering system costs. Minimize power consumption and extend battery life with our high-accuracy shunt references. Some power supplies, such as those used in servers and industrial instruments, accuracy and stability requirements demand more precise voltage references that can keep the output accurate across changes in input voltage, output load and operating temperature. Our portfolio of high-accuracy, low-temperature coefficient shunt voltage references help enable a more efficient power supply. In hybrid, electric and powertrain systems, shunt voltage references ensure feedback loop control and accuracy in system diagnostics. Our shunt voltage references are available in a range of voltage options and package sizes to meet your system requirements without draining power. Available in multiple output and accuracy options to suit your design's needs, our shunt voltage references offer accurate and cost-effective power-management solutions.

Shunt reference use cases: Wide-input voltage range or high-input voltage transients. This power savings shunt voltage reference advantageous in applications such as a mobile device, where battery life is critical. In this example, R S can be any value between 3.

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In part two of our Understanding Voltage References series, my colleague Christopher Dean talked about ultra-low dropout and how it is not just for the series reference. It is similar in concept to a linear voltage regulator LDO but designed for a lower quiescent current and much higher accuracy. It regulates the output voltage by adjusting its internal resistance such that VIN minus the drop across the resistance, R, equals the reference voltage at VOUT; see the block diagram in Figure 1. The series references generally have much better initial accuracy and temperature drift coefficient than do shunt references. Thus, if you need better than 0. However, the shunt references offer more flexibility in terms of V IN range, as well as the option to stack multiple devices on top of one another to obtain higher reference voltages and the ability to create negative or floating references. How can you combine the shunt reference design flexibility with series reference precision? By doing so the series voltage references in this family are essentially converted into Zener diodes but with greatly diminished negative effects of shot noise and reverse-breakdown resistance.

Shunt voltage reference

In part three of our Understanding Voltage References series, my colleague Marek Lis talked about how to achieve shunt reference flexibility with series reference precision. Figure 1: TLV as a comparator. In a typical adjustable shunt reference application, the output is fed through a resistor divider to the feedback pin, such that the feedback pin is equal to the internal reference voltage during steady state. In the schematic shown in Figure 1 , the TLV adjustable shunt reference is configured for open-loop operation, which means that the output is not connected to the feedback pin. Instead, the signal V X drives the feedback pin through a resistor divider. The resistor divider is set such that the value at the feedback pin is equal to the internal reference voltage when V X is at the threshold voltage, V TH. This configuration is similar to running an op-amp in an open loop, and driving the positive terminal with V X. However, instead of having to create a reference with another supply or a resistor divider for the negative terminal, the comparator reference voltage is internal to the part.

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Comparison tables do exist, but they typically provide little insight on how to choose one reference topology over the other for specific applications. When selecting a voltage reference for your next application, be sure to keep the typical use cases below in mind. You can also use a shunt reference to create floating references and negative references, and the equations for calculating remain the same. Figure 6 shows an example using two shunt references in a bipolar reference configuration. Our low-power shunt VREFs and high-accuracy shunt VREFs enable systems such as battery-powered and loop-powered industrial applications to more demanding system requirments using high-resolution data converters. Dean, Christopher. Selecting a reference topology for a given application can feel overwhelming. A typical application for a negative voltage reference is a bipolar data converter, such as a digital-to-analog converter DAC , which requires positive and negative references to generate the full range of possible output voltages. The selection of external resistor is important, but does not have to be complicated. Power management. A series reference device does not require an external resistor, and only consumes as much current as required by the load plus a small quiescent current. In this example, R S can be any value between 3. Voltage references.

There are two types of voltage references, shunt references and series references.

Featured products for low quiescent current IQ. Power trends Low quiescent current IQ Minimize idle power consumption with low-quiescent current I Q shunt voltage references. Benefits: Fixed and adjustable shunt reference selection 1-mm-bymm package size Low quiescent current options for battery-operated applications. Shunt voltage references. The external resistor must be between and , as calculated by Equations 1 and 2: You can also use a shunt reference to create floating references and negative references, and the equations for calculating remain the same. A shunt voltage reference only requires two terminals and is functionally similar to a Zener diode where the voltage drop across the device is constant after reaching a minimum operating current through the device. The dropout voltage is the minimum voltage difference between V IN and V OUT for that device under a given load, and is stated in the device datasheet. The shunt reference regulates the load by acting as a constant voltage drop and shunting excess current not required by the load through the device to ground. Figure 8 is a schematic of such a series voltage reference. Available in multiple output and accuracy options to suit your design's needs, our shunt voltage references offer accurate and cost-effective power-management solutions. Figure 6 shows an example using two shunt references in a bipolar reference configuration. Technical articles More. Featured products for high precision. Endo, Mario.