NCP431AISNT1G

Overview

The NCP431AISNT1G is a three-terminal programmable shunt regulator diode from onsemi, housed in an SOT-23-3 package. It operates as a low temperature coefficient Zener reference, programmable from Vref to 36 V using two external resistors. Key electrical characteristics include a typical minimum operating current of 40 µA at 25°C, a voltage reference tolerance of ±1% (NCP431A), and a dynamic output impedance of 0.22 Ω typical. The device supports a sink current capability ranging from 40 µA to 100 mA with an equivalent full-range temperature coefficient of 50 ppm/°C typical. It functions over an ambient temperature range of -40°C to +85°C.

Feature Summary

• Programmable output voltage adjustable from the internal reference up to 36 V via external resistor dividers.
• Low minimum operating current enables extremely low no-load consumption in secondary regulators.
• Temperature compensated for stable operation across the full rated industrial temperature range.
• Low dynamic output impedance ensures high stability and precision in feedback control loops.

Applications

• Secondary side regulation in switching power supply adapters
• Precision voltage reference circuits
• Battery chargers
• Instrumentation systems

Procurement Notes

Verify the specific suffix 'AISNT1G' corresponds to the 1% tolerance and -40°C to +85°C temperature range. Confirm the SOT-23-3 package orientation matches the design footprint. Ensure the ordering code includes the 'G' designation for lead-free compliance. Cross-reference the manufacturer's latest datasheet revision to confirm pinout and marking details before finalizing procurement specifications.

Selection Notes

Select this component when a precise, adjustable shunt reference is required with minimal quiescent current draw. The NCP431A variant offers 1% initial accuracy suitable for general precision applications. Consider the NCP431B series if tighter 0.5% tolerance is necessary. Ensure the circuit design maintains cathode current within the 40 µA to 100 mA range for optimal regulation and stability performance.

Part Context

This device belongs to the NCP431/NCP432 series of programmable precision references. It serves as a monolithic integrated circuit replacement for traditional Zener diodes in digital voltmeters and op-amp circuitry. The family includes variants with different tolerances and temperature ranges, all sharing the same core functionality and pin configuration for flexible design integration.

Replacement Considerations

The TL431 is a widely recognized functional substitute within the programmable shunt regulator category. Verify that the alternative part meets the specific 1% tolerance requirement and the -40°C to +85°C operating temperature range. Check for compatibility in the SOT-23-3 package and ensure the replacement supports the required 36 V maximum cathode-to-anode voltage rating.

FAQ

How is the output voltage of the NCP431AISNT1G adjusted?

The output voltage is programmed from Vref to 36 V using two external resistors connected between the cathode, reference, and anode pins.

What is the minimum cathode current required for regulation?

The device requires a minimum cathode current of 40 µA typ at 25°C to maintain proper regulation and stability.

Does the NCP431AISNT1G support negative voltage referencing?

Yes, because it operates as a shunt regulator, it can be configured to serve as either a positive or negative voltage reference.