TL1431CLPRE3 Replacement: LM431BCZXA, AS431IAZTR-G1

Original Part

TL1431CLPRE3

Texas Instruments

Shunt Voltage Reference IC Adjustable 2.5V 36 VV ±0.4% 100 mA TO-92-3

Alternative Part

LM431BCZXA

onsemi

Shunt Voltage Reference IC Adjustable 2.495V 36 VV ±1% 100 mA TO-92-3

AS431IAZTR-G1

Diodes Incorporated

Shunt Voltage Reference IC Adjustable 2.5V 36 VV ±0.5% 100 mA TO-92

1. LM431BCZXA Substitution Conclusion The LM431BCZXA is compatible with the original part TL1431CLPRE3 in fundamental electrical parameters, including output voltage range (2.495V minimum vs. the original 2.5V, a negligible difference), maximum voltage rating of 36V, output current of 100mA, and TO-92-3 package. However, differences exist in the relaxed tolerance of ±1% (compared to the original ±0.4%) and the specified typical temperature coefficient of 50 ppm/°C (which was unspecified in the original part). In applications requiring high reference voltage accuracy, such as precision measurement or calibration circuits, substitution may introduce greater initial error and affect system performance. While the defined temperature coefficient benefits thermal stability design, verification is needed to determine whether the original circuit relies on tighter tolerance. Cathode current remains 1mA, ensuring consistent biasing conditions. Therefore, substitution is acceptable in non‑precision applications (e.g., general power supply feedback or error amplification), but the impact of reduced accuracy must be evaluated.

2. AS431IAZTR‑G1 Substitution Conclusion The AS431IAZTR‑G1 matches the original part TL1431CLPRE3 in output voltage (2.5V), maximum voltage rating of 36V, output current of 100mA, and TO-92-3 package. Key differences include a tolerance of ±0.5% (slightly wider than the original ±0.4%) and a significantly lower cathode current of 50 µA (compared to 1mA in the original). If the original circuit is designed to operate with 1mA cathode current, direct substitution may prevent proper startup or stable operation of the reference device. Adjustment of external bias resistors would be required to ensure the minimum operating current is met. The slightly wider tolerance may have a minor impact on precision‑sensitive applications but is generally acceptable. Substitution feasibility depends on whether the circuit can supply sufficient cathode current. This may be advantageous in low‑power designs, but bias conditions must be re‑verified.

Analysis ID: 0444-7CD0000

Based on part parameters and for reference only. Not to be used for procurement or production.