Part Number: LMV431BIMFX/NOPBp

Manufacturer: Texas Instruments

Description: IC VREF SHUNT ADJ 0.5% SOT23-3

Shipped from: Shenzhen/HK Warehouse

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Description of the LMV431B

The LMV431, LMV431A, and LMV431B precise 1.24 V shunt regulators have a 30 V adjustment range. Similar to a non-inverting op-amp arrangement, the cathode voltage is controlled via negative feedback from the cathode to the adjust pin (Refer to Symbol and Functional Diagrams). A voltage divider with two resistors that terminates at the adjust pin controls the gain of a 1.24 V band-gap reference.  By connecting the cathode to the adjust pin, a 1.24 V cathode voltage is generated.

The initial tolerances of the LMV431, LMV431A, and LMV431B are 1.5%, 1%, and 0.5%, respectively, and they are functionally suited to several applications that call for low voltage Zener diode performance. Applications for this device range from a 3 V to 2.7 V low drop-out regulator to a voltage detector to an error amplifier in a 3 V offline switching regulator. Capacitive loads of more than ten nF and less than 50 pF usually cause these components to become unstable.

Features for the LMV431B

  • Low Operation Current (55 µA)
  • Low Output Impedance (0.25 Ω)
  • Fast Turn-On Response
  • Low Cost


EU RoHS Compliant
Part Status Active
HTS 8542.39.00.01
Automotive No
Reference Type Adjustable
Topology Shunt
Initial Accuracy 0.5%
Maximum Temperature Coefficient 138ppm/°C
Output Voltage (V) 1.24 to 30
Maximum Input Voltage (V) 35
Maximum Output Current (mA) 15
Minimum Operating Temperature (°C) -40
Maximum Operating Temperature (°C) 85
Supplier Temperature Grade Industrial
Packaging Tape and Reel
Mounting Surface Mount
Package Height 0.95
Package Width 1.4(Max)
Package Length 3.04(Max)
PCB changed 3
Standard Package Name SOT
Supplier Package SOT-23
Pin Count 3
Lead Shape Gull-wing

What Is Vref In Ic?

A voltage reference, often known as a VREF, is a high-precision gadget made to keep an output voltage that is accurate, low noise, and continuous. In a perfect world, the output would be unaffected by variations in the environment’s temperature, supply voltage, or load current. There are various typologies of VREFs available.

What Is The Purpose Of A 12v Shunt?

The shunt measures the current draw and the real-time voltage of your battery system. The battery monitor uses these readings to compute the charge level, power usage, predicted remaining runtime, and other useful data about your battery system.

Why Voltage References?

The world is analog. All electronic gadgets, whether they are found in a car, a microwave, or a cell phone, must somehow communicate with the “real” environment. Electronics must translate measurements made in the actual world (such as speed, pressure, length, and temperature) to equivalent measures in the electrical world (voltage). Of course, you need a standard to measure against to measure voltage. It is a voltage reference, that standard. Any system designer should consider which voltage reference, not whether he needs one.

Simply put, a voltage reference is a circuit or circuit part that offers a known potential for however long the circuit requires. It could be in seconds, minutes, or years. A standard must be compared to the signal if the product calls for information about the outside world, such as battery voltage or current, signal size or characteristics, power consumption, or problem diagnosis. A voltage reference is necessary for any comparator, DAC, ADC, or detecting circuit to function properly. Any signal can be precisely quantified by contrasting it with a known value.

Shunt Voltage Regulator Basics

Most motor controllers run into situations where energy from a motor is returned to the power source (usually when a motor is slowing down). In most cases, the power source is a battery that can withstand the current being fed into it; the reverse current can be a welcome “regenerative braking” feature that increases the battery’s overall lifespan.

However, when the power supply cannot handle the current efficiently, the reverse current might be difficult for applications that do not utilize batteries. The voltage can increase to a level the power supply can handle but could harm the motor controller or other electronics supplied by the power rail in some circumstances. Other times, power supplies have “over-voltage protection” features that detect an increase in the output voltage and turn the supply off.

Transient voltage suppressors, also known as TVSs, are large Zener diodes designed to handle large current spikes and are frequently the simplest solutions to problems. Sadly, TVS diodes frequently do not have a tight enough tolerance for use with power sources that feature overvoltage protection. A 12V power supply, for instance, might have a tolerance of 5%, which means the output voltage could go as high as 12.6V; hence, the protection device cannot activate below 12.6V. Any voltage spikes must stay below 13.8V if a 15% deviation activates the over-voltage protection. Most entry-level TVSes do not have precise tolerances to guarantee operation within that range.

Shunt regulators from Pololu are made to handle situations like these. Fixed values with 3% accuracy are available for various typical voltages, and adjustable versions are also available to handle any voltage between about 5V and 35V. Install the shunt regulator parallel (across) your power supply to use it. Under typical circumstances, the supply voltage should be lower than the shunt regulator’s set point, and the regulator should only draw its quiescent current of less than 0.5 mA. Any voltage spikes above the set point, on the other hand, will force the shunt regulator to draw significantly more current, wasting energy and reducing the magnitude of the voltage change.

Zener Diode Shunt Regulator

The simple Zener diode regulator circuit is one of the most prevalent and basic shunt regulators. It operates in a very simple manner. The Zener diode maintains a nearly constant voltage between its terminals once it has exceeded its modest minimum current.

The circuit’s series resistor reduces the voltage from the source to the Zener diode and load. Any fluctuations in load current have no impact on the voltage across the Zener diode since it maintains its voltage.

It absorbs the changes in current needed to guarantee the proper drop across the series resistor. It shunts enough current in this way to keep the load’s voltage across its terminals stable.


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