TPSI2140-Q1: How mcuh off-resistance for 400V, 800V, and 1200V between S1 and S2 pin is?

Hello Ochi-san,

Thank you for checking with our team. Off-resistance is typically calculated by taking the leakage current, I_OFF, of the device in question, and then using Ohm’s law, V = IR, to then calculate R_OFF.

With the TPSI2140-Q1, there are many I_OFF values to choose from, which are displayed below and in the datasheet:

Datasheet: https://www.ti.com/lit/ds/symlink/tpsi2140-q1.pdf?ts=1716907640152&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPSI2140-Q1

Typically, the I_OFF values are similar for voltages beneath the 1000V threshold, so it is viable to use the 1000V off-leakage current for both 400V and 800V.

For example, the minimum off-resistance at 150°C between the S1 and S2 pins (calculated by using the maximum off-leakage current) for the requested values goes as follows:

R_{OFF_400} = 400V/ 35uA ≈ 11.4 MΩ

R_{OFF_800} = 800V/ 35uA ≈ 22.9 MΩ

R_{OFF_1200} = 1200V/ 50uA ≈ 24 MΩ

Another example calculating minimum off-resistance at 25°C (room temperature) using the maximum off-leakage current:

R_{OFF_400} = 400V/ 0.1uA ≈ 4 GΩ

R_{OFF_800} = 800V/ 0.1uA ≈ 8 GΩ

R_{OFF_1200} = 1200V/ 0.1uA ≈ 12 GΩ

Typically, the off-resistance between the S1 and S2 pins tends to be high, but this can vary with the operating temperature of the device.

Best regards,

Jose Rojo