Shunt voltage reference

When designing a system for applications ranging from automobiles shunt voltage reference simple temperature measurements, 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, shunt voltage reference, or other application-specific integrated circuits ICs. Accurate measurements require a reference voltage that does not fluctuate with system conditions such as input voltage or ambient temperature. A voltage-reference IC provides the steady voltage other ICs use to make measurements with the required accuracy.

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.

Shunt voltage reference

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. There are two types of voltage references — shunt and series — and each has its own set of strengths and use cases, listed in Table 1. A shunt reference is functionally similar to a Zener diode, where the voltage drop across the device is constant after the device reaches a minimum operating current. 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. There is no maximum input voltage rating for a shunt reference, but an external resistor , is required. The input supply will always see the maximum load current as determined by the input voltage level and the external resistor. The shunt reference will sink more or less current as the current requirements of the load change.

When designing a system for applications ranging from automobiles to simple temperature measurements, interfacing with the analog world typically requ E-book E-book.

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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. Figure 2: Simplified schematic of the REF To assure V OUT initial accuracy and temperature drift, the class-AB output transistors must all operate in their linear region; thus, VDS must be greater than the transistor saturation voltage, Vsat.

Shunt voltage reference

When designing a system for applications ranging from automobiles to simple temperature measurements, 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-digital , sensors, or other application-specific integrated circuits ICs. Accurate measurements require a reference voltage that does not fluctuate with system conditions such as input voltage or ambient temperature. A voltage-reference IC provides the steady voltage other ICs use to make measurements with the required accuracy. There are two types of voltage references: shunt references and series references. Selecting a reference topology for a given application can feel overwhelming. Comparison tables Figure 1 are a good reference, but do not tell the whole story. In this paper, I describe the applications of both shunt and series references, and what makes each a strong candidate in a given application. 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. Figure 2 shows a typical current versus voltage curve for a Zener diode, where V Z is the Zener voltage when reverse-biased by a current of I Z.

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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. A shunt reference is a good choice when the load current is known to remain fairly stable and the system has a wide-input voltage range. The shunt reference in Figure 3 regulates the reference voltage by acting as a variable current sink, effectively creating a variable resistor divider with R S to provide a constant voltage at the output node. It only consumes as much current as required by the load, plus a small quiescent current. This external resistor quick-start calculator tool lets you easily calculate valid external resistor values relative to voltage reference, supply and load-current bounds. Reference with sleep or shutdown operations. Shunt reference use cases: Wide-input voltage range or high-input voltage transients. In this example, R S can be any value between 3. Shunt references are flexible because they can create a floating reference voltage not referenced to ground as well as negative references. The shunt references also meet the needs of other applications such as current sources, voltage monitors and LED drivers. Learn how to use a simple adjustable shunt voltage reference to power LEDs in automotive lighting applications. Discover featured applications Hybrid, electric and powertrain systems. The input supply will always see the maximum load current as determined by the input voltage level and the external resistor. Figure 6 shows an example using two shunt references in a bipolar reference configuration. Selection guide.

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.

If the load device does not always need to be enabled, the series voltage reference can be disabled by controlling the EN pin. In the meantime, visit www. This external resistor quick-start calculator tool lets you easily calculate valid external resistor values relative to voltage reference, supply and load-current bounds. A voltage-reference IC provides the steady voltage other ICs use to make measurements with the required accuracy. The total supply current is the sum of the load current and operating current of the shunt reference. Shunt reference family naming convention and side-by-side comparisons of the key diffeences amoingst the footprint compaitible devices. You can also set the cathode current using the various resistors in series with the supply. Power management. The series reference may include an enable pin to externally enable or disable the device to save power. The LM 2.