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TL431-Q1: TL431 output sawtooth shape

Part Number: TL431-Q1

Hi team,

My customer is testing TL431-Q1 and captured below sawtooth shape Vka waveform, could you help suggest why it happens?

Customer is testing with below circuit, input resistor 2.15k, R1 10K R2 21.5K, input voltage 9V. They directly power up and test Vka

Thank you


  • Hi Scarlett,

    This is likely due to the stability region being violated for the TL431-Q1. As you can see in the figure below any capacitance on the load effects the stability of the output. I would recommend adding a 4.7 uF load capacitor and re-testing.